The subjectivity of self and its ontology: From the world–brain relation to the point of view in the world

The search for the subjective nature of our self is intensely debated in philosophy and neuroscience. However, despite all progress, the subjectivity of self and how it fits into the seemingly objective world remains elusive. Drawing on recent empirical data, we show how the self is shaped by the brain’s scale-free activity, that is, long-range temporal correlation (LRTC) and the world’s ecological context. We assume that the scale-free LRTC of the world–brain relation provides the ontological basis for the point of view as the foundation of subjectivity within the world. We conclude that the temporal, that is, scale-free based point of view through the world–brain relation provides the ontologically necessary a posteriori condition for the subjectivity of self on a deeper neuro-ecological level. This extends phenomenological concepts like subjectivity and world beyond both Heidegger’s fundamental ontology and Sartre’s phenomenological ontology: it complements their subjectivity-based ontologies with a truly world-based ontology.

What is the self? The concept of self has long been discussed in philosophy and psycho analysis, and, more recently, in neuroscience. Since at least the beginning of modernity in the Western world, the concept of self has been conceived as the placeholder of basic human subjectivity including the mind, consciousness, and selfconsciousness in partic ular. This basic subjectivity was targeted in philosophy by, among others, Kant and his German idealistic successors (Fichte, Schelling, Hegel). More recently, subjectivity has surfaced extensively in philosophy in both phenomenology and philosophy of mind.
Briefly, phenomenology associates basic subjectivity with what is described as prere flective selfconsciousness (Gallagher & Zahavi, 2019;Zahavi, 2005). In contrast, phi losophy of mind often characterizes subjectivity by "what is it like," which Thomas Nagel attributes to a particular point of view (see below for details) in his famous article, "What is it Like to be a Bat?" (1974).
Parallel to philosophy, there has been abundant empirical research on the self in both contemporary psychology and neuroscience. For instance, the underlying neural corre lates of various cognitive processes associated with the self, like selfesteem, selfrecog nition, selfmonitoring, and selfreferential processing are investigated and debated (Gallagher & Daly, 2018;Northoff, 2016;Sui & Humphreys, 2015). The present article aims to reconcile and connect the subjectivity and objectivity of self-we are therefore operating right at the crossroads between philosophy and neuroscience.

Subjectivity of the self: From world and brain to point of view
There is a gap between philosophy and neuroscience, though. Both disciplines are not talking about exactly the same kind of self. Philosophy focuses predominantly on the self as a placeholder of subjectivity: Why and how is it possible for something as subjective as the self to exist in an otherwise purely objective world? In contrast, neuroscience, fol lowing the conceptual split between subjective self ("I") and objective self ("me"; James, 1890;Northoff, 2016), focuses more on the objective psychological and neuronal aspects of the self while leaving out its most basic subjectivity (as that is supposedly not amena ble to scientific thirdperson investigation; Klein, 2014;Sui & Humphreys, 2015). That leaves us with a dichotomy between the subjectivity of self in philosophy and the objec tivity of self in neuroscience.
How can we bridge the gap between subjective and objective features of self? The aim of our article is to make a first proposal for bridging this gap by introducing three key concepts: (a) the world-brain relation, (b) the neuro-ecological self, and (c) the point of view. Converging these three key concepts reveals the source of the basic subjectivity of self: the self is ontologically situated and embedded within the world (i.e., "being in the world"; Gallagher & Daly, 2018, p. 3, footnote 3;Heidegger, 1927Heidegger, /2008 through what is often described as a "point of view" (Nagel, 1974). At the same time, the point of view can be well connected with the more objective psychological and neuronal characteriza tion of self as related to the brain and how it relates to the world in a scalefree way (i.e., world-brain relation).
Our main argument is that the concept of world-brain relation (see below and Northoff, 2016and Northoff, , 2018 can well account for the subjectivity of self in an ontological way, namely through the point of view that situates the self within the world. This ontological situatedness of the self within the world is, empirically, mediated by the brain's temporal features (i.e., scalefree activity) which connect it to the world. Accordingly, the first part of our paper provides empirical support for a neuroecological concept of self. That, in the second part, is extended to the ontological domain where the subjectivity of the neuroecological concept of self is traced to its point of view which, in turn, is supposed to be based on the temporal scalefree nestedness of the brain within the world.
Nonreductive neuro-philosophical approach: Point of view as an ontological bridge between world, brain, and subjectivity Phenomenology introduced the notion of prereflective selfconsciousness as the most basic feature of subjectivity as manifest in consciousness (Zahavi, 2005). This was further extended to the world by subsequent phenomenologists like Heidegger and Sartre who assumed an existential foundation of the self in the world as reflected in "being in the world" (Heidegger, 1927(Heidegger, /2008) and a phenomenological ontology (Sartre, 1948(Sartre, /1993. At the same time, neuroscience made considerable progress in recent years in showing that our sense of self is closely related to the brain (Northoff et al., 2006; see below for details). Moreover, there is not only one self but multiple concepts of self, which may be related to distinct neural features (Frewen et al., 2020;Gallagher & Daly, 2018;Qin et al., 2020).
Can we converge the phenomenological and neuroscientific perspectives? This would require a bridge between the worldbased subjectivity of self in the phenomenological context and the neuroscientific evidence of the brainbased self. More specifically, it would mean that we need to integrate the brain, as dealt with in neuroscience, with the concept of world in such way that their relationship (i.e., world-brain relation; Northoff, 2016Northoff, , 2018 permits a truly worldbased subjectivity of self that is aimed for in phenom enology. First and foremost, this raises the question of which methodological strategy allows us to link them. We currently pursue a nonreductive neurophilosophical approach (Northoff, 2014a(Northoff, , 2014b(Northoff, , 2016(Northoff, , 2018. Rather than reducing or simply identifying empirical and phenom enological concepts, we search for empirically plausible bridging concepts that provide necessary (a posteriori) connections between worldbased subjectivity and brainbased self. We postulate that one such concept is the point of view. As implied by Nagel's (1974) description of the bat, the point of view situates and locates us within the world which, as we see it, engenders (but cannot be equated with) the firstperson perspective as a key feature of consciousness. This makes the point of view a viable bridge between the world on the one hand and the firstperson perspective of consciousness on the other-it may thus provide the source of worldbased subjectivity, that is, the link between world and consciousness.
How is the point of view related to the brain? To address this question, we first need to go back to the brain and how it is related to the world. Ontologically speaking, the brain is part of the world as a whole with both standing in a mereological relationship. Given that the brain is part of the world, both the brain and world must share certain features while, at the same time, remaining distinct. Drawing on the recent development of temporospatial ontology (Northoff, 2018), we assume that the world and brain share their temporospatial features, that is, they stand in a temporospatial relationship to each other with the latter being nested within the former (just like the smaller Russian doll nests within the next larger one). Without being able to elaborate the details, this marks temporospatial ontology as a form of relational ontology (as distinct from property based ontology; Northoff, 2018). World and brain are thus ontologically linked by a temporospatial relation. Ontologically conceived, the brain is therefore viewed in an intrinsically relational and henceforth neuroecological way, rather than purely neu ronally. We employ the term "ecological" in a double sense. Taken in the context of the subjectivity of self, the term ecological refers to the environment as we perceive it; the environment in a subjective sense-this is in line with the concepts of environment introduced by Gibson (1967Gibson ( , 1979 and Lewin (1936). Here, the environment is intrinsi cally subjective as it is related to, and perceived by, the subject itself. However, we aim to extend beyond that. Specifically, we raise the question of how such an environment, taken in a subjective sense, is constituted. This leads us to the world understood in an ontological sense, independent of any subject. Hence, the term "world" refers to the world as it is prior to the subject (i.e., mindindependent) as distinguished from the sub jective or minddependent environment.
At the same time, the world in this mindindependent sense provides the necessary conditions for the possible constitution of the subject (i.e., the predisposition of its pos sible existence and reality in the world as featured by its subjective environment within the objective world). We consider the brain, understood ontologically, to be key in medi ating that predisposition of the world (in an objective sense) to constitute the subjective nature of self including its subjective environment. This amounts to what we describe ontologically as world-based subjectivity for which we consider the world-brain relation a key feature. Our paper can be understood as an ontological investigation into these relationships as distinguished from a more psychological approach as in ecological psy chology, where the concept of world is understood in a more subjective sense, that is, as environment.
The goal of our article is now to connect both perspectives, that is, the determination of worldbased subjectivity with a point of view with the ontological view of the brain in terms of the world-brain relation characterized by temporospatial features. For that purpose, we characterize the point of view in temporospatial terms, which provides the ontological bridge between world, brain, and subjectivity (see Figure 1 for a general overview).

Overview of the article
We first focus on the empirical side by discussing neuroscientific data that characterize the brainbased nature of self in temporospatial (i.e., scalefree) terms, which is highly dependent upon the environmental context as revealed by traumatic life events and cul tural shaping. This points to the neuroecological (rather than purely neuronal) nature of the brain and the self, which carries important conceptual implications. These data illus trate the need to conceive of the brain in terms of a world-brain relation, which can serve as the ontological basis of the self.
Note that we currently only target a most fundamental layer of self: the neuroecolog ical self. In contrast, we leave out various other conceptualizations such as the minimal self or prereflective selfconsciousness (Gallagher & Daly, 2018) and other concepts of self like bodily and cognitive self (Frewen et al., 2020). Instead, our approach targets a deeper layer, that is, the neuroecological self featured by its point of view, that, as we assume, provides the most basic layer shared by these various concepts of self. Finally, it shall be noted that it is beyond the scope of this article to discuss all these different concepts of self and how they relate to the neuroecological self. Instead, our paper focuses on sketching the neuroecological self and how that, being based on the worldbrain relation, is related to the point of view.
The second more conceptual aim is to connect the neuroecological self and worldbrain relation with the point of view as the basis of worldbased subjectivity. The focus here is on elaborating the concept of point of view: it is situated within the world (i.e., neuroecological) while, at the same time, providing a necessary (a posteriori) connec tion to the brain (i.e., world-brain relation) as the basis or source of worldbased subjectivity.
Next, we will distinguish different notions of the point of view (and, importantly, will characterize it in ecological and temporospatial terms) which permits a connection to the temporospatially determined world-brain relation. That, in turn, makes it possible to hypothesize that the temporospatial features of the point of view provide the necessary a posteriori connection between the world-brain relation and worldbased subjectivity. We therefore conclude that an ontological and temporospatial concept, the point of view, is a viable candidate to bridge the gap between phenomenological conceptualiza tions of worldbased subjectivity of self on the one hand, and neuroscientific views of the brainbased nature of self on the other.

World, brain, and self: Empirical evidence of a scale-free neuro-ecological self
How is our self shaped by its environment? We will present two lines of empirical evi dence linking psychology and neuroscience that demonstrate how the environment and brain interact to shape the self. The first empirical line takes a more general view by showing how the brain's spontaneous activity is characterized by scalefree (see below for explanation) temporal features and how those are related to the self. The second line of empirical evidence concerns the impact of early childhood traumatic experience on the self through the brain's resting state (i.e., its spontaneous activity). Note that we focus primarily on the link between self and world (i.e., neuroecological self) while neglecting other concepts such as minimal and bodily self (Frewen et al., 2020;Gallagher & Daly, 2018). Furthermore, we will omit details regarding the generative mechanisms underpin ning scalefree activity as this currently remains an open issue (He, 2014).
The scale-free brain: Scale-Free temporal structure of the brain's spontaneous activity The brain's spontaneous neural activity can be characterized by different frequencies ranging from infraslow (0.01-0.1 Hz), over slow (0.1-1 Hz), fast (1-40 Hz), to ultrafast (40-180 Hz); Buzsaki, 2006). Power is strongest in the infraslow range and decreases across the slow, fast, and ultrafast ranges following a power law distribution (He, 2014;He et al., 2010;Huang et al., 2016). Together, the different frequencies and their distinct degrees of power constitute a complex temporal structure in the brain's spontaneous activity which, in large parts, can be featured by the balance between infraslow, slow, and faster frequencies.
The relationship between these frequencies is maintained across different temporal scales and can therefore be characterized by what is described as "scalefree dynamics" (He, 2014;He et al., 2010;LinkenkaerHansen et al., 2001). Roughly, scalefree activity describes the fractal (i.e., selfsimilar) organization and thus temporal nestedness in the relationship between power and the different frequency ranges: the longer and more powerful slower frequencies nest and contain the shorter and less powerful faster frequencies-this amounts to longrange temporal correlation (LRTC), which operates across different time scales or frequencies (He, 2014;He et al., 2010;Linkenkaer Hansen et al., 2001;see Figures 2a and 2b). This makes it clear that we here understand scale-freeness in explicitly temporal terms, that is, in terms of frequencies and their power spectrum; in contrast, we refrain from any spatial exploitation of scalefree activity as it has recently been criticized on methodological grounds (Barabasi, 2009;Broido & Clauset, 2019).
The LRTC can be described as scalefree or scaleinvariant that can be expressed by, P ∝ 1/f β , where P is power, f is frequency, and β is called the powerlaw exponent (PLE; He, 2014). A high PLE value indicates relatively stronger power in slow frequencies and relatively less power in the faster ones, whereas the opposite is the case in a low PLE value. As an alternative to the PLE that accounts for the power relationship across differ ent frequencies, one can also probe the LRTC in the temporal domain by measuring oscillatory amplitude fluctuations using detrended fluctuation analysis (DFA; He et al., 2010;LinkenkaerHansen et al., 2001;Palva et al., 2013;however, see Bryce & Sprague, 2012, for criticism of scalefree activity).
Independent of their differences, both PLE and DFA measure neural activity across multiple time scales and are therefore indices of scalefree or scaleinvariant activity. That makes it possible to assess the degree to which past neuronal patterns exert their influence on future dynamics, thus accounting for LRTC (LinkenkaerHansen et al., 2001;. High values in PLE/DFA indicate high degrees of LRTC, with long stretches of neural activity exhibiting temporal correlations between  past, present, and future states-this reflects the relatively stronger impact of slower frequencies with their longer cycles. The opposite is the case in low PLE/DFA values, where only the most recent time intervals exert any impact on present and future onesthis is manifested in the relatively stronger impact of faster frequencies with their shorter cycles. The scale-free self: Temporal nestedness and long-range temporal correlation (LRTC) on neuronal and mental levels Recent studies have shown that the brain's scalefree activity, as measured with either PLE or DFA, is related to mental phenomena such as the self (Huang et al., 2016;Scalabrini et al., 2019;Scalabrini et al., 2017;Wolff et al., 2019; see Figure 2c). These studies show that the degree of resting state PLE directly predicts: (a) the degree of self consciousness (as operationalized by the selfconsciousness scale; Huang et al., 2016;Wolff et al., 2019), (b) taskrelated activity during selfspecific stimuli (like animate versus inanimate touch; Scalabrini et al., 2019), and (c) the degree of temporal integra tion on a psychological level of selfspecificity as measured by a matching task where participants have to associate the own self, nonself, or celebrity with a particular geometric shape (Kolvoort et al., 2020). Given that in all these studies it is the resting state's scalefree activity that correlates with different psychological tasks all probing for selfspecificity, we assume that the resting state scalefreeness seems to be central in mediating distinct components of self specificity like selfconsciousness, taskrelated activity, and temporal integration. Moreover, additional studies have demonstrated that scalefree activity is central in mediating other mental features such as consciousness Zhang et al., 2018) and mental abnormalities in psychiatric disorders like autism (Damiani et al., 2019) and schizophrenia .
Taken together, these findings suggest that the brain's scalefree properties are central for mental features and thus, more generally, the mind including self and consciousness. Mental features such as self and consciousness seem to operate across different time scales by integrating and nesting them within each other. Applying this terminology to the self in a novel way, the self can be considered scalefree and can therefore be charac terized by temporal nestedness and longrange temporal correlations (LRTC) on a mental level, which seem to find their analogues on the neuronal level in the brain's spontaneous activity.

The neuro-ecological self: Traumatic life experience shapes the brain's spontaneous activity
We all experience adverse life events in both childhood and adulthood which shape our self. How can traumatic experiences, especially those in early childhood, shape our self in adulthood? Various brain imaging studies have shown that early traumatic childhood experiences impact the spontaneous activity's temporospatial dynamics later in life. For instance, one fMRI study by Lu et al. (2017) compared participants with and without a history of childhood trauma. They demonstrated changes in both intra and interregional synchronization (e.g., regional homogeneity and functional connectivity) in regions of the defaultmode network (DMN) and salience network (SN) such as the insula in participants reporting early traumatic experiences. Somewhat analogous resting state functional connectivity in the insula and related regions of the SN was also observed in a study by Gupta et al. (2017). The impact of traumatic life experiences on the brain's spontaneous activity is further corroborated by results in studies examining posttraumatic stress disorder (PTSD; Disner et al., 2018;Koch et al., 2016). One recent largescale metaanalysis showed that here too, regions of the DMN (e.g., the inferior parietal lobule [IPL]) and the SN (e.g., the amygdala and caudate) exhibit decreased resting state activity (i.e., intraregional syn chronization and neural variability) in subjects suffering from PTSD (Disner et al., 2018). Focusing more on interregional changes (i.e., functional connectivity), a meta analysis by Koch et al. (2016) observed disbalance between decreased resting state functional connectivity (rsFC) in the DMN and increased rsFC in the SN.
Additional studies demonstrate how early traumatic experience does not only impact the resting state but that the latter, in turn, shapes the adult subject's taskrelated activity. For instance, one fMRI study by Duncan et al. (2015) first measured entropy (i.e., the degree of disorder) in the resting state in adult participants reporting early traumatic childhood experiences. They observed that the degree of resting state entropy in a region of the DMN (anterior cingulate cortex) directly correlated with the degree of early life traumatic experience: the more participants experienced early trauma, the higher their entropy in resting state activity during adulthood (Duncan et al., 2015).
In a second step, the same study investigated taskrelated activity by applying an aversive stimulus (i.e., an electric shock). They observed that participants reporting a high degree of early traumatic experience exhibited reduced somatomotor cortex and insula activity in anticipation of the shock. Critically, this was directly modulated by increased entropy in the DMN (i.e., anterior cingulate cortex; see Figure 3). Accordingly, as anticipation implicates spontaneous or resting state activity during the prestimulus period, these data show how abnormal imprinting of the spontaneous activity by traumatic life events affects how participants respond to aversive stimuli in their environment.
Another study by Nakao et al. (2013), using nearinfrared spectroscopy (f NIRS), demonstrated that power in the very low infraslow frequency ranges (< 0.04 Hz) was negatively related to early traumatic life experience in the anterior DMN (i.e., medial prefrontal cortex): the higher the degree of early traumatic experiences, the less power in infraslow frequency ranges in the resting state of the medial prefrontal cortex during adulthood. Nakao et al. (2013) also included two tasks: one task involving the self (i.e., color preference judgment), and one task not involving the self (i.e., color similarity judg ment). Interestingly, the degree of early traumatic life experience only correlated with infraslow frequency power in the medial prefrontal cortex during the selfrelated task: lower infraslow frequency power and fewer selfrelated judgments correlated with a higher degree of early traumatic experience.
Together, these studies clearly demonstrate that early traumatic experience strongly shapes both resting state and taskrelated activity in adulthood. In particular, this con cerns brain regions such as the DMN (i.e., medial prefrontal cortex, anterior cingulate, posterior cingulate) and SN (i.e., insula, amygdala) that have been implicated in process ing selfspecificity (Qin & Northoff, 2011;Qin et al., 2020). Selfspecific, selfrelated, or selfreferential processing means that a stimulus is processed relative to and in its meaning for the self, that is, its relative proximity or distance to the own self-the degree of neural activity may then be dependent upon the degree or strength of the relation between self and stimulus (Northoff, 2011(Northoff, , 2016. The own face, for instance, is usually processed in closer relation to the own self than to another person's face. We can consequently assume on empirical grounds that the self in adolescence and adulthood is strongly shaped by its subjectively perceived environmental context (see above for the conceptual distinction between environment and world) through the brain's spontaneous activity and its temporospatial dynamics in a scalefree way (i.e., spanning both short and long timescales). In more conceptual terms, there is empirical support for: (a) the world-brain relation, with significant life events shaping the brain's spontaneous activity; (b) the brain's spontaneous activity, in turn, shaping the self in a neuroecolog ical way through its own modulation by significant life events; and (c) such neuroeco logical shaping operating in a scalefree way, that is, across different time scales.
We should mention, however, that these findings concern the impact of the childhood environmental context on the adult self. There is a long timespan between childhood and adulthood. What we want to illustrate is that, despite this interval and the numerous changes in the self from childhood to adolescence, the effects of the former can still be seen in the latter and its brain's spontaneous activity. Albeit tentatively and on conceptual . Early childhood trauma modulates the brain's ongoing and task-related activity (Duncan et al., 2015). grounds, we therefore assume some temporal continuity between the self in childhood and the self in adulthood that, on a deeper layer, connects them with each other even though they, on a more surface layer in terms of their mental contents, may markedly differ.
On the more empirical side, this raises the question of whether there are analogous contextual influences on the self during adulthood. This is indeed the case. For instance, cultural contexts are known to shape our self and its brain. Asian cultural contexts are signified by a more interdependent self that is defined through its relation to and similari ties with others (Han & Northoff, 2008;Markus & Kitayama, 1991). Western contexts show a more independent self characterized by its distinction to others (see also Scalabrini et al., 2021). Notably, these cultural differences in self go along with neural differences in the brain including in their scalefree activity (Han & Northoff, 2008). Together, these empirical findings strongly support our conceptual assumption of the intrinsic context dependence of brain and self and, more generally, the neuroecological nature of both. These conceptual implications shall be pointed out in the next section.

Shared features of brain, self, and world: Scale-Free temporal structure
What do the brain, weather, seismic waves, and stock markets have in common? Prima facie, you will insist that they are unrelated; the brain is a lump of grey matter consisting of neurons, which of course, cannot be observed in the others. Despite their differences on the surface, these seemingly disparate phenomena nevertheless show a degree of commonality on a deeper level. Namely, fluctuations in their activity exhibit the same scalefree structure characterized by temporal nestedness and LRTC.
One of the most interesting aspects of scalefree activity is its universality. Scalefree activity is not unique to the brain; rather, it is ubiquitous in nature, evident across systems as varied as climate, seismic activity, magnetic fields, and stock markets (Cocchi et al., 2017;He et al., 2010). Basically, wherever irregular fluctuations in activity are observed, LRTC and scalefree activity may provide structure to what initially appears to be ran dom noise. There is "structure to irregularity," and that seems to be a unifying principle and key feature of nature.
For instance, He et al. (2010) investigated the scalefree dynamics of the brain's neu ral activity and its nested frequencies using electrocorticography (ECoG). In addition, they investigated the time series of spontaneous seismic activity collected over 4 months and fluctuations in the Dow Jones index obtained over a period of 80 years. Time series from both seismic waves and stock market fluctuations followed a powerlaw distribu tion in their temporal power spectrum. Interestingly, their powerlaw exponents (1.99 for seismic waves and 1.95 for the stock market) resembled that of the brain's intrinsic activ ity measured in ECoG during wakefulness (mean of 2.2 for < 0.1 Hz). Of further signifi cance, like the brain's intrinsic activity, the time series of both seismic waves and stock market fluctuations contained nested frequencies (i.e., higher frequency fluctuations nesting in lower frequency fluctuations).

Neuro-Ecological self: Long-Range temporal correlations of the brain connect self and world
How are the world's scalefree features related to those of the brain? Given that the world can shape the brain through traumatic life events, one would expect a close relationship, if not an interaction, between their respective scalefree features. Specifically, one would predict that the LRTC of the environmental structures contain and nest those of the brain's spontaneous activity-both ecological and neuronal LRTC would be expected to match across (and despite) their different time scales. Such "complexity matching" has indeed been shown in recent studies on language and music. Borges et al. (2018), for instance, demonstrated how the degree of scalefreeness in the brain in different frequency bands follows variations in the scalefree envelope of speech, and how their degree of correspondence impacts speech comprehension. Analogously, Borges et al. (2019) show how the scalefree structures of the brain and music adapt to each other, with the brain's neural activity somewhat rescaling the musi cal structure. The timing of the neuronal fluctuations, as observed in the brain's scale free activity, followed the timing of the fluctuations in the music (i.e., its scalefree activity), although the latter operated on a wider range of temporal scales than did the brain. Moreover, the scalefree adaptation of participants' neural activity to the music predicted their degree of pleasure. Together, these findings show that the degree of matching or concordance of the scalefree properties in the environmental context (i.e., music in our case) and brain strongly shape one's mental features like the feeling of pleasure and the sense of self. This suggests a truly neuroecological basis of subjectivity within the world, mediated by what we describe as the world-brain relation.
Conceptual characterization of the neuro-ecological self: Self is nested within the world through the brain's long-range temporal correlations Taken together, scalefree activity is ubiquitous in nature rather than being a unique feature of the brain. This allows the brain to compare and match its own scalefree nest edness and LRTC with those of its respective environment, with the degree of their matching shaping mental features like perception. Unfortunately, no studies have been reported that investigate whether the degree of matching between world and brain LRTC is related to the self and how we perceive ourselves to be part of the world (i.e., the neuroecological self).
We nevertheless may want to make a more philosophical or theoretical claim: the fact that the brain's scalefreeness is directly related to the self implies that the self is con nected and integrated within the world's scalefree structure through temporal nested ness and LRTC. Analogous to how the smallest Russian doll is integrated within the next larger one and so forth, the self is integrated and nested within the brain which, in turn, is ontologically nested and integrated within the largest and most comprehensive tempo ral scale: the world. On conceptual grounds, we can thus say that what connects the self through the brain to the world is its scalefreeness featured by temporal nestedness and LRTC.
To summarize, we can say that: (a) the world-brain relation is scalefree and charac terized by temporal nestedness and LRTC, implying that the world's larger scale nests the brain's smaller scale; (b) the scalefree nature of the world-brain relation may be critical in shaping and constituting the self; (c) the self is intrinsically neuroecological and scalefree; and (d) the self is intrinsically integrated within the world through the temporal nestedness and LRTC of the world-brain relation.
These theoretical but empirically plausible considerations imply that we may also need to change our conceptual determination of the self. Instead of a purely neuronal concept of self, we may need to view the self through a neuroecological lens entailing a biological-ecological approach as described, for instance, by ecological psychology (Bruineberg et al., 2018;Heft, 2020aHeft, , 2020b; this, through the world-brain relation, can be extended to neuroscience (i.e., ecological or temporospatial neuroscience; Northoff et al., 2020). Admittedly, we omit the psychological and neuronal details related to the concept of the world itself-concepts like affordances, ecological niche, and others that describe different layers within the world (Heft, 2020a(Heft, , 2020b will need to be explored in their relevance for both the world-brain and world-self relations.

Point of view: Mental surface layer and ecological background layer
What is a point of view (POV)? The notion of POV is pervasive in literature and theatre, with different persons expressing different points of view on the same topic. Painting and photography rely on a slightly different notion of POV that involves providing access to events or objects in the world. Despite the extensive colloquial usage of POV in many disciplines, the concept is often neglected in philosophy, as there is no established theory (see Campos & Gutierrez, 2015, for a notable exception). Yet another noteworthy excep tion is the embodied approach where the lived (rather than objective) body is supposed to provide the point of view or anchor of the self in the world (Gallagher, 2005;Gallagher & Daly, 2018). Without being able to go into details (see Northoff, 2016Northoff, , 2018, we assume that the notion of the lived body presupposes the scalefree nature of the brain: the body's various temporal scales are connected with those of the brain's spontaneous activity as well as with those of the world that are processed through the brain. Hence, conceptually considered, the brain can be conceived as a multiscale integrator as it con nects the different timescales of the brain, body, and world in a scalefree way. If, for instance, the brain's capacity to integrate these timescales in a scalefree way is dimin ished (i.e., indexed with PLE or DFA), we lose consciousness as in that case, the neuro ecological connection of brain and self to body and world is severed and thus, conceptually speaking, the point of view is lost (Zilio et al., 2021).
We will introduce Campos and Gutierrez's (2015) account of POV and then provide our own ecological and ontological extension. Our main argument will be that the con cept of POV can provide the source of subjectivity by constituting an intrinsic, necessary connection between the world and the self-the necessary intrinsic connection of world and self as mediated by POV can ultimately be traced to the necessary connection of world and brain, the world-brain relation (Northoff, 2018). In a nutshell, we propose that the world-brain relation as the basis of the point of view provides the most fundamental ground of subjectivity within the world.
According to Campos and Gutierrez (2015), POV can be determined by two main features: reference to mental life (including subject), and access to the world beyond the self and its mental life. Following in their footsteps, we will reformulate and rename these two features as the surface and background layers of POV, respectively. The POV's reference to the subject and mental life is the surface layer of POV-we call this a mental surface layer. At the same time, the POV is situated within the world as its ultimate ontological background, which renders it ecological-we therefore additionally posit an ecological background layer. Let us detail these two concepts in the following.
The mental surface layer of POV refers to a subject with personal and mental features; importantly, this layer provides the source or basis for the mental features of self: In that variety of uses, the notion of point of view may have two distinct meanings. In one of them, points of view are part of a mental life. They are connected to the mental life of some subjects with a personal character. In that sense, the expression "point of view" is interchangeable with words like "view", "opinion", "belief", "attitude", "feeling", "sentiment", "thought", etc. Points of view in that sense could not exist without a subject with quite a rich mental life. (Campos & Gutierrez, 2015, p. 2) In contrast, the ecological background layer of POV is characterized by providing access to something that lies beyond the POV itself, namely the world with its ecological features. Rather than on mental states within the subject itself, the focus here is on how the subject connects and relates to the ecological features of the world. Intrasubjectivity is therefore replaced by intersubjectivity, and isolation is replaced by relation: There is another quite important meaning in the ordinary notion of point of view. In that second sense, points of view could exist without any actual subject exemplifying them. Here, points of view explicitly have a strong relational and modal, especially subjunctive, character. Points of view offer possibilities of having access to the world. They offer possibilities of seeing things (hearing them, touching them, etc.), possibilities of thinking about them (considering them, imagining them, etc.), and possibilities of valuing them (assessing them, pondering them, etc.). (Campos & Gutierrez, 2015, p. 3)

Ecological background layer of point of view I: Scale-Free relation of world and self
We argue that the ecological background layer of POV is key in providing the ontologi cal ground of subjectivity and ultimately of the self. This distinguishes our approach from both past and present philosophical and neuroscientific approaches that, usually, claim the phenomenal and mental features of self (and hence the mental surface layer of POV) to provide the source of subjectivity (see our conclusion where we situate our approach in a methodological-historical context).
The key feature of the ecological background layer of POV is its relational character, as it relates and connects the self to and within the world. Relation means that the POV is connected and related to something beyond itself. Put into the context of ecological psychology, that "something beyond itself" is the environment characterized by its eco logical features. This includes natural, social, and cultural kinds of information along with their descriptive and normative aspects-for the sake of simplicity, we will lump them all together under the notion of ecological information understood in a broad sense.
The ecological background layer of POV includes that ecological information that it shares with the world. The world itself contains at least two types of ecological informa tion: that which is shared with the organism and that which is not shared with the specific organism, thus extending beyond the latter. Importantly, this entails partial rather than total overlap since the sharing between world and brain, and ultimately of world and POV, is incomplete. Consider the timescales. An organism has a limited repertoire of timescales compared to the world. For instance, we as humans cannot directly perceive the ultraslow seismic waves preceding earthquakes, nor can we perceive the ultrasonic frequency ranges accessible to bats.
The overlap in the amount of ecological information between the world (as a whole) and the ecological background layer of POV (as part of the world) constitutes an ontologi cal relation between the world and POV as this relation (i.e., the overlap in ecological information) defines the existence and reality of POV and consecutively the subjectivity of self. What do we mean by ecological information shared between world and POV? We refer to biophysical features and their related spatial and temporal scales, which can be traced to the brain and how it stands relative to the world. For instance, the bat, based on its biophysical features, shows a POV that enables it to access ultrasonic information (Nagel, 1974). In contrast, the human POV does not allow us to access ultrasonic features, since our brain does not possess the proper biophysical characteristics, as it is ultimately based on different temporal and spatial scales (when compared to those of the bat).
This leads us back to scalefree activity and its contribution to constituting the eco logical background layer of POV: the broader the range of temporal and spatial scales encompassed by the ecological background layer of POV, the more extensively the self can relate to the world and its ecological information. We consequently assume that the ecological background layer of POV is nested and contained within the world and its ecological information in a scalefree way, analogous to how a smaller Russian doll is nested within a larger, selfsimilar version of itself. Scalefree nesting of the POV's eco logical background layer within the world implies that one would expect to find long range temporal correlations (LRTC) between the world and self: the world's much longer timescales are related to the self's shorter time scales in a selfaffine and crossscale way, as the former nests and contains the latter.
We propose that such scalefree LRTC between world and self constitutes the ecologi cal background layer of POV as the source of subjectivity for the self. The concept of "source" refers to a necessary nonsufficient condition, or a predisposition (Northoff, 2018). Moreover, this necessary condition is to be understood not in the traditional philo sophical terms as necessary a priori but, drawing on Kripke (1972) and Nagel (1998), as necessary a posteriori (see Northoff, 2018, Chapter 10, for a full development). Moreover, subjectivity is determined here in an ontological (rather than epistemological [Kant], phenomenological [Husserl], or existential [Heidegger, Sartre]) and temporospatial way: it reflects the existence and reality of the self in the world, that is, how its own range of temporospatial scales relates to the temporospatial scales of the world. Moreover, the ontology of subjectivity is scalefree as it operates across the different temporospa tial scales of world and self. The ecological background layer of POV is the relation between their different temporospatial scales as marked by their degree of crossscale LRTC between world and self based on the organism's biophysical features (like in humans or bats; Northoff, 2014aNorthoff, , 2014b.
This makes it clear that the ontological nature of self is determined by temporospatial relations. Namely, the scalefree relationship between world and brain provides the nec essary a posteriori condition for the possible constitution of the neuroecological back ground layer of POV as the basis of self. More generally, this presupposes the determination of existence and reality by relation, rather than by properties, which there fore entails a relational rather than propertybased ontology (Northoff, 2016(Northoff, , 2018. This relationbased ontology is now specified in temporospatial terms (i.e., Spatiotemporal Ontology; Northoff, 2016Northoff, , 2018. Applied to self, this means that the neuroecological self and its POV are intrinsically relational.

Ecological background layer of point of view II: Scale-Free temporo-spatial relation of world and brain
What about the brain and its role in constituting the ecological background layer of POV? We have seen that the self is scalefree and mediated through the brain's scalefree activity. The latter, in turn, is strongly shaped by the scalefree activity of the world, entailing the scaleinvariant nature of the world-brain relation. Putting it all together, we now postulate that the ecological background layer of POV is ontologically based on the world-brain relation through scalefree activity: the more the world and brain are tempo rally (and spatially) nested within each other and exhibiting LRTC, the greater the tem porospatial range of the ecological background layer.
Ultimately, this broader, more expansive range of LRTC of self with the world (through the brain and world-brain relation) permits greater ecological extension of the self towards and within the world. In contrast, if the temporal range of the ecological background layer is limited, meaning lower degrees of temporal nestedness and LRTC, the self becomes more restricted and isolated in its relation to the world.
Let us consider the comparison of bats and humans. Bats, as pointed out by Nagel (1974), can process ultrasonic waves, which humans and their brains cannot. This means that the world's LRTC aligns with different timescales in bats and humans, namely the ultrasonic and nonultrasonic, respectively. The bat's point of view and its neuroecological background layer are consequently nested and contained within a different timescale of the world when compared to humans and their POV. The differences in the temporal extension of the bat's and human's points of view within and relative to the world leads to differences in their subjectivity, which is manifest in their different "what is it like" (Nagel, 1974). Importantly, the differences highlighted here do not concern the actual mental contents themselves, but rather the predisposition for processing the range of possible contents. Our argument is that bats and humans differ in the ontological predispositions of their POV due to their different timescales. This temporal predisposition for the range of possible contents is then complemented by the actual contents, that is, those contents they are exposed to in their environment, and that fall within the range of their POVbased temporal predisposi tion. Together, we can see that the mental contents are doubly determined: by the predispo sition for a particular range, related to the POV, and the actual contents themselves.
This example points out that the ecological background layer of POV is intrinsically relational: it describes the POV in terms of its temporospatial scales and ranges relative to those of the world as a whole. Campos and Gutierrez (2015) hint upon that when describ ing the POV as a "relational entity." However, by combining "relational" and "entity," they remain somewhat ambiguous as their concept of entity means that something is clearly delineated from that which surrounds it. This is not compatible with the intrinsically rela tional and scalefree nature of the POV's ecological background layer, though. Without its temporospatial relation and relative difference to the world's temporospatial scales, the ecological background of POV would not be possible at all-its existence and reality is dependent upon the temporospatial relation. Relation is thus understood in an ontological sense, as it constitutes the existence and reality of the POV as the source of subjectivity within the world. The ecological background layer of POV is purely relational without any kind of entity as apparently still assumed by Campos and Gutierrez. Given the scalefree integration of the ecological background layer within the world and its scalefree features, it is better to describe POV as a "relational hub" or "node." Much like hubs or nodes are constituted by their relation or connectivity to the rest of the network, POVs are characterized by their relation or connection to the rest of the world's temporospatial networks. Taken in this sense, the ecological background layer of POV provides "structure to irregularity" by organizing and structuring the world's various temporal scales for the self within its limited temporospatial range such that the latter can access the former's ecological information in a temporospatially limited and com pressed way. An analogous prototypical example here is seismic activity. Seismic waves operate on an extremely slow frequency range, the ultraslow, which we as humans can not process as such. However, due to clever measurement devices, we are able to com press their timescales and, due to selfsimilarity related to scalefreeness, are able to decipher certain patterns in these seismic waves that may index the increased risk of potential earthquakes. Based on its own more limited but scalefree timescales, the brain, analogously, compresses the larger timescales from the world and, due to its scalefree nature, processes them in a more or less selfsimilar way-the ecological information of the world may thus, in partial and compressed form, be restructured and preserved in the brain's processing and its temporal patterns.

Ecological background layer of point of view III: Intrinsically temporal and scale-free
Traditionally, the point of view has been associated with a fixed entity like mental or physical substances that can be described as static and atemporal. This distinguishes the traditional concept of a point of view from our own characterization of the ecological background layer of POV that, rather than being static and fixed, is highly dynamic and therefore intrinsically temporal. As previously discussed, scalefree activity provides "structure to irregularity." This means that, even if the activity of different regions or the power of single frequencies changes in an irregular way, the overall structure can main tain its integrity. Therefore, scalefree activity is neither completely irregular nor entirely fixed; rather, it operates on a continuum between the conceptual extremes of total change and total stability (see also Northoff & Tumati, 2019).
This points to a core feature of the POV's ecological background layer, namely that its intrinsically temporal nature is entailed by its scalefree features. That converges with Campos and Gutierrez (2015) who also characterize POV as intrinsically temporal: Let us say understand temporal points of view as follows: A temporal point of view is a point of view identifying some differences in nonconceptual contents (qualitative, phenomenal, experiential contents) as "changes" of content. The identification can be either conceptual or not conceptual. This is a very important point. Subjects without conceptual capacities could be capable of adopting temporal points of view. In any case, in a temporal point of view certain differences in nonconceptual content count as a "change": something future becoming present, or something present becoming past. The idea behind that characterisation of temporal points of view is very simple. Temporal points of view take some differences in the nonconceptual contents of experience as being temporal differences entailing a "change". This is the crucial point. (p. 93) Where does the time of the POV's ecological background layer originate? We sup pose that the intrinsically temporal nature of the ecological background layer comes from within the world itself (i.e., worldbased time; Northoff & Chen, 2019). By con necting and relating to the world in a scalefree way, the ecological background layer of POV participates and integrates with the continuously ongoing construction of time in the world. As its temporal scale is much larger, the world's time nests and contains that of the POV-the world emplaces POV within its own larger range of timescales, which renders the ecological background layer of POV intrinsically tem poral and scalefree.

Concept of world: "Emplacement world" and "perspectival world"
What do we mean by the concept of "world"? The intrinsically temporal and scalefree emplacement of the POV's ecological background layer within the world's larger tempo ral scales converges well with the concept of emplacement world proposed by Campos and Gutierrez (2015, pp. 13-14, 40). They distinguish two concepts of world: emplacement world and perspectival world. The former is the world within which POV is situ ated, while the latter is the world that we perceive and cognize from a certain POV. Without going into too much philosophical detail, we will use these two concepts of world to further characterize the ecological and mental layers of POV.
The emplacement world reflects the background ecological layer of POV; it is the world within which POV is situated, allowing for the subject's, through its POV, direct contact and relation with the world's external reality. POV is emplaced in the world's temporal and spatial structures that constitute the world prior to and independent of POV itself. Briefly, we characterize the emplacement world as intrinsically temporal and scalefree between itself and its various parts such as POVbased subjects or selves that, through scalefree activity with LRTCs, are nested and contained within the world's much larger temporospatial scales. In this sense, the concept of emplacement world is primarily ontological and mereological as it refers to the existence and reality of the world as a whole and how it relates to its parts.
In contrast, the concept of perspectival world is primarily epistemological since it refers to the surface cognitive layer of POV and the world that we as subjects perceive from the first, second, or thirdperson perspective (FPP, SPP, TPP). The self is typically associated with FPP, which is considered to be subjective and can be distinguished from the more objective TPP. While not elaborating on this association, we argue that all three perspectives merely characterize the mental surface layer of POV rather than the ecologi cal background layer that remains preperspectival. Accordingly, all three perspectives, FPP, SPP, and TPP, must be considered subjective rather than objective: constituting the mental surface layer of POV, they are all based necessarily on the ecological background layer of POV as the most basic source of subjectivity within the world. We will illustrate this shift in the characterization of FPP, SPP, and TPP by discussing the notion of prere flective selfconsciousness in phenomenology.

How to interpret Thomas Nagel's "What is it Like to be a Bat?": First-Person perspective versus point of view
We experience our own self and the world in firstperson perspective (FPP). FPP is con sidered the hallmark feature of both subjectivity and consciousness in phenomenology, as both are conjoint in what is described as prereflective selfconsciousness (Gallagher & Zahavi, 2019;Zahavi, 2005). In a nutshell, prereflective selfconsciousness describes the immediate and firstpersonal givenness of experience that is already there prior to and independent of any reflection, attention, or recognition. Even when I am conscious of an event or object in the world, I am already conscious of myself in the prereflective mode. Prereflective selfconsciousness signifies the intrinsically subjective nature of our experience and consciousness featured by its firstperson perspective and its phenomenal character.
How does prereflective selfconsciousness stand in relation to POV? Colloquially, the firstperson perspective is thought to be based on a specific point of view, marking FPP as subjective, perspectival, phenomenal, and isolated (from the rest of the world). However, that pertains only to the mental surface layer of POV rather than the ecological background layer, which is intersubjective, ecological, relational, and what we refer to as preperspectival.
Thomas Nagel's famous example of "What is it Like to be a Bat?" (1974) is usually considered an illustration of the subjective, perspectival, phenomenal, and isolated nature of FPP as distinct from the intersubjective, nonperspectival, nonphenomenal, and noni solated TPP. Subjectivity and consciousness, including prereflective selfconsciousness are here related exclusively to FPP while, at the same time, not being available to TPP. We contest such mental interpretations of Thomas Nagel that equate subjectivity with FPP and thus the mental surface layer of POV. Instead, we argue that Nagel's example of the bat may be better conceived within an ecological context that traces subjectivity to the ecological background layer of POV.
When Nagel (1974) speaks of a point of view, he does not equate POV with FPP. For instance, this is reflected in the following quote from his famous paper, "What is it Like to be a Bat?": "I am not advertising here to the alleged privacy of experience to its pos sessor. The point of view in question is not one accessible only to a single individual. Rather it is a type" (p. 441). Moreover, it is noteworthy that Nagel does not mention the concept of FPP once in this paper. He only refers to a point of view that distinguishes bats' experience and subjectivity from those of humans. We therefore claim that Nagel presupposes a wider notion of POV that is not restricted to FPP as distinct from TPP. Instead, we postulate that he presupposes the notion of POV in a wider sense, prior to and independent of the distinction of FPP, SPP, and TPP-this is very compatible with the assumption of POV being a necessary condition of the possible differentiation into FPP, SPP, TPP, as we postulate. This carries important implications.

How can we know the ecological background layer of point of view? Preperspectival and prephenomenal access
Presupposing this wider conceptualization of POV means that the ecological background layer of POV can neither be characterized by any particular perspective like FPP, nor by prereflective selfconsciousness. Characterizing the background layer in this sense would be to confuse it with the mental (or phenomenal) surface layer of POV as the suf ficient condition for FPP and prereflective selfconsciousness. We need to characterize POV in nonmental terms distinct from those used to describe its mental surface layer. Instead, we need to revert to ecological terms to describe such wider, more basic con cepts of POV.
Without being able to fully flesh out the details, we propose that the ecological back ground layer of POV is preperspectival and prephenomenal (Northoff, 2014a(Northoff, , 2014b(Northoff, , 2018 as it provides the necessary, albeit nonsufficient, condition of possible perspectives (FPP, SPP, TPP) and phenomenality without realizing them as such. In other terms, the ecological background layer of POV provides the ontological capacity or predisposition of perspectives (i.e., FPP, SPP, TPP) and prereflective selfconsciousness (see Northoff, 2018, Chapter 10, for the concept of ontological predisposition). This means that the eco logical background layer of POV is preperspectival and prephenomenal rather than being either perspectival and phenomenal by itself or, alternatively, nonperspectival and non phenomenal (in which case it would no longer provide the predisposition at all).
Together with the aforementioned characterization, we assume that the preperspecti val and prephenomenal nature of POV's ecological background layer (as an ontological predisposition of the perspectival and phenomenal nature of self) is based on its intrinsi cally temporal and scalefree nature that constitutes its relation to, and emplacement within, the world (i.e., emplacement world). This marks the self as preperspectival, pre phenomenal, and neuroecological (see Northoff, 2014b, for the concept of prephenom enality), which first and foremost predisposes the phenomenal, mental, and cognitive features of self as they can be associated with the mental surface layer of POV (see Figures 4a and 4b). More generally, this means that the prephenomenal and preperspec tival nature of POV provides the source of necessary (a posteriori) albeit nonsufficient condition of subjectivity in the world (i.e., worldbased subjectivity), as elaborated in phenomenological accounts by Husserl, Heidegger, and Sartre.

Ontological, temporo-spatial, and neuro-ecological view of subjectivity
We are now ready to address the more philosophical issues of how to converge the world based subjectivity of self in phenomenology with the brainbased nature of self as observed in neuroscience. Albeit tentatively, this conclusion serves to highlight some of those connections based on our neuroecological and temporospatial notion of the point of view. The key question arising from this is: How do the ontological concepts of worldbrain relation, neuroecological self, and point of view stand in relation to the concept of subjectivity discussed in philosophy? Without being able to provide a comprehensive account at this time, we will make some overtures in this direction.
The key concept serving as a bridge is the point of view. Following Thomas Nagel, we understand the point of view in a temporospatial sense, that is, as a temporospatial structure that, being intrinsically scalefree, operates across different spatial and  Figure 4a. Scale-Free nestedness of self within brain and world -world-brain relation and neuro-ecological self.
temporal ranges. Critically, we conceptualize time and space in an ontological sense (i.e., as featuring the world's existence and reality), and how they constitute the world's rela tion to its parts like the brain (i.e., world-brain relation)-this makes it unavoidable that the brain is intrinsically neuroecological rather than purely neuronal as manifested in the ecological background layer of the point of view. The point of view, understood in neuroecological and scalefree terms, allows the subjectivity of self to be constituted ontologically and temporospatially. Specifically, from an ontological perspective, we propose that the world emplaces the ecological background layer of POV through its relation to the brain's temporospatial features in a scalefree way (i.e., by means of temporal nestedness and LRTC); this, in turn, consti tutes the situatedness of the self within the world and thereby its subjectivity. This pre supposes a relational, rather than a propertybased ontology: Relations between the world and brain, rather than singular entities like the world, brain, or body alone are the basic units of existence and reality (Northoff, 2018). This relational ontology is intrinsi cally ecological, mereological, and temporospatial as these are the features through which the world as a whole and its parts like brain and self are related to each other in a scalefree way-one may thus want to speak of a scale-free ontology.  We consider a relational and ecological scalefree ontology to be key in developing a proper ontology of subjectivity and self. We have focused only on the point of view and, specifically, its ecological background layer as to link the self intrinsically to its ecologi cal context within the world. This sets up a novel framework for the development of a neuroecological, temporospatial, and relational ontological concept of self which, through its intrinsically temporal nature, may then also be closely linked to temporal continuity, longterm temporality, and ultimately, personal identity (Brüntrup et al., 2020;Wagner & Northoff, 2014. Finally, conceived in a larger context, the ontological triangle of world-brain relation, point of view, and neuroecological self addresses the incommensurability of subjectivity and objectivity in its ontological facet (Nagel, 1974(Nagel, , 1986) that has plagued psychology, neuroscience, and philosophy in both past and present. The dichotomy of subjectivity and objectivity has led to some of the key questions of our time: How can something subjective like a self exist and be real in an objective world? Rather than reducing or parallelizing them, we opt for reconciling and integrating subjectivity and objectivity within a commonly shared ontological framework that, by being temporospatial, allows for the connection between world and self through the world's scalefree temporospatial organization that ontologically predisposes the world-brain relation as a necessary, a posteriori condition for the possible generation of POV and its neuroecological self.

Avoiding methodological circularity: Subjectivity-Based versus world-based view of subjectivity
We are obviously not the first to search for a deeper background layer of self and sub ject. Kant introduced a deeper background layer of the subject when distinguishing transcendental and empirical selfconsciousness. The transcendental subject was deter mined mainly in conceptuallogical terms entailing what can be described as "reflective selfconsciousness." Husserl went beyond Kant by replacing the latter's transcendental level of the subject by focusing on consciousness and its phenomenal level. The subject could now be determined phenomenally rather than in conceptuallogical terms-this shifted the focus from reflective selfconsciousness to prereflective selfconsciousness (Zahavi, 2005).
We now extend Husserl from prereflective selfconsciousness to an even more basic notion of the prephenomenal self (see Northoff, 2014b, for a discussion of the prephe nomenal as distinct from the prereflective self). That is possible by introducing the eco logical background layer in addition to the prereflective surface layer of POV. The ecological background layer of POV makes it possible to situate and emplace prereflec tive selfconsciousness within the context of the world in a necessary (a posteriori) and intrinsic way. Since that is ontologically mediated by the scalefree world-brain relation, this marks the self as intrinsically neuroecological. Importantly, the neuroecological character is not experienced as such but provides the necessary condition or predisposi tion for any possible experience of the self in terms of prereflective selfconsciousness (which, phenomenologically, is also often described as the minimal self; Zahavi, 2005). For this reason, we designate the neuroecological layer of self as prephenomenal rather than either nonphenomenal or prereflective. Let us explicate that.
Our main claim is that the neuroecological layer of self provides the capacity or pre disposition for its possible experience in terms of prereflective selfconsciousness as distinguished from the latter's actual realization. This means that the neuroecological level cannot be described by prereflective selfconsciousness itself, as that would con fuse the necessary conditions or predisposition of its possible realization with the suffi cient conditions of the self's actual realization. As the neuroecological layer and its point of view cannot be experienced as such, we therefore characterize it as prephenom enal rather than as phenomenal as entailed by prereflective and reflective selfconscious ness. The reflective and prereflective self are therefore now complemented by what we describe as the prephenomenal self. This extends Husserl's phenomenological notion of prereflective selfconsciousness to an ontological level, namely to a prephenomenal self based on the neuroecological background layer of POV and its scalefree nature which, ontologically, is ultimately based on the temporospatial features of the world-brain relation.
The presupposed ontological level is even deeper and more fundamental than what Heidegger described as "Fundamental Ontology." Unlike Heidegger, the present approach no longer infers the self from the phenomenological level and its existential extensions like Dasein and Beingintheworld. Rather than taking the self as the point of departure for characterizing its role and place in the world, the present approach takes a reverse stance: it describes the world in temporospatial and ontological terms, which serves as a basis for exploring the ontological similarities between the world and self which, as we postulate, can be found in the temporospatial and scalefree features of the point of view (and its basis on the world-brain relation). Hence, where Heidegger describes the world in terms of subjectivity (i.e., in existential terms), we, taking a reverse stance, describe the subjectivity of self in terms of the world as featured by scale free and temporospatial relationships. Converging both, we tentatively consider the scalefree and temporospatial relation of world and self through the world-brain rela tion as a necessary (a posteriori) condition of the kind of worldbased subjectivity (i.e., Beingintheworld) that Heidegger and Sartre describe.
The unravelling of a deeper prephenomenal, temporospatial, and neuroecological layer of the subjectivity of self makes it possible to methodologically extend beyond both Heidegger's fundamental ontology and Sartre's phenomenological ontology. Even though they strive for an ontology of subjectivity in the world, both Heidegger and Sartre still determine such subjectivity in dependence on, and in terms of, the concept of sub jectivity itself. Specifically, their characterization of the world is still based on the phe nomenal and existential features of the self. Methodologically, this amounts to what can be described as a subjectivity-based ontology of the self in the world. However, that cannot avoid being methodologically circular, at least to some extent, as here the onto logical account of subjectivity in the world is methodologically dependent and based upon itself (i.e., the phenomenal and existential features of subjectivity).
To avoid any such methodological circularity, we require an ontological concept of subjectivity within the world that, methodologically, remains independent of the subjec tivity itself (including its phenomenal and existential features)-a world-based ontology of self in the world that must unravel its prephenomenal (rather than phenomenal and existential) features. Our triangular conceptualization of the world-brain relation, point of view, and neuroecological self serves exactly that purpose, namely to establish a truly ontological and prephenomenal, worldbased account of the subjectivity of self within the world. While further developments are necessary, we hope that our combined onto logical-empirical approach can avoid the kind of methodological circularities that plague the concept of subjectivity in both past and current philosophy and neuroscience.