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The role of the inferior frontal gyrus and of the uncinate and of the inferior frontal occipital fasciculi in the recognition of emotional facial expressions
No full textThe perception of faces expressing emotions is one of the most developed human visual abilities and involves various cortical and subcortical brain regions, such as some occipital and temporal areas, involved in the processing of pictorial aspects of the visual stimuli, and the amygdala, which plays a crucial role in assessing their emotional content. The first part of the article will review the classical models proposed to explain this particular perceptual process, while the second part will deal with the most recent evidence, which places emphasis on anatomical substrates not initially considered, and which leads to unprecedented interpretations of the processing of emotional facial expressions. Previous theoretical models described this brain function as the result of a modular analysis performed exclusively within the visual system and based on separate processing pathways for the recognition of the different visual features, such as identity and emotional expressions. Subsequent studies have suggested that the motor and prefrontal territories should be added to the classical regions considered as involved in the perception of faces. This evidence has prompted the proposal of new models that envisage an information processing not purely hierarchical but rather serial and/or based on top-down and simulation mechanisms. In line with this evidence, recent studies have emphasized the crucial role of the inferior frontal gyrus (IFG) for the explicit recognition of emotional facial expressions. While the anatomical pathways through which the occipital and temporal regions interact with each other are relatively well known, the connections between these regions and the IFG have not yet been studied in detail. Nonetheless, based on the data already present in the literature, it is possible to hypothesize that the inferior fronto-occipital and uncinate fasciculi represent the two preferential anatomical pathways through which this prefrontal region interacts with the visual regions during the processing of emotional faces. In particular, it is likely that the uncinate fasciculus is the route through which visual information from subcortical territories, including the colliculus, pulvinar, and amygdala, reaches the IFG, that in parallel receives further visual information from a cortical pathway constituted by temporal and the occipital areas and the inferior occipital fasciculus. Since lesion and functional studies suggest that the IFG plays a role in the conscious recognition of facial expressions, one intriguing hypothesis is that this ability emerges from the integration of purely visual cortical information with subcortical information, in which the visual aspects of stimuli are encoded unconsciously and in a rough way, but at the same time endowed with emotional content. The effects of the lesions of these fascicles support this hypothesis although specific studies are needed to test its actual validity..All this evidence suggests the intriguing hypothesis that the role of the IFG in the conscious recognition of facial expressions emerges from its capacity to integrate purely visual cortical information with subcortical one, in which the visual aspects of the stimuli are unconsciously and coarsely encoded, but at the same time endowed with emotional content. Although the effects of the lesions of these fasciculi support this hypothesis, specific studies are needed to test its actual validity
Single neurons in the insular cortex of a macaque monkey respond to skin brushing: Preliminary data of the possible representation of pleasant touch
No full textPleasant touch may serve as a foundation for affiliative behavior, providing a mechanism for the formation and maintenance of social bonds among conspecifics. In humans, this touch is usually referred to as the caress. Dynamic caressing performed on the hairy skin with a velocity of 1-10 cm/s is perceived as being pleasant and determines positive cardio-physiological effects. Furthermore, imaging human studies show that affiliative touch activates the posterior insular cortex (pIC). Recently, it was demonstrated that pleasant touch in monkeys (i.e., sweeping in a grooming-like manner) is performed with velocities similar to those characteristics of human caress (9.31 cm/s), and causes similarly positive autonomic effects, if performed with velocity of 5 cm/s and 10 cm/s, but not lower or higher. Due to similarities between the human caress and non-human primate sweeping, we investigated for the first time whether single neurons of the perisylvian regions (secondary somatosensory cortex [SII] and pIC) of a rhesus monkey can process sweeping touch differently depending on the stimulus speed. We applied stimulation with two speeds: one that optimally induces positive cardio-physiological effects in the monkey who receives it, and includes the real speed of sweep (5-15 cm/s, sweep fast), and a non-optimal speed (1-5 cm/s, sweep slow). The results show that single neurons of insular cortex differently encode the stimulus speed. In particular, even the majority of recorded somatosensory neurons (82.96%) did not discriminate the two speeds, a small set of neurons (16.59%) were modulated just during the sweep fast. These findings represent the first evidence that single neurons of the non-human primates insular cortex can code affiliative touch, highlighting the similarity between human and non-human primates' social touch systems. This study constitutes an important starting point to carry out deeper investigation on neuronal processing of pleasant sweeping in the central nervous system
The neural bases of vitality forms
Full text linkUnlike emotions, which are short-lasting events accompanied by viscero-motor responses, vitality forms are continuous internal states that modulate the motor behaviors of individuals and are devoid of the autonomic modifications that characterize real emotions. Despite the importance of vitality forms in social life, only recently have neurophysiological studies been devoted to this issue. The first part of this review describes fMRI experiments, showing that the dorso-central insula is activated during the execution, the perception and the imagination of arm actions endowed with different vitality forms as well as during the hearing and the production of speech conveying vitality forms. In the second part, we address the means by which the dorso-central insula modulates the networks for controlling action execution and how the sensory and interoceptive information is conveyed to this insular sector. Finally, we present behavioral data showing the importance of vitality forms in social interactions
4.20 - The Posterior Parietal Cortex
No full textIn this chapter we describe the anatomical and functional characteristics of the Posterior Parietal Cortex (PPC) of macaque monkeys and humans. We critically discuss the classical notion that the posterior parietal lobule is an association region, and contrast it with the more recent view that PPC is endowed with motor properties. We conclude that PPC motor organization represents the basic scaffold of this region on the top of which sensory information is organized
Pathways for smiling, disgust and fear recognition in blindsight patients
No full textThe aim of the present review is to discuss the localization of circuits that allow recognition of emotional facial expressions in blindsight patients. Because recognition of facial expressions is function of different centers, and their localization is not always clear, we decided to discuss here three emotional facial expression - smiling, disgust, and fear - whose anatomical localization in the pregenual sector of the anterior cingulate cortex (pACC), anterior insula (AI), and amygdala, respectively, is well established. We examined, then, the possible pathways that may convey affective visual information to these centers following lesions of V1. We concluded that the pathway leading to pACC, AI, and amygdala involves the deep layers of the superior colliculus, the medial pulvinar, and the superior temporal sulcus region. We suggest that this visual pathway provides an image of the observed affective faces, which, although deteriorated, is sufficient to determine some overt behavior, but not to provide conscious experience of the presented stimuli
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Multimodal architectonic subdivision of the rostral part (area F5) of the macaque ventral premotor cortex
No full textWe used a cyto-, myelo-, and chemoarchitectonic (distribution of SMI-32 and calbindin immunoreactivity) approach to assess whether the rostral histochemical area F5 of the ventral premotor cortex (PMv) comprises architectonically distinct areas, possibly corresponding to functionally different fields. Three areas were identified, occupying different parts of F5. One area, designated as "convexity" F5 (F5c), extends on the postarcuate convexity cortex adjacent to the inferior arcuate sulcus and is characterized, cytoarchitectonically, by a poorly laminated appearance, resulting from an overall cell population rather homogeneous in size and density. The other two areas, designated as "posterior" and "anterior" F5 (F5p and F5a, respectively), lie within the postarcuate bank at different anteroposterior levels. Major cytoarchitectonic features of F5p are a layer III relatively homogeneous in cell size and density, a cell-dense layer Va, and the presence of relatively large pyramids in layer Vb. Major cytoarchitectonic features of F5a are the presence of relatively large pyramids in lowest layer III and a prominent, homogenous layer V. Furthermore, our results showed that F5c and F5p border caudally with a caudal PMv area corresponding to histochemical area F4, providing additional evidence for a general subdivision of the macaque PMv into a caudal and a rostral part, corresponding to F4 and to the F5 complex, respectively. The present data, together with other functional and connectional data, suggest that the three rostral PMv areas F5p, F5a, and F5c correspond to distinct cortical entities, possibly involved in different aspects of motor control and cognitive motor functions
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Cortical connections of the macaque anterior intraparietal (AIP) area
No full textWe traced the cortical connections of the anterior intraparietal (AIP) area, which is known to play a crucial role in visuomotor transformations for grasping. AIP displayed major connections with 1) areas of the inferior parietal lobule convexity, the rostral part of the lateral intraparietal area and the SII region; 2) ventral visual stream areas of the lower bank of the superior temporal sulcus and the middle temporal gyrus; and 3) the premotor area F5 and prefrontal areas 46 and 12. Additional connections were observed with the caudal intraparietal area and the ventral part of the frontal eye field. This study suggests that visuomotor transformations for object-oriented actions, processed in AIP, rely not only on dorsal visual stream information related to the object's physical properties but also on ventral visual stream information related to object identity. The identification of direct anatomical connections with the inferotemporal cortex suggests that AIP also has a unique role in linking the parietofrontal network of areas involved in sensorimotor transformations for grasping with areas involved in object recognition. Thus, AIP could represent a crucial node in a cortical circuit in which hand-related sensory and motor signals gain access to representations of object identity for tactile object recognition
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