Neuronal responses to orientation and motion contrast in cat striate cortex

Abstract

Responses of striate neurons to line textures were investigated in anesthetized and paralyzed adult cats. Light bars centered over the excitatory receptive field (RF) were presented with different texture surrounds composed of many similar bars. In two test series, responses of 169 neurons to textures with orientation contrast (surrounding bars orthogonal to the center bar) or motion contrast (surrounding bars moving opposite to the center bar) were compared to the responses to the corresponding uniform texture conditions (all lines parallel, coherent motion) and to the center bar alone. In the majority of neurons center bar responses were suppressed by the texture surrounds. Two main effects were found. Some neurons were generally suppressed by either texture surround. Other neurons were less suppressed by texture displaying orientation or motion (i.e. feature) contrast than by the respective uniform texture, so that their responses to orientation or motion contrast appeared to be relatively enhanced (preference for feature contrast). General suppression was obtained in 33% of neurons tested for orientation and in 19% of neurons tested for motion. Preference for orientation or motion contrast was obtained in 22% and 34% of the neurons, respectively, and was also seen in the mean response of the population. One hundred nineteen neurons were studied in both orientation and motion tests. General suppression was correlated across the orientation and motion dimension, but not preference for feature contrast. We also distinguished modulatory effects from end-zones and flanks using butterfly-configured texture patterns. Both regions contributed to the generally suppressive effects. Preference for orientation or motion contrast was not generated from either end-zones or flanks exclusively. Neurons with preference for feature contrast may form the physiological basis of the perceptual saliency of pop-out elements in line textures. If so, pop-out of motion and pop-out of orientation would be encoded in different pools of neurons at the level of striate cortex.

Stimulus context modulates competition in human extrastriate cortex

“…3b). The reversal of the presentation condition effect with the pop-out, but not with the heterogeneous display condition, is consistent with singlecell physiology studies showing that neural correlates of pop-out can be found as early as in area V1 [22][23][24] . Indeed, such a result is suggestive that V1 may be the source of the signal that modulates the suppressive interactions among multiple stimuli at subsequent stages of processing, consistent with the idea that competitive interactions in extrastriate cortex can be modulated by stimulus context in a bottom-up manner.…”

Separate evaluation of target facilitation and distractor suppression in the activity of macaque lateral intraparietal neurons during visual search

“…1D). Visual area neurons exhibit stronger responses to a stimulus that differs from neighbor stimuli in some basic visual features than to a stimulus that is identical to surrounding stimuli (e.g., Kastner et al 1999;Knierim and van Essen 1992;Nothdurft et al 1999;Ogawa and Komatsu 2004;Schein and Desimone 1990). Therefore, in the TP trials (Fig.…”

Target Selection in Area V4 during a Multidimensional Visual Search Task

“…Previous studies have shown that responses to stimuli in the classical receptive field are modulated by "surround" stimuli outside the receptive filed, and neural responses tend to be stronger when there is feature contrast between the receptive field stimulus and the surround stimuli than when there is no such contrast (Allman et al, 1985;Tanaka et al, 1986;Schein and Desimone, 1990;Knierim and van Essen, 1992;Kastner et al, 1999;Li et al, 2000). The stimulus configuration used in the present study differed from those in earlier studies in that the surround stimuli comprised a relatively small number of independent objects that were separated from the receptive field stimulus by long distances.…”