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Cells selectively responsive to the face have been found in several visual sub-areas of temporal cortex in the macaque brain. These include the lateral and ventral surfaces of inferior temporal cortex and the upper bank, lower bank and fundus of the superior temporal sulcus (STS). Cells in the different regions may contribute in different ways to the processing of the facial image. Within the upper bank of the STS different populations of cells are selective for different views of the face and head. These cells occur in functionally discrete patches (3-5 mm across) within the STS cortex. Studies of output connections from the STS also reveal a modular anatomical organization of repeating 3-5 mm patches connected to the parietal cortex, an area thought to be involved in spatial awareness and in the control of attention. The properties of some cells suggest a role in the discrimination of heads from other objects, and in the recognition of familiar individuals. The selectivity for view suggests that the neural operations underlying face or head recognition rely on parallel analyses of different characteristic views of the head, the outputs of these view-specific analyses being subsequently combined to support view-independent (object-centred) recognition. An alternative functional interpretation of the sensitivity to head view is that the cells enable an analysis of 'social attention', i.e. they signal where other individuals are directing their attention. A cell maximally responsive to the left profile thus provides a signal that the attention (of another individual) is directed to the observer's left. Such information is useful for analysing social interactions between other individuals.(ABSTRACT TRUNCATED AT 250 WORDS)

A single case study of a patient with 'visual form agnosia' is presented. A severe visual recognition deficit was accompanied by impairments in discriminating shape, reflectance, and orientation, although visual acuity and colour vision, along with tactile recognition and intelligence, were largely preserved. Neuropsychological and behavioural investigations have indicated that the patient is able to utilize visual pattern information surprisingly well for the control of hand movements during reaching, and can even read many whole words, despite being unable to make simple discriminative judgements of shape or orientation. She seems to have no awareness of shape primitives through Gestalt grouping by similarity, continuity or symmetry. It is proposed that many of these perceptual disorders might be the combined result of (1) a selective loss of the cortical elaboration of the magnocellular visual processing stream, and (2) a selective output disconnection from a central processor of visual boundaries and shape primitives in the occipital cortex.

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An investigation was made into the sensitivity of cells in the macaque superior temporal sulcus (STS) to the sight of different perspective views of the head. This allowed assessment of (a) whether coding was 'viewer-centred' (view specific) or 'object-centred' (view invariant) and (b) whether viewer-centred cells were preferentially tuned to 'characteristic' views of the head. The majority of cells (110) were found to be viewer-centred and exhibited unimodal tuning to one view. 5 cells displayed object-centred coding responding equally to all views of the head. A further 5 cells showed 'mixed' properties, responding to all views of the head but also discriminating between views. 6 out of 56 viewer and object-centred cells exhibited selectivity for face identity or species. Tuning to view varied in sharpness. For most (54/73) cells the angle of perspective rotation reducing response to half maximal was 45-70 degrees but for 19/73 it was greater than 90 degrees. More cells were optimally tuned to characteristic views of the head (the full face or profile) than to other views. Some cells were, however, found tuned to intermediate views throughout the full 360 degree range. This coding of many distinct head views may have a role in the analysis of social signals based on the interpretation of the direction of other individuals' attention.