Corticofugal Modulation of Tactile Responses of Neurons in the Spinal Trigeminal Nucleus - Advancing Artificial Intelligence Through Biological Process Applications - page 13

whisker decreases the coupling between the vi-
brissa deflection events and the sensory response
of the trigeminal neuron. We also note that the
sensory interference effect is not constant along
the experiment. The maximum decrease of the
sensory response coherence is observed at the
beginning of the sensory-interference application
period. This suggests that a novel stimulus attracts
“highest attention” by the sensory system, and
then the distracter effect drops down.
To examine the variation of the stimulus-
neural response coupling we average the local
coherence over the stimulus period band. Figure
5 shows obtained this way time series for the
control conditions and during ipsi- and contra-
lateral distractions. We observe that the mean
level of the response coherence decreases when
sensory-interference stimuli were applied and the
oscillation amplitude of the coherence increases.
The decrease of the coherence is more drastic at
the beginning of the contralateral sensory-interfer-
ence. However, after 10 s the coherence tends to
recover although with a non persistent behavior.

In this figure we can clearly observe slow oscil-
lation appearing during sensory-interference and
also note the high and constant coherent response
to stimulus in the control condition.
Applying the above described analysis to each
spike train we obtain characteristic values of the
neural response coherence describing its reliabil-
ity to vibrissae stimulation in the corresponding
epoch. To classify the effect of distractive stimuli
we define three types of sensory-interference types
on the coherence of neural response to the vibrissa
deflection: I-effect, when the coherence increases
with distraction, D-effect, when the coherence
decreases with distraction and No-effect when
the coherence remains the same after distraction.
Figure 6 shows percentage of cases for each type
of the effect for ipsi- and contralateral distrac-
tions. There exists a clear tendency to decrease
the neuronal response coherence with application
of distractive stimuli. The ipsilateral sensory-in-
terference diminishes coherence in 86% of cases,
whereas the contralateral has D-effect in 70% of
recordings. In few cases (10% for ipsilateral and

Figure 6. Percentage of I, D and No effects of tactile distraction on the coherence of neural response
to vibrissa deflection relative to the control stimulation. Black and grey bars correspond to ipsilateral
and contralateral distractions, respectively.