Figure 1.

Response of a rat trained to lick a sucrose solution after stimulation of a specific facial whisker. Animals were trained to lick for a sweetened water reward when a particular whisker was stimulated (Stim Reward), but not to lick when a different whisker was stimulated (Sham No Reward). Training occurred over a 3 to 6 month period. Before training, a 64 channel electrode array was also implanted over the surface of the somatosensory cortex, and individual whisker cortical columns (barrels) were mapped and associated with the particular whiskers being stimulated. Once animals achieved greater than 80% correct responses, the electrical evoked responses from each electrode corresponding to the Stim and Sham whisker were sorted into those trials that were correct (Stim Reward with Licks or Sham No Reward no Licks) and those that were incorrect (Stim Reward with no Licks or Sham No Reward with Licks), and averaged across trials. Evoked responses were over 200 uV larger before incorrect responses, suggesting that the cortical column for each whisker was in its sleep-like state during the trial that resulted in an incorrect response.