Situating mental time travel in the broad context of temporal cognition : A neural systems approach

Mental time travel (MTT) is the ability of remembering personal past events or thinking about possible personal future happenings. This mental property is possible due to our capacity to be aware of subjective time, which enables us to experience the flow of time, to conceive non-present times, and to process time as a dimension of real world phenomena. Temporal cognition encompasses the mental functions which rely on temporal information enabling the experience of the temporal flow and the processing of the temporal dimension of external phenomena. Given the broad range of our time experiences and, hence, the broad scope of our temporal cognition, it is expected that certain kinds of temporal information can be of particular importance when we mentally transport ourselves to events in the past or future, whereas others could be unrelated to this mental property. The present paper seeks to situate the process of MTT within human temporal cognition. This will be done by identifying the commonalities and differences in the neural correlates of MTT and those of the three main subjective time processing systems, namely metric timing, ordinal timing and autobiographical timing.

Viagem mental no tempo (VMT) diz respeito à habilidade de se lembrar de eventos pessoais do passado ou pensar sobre possíveis acontecimentos pessoais futuros.Essa propriedade mental é possível devido a nossa capacidade de estar ciente do tempo subjetivo, o que nos permite ter a experiência do fluxo do tempo, conceber tempos não presentes e processar 'tempo' como uma dimensão de fenômenos do mundo real.Dada a vasta gama das nossas experiências temporais e, portanto, o amplo escopo da nossa cognição temporal, é de se esperar que alguns tipos de informação temporal sejam de particular importância quando nos transportamos mentalmente para eventos no passado ou futuro, enquanto que outros Mental time travel (MTT) is a psychological concept coined by Endel Tulving (1993) from his own formulation of the nature of episodic memory.Since the late nineties, it has received considera le attention in the cognitive psychology literature and has been further investigated and developed (Su dendorf and Corba lis, 1997).MTT refers to the ability to menta ly reconstruct personal past events and menta ly construct possi le future events.Thus, it is directed towards personal non-present times and it is only possi le due to our capacity to process time as a dimension of real world phenomena (Szpunar, 2011).Several authors agree that the phenomenal a ect of MTT goes beyond the mere content of the reco lection or future thinking in question (i.e., the what, where and when tied to the event).It is said that the phenomenal a ect that accompanies the content requires chronesthesia and autonoetic awareness3 .Another concept tangled to that of MTT is the concept of episodic memory, which refers to conscious reco lection of ecific episodes in one's personal past.Indeed, it could be assumed that when MTT is directed toward the past it is termed episodic memory (Suddendorf et al., 2009).
As it is a general mental faculty which depends upon subjective time perception, one might wonder to what extent and by which means MTT is related to the broader concept of temporal cognition.Temporal cognition encompasses the mental functions which rely on temporal information ena ling the experience of the temporal flow and the processing of the temporal dimension of external phenomena (Maniadakis and Trahanias, 2011;Matthews and Meck, 2016).It includes subjective time perception (e.g., judgements about temporal order and duration) as we l as memory processes (e.g., working memory and episodic memory).Although psychological and neurobiological studies have made considera le progress in elucidating the role of episodic memory and pro ective thought in MTT, the contribution of time per-ception itself to MTT sti l remains elusive.This is in part due to the fact that time perception has often been investigated and discussed in relative isolation from the mnemonic a ects of temporal cognition (Matthews and Meck, 2016).
The present article aims at a dressing the question of which kind of temporal information is of particular importance when we menta ly transport ourselves to events in the past or future in order to situate MTT within the broader theoretical framework of human temporal cognition.This wi l be done by identifying the commonalities and differences in the neural cor elates of MTT and those of the three main subjective time processing systems: (i) the processing of temporal order in past and future events, which is the event-sequencing a ect of time perception, (ii) the processing of interval timing of events, which is the a ect of duration estimation of time perception, and (iii) the processing of the temporal dimension of episodic memories, which includes the encoding of temporal context information as we l as the encoding of the passage of time.The article is structured as fo lows.First, the neurobiological substrates of temporal order and interval timing, which are part of the so-ca led "perception of time" literature, wi l be reviewed.Then, the neural cor elates of episodic memory wi l be presented, fo lowed by the discussion of neuroimaging studies on self-related memory, imagination and MTT.Fina ly, I wi l compare the neural bases of MTT and episodic memory with those of perception of time.Elucidating the type of temporal information MTT is dependent on is crucial to understand how MTT is related to temporal cognition.

Perception of time of external events: Definition of terms and neurobiological substrates
Although we a l have a sense of time, our bodies are not equip ed with a sensory system for detecting time in the podem ser irrelevantes para essa propriedade mental.O presente artigo busca situar o processo de VMT dentro da cognição temporal humana.Isto será feito identificando-se convergências e divergências dos correlatos neurais da VMT com aqueles dos três principais sistemas neurais de processamento temporal, a saber, temporização métrica, temporização ordinal e temporização autobiográfica.
same way we detect light and sound -i.e., time is not a type of material object of the world for which there are ecifica ly dedicated sense organs, receptors and sensory cortices.Yet the perception of the passage of time by the experiencing subject is as obvious as the colour of an object or the timbre of a sound.How is temporal information represented in the subject's brain?
First of a l, it is important to make clear that "temporal processing" is not a monolithic concept.It comprises several chara eristics of timing that can be functiona ly 4 dismantled.Studies on perception of time consider a more general distinction between duration estimation (how long an event lasts, or when an event is likely to occur), which involves analysis of elapsed time and requires a met ical representation of time, and temporal order judgement (order of successive events in a series), which requires an o dinal representation of time (Ivry and Spencer, 2004;Cou l et al., 2011).It is also important to note that these studies employ supra-second time intervals, that is, intervals spanning a few seconds.This means that the temporal processing mechanisms of interest rely on conscious encoding of duration, which require cognitive control (as op osed to sub-second intervals which are embe ded in automatic sensory processes and a ion plans 5 ).
Within metrical timing, two functional distinctions have been made.The first is a distinction between "explicit" and "implicit" timing, whereas the second is a distinction between "perceptual" and "motor" timing.These functional concepts are defined as fo lows.Explicit timing refers to overt estimations of duration required from subjects during a temporal task (the task's goal is to estimate elapsed time).Being asked to estimate for how long the red traffic light stayed on is an example of explicit timing.Contrarily, implicit timing regards the implicit engagement of timing mechanisms in a task which has an inherent temporal structure (the task's goal is non-temporal, but temporal expectation is induced by temporal elements such as eed or rhythm).For instance, crossing a busy streets requires an implicit interval estimation (expectation) given by the position and eed of vehicles.Both explicit and implicit timing tasks may require subjects to either provide a perceptual judgement or to perform a motor act, which have been refer ed to as "perceptual timing" and "motor timing" , re ectively.
Sti l regarding metrical timing, neuroimaging studies of explicit duration estimation have revealed a core 6 corticostriatal network composed of the basal ganglia (BG), the sup lementary motor area (SMA), and the right-lateralized inferior frontal cortex.Studies of implicit timing (or temporal expectation) have also implicated a core network constituted by the BG and the SMA, together with the cerebe lum, and the left-lateralized premotor and parietal cortices (Cou l et al., 2011).The BG and the SMA participate in both types of metrical timing, independently whether perceptual or motor responses were given.These two brain regions have been associated with distinct stages of the pacemaker-accumulator model (Buhusi and Meck, 2005).According to the model, the pacemaker BG participates in the encoding phase of longterm memory of duration (i.e., creation of our "offline" reference of duration) whereas the SMA is involved in keeping the elapsing time of a cur ent stimulus in short-term memory (accumulation) and comparing this "online" duration with the "offline" reference of duration.
In a dition to metrical timing, the other component of perception of time is ordinal timing.Being a le to judge whether two events are simultaneous or successive is crucial to the moment-to-moment interpretation of the sensory world.Neuroimaging studies have pointed towards a core brain region involved in judgments of the temporal order of two stimuli, ir e ective of the sensory modality: the right-lateralized temporal parietal junction (TPJ).The demonstration of the role of the right inferior parietal lobe (which is part of the TPJ) in judgments of temporal order has been so robust that this region has been considered the "when" pathway of the visual system (in a dition to the we l-known "where" and "what" pathways) (Batte li et al., 2007).
It is clear that metric and ordinal timing engage different brain regions, or two distinct functional systems.Nonetheless these brain regions have also been described as the neural components of either of two major networks, namely the salience network and the motor control network.The salience network is a ive whenever worl ly stimulation demands awareness.Amongst the myriad of sensory information we are constantly bombarded with, only a tiny part is actua ly relevant for our goals and interests.The salience network is involved in selecting what matters in a given context.It is composed of frontal and parietal cortices which exert topdown modulation of attention and working memory.Regarding the motor control network, it is engaged not only by a ions pe se, a ion planning or a ion emulation, but also by prediction of the unfolding of external events, both biological and non-biological (Schubotz, 2007).We live in a dynamic 4 By functional I mean mapped using functional neuroimaging techniques (e.g., PET, fMRI, ERP).Such techniques allow researchers to investigate the set of brain regions which robustly correlate with certain mental functions delivered via a perceptual or cognitive task.The set of brain regions can be referred to as functional system (e.g., the functional system of attentional control). 5Different types of perception and behaviour implicate different ranges of time intervals.The estimation of the duration of a few hundreds of milliseconds (i.e., sub-second) is called "automatic timing" and is crucial for motor control in automated motor sequences (e.g., walking on the street, speech perception and production).Estimating the duration of over a few seconds (i.e., supra-second) is called "cognitively controlled timing".It requires attention and working memory and is necessary for conscious time estimation and decision making. 6By "core" network I mean regions that are recruited by different types of motor and perceptual tasks, and irrespective of the sensory modality in which stimuli were presented.Thus, core network would refer to a context-independent, supramodal representation of duration (in explicit timing) and of temporal expectation (in implicit timing).
world, and anticipating future states of relevant events is important to grasp the causal relationship between the dynamic behaviour of our body and the environment, as we l as their consequences.The salience and the motor control networks work together since selecting what matters in a given context involves capturing its dynamic a ects.
Thus, the core timing network utterly overlaps the salience network and the motor control network.What does this embedment su gest?It could be interpreted by considering "timing" (i.e., subjective time perception) an essential component of human cognition which underlies mental functions such as attention, working memory and anticipation of external events.In other words, processing of temporal information could be seen as a central subcomponent of these mental functions.In fact, empirica ly eaking, the concept of timing cannot be easily untangled from the concepts of attention and working memory (Cou l et al., 2011).This conceptual interdependence su gests that "timing" is not an inaccessi le foundational component: At the same time that "timing" underlies certain mental functions, it is also modulated by these very functions.This makes it quite cha lenging to accept "timing" as an encapsulated neurobiological mechanism.Rather, given the empirical evidence, it is more tenale to conceive or ap roach the questions on where and how "timing" is represented in the brain in relation to mental functions (i.e., attention and working memory) to which it seems to be deeply bound up with.In other words, trying to escape conceptual circularity on the search for the neurobiological mechanisms of time perception is a thorny task.

The concept of episodic memory and its neurobiological substrates
The intuition that the concept of memory is rather broad and does not cor espond to only a single mental faculty is an old one.Experimental inquiry by cognitive neuroscience, complementary to philosophical questioning and psychological explorations, has been crucial in understanding the neural a ect of memory systems.The modern experimental ap roach has be un with the famous patient H.M. (Henry Gustav Molaison), who in 1953, and at the age of 27, underwent a bilateral medial temporal lobectomy due to epilepsy.The successful surgery made him an anterograde amnesic patient, but despite his amnesia he could sti l learn new motor ski ls with pra ice, as we l as maintain and manipulate information for a few minutes (i.e., hold a conversation).These observations showed that memory was not a unitary construct.First, it could be understood in terms of accessibility of temporary and permanent information to the subject.These two types of memory are ca led short-and long-term memory, re ectively, and they involve separate neural mechanisms and are independently processed.Second, long-term memory includes motor (non-declarative or implicit) and cognitive (declarative or explicit) forms of memory.Later, affective mnemonic properties, usua ly acquired as subtle associations, were included as another form of non-declarative memory.The declarative form of long-term memory is also ca led autobiographical memory, since it concerns reco lections of ecific personal events and facts.In the 1970s, Tulving (1972) su ge ed that autobiographical memory should be separated into episodic (particular events or e iso es about the self) and semantic (facts about the self and the world) systems.
Since then, autobiographical memory has been conceptualized and empirica ly ap roached in terms of, on one hand, reca ling personal semantic information linked to feelings of familiarity and of, on the other hand, reca ling personal episodic information which requires re-experiencing or re-constructing unique past events.Indeed, functional neuroimaging and lesion studies have strongly su ge ed that the neural basis of the declarative self can be fra ionated into two functionally independent systems.One system involves lateral cortical regions in the frontal (inferior frontal gyrus), parietal (inferior parietal lobe), and temporal (superior temporal gyrus, anterior temporal lobe) lobes as we l as medial frontal (medial prefrontal cortex), parietal (precuneus), and temporal cortices (fusiform gyrus) (Binder and Desai, 2011).It sup orts semantic knowledge of facts about one' s own life and personal identity, and is associated with noetic awareness (i.e., a sense of simply "knowing" without contextual -including temporal -details).The content of semantic memory is usua ly abstra ed from actual experience and is therefore said to be conceptual (i.e., generalized).The other system is composed of the hip ocampus and sur ounding medial cortices such as the entorhinal and parahip ocampal cortices -the so-ca led medial temporal lobe, and also the medial prefrontal cortex and the precuneus (Moscovitch et al., 2016).It ena les reco lection of personal episodes, including information ecific to the time and place of acquisition, and is associated with autonoetic awareness.Thus, this ability goes beyond simply knowing "what" hap ened, "where" it hap ened and "when" it hap ened -the so-ca led www criteria (Su dendorf et al., 2009).It requires a subjective sense of time and of the self as the one who experienced the episode and possesses the memory.The agent' s personal relation with the ecific episodic context (a context which includes the www criteria) is central for the mental capacity for reconstructing and reliving that episode.
As su ge ed by the neuroimaging data, the content of episodic memory depends heavily on retrieval of semantic knowledge.Reca ling, for instance, having a glass of wine during dinner last night requires retrieving the concepts of glass, wine and dinner.The semantic knowledge plays a role in encoding semantica ly meaningful events in episodic memory.Therefore, it is not surprising that the two memory systems described above are highly interconnected.There are strong reciprocal connections between the hip ocampus in the episodic network and the precuneus as we l as the lateral and anterior temporal cortices in the semantic network.
Having brought forth the conceptual and neurobiological relations between semantic and episodic memory, it is clear that, although both memory systems are fundamental parts of the declarative self, only episodic memory is associated with autonoetic awareness.Thus, there must be something about the hip ocampus and associated cortices regarding tracking personal time which makes up the sense of a continuous self 7 that is part of the totality of the phenomenal experience.This would a low the phenomenal reco lection during mental re-enactment of previous personal episodes.In fact, a key role for the hip ocampus has been shown both in temporal organization of episodic memories (i.e., the dating of memories) and in remembering sequential organization of events within memories.
Regarding the labe ling of "when" episodes occur ed, studies have demonstrated that the hip ocampal CA1 neurons are central in the retrieval of both remote and recent episodes (Bartsch et al., 2011), and that the distinction between memories that are widely separated in time is given by the hip ocampal a ivity patterns of CA1 neurons (Eichenbaum et al., 2014, p. 275).These studies indicate that shifts in the spatiotemporal firing patterns of CA1 neurons are associated with evolving temporal context representation, with gradual changes in the neural representation of the hip ocampal CA1 neural population over many days.Thus, it seems that these changes in the firing patterns of CA1 neurons represent the temporal labels of the tempora ly organized episodic memories.The retrieval of an episodic memory and its re-consolidation with a new memory trace goes beyond the CA1 neurons -it depends on the entrainment of a dynamica ly distributed hip ocampal-cortical network (Moscovitch et al., 2016).On the other hand, the preservation of the sequential order of events within episodes, including spatial and temporal contextual details, depends upon the stability of the a ivity patterns of hip ocampal CA3 neurons (Davachi and DuBrow, 2015).More sta le firing patterns -compared to the dynamic CA1 patterns discussed above -sup ort the enduring feature of context-mediated episodic sequence.These findings indicate that both hip ocampal subregions are critical in representing temporal information (involving ordered stimuli) across multiple timescales.While CA1 neurons show a gradua ly changing firing pattern across multiple days and are important in e a lishing the temporal gap between distant episodes, the sta le response of CA3 neurons is critical in bridging events much closer in time and that sup ose ly belong together.In other words, CA1 represents how long ago an episode took place ("feeling of remoteness") whereas CA3 represents the semantic cohesiveness of retrieved memories ("feeling of rightness").Thus, the hip ocampus is central for the event-sequencing a ect of time, in both short and long timescales.This is important not only for the reconstruction of episodic memory, but also for the construction and organization of future planning -which wi l be discussed in the next section.

Neural correlates of MTT and self-referential cognition
MTT is the ability of an agent to menta ly reconstruct past events as we l as construct possi le future events that involves the self.When it is directed toward the past it is ca led episodic memory (see the previous section); when it points toward the future it has been ca led future planning or future thinking and it concerns thinking about a hypothetical personal future event which can be flexi ly used to plan future a ions (Su dendorf et al., 2009).In recent years, the field of cognitive neuroscience has prolifica ly produced studies investigating the neural underpinnings of this mental phenomenon -particularly examining the relation between re-experiencing one's personal past and pre-experiencing an event by moving one's self forward in time.
Neuroimaging research has revealed remarka le similarities between remembering the past and imagining or simulating the future.Also, counterfactual thinking seems to a ivate the same pattern of brain regions but with more pronounced a ivity (in both strength and extension) in some particular areas.These studies, thus, su gest a common core brain network underlying episodic memory, imagination, and counterfactual thinking (Scha er et al., 2012;Van Hoeck et al., 2013), which includes the medial frontal, parietal and temporal lobes (including the hip ocampus) together with lateral parietal and temporal areas (overlap ing the TPJ -see the section "Perception of time of external events").These regions overlap substantia ly with the so-ca led default mode network (DMN) 8 .Activity in the DMN has been observed whenever the participant is put in a passive test condition with no requirements of broa ly monitoring the external environment (i.e., watchfulness).The DMN seems to maintain unfocused external attention while engaging interna ly cognitive processes (i.e., external sentinel and internal mentation).Several studies have observed that task contexts that encouraged or a lowed for stimulus-independent thoughts (i.e., mind-wandering or daydreaming) are associated with increased a ivity in the DMN.However, these internal mentations include not only remem-7 I take for granted that a neurotypical human adult subject has a sense of self extended in time (or continuous self), since it is impossible to conceive a neurotypical subject not extended in time (the very concept of "subject" must involve "continuation in time").However, discussing how the representation of the self as an entity extended in time emerges or is built up is not the focus of the present article -it is a debated philosophical topic with several conflicting theories.For a neurocognitive approach, please see Gallagher (2000). 8The discovery of the DMN was entirely accidental since no early neuroimaging studies were explicitly designed to examine unconstrained mental states.The DMN was identified when researchers decided to analyse the data by looking for significant increase of activation during the control (passive) condition compared to the experimental (goal-directed task) condition.Activity of a specific set of brain regions increased during undirected mentation rest conditions compared to virtually all cognitive tasks.This set of regions was labelled as the "default mode network" (for a review, see Buckner et al., 2008).bering the past and imagining the future, but also taking the per ective of others and engaging in spatial navigation in the present time.Thus, virtua ly the same brain regions subserve the mental transportation of one' s self to events in the past or future and the imagination of self-referential situations which do not require this temporal displacement.These findings have complicated the hypothesis of mental time travel as an ability underpinned by an independent cognitive mechanism (Buckner and Car o l, 2007).It is more likely that the construct of mental time travel can be further reduced to several dissocia le and more basic cognitive processes.
The aforementioned conceptual intricacy present in studies of timing (section "Perception of time of external events") is also present in studies of MTT, which poses experimental cha lenges in contro ling for confounds of more basic processes that are part of the MTT ability.The process of MTT comprises the DMN to some extent.It is known that the DMN underlies internal mental exploration within the "self " dimension, i.e., thoughts that are self-relevant or self-referential.Thus, it is accepta le to say that MTT is a self-reflexive mental process.On the other hand, it sti l remains unclear what a ects of the DMN -or MTT function -reflect the conscious awareness of the existence of one' s self in subjective time (i.e., the te poral component) as op osed to the constructive features of events of the declarative self (i.e., the narrati e component) (Scha er et al., 2012).Several studies on self-referential imagination tasks favour a non-temporal per ective of cognitive processes such as episodic memory, pro ection, theory of mind, and spatial navigation.They defend that these processes are primarily nar ative or constructive, that is, they rely upon the ability to retrieve disparate elements from a number of sources and bind details into coherent self-nar atives rather menta ly travel through time (Eacott and Easton, 2012), eliminating the need for a concept of mental time travel.Contrarily, studies with careful experimental designs targeting precisely processes of interest have tap ed into ecific contributions of temporal and atemporal factors in MTT.These studies strongly indicate differences in neural representations between temporal and atemporal imagined scenarios (Nyberg et al., 2010) -within the DMN areas, the mi dle frontal cortex showed greater a ivity in the non-present time (past and future) conditions compared to the present time condition.
Despite the great experimental cha lenge in isolating the cognitive processes associated with temporal factors from non-temporal cognitive a ivities and in balancing the cognitive load of the temporal and atemporal conditions, neuroimaging studies have started to uncover the neural substrate involved in imagery structured in time.But there is sti l a long way to be explored.

How does MTT relate to other temporal systems in the brain?
Modest contributions of neuroimaging studies of MTT relate the ability to menta ly project oneself to non-present times to the DMN, which is recruited during remembering the past and imagining the future.These findings in healthy adults are sup orted by two other types of studies.First, it has been observed that brain lesions and neurodegenerative diseases which disrupt certain types of a ivity in the DMN also impair only the autonoetic component of self-reference tasks.For instance, Rosenbaum et al. (2007) report that amnesic individuals who cannot transport themselves into past or future personal episodes (i.e., are limited to a life about their immediate environment) could nevertheless take the per ective of others by imagining what others might be thinking.Second, developmental studies have reported a relationship between memory and imagination, MTT and the functional architecture of the default-mode network in the developing brain (Østby et al., 2012).Thus, although we cannot make absolute claims about the neural cor elates of autonoetic awareness during MTT, there is sufficient scientific evidence to a low the inference that it possi ly has to do with the DMN.
So, considering that the DMN somehow underlies the subjective sense of time during MTT tasks, how would it be associated to the neural substrates of the also ca led "subjective time" in tasks of duration estimation and order judgements?In other words, how and to what extent are the internal (projective "travel") and the external (watching) subjective time systems related?
The medial temporal lobe -which includes the hip ocampus -is part of the DMN.The hip ocampus is strongly connected to the striatum, which is one of the nuclei in the BG (see section "Perception of time of external events").The striatum is one of the main components of the corticostriatal network which underlies metric timing, i.e., the explicit and implicit interval timing.Hip ocampal lesions result in increased dopaminergic transmission in the striatum, which leads to long-term alterations in the accuracy and precision of estimating the duration of intervals (in the seconds-to-minutes range) (Meck, 2005).Therefore, patients with hip ocampal amnesia, in a dition to impaired episodic memory and future imagining, also underestimate retro ective durations and underproduce pro ective durations.Conversely, the disruption of striatal dopaminergic circuits also impair the hip ocampal function of constructing non-present time episodes.Parkinson's disease patients, which have low dopamine in the nigrostriatal pathway, exhibit an impaired ability in imagining future events, but have no difficulties in imagining atemporal scenarios (de Vito et al., 2012).Other studies have reported that schizophrenic patients, who have dopaminergic hyperfunction in the mesolimbic pathway (which includes the striatum), experience a distorted sense of continuity of self across time.They show pronounced difficulties in reca ling events from their personal past and in generating events that might hap en to them in the future (D' Argembeau et al., 2008).
These results strongly su gest a connection between the functional systems sup orting internal subjective time awareness and external subjective time perception.The per-ception of the passage of time seems to be dependent on a balanced dopaminergic transmission between the striatum on the one hand, which is part of the metric timing network, and the hip ocampus on the other hand, which is part of the DMN.

Conclusion
Neuroimaging evidence described in the present article points towards more than one subjective timing network.The two major "timekeeping" systems described in the literature are those related to the perception of time of external events and the internal mentation of projecting ourselves through time.It has been su ge ed that the former is underpinned by a network of brain regions that are part of the salience network and the motor network.There is evidence that the latter is sup orted by the default mode network.In a dition, the former could be seen as the timing mechanism for processing "the now" (by which the subject perceives events hap ening in the present moment), and the latter could be seen as the timing mechanism which a lows the subject to engage in past and future episodes (processing the non-present moments).Also, the structuring in our minds of our subjective feeling of the passage of time seems to involve the integration of these two main systems, particularly via connections between the basal ganglia (striatum) and the hip ocampus.Neuroimaging and neuropsychological data su gest that the dynamic coupling between the externa ly-and interna ly-oriented temporal attention sup orts temporal cognition across a broad range of stimulus contexts and temporal scales.
However, in neuropsychology, the concepts of working memory and attention cannot be defined (and, thus, assessed) without resorting to the concept of timing, which in turn cannot be understood without making reference to the concepts of attention and working memory.This conceptual circularity causes timing to both underpin and be underpinned by attention and working memory.Thus, attention and working memory are not simply confounding factors, as authors put it.For that, they would have to be task-related but non-temporal processes, which seems not to be the case since they belong in the very definition of "timing".Similarly (but to a lesser extent), the neuropsychological concept of subjective time is intertwined with that of self-reference.Conceptual confusion leads to incoherent experimental premises, dampening clarity in experimental design and data interpretation.
Given the extent of recent interest in MTT in cognitive neuroscience, it would be important to investigate the logical relations among key concepts.This is a philosophical task that should be conducted in cooperation with the field of neuroscience.Understanding the neural structures and dynamics involved in temporal mental processes -including the complex construct of MTT -demands ingenious experimental designs that cannot be achieved without conceptual and categorical clarity.