Figure 3. Fast decoding of object category.

A. Distribution of IFP latencies for all the electrodes that showed selective responses (n=94, see text). The latency was defined as the first time point where 10 consecutive points yielded p < 0.01 in a one-way ANOVA across object categories (see Experimental Procedures and Figure S6A). The dashed line shows the mean of the distribution and the arrows show the position of the example electrodes in Figure 1A, 1F and 4. B Average classification performance as a function of time from stimulus onset. We built a neural ensemble vector that contained the IFP power in individual bins of 25 ms duration (12 sampling points at BWH, 6 sampling points at CHB) using 11 electrodes with the highest r_v value (ratio of variance across categories to variance within categories, computed using only the training data and using the 50 to 300 ms interval, see Experimental Procedures and (Hung et al., 2005)). This figure shows the classification performance as a function of time from stimulus onset averaged over all 5 categories (see Figure S7 A–C for the classification performance for each category and for other bin sizes). The horizontal dashed line indicates chance classification performance and the dotted line indicates the statistical significance threshold based on randomly shuffling the category labels. The vertical dashed lines are spaced every 100 ms to aid visualization of the dynamics of the response.