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Christopher C. Pack; Pattern motion selectivity in macaque visual cortex. Journal of Vision 2011;11(11):33. doi: 10.1167/11.11.33.
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© ARVO (1962-2015); The Authors (2016-present)
The dorsal visual pathway in primates has a hierarchical organization, with neurons in V1 coding local velocities and neurons in the later stages of the extrastriate cortex encoding complex motion patterns. In order to understand the computations that occur along each stage of the hierarchy, we have recorded from single neurons in areas V1, MT, and MST of the alert macaque monkey. Results with standard plaid stimuli show that pattern motion selectivity is, not surprisingly, more common in area MST than in MT or V1. However, similar results were found with plaids that were made perceptually transparent, suggesting that neurons at more advanced stages of the hierarchy tend to integrate motion signals obligatorily, even when the composition of the stimulus is more consistent with the motion of multiple objects. Thus neurons in area MST in particular show a tendency for increased motion integration that does not necessarily correlate with the (presumptive) perception of the stimulus. Data from local field potentials recorded simultaneously show a strong bias toward component selectivity, even in brain regions in which the spiking activity is overwhelmingly pattern selective. This suggests that neurons with greater pattern selectivity are not overrepresented in the outputs of areas like V1 and MT, but rather that the visual system computes pattern motion multiple times at different hierarchical stages. Moreover, our results are consistent with the idea that LFPs can be used to estimate different anatomical contributions to processing at each visual cortical stage.
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