Figure 5.

Interneurons segregated into groups based on mutual information matching to components in intermediate zone (IZ; 800 μm depth). Components were related to primitives identified previously by both statistical and physiological means (Hart and Giszter, 2004; Kargo and Giszter, 2008; Kargo et al., 2009). Interneuronal firing was phasically related to primitive/component group activity. A, Rasters of two neurons in two frogs with strong relationships to the hip extensor component/primitive are shown. The rates of the neurons clearly relate to component amplitudes and the burst or pulse-like behavior. These neurons were also used in STA analysis. B, Two neurons best related to the period preceding (above) or the onset (below) of the hip extensor component burst. C, Neurons best related to one of the most frequent components (the hip flexor component) were aligned with component burst/pulse onsets (defined as 3 SDs above baseline noise). The neural activity was then binned to form a population peri-onset time histogram (PSTH), and the component burst/pulses that were aligned in this way were also averaged. It can be seen that the aggregate activity of the informationally related neuron population can be related especially well to the motor burst onsets and duration. However, strong preceding and following population activity can also be seen as might be expected based on the mutual information criteria for selection used (see Results). DH, Dorsal horn; IZ, intermediate zone; VH, ventral horn.