Average activity of 29 V1 single cells following the passive presentation of an auditory stimulus. The upper graph shows the average activity of the entire population. No response can be observed following the 25 ms presentation of the broad band noise at time 0. This is also apparent in the lower graph that compares the relative difference of the neuronal activity before and during the auditory presentation. No statistical differences were obtained (see text) confirming the lack of auditory response.