Viewer-centred and object-centred coding of heads in the macaque temporal cortex

Abstract

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.

Visual Stimulation Decorrelates Neuronal Activity

“…Details of the stimulus selectivity of these neurons has been reported elsewhere (Barraclough et al 2005(Barraclough et al , 2006Edwards et al 2003;Foldiak et al 2003;Oram et al 2002;van Rossum et al 2008). The anterior-posterior extent of the recorded cells was from 7 to 10 mm anterior of the interaural plane, consistent with previous studies showing visual responses to static images in the STSa (Baylis and Rolls 1987;Bruce et al 1981;Perrett et al 1982Perrett et al , 1991.…”

“…The results from initial screening were used to select stimuli that elicited large responses from the neuron (effective stimuli) and to select stimuli that elicited small or no response (ineffective stimuli). For different neurons effective and ineffective stimuli included different views of the head (Perrett et al 1991), abstract patterns, and familiar objects . Details of the stimulus selectivity of these neurons has been reported elsewhere (Barraclough et al 2005(Barraclough et al , 2006Edwards et al 2003;Foldiak et al 2003;Oram et al 2002;van Rossum et al 2008).…”

Object-based attentional selection—Grouped arrays or spatially invariant representations?: Comment on Vecera and Farah (1994).

“…Indeed, both psychophysical and neurophysiological studies have obtained data that is consistent with object-centered representations (Palmer, Rosch, & Chase 1981;Perrett et al, 1991;Warrington & Taylor, 1973). We wish to make clear that we are not disputing the existence of object-centered or high-level, viewer-centered representations (see Perrett, Oram, Hietanen, & Benson, 1994, for an interesting review of this position) in memory.…”

Diagnostic recognition: task constraints, object information, and their interactions

“…This is not to say that object recognition is fully viewpoint-invariant; there are now many independent sources of evidence suggesting that a large number of object classes are better recognized when shown from particular viewpoints (e.g. Palmer et al, 1981;Rock and Di Vita, 1987;Tarr and Pinker, 1989;Perrett et al, 1991;Bülthoff and Edelman, 1992;Edelman and Bülthoff, 1992;Vetter et al, 1994). Subjects label such object views as 'better' and are faster to categorize the objects shown in these views.…”