Stability of Neural Firing in the Trigeminal Nuclei under Mechanical Whisker Stimulation

Abstract

Sensory information handling is an essentially nonstationary process even under a periodic stimulation. We show how the time evolution of ridges in the wavelet spectrum of spike trains can be used for quantification of the dynamical stability of the neuronal responses to a stimulus. We employ this method to study neuronal responses in trigeminal nuclei of the rat provoked by tactile whisker stimulation. Neurons from principalis (Pr5) and interpolaris (Sp5i) show the maximal stability at the intermediate (50 ms) stimulus duration, whereas Sp5o cells “prefer” shorter (10 ms) stimulation. We also show that neurons in all three nuclei can perform as stimulus frequency filters. The response stability of about 33% of cells exhibits low-pass frequency dynamics. About 57% of cells have band-pass dynamics with the optimal frequency at 5 Hz for Pr5 and Sp5i, and 4 Hz for Sp5o, and the remaining 10% show no prominent dependence on the stimulus frequency. This suggests that the neural coding scheme in trigeminal nuclei is not fixed, but instead it adapts to the stimulus characteristics.

Sensory Coding by Cerebellar Mossy Fibres through Inhibition-Driven Phase Resetting and Synchronisation

“…white dotted line in Figure 5A . These findings suggest that across the population of metronome cells subsets of cells are capable of stimulus-locking to a broad range of input frequencies, consistent with individual cells performing a ‘band-pass’ operation similar to that seen in cortical and trigeminal neurones [55] , [56] .…”

“…Such behaviour suggests that metronome cells can behave in a manner similar to band-pass filters [c.f. 55] , [56] and that as a population they broadcast a ‘packetised’ code of sensory input frequency [74] , established through brief-lived epochs of synchronisation, to their downstream targets in the cerebellum. However, the reliability of such a code at the single neurone level may be low since stimulus-spike locking can be <1∶1 (see Figure 4 and 5 ).…”

Correction: Sensory Coding by Cerebellar Mossy Fibres through Inhibition-Driven Phase Resetting and Synchronisation

“…white dotted line in Figure 5A. These findings suggest that across the population of metronome cells subsets of cells are capable of stimulus-locking to a broad range of input frequencies, consistent with individual cells performing a 'band-pass' operation similar to that seen in cortical and trigeminal neurones [55,56].…”

Application of wavelet analysis and artificial neural networks in solving the problem concerning shape recognition of noisy pulsed signals

“…In the latter case, the dynamics of dif ferent neurons is identified according to the amplitude criterion: the recorded signal amplitude diminishes when the distance from a microelectrode grows. A detailed description of the experimental data used is presented in [29][30][31]. Thereafter, test signals used in recognition procedures, which involved randomly dis tributed spikes of two types and a noise sequence, were created.…”