ME_Gabor

iModel

ME_Gabor
Motion Energy, Gabor Filter

Summary

This non-opponent motion energy (ME) model has linear filters that are 3-D Gabor functions (Gaussian times sinusoid). A 2-dimensional form of this model was first described by Adelson and Bergen (1985; their Fig 9). This type of ME unit has been used to model responses of direction selective (DS) cortical neurons (Heeger, 1987; Grzywacz and Yuille, 1990), although it fails to capture some basic properties of DS neurons in macaque (Bair and Movshon, 2004).

Results

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References

Adelson EH, Bergen JR (1985) Spatiotemporal energy models for the perception of motion. J Opt Soc Am A 2:284-299.
Bair W, Movshon JA (2004) Adaptive temporal integration of motion in direction-selective cells in macaque visual cortex. J Neurosci 24:7305--7323.
Grzywacz NM, Yuille AL (1990) A model for the estimate of local image velocity by cells in the visual cortex. Proc Roy Soc Lond B 239:129-161.
Heeger DJ (1987) Model for the extraction of image flow. J Opt Soc Am A 4:1455-1471.

The visual stimulus is processed (convolved) by two linear Gabor filters (icons show x-t slices of 3D filters) to yield the signals fpe (filter preferred even) and fpo (filter preferred odd). The filter outputs are squared, and the signals are added to form mep, the motion energy in the preferred direction.

The raw signal (mep) is then offset, scaled and half-wave rectified (although the signal is typically already non-zero unless the scaling or offset has introduced negative values), and it is used to drive a Poisson spiking mechanism. The spikes are time shifted to simulate a neurobiological latency. See the model (.moo) files for the parameters that govern these computations.