1,721,050 research outputs found
Blind Vision: The neuroscience of visual impairment
No full textCan a blind person see? The very idea seems paradoxical. And yet, if we conceive of "seeing" as the ability to generate internal mental representations that may contain visual details, the idea of blind vision becomes a concept subject to investigation. In this book, Zaira Cattaneo and Tomaso Vecchi examine the effects of blindness and other types of visual deficit on the development and functioning of the human cognitive system. Drawing on behavioral and neurophysiological data, Cattaneo and Vecchi analyze research on mental imagery, spatial cognition, and compensatory mechanisms at the sensorial, cognitive, and cortical levels in individuals with complete or profound visual impairment. They find that our brain does not need our eyes to "see." Cattaneo and Vecchi address critical questions of broad importance; the relationship of visual perception to imagery and working memory and the extent to which mental imagery depends on normal vision; the functional and neural relationships between vision and the other senses; the specific aspects of the visual experience that are crucial to cognitive development or specific cognitive mechanisms; and the extraordinary plasticity of the brain—as illustrated by the way that, in the blind, the visual cortex may be reorganized to support other perceptual or cognitive functions. In the absence of vision, the other senses work as functional substitutes and are often improved. With Blind Vision, Cattaneo and Vecchi take on the "tyranny of the visual," pointing to the importance of the other senses in cognition
Effects of late visual impairment on mental representations activated by visual and tactile stimuli.
No full textSimilarly to sighted people, individuals congenitally affected by a severe visual impairment can maintain and mentally manipulate spatial information about tactile stimuli [Vecchi, T., Cattaneo, Z., Monegato, M., Pece, A., Cornoldi, C., Pietrini, P., 2006. Why Cyclops could not compete with Ulysses: monocular vision and mental images. NeuroReport 17, 723-726]. The aim of the present study was to assess whether the onset timing of a severe (but not total) sight loss may influence spatial imagery abilities based on haptic input. To this purpose, a group of late severe visually impaired people and a matched group of normally sighted participants (all blindfolded) were presented with an imagery task requiring to memorize and retrieve a number of locations presented on tactile matrices. Results indicate that a severe visual deficit occurring later in life significantly impairs spatial imagery abilities to a greater extent than in the case of congenital blindness, probably as a consequence of a modest development of specific compensatory mechanisms associated with congenital deficits
Cerebellar Contribution to Emotional Body Language Perception
No full textBody language is a powerful form of non-verbal communication providing important information about the emotions and intentions of others. The ability to infer other's emotions from their bodily movements and postures recruits an extended network in the brain that encompasses both cortical and subcortical regions. In this chapter, we review recent evidence suggesting that the cerebellum is a critical node of this network. Specifically, we present convergent findings from patients', neuroimaging and non-invasive brain stimulation studies that have shown that the cerebellum is involved in both biological motion perception and in discrimination of bodily emotional expressions. We discuss the potential underlying mechanisms that drive the recruitment of the sensorimotor (anterior) and cognitive (posterior) cerebellum in inferring others' emotions through their bodily movements and postures and how the cerebellum may exert these functions within different cortico-cerebellar and limbic-cerebellar networks dedicated to body language perception
TMS over the superior temporal sulcus affects expressivity evaluation of portraits
No full textWhen viewing a portrait, we are often captured by its expressivity, even if the emotion depicted is not immediately identifiable. If the neural mechanisms underlying emotion processing of real faces have been largely clarified, we still know little about the neural basis of evaluation of (emotional) expressivity in portraits. In this study, we aimed at assessing—by means of transcranial magnetic stimulation (TMS)—whether the right superior temporal sulcus (STS) and the right somatosensory cortex (SC), that are important in discriminating facial emotion expressions, are also causally involved in the evaluation of expressivity of portraits. We found that interfering via TMS with activity in (the face region of) right STS significantly reduced the extent to which portraits (but not other paintings depicting human figures with faces only in the background) were perceived as expressive, without, though, affecting their liking. In turn, interfering with activity of the right SC had no impact on evaluating either expressivity or liking of either paintings’ category. Our findings suggest that evaluation of emotional cues in artworks recruit (at least partially) the same neural mechanisms involved in processing genuine biological others. Moreover, they shed light on the neural basis of liking decisions in art by art-naïve people, supporting the view that aesthetic appreciation relies on a multitude of factors beyond emotional evaluation
Spatial biases in deaf, blind, and deafblind individuals as revealed by a haptic line bisection task
No full textIn this study, we investigated whether auditory deprivation leads to a more balanced bilateral control of spatial attention in the haptic space. We tested four groups of participants: early deaf, early blind, deafblind, and control (normally hearing and sighted) participants. Using a haptic line bisection task, we found that while normally hearing individuals (even when blind) showed a significant tendency to bisect to the left of the veridical midpoint (i.e., pseudoneglect), deaf individuals did not show any significant directional bias. This was the case of both deaf signers and non-signers, in line with prior findings obtained using a visual line bisection task. Interestingly, deafblind individuals also erred significantly to the left, resembling the pattern of early blind and control participants. Overall, these data critically suggest that deafness induces changes in the hemispheric asymmetry subtending the orientation of spatial attention also in the haptic modality. Moreover, our findings indicate that what counterbalances the right-hemisphere dominance in the control of spatial attention is not the lack of auditory input per se, nor sign language use, but rather the heavier reliance on visual experience induced by early auditory deprivation
Functional Segregation of the Human Cerebellum in Social Cognitive Tasks Revealed by TMS
No full text: The role of the posterior cerebellum in social cognition is well established; however, it is still unclear whether different cerebellar subregions contribute to different social cognitive processes by exerting specific functions. Here, we employed transcranial magnetic stimulation (TMS) in male and female healthy humans to test the hypothesis of the existence of a medial-to-lateral gradient in the functional organization of the posterior cerebellum, according to which the phylogenetically newer cerebellar hemispheres are involved in tasks requiring higher-level social inferences whereas vermal/medial sectors are involved in basic perceptual emotional mechanisms. We found that interfering via TMS with activity of the medial cerebellum significantly impaired basic emotional recognition/discrimination. In turn, only TMS over the lateral cerebellum affected a task requiring recognizing an emotion considering the social context in which it was experienced. Overall, our data support the existence of a medial-to-lateral gradient in the posterior cerebellum, with medial sectors supporting basic emotion recognition and lateral sectors being recruited when the task taps on higher inferential processing/mentalizing. Interestingly, the contribution of the cerebellum in these different processes seems to be restricted to negative emotional stimuli.SIGNIFICANCE STATEMENT The cerebellum has been recently recognized as a critical component of the social brain, however, the functional topography of this structure in relation to social and emotional processes is still debated. By adopting a causative approach through the use of transcranial magnetic stimulation (TMS), the present study critically insights into the functional organization of the posterior cerebellum by testing the hypothesis of a medial-to-lateral gradient that reflects increasing complexity of social cognitive processes. Our findings demonstrate that lateral and medial cerebellar regions exert partially distinguishable functions in the social cognitive domain, with the medial cerebellum that mainly mediates basic perceptual emotional mechanisms while the lateral cerebellum, although supporting more basic functions, further subserves higher-level social operations
Dorsomedial prefrontal cortex and cerebellar contribution to in-group attitudes: a transcranial magnetic stimulation study
No full textWe tend to express more positive judgments and behaviors toward individuals belonging to our own group compared to other (out-) groups. In this study, we assessed the role of the cerebellum and of the dorsomedial prefrontal cortex (dmPFC) – two regions critically implicated in social cognition processes – in mediating implicit valenced attitudes toward in-group and out-group individuals. To this aim, we used transcranial magnetic stimulation (TMS) in combination with a standard attitude priming task, in which Caucasian participants had to categorize the valence of a series of adjectives primed by either an in-group or an out-group face. In two behavioral experiments, we found an in-group bias (i.e. faster categorization of positive adjectives when preceded by in-group faces) but no evidence of an out-group bias. Interestingly, TMS over both the dmPFC and over the (right) cerebellum significantly interfered with the modulation exerted by group membership on adjective valence classification, abolishing the in-group bias observed at baseline. Overall, our data suggest that both the dmPFC and the cerebellum play a causal role in mediating implicit social attitudes
Listening to white noise counteracts visual and haptic pseudoneglect
No full textNeurologically intact individuals usually show a leftward bias in line bisection, a tendency known as "pseudoneglect", likely reflecting a right-hemisphere dominance in controlling the allocation of spatial attention. Studies in brain-damaged patients with left visuospatial neglect have reported that auditory stimulation may reduce the deficit, both in a spatially dependent and in a spatially independent way. Here we show for the first time that the concurrent binaural presentation of auditory white noise affects healthy individuals' performance in both visual and haptic bisection, reducing their leftward error. We suggest that this effect depends on the noise boosting alertness and restoring the hemispheric activation balance. Our data clearly show that task-irrelevant auditory noise crossmodally affects the allocation of spatial resources in both the haptic and the visual space; future research may clarify whether these effects are specific for the type of auditory stimulatio
A chronometric study of the posterior cerebellum's function in emotional processing
No full textThe posterior cerebellum is a recently discovered hub of the affective and social brain, with different subsectors contributing to different social functions. However, very little is known about when the posterior cerebellum plays a critical role in social processing. Due to its location and anatomy, it has been difficult to use traditional approaches to directly study the chronometry of the cerebellum. To address this gap in cerebellar knowledge, here we investigated the causal contribution of the posterior cerebellum to social processing using a chronometric transcranial magnetic stimulation (TMS) approach. We show that the posterior cerebellum is recruited at an early stage of emotional processing (starting from 100 ms after stimulus onset), simultaneously with the posterior superior temporal sulcus (pSTS), a key node of the social brain. Moreover, using a condition -and -perturb TMS approach, we found that the recruitment of the pSTS in emotional processing is dependent on cerebellar activation. Our results are the first to shed light on chronometric aspects of cerebellar function and its causal functional connectivity with other nodes of the social brain
Viewing of figurative paintings affects pseudoneglect as measured by line bisection
No full textNeurologically intact individuals usually show a leftward bias in spatial attention, known as pseudoneglect, likely reflecting a right-hemisphere dominance in the control of spatial attention. A leftward bias also seems to manifest when individuals are asked to provide aesthetic judgments about visual stimuli, like artworks. However, whether artwork perception affects the allocation of spatial attention has never been directly investigated. Here, we assessed whether viewing figurative paintings affects hemispheric imbalance in the control of spatial attention by asking participants to bisect a series of lines presented on a grey background, on figurative paintings or on non-artistic photographs of real-world scenes, while either simply observing or explicitly evaluating each image. In line with previous evidence, participants showed a leftward bisection bias in the baseline condition, reflecting pseudoneglect. Critically, the presence of a painting in the background (irrespective of whether an aesthetic evaluation was required or not) significantly shifted the bias further to the left compared to when lines were bisected over a grey background (baseline) or a photographed scene. This finding suggests that perception of visual art may affect the control of spatial attention, possibly tapping on right-hemisphere resources related to visuospatial exploration, regardless of reward apprehension mechanisms (at least when images do not evoke strong emotional reactions leading to polarized like/dislike judgements)
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