A computational neuroethology perspective on body and expression perception
2021; Elsevier BV; Volume: 25; Issue: 9 Linguagem: Inglês
10.1016/j.tics.2021.05.010
ISSN1879-307X
AutoresBéatrice de Gelder, Marta Poyo Solanas,
Tópico(s)Visual perception and processing mechanisms
ResumoBody and expression perception may be sustained by midlevel feature computations rather than by body category-selective processes.Body expression coding in the brain may be organized by feature statistics of body posture and movements rather than by natural language semantic categories.Midlevel features at stake in biological computations of body posture and movements exploit ethological characteristics of organism–environment interactions.Midlevel feature processing may on its own sustain rapid expression perception and action preparation, and may not require or depend on computations of the high-order category.Feelings can be associated with midlevel processing and may be precursors to conscious emotional states because they are an intermediate layer between unconscious processes and fully formed conscious emotional states. Survival prompts organisms to prepare adaptive behavior in response to environmental and social threat. However, what are the specific features of the appearance of a conspecific that trigger such adaptive behaviors? For social species, the prime candidates for triggering defense systems are the visual features of the face and the body. We propose a novel approach for studying the ability of the brain to gather survival-relevant information from seeing conspecific body features. Specifically, we propose that behaviorally relevant information from bodies and body expressions is coded at the levels of midlevel features in the brain. These levels are relatively independent from higher-order cognitive and conscious perception of bodies and emotions. Instead, our approach is embedded in an ethological framework and mobilizes computational models for feature discovery. Survival prompts organisms to prepare adaptive behavior in response to environmental and social threat. However, what are the specific features of the appearance of a conspecific that trigger such adaptive behaviors? For social species, the prime candidates for triggering defense systems are the visual features of the face and the body. We propose a novel approach for studying the ability of the brain to gather survival-relevant information from seeing conspecific body features. Specifically, we propose that behaviorally relevant information from bodies and body expressions is coded at the levels of midlevel features in the brain. These levels are relatively independent from higher-order cognitive and conscious perception of bodies and emotions. Instead, our approach is embedded in an ethological framework and mobilizes computational models for feature discovery. Human and nonhuman primates are experts at gathering crucial survival information from body posture and movement perception. Social threat situations and reactions to them are among the most studied [1.Roelofs K. Freeze for action: neurobiological mechanisms in animal and human freezing.Philos. Trans. R. Soc. B. 2017; 372: 20160206Crossref PubMed Scopus (5) Google Scholar,2.Terburg D. et al.The basolateral amygdala is essential for rapid escape: a human and rodent study.Cell. 2018; 175: 723-735Abstract Full Text Full Text PDF PubMed Scopus (47) Google Scholar]. However, what is it specifically about the body posture or movement of a conspecific that triggers adaptive behavior? In our intuitive thinking about that question, we typically retrieve one or another salient characteristic such as head orientation, the position of the arms, or the overall movement velocity [3.Poyo Solanas M. et al.The role of computational and subjective features in emotional body expressions.Sci. Rep. 2020; 10: 6202Crossref PubMed Scopus (1) Google Scholar]. So far, very few studies have objectively measured which visual features are crucial for understanding expressive body postures and movements, and even fewer have looked at their possible brain correlates. To understand why this novel approach is needed, we must frame it in the context of current research on the brain basis of body perception. Most studies on body perception have followed in the tracks of face research by adopting a theoretical framework of object category (see Glossary)-selective areas [4.Kanwisher N. Domain specificity in face perception.Nat. Neurosci. 2000; 3: 759-763Crossref PubMed Scopus (636) Google Scholar] as the top level of a hierarchical model [5.Bruce V. Young A. Understanding face recognition.Br. J. Psychol. 1986; 77: 305-327Crossref PubMed Google Scholar,6.Haxby J.V. et al.The distributed human neural system for face perception.Trends Cogn. Sci. 2000; 4: 223-233Abstract Full Text Full Text PDF PubMed Scopus (3117) Google Scholar]. In this framework, emotion expression processes are dependent on successful high-order visual category perception. We sketch here a different approach centered not on the notion of high-level body representation as the gateway to subsequent expression decoding, but on midlevel body feature computations (Figure 1). Midlevel features are different from classical low-level visual features (e.g., edges, spatial frequency, motion direction) [7.Giese M.A. Poggio T. Neural mechanisms for the recognition of biological movements.Nat. Rev. Neurosci. 2003; 4: 179-192Crossref PubMed Scopus (625) Google Scholar] as well as from subjective semantic features that we intuitively notice and believe to be the features we act upon (i.e., high-level semantic categories of emotions, actions, and intentions) [8.Grill-Spector K. Weiner K.S. The functional architecture of the ventral temporal cortex and its role in categorization.Nat. Rev. Neurosci. 2014; 15: 536-548Crossref PubMed Scopus (307) Google Scholar]. Some examples of midlevel feature candidates derived from computational analysis of body posture and movements are limb contraction [3.Poyo Solanas M. et al.The role of computational and subjective features in emotional body expressions.Sci. Rep. 2020; 10: 6202Crossref PubMed Scopus (1) Google Scholar,9.Poyo Solanas M. et al.Computation-based feature representation of body expressions in the human brain.Cereb. Cortex. 2020; 30: 6376-6390Crossref PubMed Scopus (0) Google Scholar], head orientation, and hand to head distance [10.Zhan M. et al.Subjective understanding of actions and emotions involves the interplay of the semantic and action observation networks in the brain.BioRxiv. 2021; (Published online April 15, 2021. http://dx.doi.org/10.1101/2021.04.15.439961)PubMed Google Scholar]. Recent studies identified brain correlates of semantic features such as agentic action [11.Haxby J.V. et al.Naturalistic stimuli reveal a dominant role for agentic action in visual representation.NeuroImage. 2020; 216: 116561Crossref PubMed Scopus (4) Google Scholar], animacy [12.Thorat S. et al.The nature of the animacy organization in human ventral temporal cortex.eLife. 2019; 8e47142Crossref PubMed Scopus (5) Google Scholar], and sociality [13.Tarhan L. Konkle T. Sociality and interaction envelope organize visual action representations.Nat. Commun. 2020; 11: 3002Crossref PubMed Scopus (5) Google Scholar]. These high-level concepts are used and validated in subjective perception, but they may turn out to reduce to, or emerge from, midlevel feature computations. The goal of midlevel feature models is to provide a functional and adaptive characterization of whole-body expressions in naturalistic contexts. Notions such as ethological action maps [14.Graziano M.S. 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Systematic discovery of midlevel features of naturalistic behavior needs ethological observation of behavior combined with computational methods to counter, on the one hand, the naïve observer bias and, on the other, the dimensionality explosion of unconstrained neural networks. Studies on body perception have consistently described areas in the human brain [17.Downing P.E. et al.A cortical area selective for visual processing of the human body.Science. 2001; 293: 2470-2473Crossref PubMed Scopus (1281) Google Scholar,18.Peelen M.V. Downing P.E. Selectivity for the human body in the fusiform gyrus.J. Neurophysiol. 2005; 93: 603-608Crossref PubMed Scopus (420) Google Scholar] and body patches in the monkey brain [19.Pinsk M.A. et al.Representations of faces and body parts in macaque temporal cortex: a functional MRI study.PNAS. 2005; 102: 6996-7001Crossref PubMed Scopus (0) Google Scholar] that are selective for body images. In humans, originally one and later two areas were reported: the extrastriate body area (EBA) in the middle occipital gyrus/middle temporal gyrus [17.Downing P.E. et al.A cortical area selective for visual processing of the human body.Science. 2001; 293: 2470-2473Crossref PubMed Scopus (1281) Google Scholar,20.van de Riet W.A. et al.Specific and common brain regions involved in the perception of faces and bodies and the representation of their emotional expressions.Soc. Neurosci. 2009; 4: 101-120Crossref PubMed Scopus (83) Google Scholar], and the fusiform body area (FBA) in the fusiform cortex [18.Peelen M.V. Downing P.E. Selectivity for the human body in the fusiform gyrus.J. Neurophysiol. 2005; 93: 603-608Crossref PubMed Scopus (420) Google Scholar,20.van de Riet W.A. et al.Specific and common brain regions involved in the perception of faces and bodies and the representation of their emotional expressions.Soc. Neurosci. 2009; 4: 101-120Crossref PubMed Scopus (83) Google Scholar,21.Hadjikhani N. de Gelder B. Seeing fearful body expressions activates the fusiform cortex and amygdala.Curr. Biol. 2003; 13: 2201-2205Abstract Full Text Full Text PDF PubMed Scopus (208) Google Scholar]. The respective roles of the EBA and FBA are still not well understood. It has been suggested that the EBA may be more selective for body parts whereas the FBA may be biased towards whole-body images [22.Taylor J.C. et al.Functional MRI analysis of body and body part representations in the extrastriate and fusiform body areas.J. Neurophysiol. 2007; 98: 1626-1633Crossref PubMed Scopus (185) Google Scholar]. More recent evidence indicates that the EBA may also encode details pertaining to the shape, posture, and position of the body [23.Downing P.E. Peelen M.V. The role of occipitotemporal body-selective regions in person perception.Cogn. Neurosci. 2011; 2: 186-203Crossref PubMed Scopus (112) Google Scholar]. The current lack of clarity concerning the functions of the two body areas may in part be related to their anatomical complexity. For example, there is substantial overlap between the EBA and the human motion complex (hMT+), which makes it difficult to determine the actual involvement of the former in body motion processing [24.Ross P.D. Body form and body motion processing are dissociable in the visual pathways.Front. Psychol. 2014; 5: 767Crossref PubMed Scopus (3) Google Scholar,25.Vangeneugden J. et al.Distinct neural mechanisms for body form and body motion discriminations.J. Neurosci. 2014; 34: 574-585Crossref PubMed Scopus (0) Google Scholar]. In addition, the EBA is not a single area, as illustrated by evidence from anatomical landmarks, visual field maps, and functional stimulus comparisons [26.Weiner K.S. Grill-Spector K. Not one extrastriate body area: using anatomical landmarks, hMT+, and visual field maps to parcellate limb-selective activations in human lateral occipitotemporal cortex.NeuroImage. 2011; 56: 2183-2199Crossref PubMed Scopus (0) Google Scholar]. Although current evidence clearly supports the involvement of the FBA and EBA in body expression perception [21.Hadjikhani N. de Gelder B. Seeing fearful body expressions activates the fusiform cortex and amygdala.Curr. Biol. 2003; 13: 2201-2205Abstract Full Text Full Text PDF PubMed Scopus (208) Google Scholar,27.Grèzes J. et al.Perceiving fear in dynamic body expressions.NeuroImage. 2007; 35: 959-967Crossref PubMed Scopus (0) Google Scholar,28.Pichon S. et al.Threat prompts defensive brain responses independently of attentional control.Cereb. Cortex. 2012; 22: 274-285Crossref PubMed Scopus (0) Google Scholar], it is not clear whether the EBA or the FBA is more important for expression recognition, or whether they may have different roles depending on the specific emotion. For example, it has been shown that fear modulates the activity of the EBA but not of the FBA, although no difference has been found for other emotions [29.Peelen M.V. et al.Emotional modulation of body-selective visual areas.Soc. Cogn. Affect. Neurosci. 2007; 2: 274-283Crossref PubMed Google Scholar]. Emotion-specific differences may also be related to their different connectivity patterns (Figure 2C ). Interestingly, and along these lines, the fact that the EBA seems to be more sensitive to fearful body expressions than the FBA makes more sense from a survival point of view because the EBA has been suggested to be the interface between perceptual and motor processes [30.Zimmermann M. et al.Is the extrastriate body area part of the dorsal visuomotor stream?.Brain Struct. Funct. 2018; 223: 31-46Crossref PubMed Scopus (3) Google Scholar]. In addition to body-selective areas, the first functional magnetic resonance imaging (fMRI) studies on body expressions showed that other areas are also involved in their processing (Figure 2) [27.Grèzes J. et al.Perceiving fear in dynamic body expressions.NeuroImage. 2007; 35: 959-967Crossref PubMed Scopus (0) Google Scholar,31.de Gelder B. et al.Fear fosters flight: a mechanism for fear contagion when perceiving emotion expressed by a whole body.PNAS. 2004; 101: 16701-16706Crossref PubMed Scopus (0) Google Scholar,32.Goldberg H. et al.The emotion–action link? Naturalistic emotional stimuli preferentially activate the human dorsal visual stream.NeuroImage. 2014; 84: 254-264Crossref PubMed Scopus (0) Google Scholar]. For example, the action observation network shows increased activity for threatening body expressions than for neutral expressions [27.Grèzes J. et al.Perceiving fear in dynamic body expressions.NeuroImage. 2007; 35: 959-967Crossref PubMed Scopus (0) Google Scholar,32.Goldberg H. et al.The emotion–action link? Naturalistic emotional stimuli preferentially activate the human dorsal visual stream.NeuroImage. 2014; 84: 254-264Crossref PubMed Scopus (0) Google Scholar,33.Pichon S. et al.Two different faces of threat. Comparing the neural systems for recognizing fear and anger in dynamic body expressions.NeuroImage. 2009; 47: 1873-1883Crossref PubMed Scopus (115) Google Scholar]. The motor system, that is responsible for action preparation, also plays an important role, especially in the case of fear [31.de Gelder B. et al.Fear fosters flight: a mechanism for fear contagion when perceiving emotion expressed by a whole body.PNAS. 2004; 101: 16701-16706Crossref PubMed Scopus (0) Google Scholar,34.Borgomaneri S. et al.Early changes in corticospinal excitability when seeing fearful body expressions.Sci. Rep. 2015; 5: 14122Crossref PubMed Scopus (20) Google Scholar, 35.Hortensius R. et al.When anger dominates the mind: increased motor corticospinal excitability in the face of threat.Psychophysiology. 2016; 53: 1307-1316Crossref PubMed Scopus (14) Google Scholar, 36.Meeren H.K.M. et al.Early preferential responses to fear stimuli in human right dorsal visual stream – a MEG study.Sci. Rep. 2016; 6: 24831Crossref PubMed Scopus (16) Google Scholar, 37.Borgomaneri S. et al.Behavioral inhibition system sensitivity enhances motor cortex suppression when watching fearful body expressions.Brain Struct. Funct. 2017; 222: 3267-3282Crossref PubMed Scopus (16) Google Scholar], as do subcortical areas [9.Poyo Solanas M. et al.Computation-based feature representation of body expressions in the human brain.Cereb. Cortex. 2020; 30: 6376-6390Crossref PubMed Scopus (0) Google Scholar,38.Utter A.A. Basso M.A. The basal ganglia: an overview of circuits and function.Neurosci. Biobehav. Rev. 2008; 32: 333-342Crossref PubMed Scopus (119) Google Scholar] and cerebellum [39.Sokolov A.A. et al.Brain circuits signaling the absence of emotion in body language.PNAS. 2020; 117: 20868-20873Crossref PubMed Scopus (1) Google Scholar]. A subcortical pathway between the pulvinar, superior colliculus, and amygdala interacts with other areas to support defensive reflexes (e.g., withdrawal, freezing, startle) [40.de Gelder B. Towards the neurobiology of emotional body language.Nat. Rev. Neurosci. 2006; 7: 242-249Crossref PubMed Scopus (460) Google Scholar,41.Dean P. et al.Event or emergency? Two response systems in the mammalian superior colliculus.Trends Neurosci. 1989; 12: 137-147Abstract Full Text PDF PubMed Scopus (397) Google Scholar], and specifically does so for threatening body expressions [28.Pichon S. et al.Threat prompts defensive brain responses independently of attentional control.Cereb. Cortex. 2012; 22: 274-285Crossref PubMed Scopus (0) Google Scholar]. In particular, there is substantial evidence supporting a pivotal role of the amygdala in the assignment of affective value to incoming stimuli, and in the preparation for adaptive behaviors, by modulating attentional, perceptual, and motor processes [42.Emery N.J. Amaral D.G. The role of the amygdala in primate social cognition.in: Lane R.D. Nadel L. Cognitive Neurocience of Emotion. Oxford University Press, 2000: 156-191Google Scholar]. For over a decade, studies on body perception have implicitly assumed that body category areas constitute the gateway for processing various body attributes, in the same way as face category areas are involved in face perception [4.Kanwisher N. Domain specificity in face perception.Nat. Neurosci. 2000; 3: 759-763Crossref PubMed Scopus (636) Google Scholar,43.Shallice T. From Neuropsychology to Mental Structure. Cambridge University Press, 1988Crossref Google Scholar, 44.Kanwisher N. Yovel G. The fusiform face area: a cortical region specialized for the perception of faces.Philos. Trans. R. Soc. B. 2006; 361: 2109-2128Crossref PubMed Scopus (0) Google Scholar, 45.Kanwisher N. et al.The fusiform face area: a module in human extrastriate cortex specialized for face perception.J. Neurosci. 1997; 17: 4302-4311Crossref PubMed Google Scholar, 46.Peelen M.V. Downing P.E. The neural basis of visual body perception.Nat. Rev. Neurosci. 2007; 8: 636-648Crossref PubMed Scopus (420) Google Scholar]. With the gradual shift from category-based to network models, the notion of encapsulated category computations is loosened. Certainly, the available evidence shows that body expression perception is associated with activity in ventral body areas, but is associated equally well with activity in areas outside the body-selective areas [32.Goldberg H. et al.The emotion–action link? Naturalistic emotional stimuli preferentially activate the human dorsal visual stream.NeuroImage. 2014; 84: 254-264Crossref PubMed Scopus (0) Google Scholar,40.de Gelder B. Towards the neurobiology of emotional body language.Nat. Rev. Neurosci. 2006; 7: 242-249Crossref PubMed Scopus (460) Google Scholar]. However, whether the computations attributed to category-selective areas are needed at all for expression and action perception is an open question. Functional category models assume that category areas represent the category [47.Van Essen D.C. Maunsell J.H. Hierarchical organization and functional streams in the visual cortex.Trends Neurosci. 1983; 6: 370-375Abstract Full Text PDF Scopus (523) Google Scholar,48.Josephs E.L. Konkle T. Large-scale dissociations between views of objects, scenes, and reachable-scale environments in visual cortex.PNAS. 2020; 117: 29354-29362Crossref PubMed Scopus (1) Google Scholar] in a way that is relatively stable, and is also independent from the actual task (e.g., detection, object and/or attribute identification, passive viewing, explicit recognition) and from specific stimulus attributes (e.g., emotion, gender) [29.Peelen M.V. et al.Emotional modulation of body-selective visual areas.Soc. Cogn. Affect. Neurosci. 2007; 2: 274-283Crossref PubMed Google Scholar,49.Kanwisher N. The quest for the FFA and where it led.J. Neurosci. 2017; 37: 1056-1061Crossref PubMed Scopus (42) Google Scholar]. However, there is growing evidence showing that all these factors significantly impact on the activity in object category areas, including body-selective areas (Box 1). For example, selective attention-related increases have been found in category representation areas for the preferred category during visual search tasks [50.Çukur T. et al.Attention during natural vision warps semantic representation across the human brain.Nat. Neurosci. 2013; 16: 763-770Crossref PubMed Scopus (184) Google Scholar,51.Peelen M.V. et al.Neural mechanisms of rapid natural scene categorization in human visual cortex.Nature. 2009; 460: 94-97Crossref PubMed Scopus (0) Google Scholar].Box 1A more dynamic view on body areasHierarchical models assume that each area elaborates on the stimulus representation of previous areas [48.Josephs E.L. Konkle T. Large-scale dissociations between views of objects, scenes, and reachable-scale environments in visual cortex.PNAS. 2020; 117: 29354-29362Crossref PubMed Scopus (1) Google Scholar] in a way that is relatively stable, independently from various task-related processes and the different stimuli attributes involved (e.g., detection, identification, emotion, gender). However, some studies have reported substantial variability in how stimuli are represented in their specific category areas, indicating that their role may not be as abstract, static, high-level, and conceptual as often assumed. From research on facial expressions it is well known that, for identical stimuli, the type of task clearly influences activity in face areas (e.g., active vs passive observation, emotion recognition vs an orthogonal task) [116.Gur R.C. et al.Brain activation during facial emotion processing.NeuroImage. 2002; 16: 651-662Crossref PubMed Scopus (256) Google Scholar, 117.Habel U. et al.Amygdala activation and facial expressions: explicit emotion discrimination versus implicit emotion processing.Neuropsychologia. 2007; 45: 2369-2377Crossref PubMed Scopus (110) Google Scholar, 118.Hariri A.R. et al.Neocortical modulation of the amygdala response to fearful stimuli.Biol. Psychiatry. 2003; 53: 494-501Abstract Full Text Full Text PDF PubMed Scopus (615) Google Scholar, 119.Winston J. et al.Common and distinct neural responses during direct and incidental processing of multiple facial emotions.NeuroImage. 2003; 20: 84-97Crossref PubMed Scopus (297) Google Scholar]. There are similar findings about task effects on brain activity in the body perception literature. For example, increased activity in the FBA and EBA has been reported for emotion-naming compared to a color-naming task [28.Pichon S. et al.Threat prompts defensive brain responses independently of attentional control.Cereb. Cortex. 2012; 22: 274-285Crossref PubMed Scopus (0) Google Scholar]. Using multivariate pattern analysis we found that the difference between explicit and implicit body expression processing can be decoded with high accuracy specifically in the EBA but not in FBA [120.Marrazzo G. et al.The dynamics of body category and emotion processing in high-level visual, prefrontal and parietal cortex.BioRxiv. 2020; (Published online July 15, 2020. https://doi.org/10.1101/2020.07.14.202515)Google Scholar]. Similar strong task-driven variability in body representation has been reported with electroencephalography (EEG) [121.Jessen S. Kotz S.A. The temporal dynamics of processing emotions from vocal, facial, and bodily expressions.NeuroImage. 2011; 58: 665-674Crossref PubMed Scopus (89) Google Scholar].Substantial variations in body processing are also linked to attention and stimulus awareness. Along these lines, affective body information has been shown to modulate attention processes, as observed for example with the differential effects that fearful body expressions have on saccades compared to neutral bodies [122.Milders M. et al.Detection of emotional faces is modulated by the direction of eye gaze.Emotion. 2011; 11: 1456Crossref PubMed Scopus (38) Google Scholar]. In hemispatial neglect patients, contralesional presentation of fearful body expressions overcomes attentional deficits [123.Tamietto M. et al.Once you feel it, you see it: insula and sensory-motor contribution to visual awareness for fearful bodies in parietal neglect.Cortex. 2015; 62: 56-72Crossref PubMed Scopus (47) Google Scholar]. In the intact brain, consciously, as opposed to non-consciously, viewed images are associated with major differences in brain responses in ventral body category areas and in frontoparietal regions [61.Zhan M. et al.Ventral and dorsal pathways relate differently to visual awareness of body postures under continuous flash suppression.eNeuro. 2018; 5 (ENEURO.0285-17.2017)Crossref Scopus (5) Google Scholar,124.de Gelder B. et al.Attention and awareness each influence amygdala activity for dynamic bodily expressions – a short review.Front. Integr. Neurosci. 2012; 6: 54Crossref PubMed Scopus (42) Google Scholar,125.Zhan M. et al.The body as a tool for anger awareness – differential effects of angry facial and bodily expressions on suppression from awareness.PLoS One. 2015; 10e0139768Crossref PubMed Scopus (14) Google Scholar]. There is also evidence for body processing without awareness in EBA, but not in FBA, in patients with full bilateral visual cortex lesion [126.Van den Stock J. et al.Body recognition in a patient with bilateral primary visual cortex lesions.Biol. Psychiatry. 2015; 77: e31-e33Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar]. This EBA activation indicates that category-specific areas in the ventral stream can still receive visual input through a V1-independent pathway (Box 2). Some features of the body shape or movement may be sufficient to drive these responses, but we do not know which partial and feature-based computations of the body image sustain the non-conscious percept. Hierarchical models assume that each area elaborates on the stimulus representation of previous areas [48.Josephs E.L. Konkle T. Large-scale dissociations between views of objects, scenes, and reachable-scale environments in visual cortex.PNAS. 2020; 117: 29354-29362Crossref PubMed Scopus (1) Google Scholar] in a way that is relatively stable, independently from various task-related processes and the different stimuli attributes involved (e.g., detection, identification, emotion, gender). However, some studies have reported substantial variability in how stimuli are represented in their specific category areas, indicating that their role may not be as abstract, static, high-level, and conceptual as often assumed. From research on facial expressions it is well known that, for identical stimuli, the type of task clearly influences activity in face areas (e.g., active vs passive observation, emotion recognition vs an orthogonal task) [116.Gur R.C. et al.Brain activation during facial emotion processing.NeuroImage. 2002; 16: 651-662Crossref PubMed Scopus (256) Google Scholar, 117.Habel U. et al.Amygdala activation and facial expressions: explicit emotion discrimination versus implicit emotion processing.Neuropsychologia. 2007; 45: 2369-2377Crossref PubMed Scopus (110) Google Scholar, 118.Hariri A.R. et al.Neocortical modulation of the amygdala response to fearful stimuli.Biol. Psychiatry. 2003; 53: 494-501Abstract Full Text Full Text PDF PubMed Scopus (615) Google Scholar, 119.Winston J. et al.Common and distinct neural responses during direct and incidental processing of multiple facial emotions.NeuroImage. 2003; 20: 84-97Crossref PubMed Scopus (297) Google Scholar]. There are similar findings about task effects on brain activity in the body perception literature. For example, increased activity in the FBA and EBA has been reported for emotion-naming compared to a color-naming task [28.Pichon S. et al.Threat prompts defensive brain responses independently of attentional control.Cereb. Cortex. 2012; 22: 274-285Crossref PubMed Scopus (0) Google Scholar]. Using multivariate pattern analysis we found that the difference between explicit and implicit body expression processing can be decoded with high accuracy specifically in the EBA but not in FBA [120.Marrazzo G. et al.The dynamics of body category and emotion processing in high-level visual, prefrontal and parietal cortex.BioRxiv. 2020; (Published online July 15, 2020. https://doi.org/10.1101/2020.07.14.202515)Google Scholar]. Similar strong task-driven variability in body representation has been reported with electroencephalography (EEG) [121.Jessen S. Kotz S.A. The temporal dynamics of processing emotions from vocal, facial, and bodily expressions.NeuroImage. 2011; 58: 665-674Crossref PubMed Scopus (89) Google Scholar]. Substantial variations in body processing are also linked to attention and stimulus awareness. Along these lines, affective body information has been shown to modulate attention processes, as observed for example with the differential effects that fearful body expressions have on saccades compared to neutral bodies [122.Milders M. et al.Detection of emotional faces is modulated by the direction of eye gaze.Emotion. 2011; 11: 1456Crossref PubMed Scopus (38) Google Scholar]. In hemispatial neglect patients,
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