Neural Encoding Schemes of Tactile Information in Afferent Activity of the Vibrissal System

FARFÁN FD; ALBARRACÍN AL; FELICE CJ

JOURNAL OF COMPUTATIONAL NEUROSCIENCE

SPRINGER

Lugar: Berlin; Año: 2013 vol. 34 p. 89 - 101

0929-5313

When rats acquire sensory information by actively moving their vibrissae, a neural code is manifested at different levels of the sensory system. Behavioral studies in tactile discrimination agree that rats can distinguish surfaces of different roughness by whisking their vibrissae. This work explores the existence of neural codes in the afferent activity of one vibrissal nerve, and that those codes would explain the differences among rough surfaces detected by rats. Two neural encoding schemes based on “events” were proposed (cumulative event count and inter-event time). Events were detected by using an event detection algorithm based on multiscale decomposition of the signal (Continuous Wavelet Transform). The encoding schemes were evaluated quantitatively through the maximum amount of information which was obtained by the Shannon’s mutual information formula. On the other hand, the effect of slip-resistance levels on the information values was also studied. From these results, it was possible to estimate the optimal slip-resistance levels by which the sweep situations were best discriminated. We found that roughness information would be encoded by events whose duration would depend on neural encoding scheme considered. In particular, events of shorter duration are useful when cumulative event count is considered, while longer durations of events are relevant when inter-event time is considered. On the other hand, we observed that for encoding schemes proposed, the optimal slip-resistance level was 2. Thus, in this study we have demonstrated (and quantified) the existence of two biologically plausible neural coding schemes based on events temporal patterns, and we are also suggesting that slip-resistance would be a possible behavioral strategy for rough surfaces discrimination.