Relationship between neural response and adaptation selectivity to form and color: an ERP study

Abstract

Adaptation is widely used as a tool for studying selectivity to visual features. In these studies it is usually assumed that the loci of feature selective neural responses and adaptation coincide. We used an adaptation paradigm to investigate the relationship between response and adaptation selectivity in event-related potentials (ERPs). ERPs were evoked by the presentation of colored Glass patterns in a form discrimination task. Response selectivities to form and, to some extent, color of the patterns were reflected in the C1 and N1 ERP components. Adaptation selectivity to color was reflected in N1 and was followed by a late (300-500 ms after stimulus onset) effect of form adaptation. Thus for form, response and adaptation selectivity were manifested in non-overlapping intervals. These results indicate that adaptation and response selectivity can be associated with different processes. Therefore, inferring selectivity from an adaptation paradigm requires analysis of both adaptation and neural response data.

Keywords: EEG; adaptation selectivity; color; form; response selectivity; vision.

Figure 1

Time course of a trial in EEG experiment. A series of adaptation patterns of the same form and color updated every 500 ms for 3 s preceded the presentation of the test stimuli which was presented for 300 ms. After the test stimulus offset, the participants responded by moving a sliding bar. In the trial shown, the adaptation pattern is green concentric; the test pattern is red radial with 70% coherence. In the figure the luminance contrast of the Glass pattern dots is increased for illustrative purposes.

Figure 2

Behavioral results. (A) The distribution of responses for the following relationships between adapting and test stimuli: same form and color (sf-sc), same form and different color (sf-dc), different form and same color (df-sc), and different form and color (df-dc). The values of the x-axis indicate the 7 contiguous positions that the sliding bar can take. 1 corresponds to certainty for radial, 7 to certainty for concentric, and 4 to complete uncertainty. (B) The mean ROCs for the same conditions as in A. (C) Mean ROC areas for each condition. Error bars in A and C indicate the standard error of the mean (± s.e.m.)

Figure 3

ERP results: adaptation selectivity (test stimulus epoch). (A) Mean-error plots of N1 amplitude (160–230 ms after the onset of the test stimulus). (B) Mean-error plots of the amplitude of the late positive component (300–500 ms after the onset of the test stimulus). (C) Grand-average waveforms for four conditions: same form and color (sf-sc), same form and different color (sf-dc), different form and same color (df-sc), and different form and color (df-dc). Time course of the F-values for the form adaptation, color adaptation, and form adaptation × color adaptation interaction effect. F-values above the dotted line have p-values less than 0.05. (E) Voltage difference maps. First row: Color adaptation effect. Voltage maps show the same minus different color conditions. Second row: Form adaptation effect. Voltage maps show the same minus different form conditions. The voltage maps are shown from 140 ms to 500 ms after stimulus onset with a step of 40 ms. Each voltage map is a 40 ms average.

Figure 4

ERP results: neural response selectivity (test stimulus epoch). (A) Mean-error plots of C1 amplitude (40–90 ms after the onset of the test stimulus). (B) Mean-error plots of N1 amplitude (160–230 ms after the onset of the test stimulus). (C) Grand-average waveforms for four conditions. Time 0 indicates the onset of the test stimulus. (D) Time course of the F-values for the form response, color response, and form response × color response interaction effect. F-values above the dotted line have p-values less than 0.05.

Figure 5

ERP results: neural response selectivity (adapting stimulus epoch). (A–D) Same analysis as in Figure 4.

Figure 6

A scheme of the temporal windows where neural response and adaptation selectivity to form and color are manifested in the ERP components. The color and color × form response selectivities were prominent from the analysis of the test stimulus but not of the adapting stimulus.