Power-Law Inter-Spike Interval Distributions Infer a Conditional Maximization of Entropy in Cortical Neurons
Juxta-cellular visualization and double-logarithmic plots of the ISI histograms (blue curves) of pyramidal neurons (A) and fast-spiking interneurons (B) recorded in cortical layers 3, 4, 5 and 6. The plots were fitted by neuron-dependent beta-2 distributions (red curves). The four neurons in (B) expressed parvalbumin (PV), a fast-spiking interneuron specific marker (blue: PV, green: biocytin or Neurobiotin). Inset of each panel represents the ISI distributions constructed from the 1st (black) and 2nd (green) halves of the same spike train. (C) Linear regression of the tail of the ISI histogram for one of the 8 neurons shown in (A) (η = 2.91, c.d. = 0.99). (D) The power-law exponents were calculated by linear regression for pyramidal (triangles) and fast-spiking (circles) neurons recorded at various depths of the sensorimotor cortex. Colors indicate the movement components represented by the individual neurons: hold (magenta), pre-movement (green), movement (blue), movement-off (red), post-movement (yellow) and non-related (cyan).