A visual cue modulates the firing rate and latency of auditory-cortex neurons in the chinchilla.
We studied single and multi-unit activity recorded with tetrodes, from the left auditory cortex of awake chinchillas while they performed a frequency discrimination task. Auditory stimuli were preceded by a silent visual cue. We examined firing rates and first-spike latencies of 181 units in the presence and absence of the visual cue. To discard possible auditory artifacts produced by the visual cue, cochlear potentials were simultaneously recorded by an electrode positioned at the round window of the right cochlea. We found that the visual stimulus altered the firing rate and the mean first-spike latency of 9% and 18% of the recorded auditory-cortex cells, respectively. Furthermore, we found that the subset of neurons in which the firing rate was modulated by the visual cue was distinct from the subset of neurons that changed their latency in the presence of the visual cue. Adding both groups, a visual-stimulus modulated the firing characteristics of 27% of the recorded auditory-cortex neurons in the awake chinchilla. Our results imply that in the auditory cortex, latency and firing rate can be independently altered by visual stimuli, and that both types of analysis must be considered in order to fully understand neural cross-modal interactions.
Delano
Paul H
PH
Programa de Fisiología y Biofísica, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile. pdelano@med.uchile.cl
Elgueda
Diego
D
Ramirez
Fernando
F
Robles
Luis
L
Maldonado
Pedro E
PE
D000161:Acoustic Stimulation / Q000379:methods; D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001303:Auditory Cortex / Q000166:cytology*; D001307:Auditory Perception / Q000502:physiology; D001522:Behavior, Animal; D002682:Chinchilla / Q000502:physiology*; D003463:Cues; D004193:Discrimination Learning; D009474:Neurons / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time / Q000502:physiology*; D013997:Time Factors