Millisecond-scale differences in neural activity in auditory cortex can drive decisions

Abstract

Neurons in the auditory cortex can lock to the fine timing of acoustic stimuli with millisecond precision, but it is not known whether this precise spike timing can be used to guide decisions. We used chronically implanted microelectrode pairs to stimulate neurons in the rat auditory cortex directly and found that rats can exploit differences in the timing of cortical activity that are as short as 3 ms to guide decisions.

Figure 1. Finely timed cortical microstimulation can drive behaviour

(A) Task design. Animals were water deprived under a protocol approved by the Cold Spring Harbor Laboratory Animal Committee. Each stimulus consisted of a 50 Hz train of 5 biphasic cathode-leading current pulses. In one animal (Fig. S2-a) we used a symmetric discrimination A-ISI-B vs. B-ISI-A, rather than AB vs. B-ISI-A; the results were comparable and were therefore grouped together. (B) The training history of one subject. Each data point represents the performance of one session. The error bars show standard error of the mean (s.e.m). The x-axis label indicates the stimulus ID (A vs. B or AB vs. B) or ISI (in ms) for each training session. All training sessions are plotted, including sessions when animals perform above chance (p<0.01; filled circle) and at chance (open circle). The performance varies with ISI, i.e. with task difficulty. (C) Rats learned to perform above chance at most ISIs on which they were trained. For each ISI, the bar represents the following ratio: (number of rats able to perform the task defined by this ISI above chance on at least one session)/(number of rats tested at this ISI during at least one session). The error bars show s.e.m. (D) Cumulative histogram showing the best performance session of all 15 rats trained on the ISI=5 ms task. (E) Performance declined with task difficulty within a subject. Performance is shown for sessions 5–10 for subject o (see also Fig. S2-o). The error bars show s.e.m.