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. 2021 Oct 29;15:770011. doi: 10.3389/fnins.2021.770011

Figure 1.

Figure 1

Characterisation of the adaptation profile to repetitive stimulation. (A) Histological reconstruction of a sample layer 5 pyramidal neuron juxta-cellularly recorded from the vibrissal area of S1 in anaesthetised rats while applying deflections (200 μm in amplitude) to the principal whisker. (B) Raster plots and peri-stimulus time histograms (PSTHs) for the sample neuron in (A) for different stimulation frequencies. Vertical purple lines indicate individual deflections. Dots in the lower parts of panels indicate individual spikes and rows correspond to trials. (C) The cumulative response of the sample neuron as a function of time normalised to the response to the first deflection exhibiting a systematic decrease in responsiveness with time. The decline is steeper and reaches a lower level as the stimulation frequency increased. Error bars indicate standard error of the means (s.e.m.) across trials. (D) On average, across neurons, adaptation increases with stimulation frequency in an exponential manner (solid curve). Responsiveness index (RI) is defined as the net neuronal response rate to the 3-s train of deflections divided by the response to the first deflection. Error bars indicate s.e.m. (E) Prominent response facilitation in a subset of neurons. The response profile of three sample neurons exhibiting response facilitation is shown at stimulation frequency of 8 Hz. (F) Neuronal reconstruction and diversity of adaptation. Upper panel illustrates the morphology of 14 example reconstructed neurons and their cortical location as identified by histology. The lower panel shows the diversity of adaptation for the 14 neurons. (G) Response latencies increases over the time course of stimulation, irrespective of the dynamics of their response rate (facilitation versus adaptation). PSTHs for 3 sample neurons to 6 consecutive deflections at 2 Hz stimulation. Different shades of green represent the order of deflection within the simulation train, with darker corresponding to earlier deflections. Modified from Kheradpezhouh et al. (2017).