Specific Modulation by Sound of Primary Visual Cortex Neuron Responses to Light Stimuli of Different Intensities in Rabbitsстатья
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Дата последнего поиска статьи во внешних источниках: 16 февраля 2016 г.
Аннотация:Experiments were performed on four European rabbits (Orictolagus cuniculus) and included extracellular recordings of a total of 92 neurons. The first series of experiments recorded the responses of 63 neurons to substitution of visual stimuli presented in pairs (pairs with intensities of 0.28 and 1; 1 and 3; 3 and 6; 6 and 8.5; 8.5 and 14; 14 and 17; and 17 and 20 cd/m2). The same stimulus substitutions were then presented with sound (70 dB, 2000 Hz, 40 msec). Neurons did not respond directly to the sound. Two groups of neurons were found. Responses to “light + sound” complexes (in the interval 40–100 msec from the moment of stimulus substitution) increased by a mean 41% (p < 0.0001) at the lowest stimulus intensities in neurons of group 1 (31%). As light intensity increased, discharges in response to the complex decreased to or even below the level of responses to light. Neurons of group 2 (19%) showed the opposite properties: at low light intensities, responses to complexes were comparable with or even smaller than responses to light, while at high intensities (14–20 cd/m2) responses were significantly different (p < 0.05) from responses to light (by 20–39%). The next series of experiments reconstructed the sensory vector spaces on the basis of the responses to 29 neurons to light stimuli of eight different intensities and “sound + light” complexes. Sound was also found to have a double action on the sensory spaces of complexes. Some neurons showed marked increases in the angular distance between the two lowest-intensity stimuli (0.28 and 1 cd/m2), while others showed an increase in the angular distance for the highest intensities. These changes in the structure of the spaces were consisted with the neuron groups identified in the first two series. Comparison of the dynamics of neuron responses and the amplitudes of evoked potentials in the same stimulation conditions showed that there was significant similarity. Thus, these data lead to the conclusion that modulation of visual cortex neuron activity by sound occurs in a complex, nonlinear manner.