Early visual experience and the recognition of basic facial expressions: involvement of the middle temporal and inferior frontal gyri during haptic identification by the early blind

Recognition of facial expressions of emotions in tactile drawings by blind children, children with low vision and sighted children

In the context of blindness, studies on the recognition of facial expressions of emotions by touch are essential to define the compensatory touch abilities and to create adapted tools on emotions. This study is the first to examine the effect of visual experience in the recognition of tactile drawings of facial expressions of emotions by children with different visual experiences. To this end, we compared the recognition rates of tactile drawings of emotions between blind children, children with low vision and sighted children aged 6-12 years. Results revealed no effect of visual experience on recognition rates. However, an effect of emotions and an interaction effect between emotions and visual experience were found. Indeed, while all children had a low average recognition rate, the drawings of fear, anger and disgust were particularly poorly recognized. Moreover, sighted children were significantly better at recognizing the drawings of surprise and sadness than the blind children who only showed high recognition rates for joy. The results of this study support the importance of developing emotion tools that can be understood by children with different visual experiences.

"Love looks not with the eyes": supranormal processing of emotional speech in individuals with late-blindness versus preserved processing in individuals with congenital-blindness

Processing of emotional speech in the absence of visual information relies on two auditory channels: semantics and prosody. No study to date has investigated how blindness impacts this process. Two theories, Perceptual Deficit, and Sensory Compensation, yiled different expectations about the role of visual experience (or its lack thereof) in processing emotional speech. To test the effect of vision and early visual experience on processing of emotional speech, we compared individuals with congenital blindness (CB, n = 17), individuals with late blindness (LB, n = 15), and sighted controls (SC, n = 21) on identification and selective-attention of semantic and prosodic spoken-emotions. Results showed that individuals with blindness performed at least as well as SC, supporting Sensory Compensation and the role of cortical reorganisation. Individuals with LB outperformed individuals with CB, in accordance with Perceptual Deficit, supporting the role of early visual experience. The LB advantage was moderated by executive functions (working-memory). Namely, the advantage was erased for individuals with CB who showed higher levels of executive functions. Results suggest that vision is not necessary for processing of emotional speech, but early visual experience could improve it. The findings support a combination of the two aforementioned theories and reject a dichotomous view of deficiencies/enhancements of blindness.

Developing cortex is functionally pluripotent: Evidence from blindness

How rigidly does innate architecture constrain function of developing cortex? What is the contribution of early experience? We review insights into these questions from visual cortex function in people born blind. In blindness, occipital cortices are active during auditory and tactile tasks. What 'cross-modal' plasticity tells us about cortical flexibility is debated. On the one hand, visual networks of blind people respond to higher cognitive information, such as sentence grammar, suggesting drastic repurposing. On the other, in line with 'metamodal' accounts, sighted and blind populations show shared domain preferences in ventral occipito-temporal cortex (vOTC), suggesting visual areas switch input modality but perform the same or similar perceptual functions (e.g., face recognition) in blindness. Here we bring these disparate literatures together, reviewing and synthesizing evidence that speaks to whether visual cortices have similar or different functions in blind and sighted people. Together, the evidence suggests that in blindness, visual cortices are incorporated into higher-cognitive (e.g., fronto-parietal) networks, which are a major source long-range input to the visual system. We propose the connectivity-constrained experience-dependent account. Functional development is constrained by innate anatomical connectivity, experience and behavioral needs. Infant cortex is pluripotent, the same anatomical constraints develop into different functional outcomes.

Facial emotion recognition deficits are associated with hypomimia and related brain correlates in Parkinson's disease

Hypomimia is a frequent manifestation in Parkinson's disease (PD) that can affect interpersonal relationships and quality of life. Recent studies have suggested that hypomimia is not only related to motor dysfunction but also to impairment in emotional processing networks. Therefore, we hypothesized that the severity of hypomimia could be associated with performance on a task aimed at assessing facial emotion recognition. In this study, we explored the association between hypomimia, recognition of facial expressions of basic emotions using the Ekman 60 Faces Test (EF), and brain correlates of both hypomimia and performance on the EF. A total of 94 subjects underwent clinical assessments (neurological and neuropsychological examinations), and 56 of them participated in the neuroimaging study. We found significant correlation between hypomimia, EF Disgust (r = -0.242, p = 0.022) and EF Happiness (r = -0.264, p = 0.012); an independent reduction in Cortical Thickness (Cth) in the postcentral gyrus, insula, middle and superior temporal gyri, supramarginal gyrus, banks of the superior temporal sulcus, bilateral fusiform gyri, entorhinal cortex, parahippocampal gyrus, inferior and superior parietal cortex, and right cuneus and precuneus; and multiple correlations between negative emotions such as EF Disgust or EF Anger and a reduced Cth in fronto-temporo-parietal regions. In conclusion, these results suggest that the association between hypomimia and emotion recognition deficits in individuals with PD might be mediated by shared circuits, supporting the concept that hypomimia is not only the result of the dysfunction of motor circuits, but also of higher cognitive functions.

Age-related differences in structural and resting-state functional brain network organization across the adult lifespan: A cross-sectional study

We investigated age-related trends in the topology and hierarchical organization of brain structural and functional networks using diffusion-weighted imaging and resting-state fMRI data from a large cohort of healthy aging adults. At the cross-modal level, we explored age-related patterns in the RC involvement of different functional subsystems using a high-resolution functional parcellation. We further assessed age-related differences in the structure-function coupling as well as the network vulnerability to damage to rich club connectivity. Regardless of age, the structural and functional brain networks exhibited a rich club organization and small-world topology. In older individuals, we observed reduced integration and segregation within the frontal-occipital regions and the cerebellum along the brain's medial axis. Additionally, functional brain networks displayed decreased integration and increased segregation in the prefrontal, centrotemporal, and occipital regions, and the cerebellum. In older subjects, structural networks also exhibited decreased within-network and increased between-network RC connectivity. Furthermore, both within-network and between-network RC connectivity decreased in functional networks with age. An age-related decline in structure-function coupling was observed within sensory-motor, cognitive, and subcortical networks. The structural network exhibited greater vulnerability to damage to RC connectivity within the language-auditory, visual, and subcortical networks. Similarly, for functional networks, increased vulnerability was observed with damage to RC connectivity in the cerebellum, language-auditory, and sensory-motor networks. Overall, the network vulnerability decreased significantly in subjects older than 70 in both networks. Our findings underscore significant age-related differences in both brain functional and structural RC connectivity, with distinct patterns observed across the adult lifespan.

Immune-related visual dysfunction in thyroid eye disease: a combined orbital and brain neuroimaging study

OBJECTIVES

To investigate the pathological interplay between immunity and the visual processing system (VPS) in thyroid eye disease (TED).

METHODS

A total of 24 active patients (AP), 26 inactive patients (IP) of TED, and 27 healthy controls (HCs) were enrolled. Orbital magnetic resonance imaging (MRI) and resting-state functional MRI (rs-fMRI) were conducted for each participant. Multiple MRI parameters of the intraorbital optic nerve (ON) were assessed. The amplitude of low-frequency fluctuations (ALFF) and regional homogeneity (ReHo) were calculated. Correlation analyses were carried out on the above parameters and clinical characteristics.

RESULTS

Visual functioning scores differentiated between the AP and IP groups. The ON subarachnoid space and ON sheath diameter were significantly higher in AP than in IP. Six vision-related brain regions were identified in TED patients compared with HCs, including right calcarine (CAL.R), right cuneus (CUN.R), left postcentral gyrus (PoCG.L), right middle temporal gyrus (MTG.R), left superior frontal gyrus (SFG.L), and left caudate (CAU.L). The brain activity of MTG.R, SFG.L, and CAU.L differentiated between the AP and IP groups. The correlation analysis revealed a close association among the vision-related brain regions, MRI parameters of ON, and clinical characteristics in AP and IP, respectively.

CONCLUSIONS

Combined orbital and brain neuroimaging revealed abnormalities of the VPS in TED, which had a close correlation with immune statuses. Vision-related brain regions in TED might be possibly altered by peripheral immunity via a direct or indirect approach.

CLINICAL RELEVANCE STATEMENT

The discovery of this study explained the disparity of visual dysfunction in TED patients with different immune statuses. With the uncovered neuroimaging markers, early detection and intervention of visual dysfunction could be achieved and potentially benefit TED patients.

KEY POINTS

• Patients with different immune statuses of thyroid eye disease varied in the presentation of visual dysfunction. • The combined orbital and brain neuroimaging study identified six altered vision-related brain regions, which had a significant correlation with the MRI parameters of the intraorbital optic nerve and immunological characteristics. • Peripheral immunity might possibly give rise to alterations in the central nervous system part of the visual processing system via a direct or indirect approach.

Early visual exposure primes future cross-modal specialization of the fusiform face area in tactile face processing in the blind

The fusiform face area (FFA) is a core cortical region for face information processing. Evidence suggests that its sensitivity to faces is largely innate and tuned by visual experience. However, how experience in different time windows shape the plasticity of the FFA remains unclear. In this study, we investigated the role of visual experience at different time points of an individual's early development in the cross-modal face specialization of the FFA. Participants (n = 74) were classified into five groups: congenital blind, early blind, late blind, low vision, and sighted control. Functional magnetic resonance imaging data were acquired when the participants haptically processed carved faces and other objects. Our results showed a robust and highly consistent face-selective activation in the FFA region in the early blind participants, invariant to size and level of abstraction of the face stimuli. The cross-modal face activation in the FFA was much less consistent in other groups. These results suggest that early visual experience primes cross-modal specialization of the FFA, and even after the absence of visual experience for more than 14 years in early blind participants, their FFA can engage in cross-modal processing of face information.

Developmental changes within the extended face processing network: A cross-sectional functional magnetic resonance imaging study

In the field of face processing, the so-called "core network" has been intensively researched. Its neural activity can be reliably detected in children and adults using functional magnetic resonance imaging (fMRI). However, the core network's counterpart, the so-called "extended network," has been less researched. In the present study, we compared children's and adults' brain activity in the extended system, in particular in the amygdala, the insula, and the inferior frontal gyrus (IFG). Using fMRI, we compared the brain activation pattern between children aged 7-9 years and adults during an emotional face processing task. On the one hand, children showed increased activity in the extended face processing system in relation to adults, particularly in the left amygdala, the right insula, and the left IFG. On the other hand, lateralization indices revealed a "leftward bias" in children's IFG compared to adults. These results suggest that brain activity associated with face processing is characterized by a developmental decrease in activity. They further show that the development is associated with a rightward migration of face-related IFG activation, possibly due to the competition for neural space between several developing brain functions ("developmental competition hypothesis").

The recognition of emotional prosody in students with blindness: Effects of early visual experience and age development

This study examined the role of early visual experience and age in the recognition of emotional prosody among students with visual impairments in China. A total of 75 primary and junior high school students participated in the study. The ability of participants to recognize the prosody of four basic emotions (sadness, anger, happiness, and neutrality) was explored. The findings were as follows. (1) Early visual experience had a significant effect on the recognition of emotional prosody. The accuracy rate of students with congenital blindness was lower than that of students with adventitious blindness, and the performance of students with congenital blindness was lower than that of sighted students. The students with congenital blindness exhibited the slowest recognition speeds. (2) Age had a significant effect on the emotional prosody recognition accuracy of the sighted students, but it had no effect on the students with blindness.

Brain networks underlying the processing of sound symbolism related to softness perception

Unlike the assumption of modern linguistics, there is non-arbitrary association between sound and meaning in sound symbolic words. Neuroimaging studies have suggested the unique contribution of the superior temporal sulcus to the processing of sound symbolism. However, because these findings are limited to the mapping between sound symbolism and visually presented objects, the processing of sound symbolic information may also involve the sensory-modality dependent mechanisms. Here, we conducted a functional magnetic resonance imaging experiment to test whether the brain regions engaged in the tactile processing of object properties are also involved in mapping sound symbolic information with tactually perceived object properties. Thirty-two healthy subjects conducted a matching task in which they judged the congruency between softness perceived by touch and softness associated with sound symbolic words. Congruency effect was observed in the orbitofrontal cortex, inferior frontal gyrus, insula, medial superior frontal gyrus, cingulate gyrus, and cerebellum. This effect in the insula and medial superior frontal gyri was overlapped with softness-related activity that was separately measured in the same subjects in the tactile experiment. These results indicate that the insula and medial superior frontal gyrus play a role in processing sound symbolic information and relating it to the tactile softness information.

Social cognition in the blind brain: A coordinate-based meta-analysis

Social cognition skills are typically acquired on the basis of visual information (e.g., the observation of gaze, facial expressions, gestures). In light of this, a critical issue is whether and how the lack of visual experience affects neurocognitive mechanisms underlying social skills. This issue has been largely neglected in the literature on blindness, despite difficulties in social interactions may be particular salient in the life of blind individuals (especially children). Here we provide a meta-analysis of neuroimaging studies reporting brain activations associated to the representation of self and others' in early blind individuals and in sighted controls. Our results indicate that early blindness does not critically impact on the development of the "social brain," with social tasks performed on the basis of auditory or tactile information driving consistent activations in nodes of the action observation network, typically active during actual observation of others in sighted individuals. Interestingly though, activations along this network appeared more left-lateralized in the blind than in sighted participants. These results may have important implications for the development of specific training programs to improve social skills in blind children and young adults.

Visual experience is not necessary for the development of face-selectivity in the lateral fusiform gyrus

The fusiform face area responds selectively to faces and is causally involved in face perception. How does face-selectivity in the fusiform arise in development, and why does it develop so systematically in the same location across individuals? Preferential cortical responses to faces develop early in infancy, yet evidence is conflicting on the central question of whether visual experience with faces is necessary. Here, we revisit this question by scanning congenitally blind individuals with fMRI while they haptically explored 3D-printed faces and other stimuli. We found robust face-selective responses in the lateral fusiform gyrus of individual blind participants during haptic exploration of stimuli, indicating that neither visual experience with faces nor fovea-biased inputs is necessary for face-selectivity to arise in the lateral fusiform gyrus. Our results instead suggest a role for long-range connectivity in specifying the location of face-selectivity in the human brain.

Properties of cross-modal occipital responses in early blindness: An ALE meta-analysis

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ALE meta-analysis reveals distributed brain networks for object and spatial functions in individuals with early blindness.

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ALE contrast analysis reveals specific activations in the left cuneus and lingual gyrus for language function, suggesting a reverse hierarchical organization of the visual cortex for early blind individuals.

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The findings contribute to visual rehabilitation in blind individuals by revealing the function-dependent and sensory-independent networks during nonvisual processing.

Cross-modal occipital responses appear to be essential for nonvisual processing in individuals with early blindness. However, it is not clear whether the recruitment of occipital regions depends on functional domain or sensory modality. The current study utilized a coordinate-based meta-analysis to identify the distinct brain regions involved in the functional domains of object, spatial/motion, and language processing and the common brain regions involved in both auditory and tactile modalities in individuals with early blindness. Following the PRISMA guidelines, a total of 55 studies were included in the meta-analysis. The specific analyses revealed the brain regions that are consistently recruited for each function, such as the dorsal fronto-parietal network for spatial function and ventral occipito-temporal network for object function. This is consistent with the literature, suggesting that the two visual streams are preserved in early blind individuals. The contrast analyses found specific activations in the left cuneus and lingual gyrus for language function. This finding is novel and suggests a reverse hierarchical organization of the visual cortex for early blind individuals. The conjunction analyses found common activations in the right middle temporal gyrus, right precuneus and a left parieto-occipital region. Clinically, this work contributes to visual rehabilitation in early blind individuals by revealing the function-dependent and sensory-independent networks during nonvisual processing.

Knowledge of animal appearance among sighted and blind adults

How does first-person sensory experience contribute to knowledge? Contrary to the suppositions of early empiricist philosophers, people who are born blind know about phenomena that cannot be perceived directly, such as color and light. Exactly what is learned and how remains an open question. We compared knowledge of animal appearance across congenitally blind (n = 20) and sighted individuals (two groups, n = 20 and n = 35) using a battery of tasks, including ordering (size and height), sorting (shape, skin texture, and color), odd-one-out (shape), and feature choice (texture). On all tested dimensions apart from color, sighted and blind individuals showed substantial albeit imperfect agreement, suggesting that linguistic communication and visual perception convey partially redundant appearance information. To test the hypothesis that blind individuals learn about appearance primarily by remembering sighted people's descriptions of what they see (e.g., "elephants are gray"), we measured verbalizability of animal shape, texture, and color in the sighted. Contrary to the learn-from-description hypothesis, blind and sighted groups disagreed most about the appearance dimension that was easiest for sighted people to verbalize: color. Analysis of disagreement patterns across all tasks suggest that blind individuals infer physical features from non-appearance properties of animals such as folk taxonomy and habitat (e.g., bats are textured like mammals but shaped like birds). These findings suggest that in the absence of sensory access, structured appearance knowledge is acquired through inference from ontological kind.

Plastic reorganization of neural systems for perception of others in the congenitally blind

Recent evidence suggests that the function of the core system for face perception might extend beyond visual face-perception to a broader role in person perception. To critically test the broader role of core face-system in person perception, we examined the role of the core system during the perception of others in 7 congenitally blind individuals and 15 sighted subjects by measuring their neural responses using fMRI while they listened to voices and performed identity and emotion recognition tasks. We hypothesised that in people who have had no visual experience of faces, core face-system areas may assume a role in the perception of others via voices. Results showed that emotions conveyed by voices can be decoded in homologues of the core face system only in the blind. Moreover, there was a specific enhancement of response to verbal as compared to non-verbal stimuli in bilateral fusiform face areas and the right posterior superior temporal sulcus showing that the core system also assumes some language-related functions in the blind. These results indicate that, in individuals with no history of visual experience, areas of the core system for face perception may assume a role in aspects of voice perception that are relevant to social cognition and perception of others' emotions.

Development of visual category selectivity in ventral visual cortex does not require visual experience

To what extent does functional brain organization rely on sensory input? Here, we show that for the penultimate visual-processing region, ventral-temporal cortex (VTC), visual experience is not the origin of its fundamental organizational property, category selectivity. In the fMRI study reported here, we presented 14 congenitally blind participants with face-, body-, scene-, and object-related natural sounds and presented 20 healthy controls with both auditory and visual stimuli from these categories. Using macroanatomical alignment, response mapping, and surface-based multivoxel pattern analysis, we demonstrated that VTC in blind individuals shows robust discriminatory responses elicited by the four categories and that these patterns of activity in blind subjects could successfully predict the visual categories in sighted controls. These findings were confirmed in a subset of blind participants born without eyes and thus deprived from all light perception since conception. The sounds also could be decoded in primary visual and primary auditory cortex, but these regions did not sustain generalization across modalities. Surprisingly, although not as strong as visual responses, selectivity for auditory stimulation in visual cortex was stronger in blind individuals than in controls. The opposite was observed in primary auditory cortex. Overall, we demonstrated a striking similarity in the cortical response layout of VTC in blind individuals and sighted controls, demonstrating that the overall category-selective map in extrastriate cortex develops independently from visual experience.

Emotion processing in early blind and sighted individuals

OBJECTIVE

Emotion processing is known to be mediated by a complex network of cortical and subcortical regions with evidence of specialized hemispheric lateralization within the brain. In light of prior evidence indicating that lateralization of cognitive functions (such as language) may depend on normal visual development, we investigated whether the lack of prior visual experience would have an impact on the development of specialized hemispheric lateralization in emotional processing.

METHOD

We addressed this issue by comparing performance in early blind and sighted controls on a dichotic listening task requiring the detection of specific emotional vocalizations (i.e., suggestive of happiness or sadness) presented independently to either ear.

RESULTS

Consistent with previous studies, we found that sighted individuals showed enhanced detection of positive vocalizations when presented in the right ear (i.e., processed within the left hemisphere) and negative vocalizations when presented in the left ear (i.e., right hemisphere). It is interesting to note that although blind individuals were as accurate as sighted controls in detecting the valance of the vocalization, performance was not consistent with any pattern of specialized hemispheric lateralization.

CONCLUSIONS

Overall, these results suggest that although the lack of prior visual experience may not lead to impaired emotion processing performance, the underlying neurophysiological substrate (i.e., degree of special hemispheric lateralization) may depend on normal visual development. (PsycINFO Database Record

Salivary nitrite content, cognition and power in Mixed Martial Arts fighters after rapid weight loss: a case study

BACKGROUND AND AIM

Rapid weight loss (RWL) is extensively practiced by combat sports athletes, including Mixed Martial Arts (MMA), but its effects on performance are not well established with different magnitudes of RWL, including those higher than 5% of total body weight. The aim of the present study was to follow MMA athletes during RWL with subsequent weight regain to evaluate the responses of isometric strength, power, cognition and salivary nitrite ( NO 2 - ) content.

METHODS

Two professional male MMA fighters, same age, competing in the same weight category underwent two magnitudes of RWL before a simulated competition period. Anthropometric measures, records of nutritional status, training, voluntary dehydration strategies, salivary samples, cognition response, isometric strength and muscular power were obtained: (I) 7 days before combat, (II) at the weigh-in moment, and (III) in the combat day.

RESULTS AND CONCLUSIONS

Athlete 1 lost 7.2 kg (9.1% of total bodyweight) and Athlete 2 lost 4.0 kg (5.3% of total bodyweight). Athlete 1 had a lower and misbalanced caloric ingestion (708 ± 428 kcal), ingested 6 L of water during the first 5 days of RWL, underwent 2 days of fasting, water and sodium restriction before weigh-in. Athlete 2 was supervised by a nutritionist, had a balanced diet (1600 ± 0 kcal), ingested 2 L of water during the first 6 days of RWL, underwent only 1 day of fasting and water restriction, and did not restrict sodium. As expected, there was a negative effect of RWL in the evaluated parameters at the weigh-in moment, while in the combat day, salivary NO 2 - ) content.

METHODS

Two professional male MMA fighters, same age, competing in the same weight category underwent two magnitudes of RWL before a simulated competition period. Anthropometric measures, records of nutritional status, training, voluntary dehydration strategies, salivary samples, cognition response, isometric strength and muscular power were obtained: (I) 7 days before combat, (II) at the weigh-in moment, and (III) in the combat day.

RESULTS AND CONCLUSIONS

Athlete 1 lost 7.2 kg (9.1% of total bodyweight) and Athlete 2 lost 4.0 kg (5.3% of total bodyweight). Athlete 1 had a lower and misbalanced caloric ingestion (708 ± 428 kcal), ingested 6 L of water during the first 5 days of RWL, underwent 2 days of fasting, water and sodium restriction before weigh-in. Athlete 2 was supervised by a nutritionist, had a balanced diet (1600 ± 0 kcal), ingested 2 L of water during the first 6 days of RWL, underwent only 1 day of fasting and water restriction, and did not restrict sodium. As expected, there was a negative effect of RWL in the evaluated parameters at the weigh-in moment, while in the combat day, salivary NO 2 - was not completely reestablished at baseline levels (decreased by 35.9% in Athlete 1 and, 25.2% in Athlete 2, as compared with 7 days before). The athlete who underwent a lower weight loss (5.3%) presented better recovery of cognition and upper limbs power on the combat day as compared with the athlete who lost 9.1% of body weight. Although we cannot precisely conclude, this case report led us to believe that the recovery period between weigh-in and competition may be insufficient for total reestablishment of salivary NO 2 - after RWL, and higher amounts of RWLhave negative impacts on average power and cognition when compared with lower RWL.Relevance for patients: Scientific aspects related with performance in MMA athletes brought to light the absence of studies investigating the recovery of isometric strength, power, cognition and salivary NO 2 - during RWL with subsequent weight regain. This study revealed that athletes from the same categories can adopt different magnitudes of weight loss, and that this procedure impacts several important measures, for example, the reduction of salivary NO 2 - is associated with the lower O₂ transport capacity, decreasing muscle performance.

Object Domain and Modality in the Ventral Visual Pathway

The nature of domain-specific organization in higher-order visual cortex (ventral occipital temporal cortex, VOTC) has been investigated both in the case of visual experience deprivation and of modality of stimulation in sighted individuals. Object domain interacts in an intriguing and revelatory way with visual experience and modality of stimulation: selectivity for artifacts and scene domains is largely immune to visual deprivation and is multi-modal, whereas selectivity for animate items in lateral posterior fusiform gyrus is present only with visual stimulation. This domain-by-modality interaction is not readily accommodated by existing theories of VOTC representation. We conjecture that these effects reflect a distinction between the visual features that characterize different object domains and their interaction with different types of downstream computational systems.

Functional connectivity of visual cortex in the blind follows retinotopic organization principles

Although early visual experience is essential for the proper development of visual cortex, Striem-Amit et al. show that the underlying connectivity structure of retinotopic mapping is retained even in congenitally blind individuals. This basic organisational principle emerges independently of visual input and persists despite lifelong experience-dependent plasticity.

Is visual input during critical periods of development crucial for the emergence of the fundamental topographical mapping of the visual cortex? And would this structure be retained throughout life-long blindness or would it fade as a result of plastic, use-based reorganization? We used functional connectivity magnetic resonance imaging based on intrinsic blood oxygen level-dependent fluctuations to investigate whether significant traces of topographical mapping of the visual scene in the form of retinotopic organization, could be found in congenitally blind adults. A group of 11 fully and congenitally blind subjects and 18 sighted controls were studied. The blind demonstrated an intact functional connectivity network structural organization of the three main retinotopic mapping axes: eccentricity (centre-periphery), laterality (left-right), and elevation (upper-lower) throughout the retinotopic cortex extending to high-level ventral and dorsal streams, including characteristic eccentricity biases in face- and house-selective areas. Functional connectivity-based topographic organization in the visual cortex was indistinguishable from the normally sighted retinotopic functional connectivity structure as indicated by clustering analysis, and was found even in participants who did not have a typical retinal development in utero (microphthalmics). While the internal structural organization of the visual cortex was strikingly similar, the blind exhibited profound differences in functional connectivity to other (non-visual) brain regions as compared to the sighted, which were specific to portions of V1. Central V1 was more connected to language areas but peripheral V1 to spatial attention and control networks. These findings suggest that current accounts of critical periods and experience-dependent development should be revisited even for primary sensory areas, in that the connectivity basis for visual cortex large-scale topographical organization can develop without any visual experience and be retained through life-long experience-dependent plasticity. Furthermore, retinotopic divisions of labour, such as that between the visual cortex regions normally representing the fovea and periphery, also form the basis for topographically-unique plastic changes in the blind.

Interpersonal touch suppresses visual processing of aversive stimuli

Social contact is essential for survival in human society. A previous study demonstrated that interpersonal contact alleviates pain-related distress by suppressing the activity of its underlying neural network. One explanation for this is that attention is shifted from the cause of distress to interpersonal contact. To test this hypothesis, we conducted a functional MRI (fMRI) study wherein eight pairs of close female friends rated the aversiveness of aversive and non-aversive visual stimuli under two conditions: joining hands either with a rubber model (rubber-hand condition) or with a close friend (human-hand condition). Subsequently, participants rated the overall comfortableness of each condition. The rating result after fMRI indicated that participants experienced greater comfortableness during the human-hand compared to the rubber-hand condition, whereas aversiveness ratings during fMRI were comparable across conditions. The fMRI results showed that the two conditions commonly produced aversive-related activation in both sides of the visual cortex (including V1, V2, and V5). An interaction between aversiveness and hand type showed rubber-hand-specific activation for (aversive > non-aversive) in other visual areas (including V1, V2, V3, and V4v). The effect of interpersonal contact on the processing of aversive stimuli was negatively correlated with the increment of attentional focus to aversiveness measured by a pain-catastrophizing scale. These results suggest that interpersonal touch suppresses the processing of aversive visual stimuli in the occipital cortex. This effect covaried with aversiveness-insensitivity, such that aversive-insensitive individuals might require a lesser degree of attentional capture to aversive-stimulus processing. As joining hands did not influence the subjective ratings of aversiveness, interpersonal touch may operate by redirecting excessive attention away from aversive characteristics of the stimuli.

A lack of experience-dependent plasticity after more than a decade of recovered sight

In 2000, monocular vision was restored to M. M., who had been blind between the ages of 3 and 46 years. Tests carried out over 2 years following the surgery revealed impairments of 3-D form, object, and face processing and an absence of object- and face-selective blood-oxygen-level-dependent responses in ventral visual cortex. In the present research, we reexamined M. M. to test for experience-dependent recovery of visual function. Behaviorally, M. M. remains impaired in 3-D form, object, and face processing. Accordingly, we found little to no evidence of the category-selective organization within ventral visual cortex typically associated with face, body, scene, or object processing. We did observe remarkably normal object selectivity within lateral occipital cortex, consistent with M. M.'s previously reported shape-discrimination performance. Together, these findings provide little evidence for recovery of high-level visual function after more than a decade of visual experience in adulthood.

Using structural and functional brain imaging to uncover how the brain adapts to blindness

Advances in neuroimaging technology have been instrumental in uncovering the dramatic neurological changes that result from blindness, as well as revealing the inner workings of the human brain. Specifically, modern imaging techniques enable us to examine how the brain adapts and "re-wires" itself as a result of changes in behavior, the environment, injury, or disease; a process referred to as neuroplasticity. Following an overview of commonly employed neuroimaging techniques, we discuss structural and functional neuroplastic brain changes associated with profound visual deprivation. In particular, we highlight how associated structural changes often occur within areas that process intact senses (such as hearing, touch, and smell) while functional changes tend to implicate areas of the brain normally ascribed to the processing of visual information. Evidence will primarily focus on profound blindness due to ocular cause, but related work in cerebral/cortical visual impairment (CVI) will also be discussed. The potential importance of these findings within the context of education and rehabilitation is proposed.

Schizophrenia and cortical blindness: protective effects and implications for language

The repeatedly noted absence of case-reports of individuals with schizophrenia and congenital/early developed blindness has led several authors to argue that the latter can confer protective effects against the former. In this work, we present a number of relevant case-reports from different syndromes that show comorbidity of congenital and early blindness with schizophrenia. On the basis of these reports, we argue that a distinction between different types of blindness in terms of the origin of the visual deficit, cortical or peripheral, is crucial for understanding the observed patterns of comorbidity. We discuss the genetic underpinnings and the brain structures involved in schizophrenia and blindness, with insights from language processing, laying emphasis on the three structures that particularly stand out: the occipital cortex, the lateral geniculate nucleus (LGN), and the pulvinar. Last, we build on previous literature on the nature of the protective effects in order to offer novel insights into the nature of the protection mechanism from the perspective of the brain structures involved in each type of blindness.

The brain network underlying the recognition of hand gestures in the blind: the supramodal role of the extrastriate body area

The visual perception of others' body parts is critical for understanding and imitating their behavior. The visual cortex in humans includes the extrastriate body area (EBA), which is a large portion of the occipitotemporal cortex that is selectively responsive to visually perceived body parts. Previous neuroimaging studies showed that the EBA not only receives sensory inputs regarding others' body information but also receives kinesthetic feedback regarding one's own actions. This finding raised the possibility that the EBA could be formed via nonvisual sensory modalities. However, the effect of visual deprivation on the formation of the EBA has remained largely unknown. Here, we used fMRI to investigate the effect of vision loss on the development of the EBA. Blind and sighted human subjects performed equally well in a haptic-identification task involving three categories of objects (hand shapes, toy cars, and teapots). The superior part (i.e., the middle temporal gyrus and angular gyrus) of the EBA and the supramarginal gyrus showed greater sensitivity to recognized hand shapes than to inanimate objects, regardless of the sensory modality and visual experience. Unlike the superior part of the EBA, the sensitivity of the inferior part (i.e., the inferior temporal sulcus and middle occipital gyrus) depended on visual experience. However, this vision-dependent sensitivity explained minor individual differences in hand-recognition performance. These results indicate that nonvisual modalities drive the development of the cortical network underlying the recognition of hand gestures with a node in the visual cortex.

Neural correlates associated with superior tactile symmetry perception in the early blind

Symmetry is an organizational principle that is ubiquitous throughout the visual world. However, this property can also be detected through non-visual modalities such as touch. The role of prior visual experience on detecting tactile patterns containing symmetry remains unclear. We compared the behavioral performance of early blind and sighted (blindfolded) controls on a tactile symmetry detection task. The tactile patterns used were similar in design and complexity as in previous visual perceptual studies. The neural correlates associated with this behavioral task were identified with functional magnetic resonance imaging (fMRI). In line with growing evidence demonstrating enhanced tactile processing abilities in the blind, we found that early blind individuals showed significantly superior performance in detecting tactile symmetric patterns compared to sighted controls. Furthermore, comparing patterns of activation between these two groups identified common areas of activation (e.g. superior parietal cortex) but key differences also emerged. In particular, tactile symmetry detection in the early blind was also associated with activation that included peri-calcarine cortex, lateral occipital (LO), and middle temporal (MT) cortex, as well as inferior temporal and fusiform cortex. These results contribute to the growing evidence supporting superior behavioral abilities in the blind, and the neural correlates associated with crossmodal neuroplasticity following visual deprivation.

Effects of load and maintenance duration on the time course of information encoding and retrieval in working memory: from perceptual analysis to post-categorization processes

WORKING MEMORY (WM) INVOLVES THREE COGNITIVE EVENTS

information encoding, maintenance, and retrieval; these are supported by brain activity in a network of frontal, parietal and temporal regions. Manipulation of WM load and duration of the maintenance period can modulate this activity. Although such modulations have been widely studied using the event-related potentials (ERP) technique, a precise description of the time course of brain activity during encoding and retrieval is still required. Here, we used this technique and principal component analysis to assess the time course of brain activity during encoding and retrieval in a delayed match to sample task. We also investigated the effects of memory load and duration of the maintenance period on ERP activity. Brain activity was similar during information encoding and retrieval and comprised six temporal factors, which closely matched the latency and scalp distribution of some ERP components: P1, N1, P2, N2, P300, and a slow wave. Changes in memory load modulated task performance and yielded variations in frontal lobe activation. Moreover, the P300 amplitude was smaller in the high than in the low load condition during encoding and retrieval. Conversely, the slow wave amplitude was higher in the high than in the low load condition during encoding, and the same was true for the N2 amplitude during retrieval. Thus, during encoding, memory load appears to modulate the processing resources for context updating and post-categorization processes, and during retrieval it modulates resources for stimulus classification and context updating. Besides, despite the lack of differences in task performance related to duration of the maintenance period, larger N2 amplitude and stronger activation of the left temporal lobe after long than after short maintenance periods were found during information retrieval. Thus, results regarding the duration of maintenance period were complex, and future work is required to test the time-based decay theory predictions.

Altered representation of facial expressions after early visual deprivation

We investigated the effects of early visual deprivation on the underlying representation of the six basic emotions. Using multi-dimensional scaling (MDS), we compared the similarity judgments of adults who had missed early visual input because of bilateral congenital cataracts to control adults with normal vision. Participants made similarity judgments of the six basic emotional expressions, plus neutral, at three different intensities. Consistent with previous studies, the similarity judgments of typical adults could be modeled with four underlying dimensions, which can be interpreted as representing pleasure, arousal, potency and intensity of expressions. As a group, cataract-reversal patients showed a systematic structure with dimensions representing pleasure, potency, and intensity. However, an arousal dimension was not obvious in the patient group's judgments. Hierarchical clustering analysis revealed a pattern in patients seen in typical 7-year-olds but not typical 14-year-olds or adults. There was also more variability among the patients than among the controls, as evidenced by higher stress values for the MDS fit to the patients' data and more dispersed weightings on the four dimensions. The findings suggest an important role for early visual experience in shaping the later development of the representations of emotions. Since the normal underlying structure for emotion emerges postnatally and continues to be refined until late childhood, the altered representation of emotion in adult patients suggests a sleeper effect.

Assessing facial attractiveness: individual decisions and evolutionary constraints

Background

Several studies showed that facial attractiveness, as a highly salient social cue, influences behavioral responses. It has also been found that attractive faces evoke distinctive neural activation compared to unattractive or neutral faces.

Objectives

Our aim was to design a face recognition task where individual preferences for facial cues are controlled for, and to create conditions that are more similar to natural circumstances in terms of decision making.

Design

In an event-related functional magnetic resonance imaging (fMRI) experiment, subjects were shown attractive and unattractive faces, categorized on the basis of their own individual ratings.

Results

Statistical analysis of all subjects showed elevated brain activation for attractive opposite-sex faces in contrast to less attractive ones in regions that previously have been reported to show enhanced activation with increasing attractiveness level (e.g. the medial and superior occipital gyri, fusiform gyrus, precentral gyrus, and anterior cingular cortex). Besides these, females showed additional brain activation in areas thought to be involved in basic emotions and desires (insula), detection of facial emotions (superior temporal gyrus), and memory retrieval (hippocampus).

Conclusions

From these data, we speculate that because of the risks involving mate choice faced by women during evolutionary times, selection might have preferred the development of an elaborated neural system in females to assess the attractiveness and social value of male faces.