Parietal Neurons Represent Surface Orientation From the Gradient of Binocular Disparity

Along the visual pathway, neurons generally become more specialized for signaling a limited subset of stimulus attributes and become more invariant to changes in the stimulus position within the receptive fields (RFs). One of the likely mechanisms underlying such invariance appears to be pooling of detectors located at different positions. Does such spatial pooling occur for disparity-selective neurons in primary visual cortex? To examine whether the three-dimensional (3D) binocular RFs are constructed by pooling detectors for binocular disparity, we investigated binocular interactions in the 3D space for neurons in the cat striate cortex. Approximately one-third of complex cells showed the spatial pooling of disparity detectors to a significant degree, whereas the majority of simple cells did not. The degree of spatial pooling of disparity detectors along the preferred orientation axis was generally larger than that along the axis orthogonal to the orientation axis. We then reconstructed 3D binocular RFs in their complete form and examined their structures. Disparity tuning curves were compared across positions along the orientation axis in the RFs. A small population of cells appeared to show a gradual shift of the preferred disparity along this axis, indicating that they can potentially signal inclination in the 3D space. However, the majority of cells exhibited a position-invariant disparity tuning. Finally, disparity tuning curves were examined for all oblique angles in addition to horizontal and vertical. Tunings were broadest along the orientation axis as the disparity energy model predicts.

Section: Discussionmentioning

confidence: 99%

Complex Cells in the Cat Striate Cortex Have Multiple Disparity Detectors in the Three-Dimensional Binocular Receptive Fields

Sasaki¹,

Tabuchi²,

Ohzawa³

2010

“…The distinction between the ventral and dorsal visual pathways (Ungerleider and Mishkin, 1982) cannot be based on the existence of disparity-selective neurons, because both pathways contain neurons sensitive for binocular disparity (Maunsell and Van Essen, 1983;Roy et al, 1992;Eifuku and Wurtz, 1999;Janssen et al, 1999;Taira et al, 2000;Uka et al, 2000;Connor, 2001, 2005;Watanabe et al, 2002;DeAngelis and Uka, 2003;Tanabe et al, 2005). The mere existence of these neurons does not reveal the functional role that these pathways play (Parker and Newsome, 1998).…”

Section: Discussionmentioning

confidence: 99%

“…In binocular vision, neurons selective for binocular disparities are found in many areas including the primary visual cortex (V1) and areas within the occipitoparietal (dorsal) visual pathway and the occipitotemporal (ventral) visual pathway (Hubel and Wiesel, 1970;Poggio and Fischer, 1977;Maunsell and Van Essen, 1983;Burkhalter and Van Essen, 1986;Felleman and Van Essen, 1987;Poggio et al, 1988;Roy et al, 1992;Eifuku and Wurtz, 1999;Janssen et al, 1999;Taira et al, 2000;Uka et al, 2000;Connor, 2001, 2005;Prince et al, 2002;Watanabe et al, 2002;DeAngelis and Uka, 2003;Tanabe et al, 2005). The specific roles that these multiple areas play in stereopsis are poorly understood.…”

Section: Introductionmentioning

confidence: 99%

Neural Correlates of Fine Depth Discrimination in Monkey Inferior Temporal Cortex

Uka¹,

Tanabe²,

Watanabe³

et al. 2005

Binocular disparity is an important visual cue that gives rise to the perception of depth. Disparity signals are widely spread across the visual cortex, but their relative role is poorly understood. Here, we addressed the correlation between the responses of disparity-selective neurons in the occipitotemporal (ventral) visual pathway and the behavioral discrimination of stereoscopic depth. We recorded activity of disparity-selective neurons in the inferior temporal cortex (IT) while monkeys were engaged in a fine stereoscopic depth discrimination (stereoacuity) task. We found that trial-to-trial fluctuations in neuronal responses correlated with the monkey's perceptual choice. We suggest that disparity signals in the IT, located in the ventral visual pathway, are functionally linked to the discrimination of fine-grain depth.

“…For example, the central intraparietal area in the dorsal pathway was found to contain neurons that responded selectively to surface orientation (Taira et al, 2000;Tsutsui et al, 2001).…”

Section: Distribution Of Plasticity Across Visual Cortexmentioning

confidence: 99%

The Effect of Perceptual Learning on Neuronal Responses in Monkey Visual Area V4

Yang¹,

Maunsell²

2004

387

327

Previous studies have shown that perceptual learning can substantially alter the response properties of neurons in the primary somatosensory and auditory cortices. Although psychophysical studies suggest that perceptual learning induces similar changes in primary visual cortex (V1), studies that have measured the response properties of individual neurons have failed to find effects of the size described for the other sensory systems. We have examined the effect of learning on neuronal response properties in a visual area that lies at a later stage of cortical processing, area V4. Adult macaque monkeys were trained extensively on orientation discrimination at a specific retinal location using a narrow range of orientations. During the course of training, the subjects achieved substantial improvement in orientation discrimination that was primarily restricted to the trained location. After training, neurons in V4 with receptive fields overlapping the trained location had stronger responses and narrower orientation tuning curves than neurons with receptive fields in the opposite, untrained hemifield. The changes were most prominent for neurons that preferred orientations close to the trained range of orientations. These results provide the first demonstration of perceptual learning modifying basic neuronal response properties at an intermediate level of visual cortex and give insights into the distribution of plasticity across adult visual cortex.