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http://www.nature.com/natureneuroscience/
Web End = Millisecond-scale differences in neural activity in auditory cortex can drive decisions
http://www.nature.com/natureneuroscience
Yang Yang1,2, Michael R DeWeese1,3, Gonzalo H Otazu1 & Anthony M Zador1
Neurons in the auditory cortex can lock to the ne 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.
Animals can detect the ne timing of some stimuli. For example, interaural time differences of less than 1 ms are used for the spatial
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localization of sound1. It is also clear that cortical neurons can lock with millisecond precision to the ne timing of some stimuli in the auditory cortex2,3, the visual cortex4, somatosensory cortex5,6 and in vitro7. Furthermore, spike generation in the auditory cortex is controlled by a stereotyped and precisely timed sequence of excitatory input followed approximately 3 ms later by inhibitory input8.However,althoughithas recently been established that even a few cortical spikes are sufcient to drive decisions9,10, it has been difcult to establish whether the ne timing of cortical activity can sufce.
We therefore set out to determine the precision with which the ne timing of neural activity in the auditory cortex could guide behavior in the rat. For the spatial localization of sound, the relevant sub-millisecond interaural time difference cues are extracted by specialized subcortical structures. To ensure that we were probing cortical, rather than subcortical, mechanisms, we bypassed subcortical auditory pathways and trained the rats to respond to direct intracortical electrical stimulation. We used transient biphasic current trains delivered via two chronically implanted intracortical microelectrodes11,12 to stimulate
two populations of neurons in primary auditory cortex (area A1;
Figure 1 Finely timed corticalmicrostimulation can drive behavior. (a) Taskdesign. Rats were deprived of water under aprotocol approved by the Cold Spring HarborLaboratory Animal Committee. Each stimulusconsisted of a 50-Hz train of ve biphasiccathode-leading voltage pulses. In one rat(Supplementary Fig. 3), we used a symmetricdiscrimination A-ISI-B versus B-ISI-A, ratherthan AB versus B-ISI-A; the results werecomparable and were therefore groupedtogether. (b)...