Pattern Motion Processing by MT Neurons

Parvin Zarei Eskikand,David B Grayden,Tatiana Kameneva,Michael R Ibbotson,Anthony N Burkitt

doi:10.3389/fncir.2019.00043

Parvin Zarei Eskikand, David B Grayden + Show 3 more

Open Access

https://doi.org/10.3389/fncir.2019.00043

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Abstract

Based on stimulation with plaid patterns, neurons in the Middle Temporal (MT) area of primate visual cortex are divided into two types: pattern and component cells. The prevailing theory suggests that pattern selectivity results from the summation of the outputs of component cells as part of a hierarchical visual pathway. We present a computational model of the visual pathway from primary visual cortex (V1) to MT that suggests an alternate model where the progression from component to pattern selectivity is not required. Using standard orientation-selective V1 cells, end-stopped V1 cells, and V1 cells with extra-classical receptive fields (RFs) as inputs to MT, the model shows that the degree of pattern or component selectivity in MT could arise from the relative strengths of the three V1 input types. Dominance of end-stopped V1 neurons in the model leads to pattern selectivity in MT, while dominance of V1 cells with extra-classical RFs result in component selectivity. This model may assist in designing experiments to further understand motion processing mechanisms in primate MT.

Highlights

The middle temporal area (MT or V5) within the extrastriate primate visual cortex contains a high proportion of direction-selective neurons (Dubner and Zeki, 1971; Born and Bradley, 2005)
The results of the model show that the extrinsic terminators formed at the intersections of overlapping bars have a important role in pattern motion detection in Middle Temporal (MT) neurons
The model uses several known V1 cell types and two types of MT neurons in an integrated network to accentuate the terminators in the moving image

Summary

Introduction

The middle temporal area (MT or V5) within the extrastriate primate visual cortex contains a high proportion of direction-selective neurons (Dubner and Zeki, 1971; Born and Bradley, 2005). When a bar or grating is moved through the receptive field (RF) of an MT neuron, it responds only to a restricted range of directions orthogonal to the grating’s orientation, making the cell direction selective (Figure 1A). When MT neurons are stimulated with plaid patterns, a range of cell-specific responses are observed. About one third of MT neurons, referred to as “pattern” cells, are selective to the direction of the pattern motion and have a single-lobed directional tuning function centered on the pattern direction (Figure 1C). At the opposite end of the spectrum are “component” MT cells, which do not respond optimally to the unified plaid pattern direction but rather show two peaks in their directional tuning functions, each peak coinciding with the direction of the component gratings (Figure 1D). The final third of cells have intermediate properties: they produce broad directional tuning functions that do not have significant double peaks (Albright, 1984; Rodman and Albright, 1989; Movshon et al, 1992; Li et al, 2001)

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