The role of posterior parietal cortex in the regulation of saccadic eye movements

Abstract

The posterior parietal cortex (PPC) is a node within the cerebral 'higher-order' network that has no clear homologue in non-primate mammals and is fully defined only in catarrhine primates, which include old world monkeys and hominoids. The late coming of the PPC in the eye movement circuit and the absence of an unequivocal role in saccade preparation and production suggests that the PPC should only be viewed as an innovation to enhance the sensory guidance and flexible control of visual behaviour. In line with this idea is the evidence that the lateral intraparietal area integrates sensory and goal-directed information into a map wherein representations of spatial locations can be maintained and selected as saccade targets through decision processes. Evolutionary considerations A wealth of data from neuroanatomical, neurophysiological, lesion, and imaging studies has yielded several hypotheses regarding the functions subserved and the operations performed by the several areas of the PPC. Advances on the role of PPC in space coding, coordinate transformation, visual attention, movement planning, and multisensory integration have been reviewed previously, and the reader is invited to consult this rather large literature. Together, many of these hypotheses form the outline of a PPC visuomotor theory (e.g. Goodale and Milner, 1992 ; Wise et al., 1997), but a full integration is wanting before we have a complete theoretical grounding. Towards that end, we think that there is one important area of investigation to integrate and develop further, namely, the evolutionary perspective. Comparative studies, as reviewed by Kaas (2008), suggest that the neocortex of early mammals was composed of a limited number of distinct areas, mostly primary and secondary sensory fields. The growing predominance of vision in early primates was associated with an expansion of the occipital and temporal cortices. Concomitantly, the organization of the somatosensory areas in parietal cortex underwent a significant expansion of the forepaw representation, which may partially be related to the high manual dexterity demands of arboreal life (see for review Ross and Martin, 2007). The PPC

Simultaneous analysis of the LFP and spiking activity reveals essential components of a visuomotor transformation in the frontal eye field

“…These results are consistent with the notion that LIP is primarily a visual area playing an active role in visual selection but a more passive role in the visuomotor transformation process. Consistent with this interpretation, saccade countermanding or active online cancellation of saccades is readily observed in the activity of movementrelated cells in the FEF but not in LIP (29).…”

“…We also found a spatially tuned elevation in gamma band activity , but not in the corresponding spiking activity, only during the delay epoch, whose activity predicted saccade reaction times and the cells' saccade tuning. In contrast, beta band activity (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) showed a nonspatially selective suppression during the saccade epoch. Taken together, these results suggest that motor plans leading to saccades may be generated internally within the FEF from local activity represented by gamma activity.…”

Unsold is unseen … or is it? Examining the role of peripheral vision in the consumer choice process using eye-tracking methodology

“…Extensive research (e.g., Clement, 2007;Pieters & Warlop, 1999) shows that this is indeed the case. Thus, since the consumer choice process relies heavily on visual input, it can be investigated by examining customers' visual attention, defined as the processes involved when visual information is filtered and selected, so that it can be processed more deeply and reach awareness (Pare & Dorris, 2011).…”

Facing competition: Neural mechanisms underlying parallel programming of antisaccades and prosaccades

“…LIP receives inputs from different sources, amongst them eye position, head position and gaze position and converts them into coordinate frames to create an abstract representation of space in order to plan and guide movements (Andersen, Snyder, & Bradley, 1997). Accordingly, LIP/IPS is involved in processes of visual motor integration in saccadic eye movements, in eye movement planning and coding of spatial locations (Andersen, Brotchie, & Mazzoni, 1992;Herweg et al, 2014;Paré & Dorris, 2011). …”