Biology subjects

Poyo Solanas, M.

Publications and source records attributed to Poyo Solanas, M..

7 recordsLinked to original sources

bioRxiv2026

Local Motion Is Sufficient for Human Body Movement Perception in High-Level Visual Cortex

Perceiving the movements of other living organisms is a fundamental ability across species. Although several cortical regions are selective for static body features, it is unclear whether these areas also encode motion cues independently of body shapes. Here, we isolated optical flow patterns from naturalistic body movements using synthesized videos that eliminate explicit body shape information. Behavioral results suggest that participants successfully recognized walking directions from the shape-free flow motion stimuli. Using ultra-high field fMRI, we found that three body-motion-related areas, fusiform gyrus (FG), lateral occipitotemporal cortex (LOTC), and posterior superior temporal sulcus (pSTS), were sensitive to both the amount and the spatiotemporal structure of flow motion. Critically, the flow motion effects were significantly correlated to voxel-wise body motion selectivity in FG and LOTC, but not to body shape selectivity in any of the ROIs. These findings identify flow motion as a distinct and behaviorally sufficient cue for body perception, which could dissociate the neural mechanism underlying motion and shape encoding in FG and LOTC.

neuroscience↗

bioRxiv2024

Awareness is determined by emotion and gender

Traditionally, consciousness studies focus on domain general cognitive processes rather than on specific information reaching subjective awareness. The present study (N = 45) used visual masking and whole-body images to investigate whether the specific emotional expression as well as gender of the stimuli and of the participants impact awareness. Our results show that participants awareness responses reflect differences in the specific emotion of the stimuli, that these differences are a function of the gender of the stimuli as well as the gender of the participants and that minimal awareness may be associated with emotion specific features of the body images. Overall, we observed that threatening expressions are more easily detected than fearful ones, especially by males presented with male stimuli. Our findings underscore the importance of affective factors for theories of consciousness and underscore the significance of gender differences in emotional processing, often overlooked in past face and body emotion recognition studies.

neuroscience↗

bioRxiv2024

Connectivity and functional diversity of different temporo-occipital nodes for action perception

The temporo-occipital cortex (TOC) plays a key role in body and action perception, but current understanding of its functions is still limited. TOC body regions are heterogeneous and their role in action perception is poorly understood. This study adopted data-driven approaches to region selectivity and investigated the connectivity of TOC nodes and the functional network sensitivity for different whole body action videos. In two human 7T fMRI experiments using independent component analysis, four adjacent body selective nodes were detected within the TOC network with distinct connectivity profiles and functional roles. Action type independent connectivity was observed for the posterior-ventral node to the visual cortex, the posterior-dorsal node to the precuneus and the anterior nodes to the frontal cortex. Action specific connectivity modulations were found in middle frontal gyrus for the aggressive condition with increased connectivity to the anterior node and decreased connectivity to the posterior-dorsal node. But for the defensive condition, node-nonspecific enhancement was found for the TOC-cingulate connectivity. By addressing the issue of multiple nodes in the temporo-occipital network we show a functional dissociation of different body selective centres related to the action type and a potential hierarchy within the TOC body network.

neuroscience↗

bioRxiv2022

Perceptual awareness is gradual in temporal and dichotomous in fronto-parietal cortices

Two major issues in consciousness research concern the measuring methods that determine perceptual unawareness and whether consciousness is a gradual or an all-or-nothing phenomenon. This 7T fMRI study addresses both questions using a continuous flash suppression paradigm with an emotional recognition task (fear vs neutral bodies) in combination with the perceptual awareness scale. Behaviorally, recognition sensitivity increased linearly with increased stimuli awareness and was at chance level during perceptual unawareness. Threat expressions triggered a slower heart rate than neutral ones during almost clear experience of the stimulus, indicating freezing behavior. The activity in occipital, temporal, parietal and frontal regions as well as in amygdala increased with increased stimulus awareness while the activity in early visual areas showed the opposite pattern. The relationship between temporal area activity and perceptual awareness was better characterized by a gradual model while the activity in fronto-parietal areas by a dichotomous model, suggesting different roles in conscious processing. Interestingly, no evidence of non-conscious processing was found in amygdala as well as no significant effect of emotion, in disagreement with the functions long ascribed to this subcortical structure.

neuroscience↗

bioRxiv2022

Gradual relation between perceptual awareness, recognition and pupillary responses to social threat

There is substantial evidence about affective stimulus processing outside awareness in healthy participants and brain-damaged patients. However, there are still methodological concerns mainly relating to the methods used to assess awareness. In two experiments, we investigated the processing of social threat in healthy participants by combining the continuous flash suppression paradigm and the perceptual awareness scale, a finer measure of perceptual awareness than dichotomous (seen/unseen) responses. Our behavioral results show a gradual relationship between emotional recognition and perceptual awareness. Recognition sensitivity was also higher for fearful than angry bodies for all visual awareness levels except for the perceptual unawareness condition where performance was at chance level. Interestingly, angry body expressions were suppressed for a shorter duration than neutral and fearful ones. Pupil dilation was a function of affective expression, the duration of suppression and the level of perceptual awareness. In conclusion, behavioral as well as pupillary responses showed a gradual relationship with perceptual awareness, and this relationship was influenced by the specific stimulus category.

neuroscience↗

bioRxiv2022

A large-scale brain network of species-specific dynamic human body perception

This ultrahigh field 7T fMRI study addressed the question of whether there exists a core network of brain areas at the service of different aspects of body perception. Participants viewed naturalistic videos of monkey and human faces, bodies, and objects along with mosaic-scrambled videos for control of low-level features. ICA-based network analysis was conducted to find body and species modulations at both the voxel and the network levels. Among the body areas, the highest species selectivity was found in the middle frontal gyrus and amygdala. Two large-scale networks were highly selective to bodies, dominated by the lateral occipital cortex and right superior temporal sulcus (STS) respectively. The right STS network showed high species selectivity, and its significant human body-induced node connectivity was focused around the extrastriate body area (EBA), STS, temporoparietal junction (TPJ), premotor cortex, and inferior frontal gyrus (IFG). The human body-specific network discovered here may serve as a brain-wide internal model of the human body serving as an entry point for a variety of processes relying on body descriptions as part of their more specific categorization, action, or expression recognition functions.

neuroscience↗

bioRxiv2020

Limb contraction drives fear perception

Humans and other primate species are experts at recognizing affective information from body movements but the underlying brain mechanisms are still largely unknown. Previous research focusing on the brain representation of symbolic emotion categories has led to mixed results. This study used representational similarity and multi-voxel pattern analysis techniques to investigate how postural and kinematic features computed from affective whole-body movement videos are related to brain processes. We show that body posture and kinematics differentially activated brain regions indicating that this information might be selectively encoded in these regions. Most specifically, the feature limb contraction seemed to be particularly relevant for distinguishing fear and it was represented in several regions spanning affective, action observation and motor preparation networks. Our approach goes beyond traditional methods of mapping symbolic emotion categories to brain activation/deactivation by discovering which specific movement features are encoded in the brain, and possibly drive automatic emotion perception.

neuroscience↗