Figure 5.

Distribution of percentage of neurons activated is exponential for small populations. A, Average fraction of activated neurons in response to onset whisker stimulation (red bars) and during spontaneous activity (black bars) in PW-, septum (Sept)-, and SW-related populations. B, Probability histogram of percentage of population activated from single whisker deflections (left) and during spontaneous (Spont) activity (right) for populations of different sizes (ranging from 5 to 12 neurons) compared with predicted probability based on independence and measured response probabilities from populations containing 10 neurons. Note log₁₀ scale. C, Average probability distributions of the number of repeated activations of exact-same subsets of neurons over multiple trials. All trials with a given fraction of neurons active (Fig. 4 C, a and b) were searched for repeating spatial patterns in which the exact same neurons were active and inactive (Fig. 4 D, c and f) in response to whisker stimulation (n = 4 animals, 800 total stimulations), and distributions of the number of exact repetitions were calculated. Numbers to the right of each distribution indicate how many neurons were active in the pattern of a possible 10 neurons. Note that diagrams depict how many neurons were active (red) and not active (black) in each distribution of a total of 10 possible neurons. Patterns that occur only once appear in the repeats, 1 bin.