A Functional Architecture of Optic Flow in the Inferior Parietal Lobule of the Behaving Monkey

Abstract

The representation of navigational optic flow across the inferior parietal lobule was assessed using optical imaging of intrinsic signals in behaving monkeys. The exposed cortex, corresponding to the dorsal-most portion of areas 7a and dorsal prelunate (DP), was imaged in two hemispheres of two rhesus monkeys. The monkeys actively attended to changes in motion stimuli while fixating. Radial expansion and contraction, and rotation clockwise and counter-clockwise optic flow stimuli were presented concentric to the fixation point at two angles of gaze to assess the interrelationship between the eye position and optic flow signal. The cortical response depended upon the type of flow and was modulated by eye position. The optic flow selectivity was embedded in a patchy architecture within the gain field architecture. All four optic flow stimuli tested were represented in areas 7a and DP. The location of the patches varied across days. However the spatial periodicity of the patches remained constant across days at ∼950 and 1100 µm for the two animals examined. These optical recordings agree with previous electrophysiological studies of area 7a, and provide new evidence for flow selectivity in DP and a fine scale description of its cortical topography. That the functional architectures for optic flow can change over time was unexpected. These and earlier results also from inferior parietal lobule support the inclusion of both static and dynamic functional architectures that define association cortical areas and ultimately support complex cognitive function.

Advances in Light Microscopy for Neuroscience

“…In primates, awake, head-restrained preparations have allowed functional brain mapping using intrinsic optical signatures of brain activity (Grinvald et al 1991) and studies of spatiotemporal responses from neuronal aggregates using voltage-sensitive dyes (Chen et al 2006, 2008b; Quraishi et al 2007; Raffi & Siegel 2007; Seidemann et al 2002; Slovin et al 2002; Yang et al 2007). Intrinsic signal imaging in awake, body-restrained rats has facilitated examinations of how cerebral hemodynamics differs between anesthetized and awake subjects (Martin et al 2002, 2006).…”

Thinking in spatial terms: decoupling spatial representation from sensorimotor control in monkey posterior parietal areas 7a and LIP

“…The visual receptive fields of 7a neurons are large and in many cases bilateral (Blatt et al, 1990), and can be driven either by stationary visual stimuli (Yin and Mountcastle, 1977; Robinson et al, 1978; Motter and Mountcastle, 1981; Mountcastle et al, 1981; Constantinidis and Steinmetz, 2001a, 2005) or moving visual stimuli (Motter et al, 1987; Steinmetz et al, 1987; Merchant et al, 2001, 2003, 2004a,b; Raffi and Siegel, 2007). Motion sensitive receptive fields of area 7a neurons often exhibit a radial arrangement of preferred directions throughout their receptive field (Motter and Mountcastle, 1981; Steinmetz et al, 1987), such that these neurons are maximally activated by either expanding or contracting patterns of optic flow (Siegel and Read, 1997; Merchant et al, 2001, 2003; Raffi and Siegel, 2007), as occurs when the observer moves through a fixed visual environment. It has been recently noted that visual motion information in parietal area 7a could be used to derive the positions of visual landmarks and the location of the observer with respect to those landmarks, a type of spatial processing important for navigation and spatial orientation (Kravitz et al, 2011).…”

Topographic organization of macaque area LIP

“…This has not yet been systematically attempted. However, in parietal areas 7a and DP, Siegel and coworkers have used a peripheral detection task to uncover topographic representations of the contralateral hemifield with intrinsic optical imaging (22)(23)(24).In this study, we mapped the functional and topographic organization of macaque LIP using BOLD fMRI in two macaques performing a demanding rapid serial visual presentation (RSVP) search task. The task does not address the relative roles of LIP in oculomotor planning and the allocation of spatial attention.…”

“…This has not yet been systematically attempted. However, in parietal areas 7a and DP, Siegel and coworkers have used a peripheral detection task to uncover topographic representations of the contralateral hemifield with intrinsic optical imaging (22)(23)(24).…”