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. Author manuscript; available in PMC: 2014 Oct 1.
Published in final edited form as: Dev Neurobiol. 2013 Jul 19;73(10):754–768. doi: 10.1002/dneu.22098

Figure 2.

Figure 2

A subset of HVC neurons were oscillatory, as revealed by autocovariance. Example spike trains (A,D), autocovariances (B,E), and amplitude spectra of the autocovariances (C,F) are shown for a juvenile and an adult HVC neuron. (A,D) The spike train of the juvenile neuron, A, reveals a variable pattern interspersed with short bursts of rhythmic activity. In contrast, the adult neuron, D, rhythmically fires over longer time spans. Scale bar: 1 s. (B,E) The autocovariance reflects the probability of firing, given that the same cell fired at time t = 0 ms. The autocovariances have multiple peaks of high covariance separated by time windows of negative covariance. This indicates that neurons were likely to fire in a stereotyped pattern, with spikes likely to occur in specific temporal relationships. (C,F) The amplitude spectra peaked in the alpha range for these neurons (11.72 and 17.58 Hz, respectively). This indicates that these neurons tended to fire rhythmically with a stereotyped ISI of 50–100 ms between spikes (85-ms and 57-ms ISI, respectively).