Surround suppression

Surround suppression is defined as a reduction in the activity of a neuron in response to a stimulus outside its classical receptive field.

The classical model of early vision presumes that each neuron responds independently to a specific stimulus in a localized area of the visual field.

(According to Carandini et al (2005), this computational model, which may be fit to various datasets, "degrade[s] quickly if we change almost any aspect of the test stimulus.")

During surround suppression, neurons are inhibited by a stimulus outside their classical receptive field, in an area loosely termed deemed the 'surround.'

In MT, for instance, cells can be sensitive to the direction and velocity of stimuli up to 50 to 100 times the area of their classical receptive fields.

Surround suppression was formally discovered in the visual pathway, which has been noticed first by Hubel and Wiesel[6] while mapping receptive fields.

It has been posited that lateral connections are too slow and cover too little of the visual field to fully explain surround suppression.

[14] Feedback from higher areas may explain the discrepancies seen in mechanism for surround suppression based purely on lateral connections.

[14] At least one model of excitatory connections from higher levels has been formed in the effort to more fully explain surround suppression.

[15] However, recurrent feedback is difficult to determine using electrophysiology, and the potential mechanisms at play are not as well studied as feedforward or lateral connections.

Surround suppression behavior (and its opposite) gives the sensory system several advantages from both a perceptual and information theory standpoint.

[20] It has recently been shown that stimulation of the surround may support the efficient coding hypothesis proposed by Horace Barlow in 1961.

It has been shown that surround suppression increases the efficiency of transmitting visual information, and may form a sparse code.