Feature-based attention influences motion processing gain in macaque visual cortex

Abstract

Changes in neural responses based on spatial attention have been demonstrated in many areas of visual cortex, indicating that the neural correlate of attention is an enhanced response to stimuli at an attended location and reduced responses to stimuli elsewhere. Here we demonstrate non-spatial, feature-based attentional modulation of visual motion processing, and show that attention increases the gain of direction-selective neurons in visual cortical area MT without narrowing the direction-tuning curves. These findings place important constraints on the neural mechanisms of attention and we propose to unify the effects of spatial location, direction of motion and other features of the attended stimuli in a 'feature similarity gain model' of attention.

Attention and contrast differently affect contextual integration in an orientation discrimination task

“…Thus, our experiment probed the effect of high versus low levels of spatial attention and also the effect of feature selective attention. Previous results probing the effects of feature and spatial attention have often reported similar effects of these two on firing rates in macaque visual cortex (Treue and Trujillo 1999;McAdams and Maunsell 2000). Thus, while we cannot determine whether feature or spatial attention effects contributed more to our findings, it is not obvious that the two should result in different perceptual effect.…”

On the functions, mechanisms, and malfunctions of intracortical contextual modulation

“…The amplifying effects of attention are similar to the disambiguating effects of stimulus contexts and to the effects of reducing ambiguity by increasing stimulus contrast (Treue and Martinez Trujillo, 1999;Williford and Maunsell, 2006). In some conditions the amplifying effects of attention occur with latencies of more than 100 msec (e.g.…”

Psychophysically measured task strategy for disparity discrimination is reflected in V2 neurons

“…A number of physiological studies that manipulate attention e.g. [23][24][25][26][27] have likewise supported 'early selection'.…”

“…If the perceptual decision is formed elsewhere in the brain (compare 30 ), it would be unsurprising that this signal be fed back more strongly into those neurons used in the task, as has been shown for neurons at higher stages of processing, such as VIP 31 . Feature based attention 23,25,32 is an alternative top-down mechanism which could give rise to significant choice probabilities. Findings of task-dependent changes of inter-neuronal noise correlations, which are closely coupled to choice probability 17 , in MT (M.R.…”