Fig. 9.

PI as a function of time. Eachbar shows the value of the PI calculated over a 400 msec bin. The PI value for each cell was calculated by first subtracting the NDA from the NDN value at each time bin. These values were then averaged across the 87 cells with selective activity in both the sample and delay epochs. High PI values indicate more similarity in activity when the same target object is expected relative to trials when different targets were expected. That is, the higher the PI value, the more prospective the activity. The gray shaded areacorresponds to the period of sample object presentation. Theasterisks indicate a significant difference between NDN and NDA values, evaluated at p < 0.01 using at test.