Phasic increase of monoamine-related electrochemical signal in the rat caudate nucleus following conditioned auditory stimulation during the reaction-time task.
Monoamine-related electrochemical signal was measured by in vivo chronoamperometry at a sampling rate of 5 Hz with a Nafion-coated carbon fiber placed in the caudate nucleus of the rat (n=5) performing an auditory reaction-time task. During the task, the rat pressed a lever in response to a tone stimulus to get food reward. An averaging technique was employed to extract event-related changes in monoamine concentration with respect to the tone stimulus, lever pressing or feeding. It was found that the oxidation current increased phasically for several seconds following the tone presentation with the mean onset latency being 0.4+/-0.2 s. Lever pressing was preceded by the onset of increase in two rats. Prominent increase was not observed following the tone presentation during the resting state, passive feeding, and lever pressing unrelated to the task. The results indicate that phasic increase in monoamine concentration occurs at the caudate nucleus in response to conditioned auditory stimulation in the reaction-time task. This response is not simply the consequence of sensory stimulation, motor reaction, or feeding, but is possibly influenced by integrative processes. The present electrochemical findings are consistent with the previous electrophysiological data on dopamine neuronal activity. However, pharmacological researches will be necessary in order to determine the substance involved in the phasic response.
Shinba
T
T
Department of Neurophysiology, Tokyo Institute of Psychiatry, 2-1-8 Kamikitazawa, Setagaya-ku, Tokyo 156, Japan. shinba@prit.go.jp
Andow
Y
Y
Shinozaki
T
T
Ozawa
N
N
Yamamoto
K
K
D000161:Acoustic Stimulation; D000818:Animals; D015306:Biogenic Monoamines / Q000502:physiology*; D002421:Caudate Nucleus / Q000502:physiology*; D003216:Conditioning, Operant / Q000502:physiology*; D004563:Electrochemistry; D005247:Feeding Behavior / Q000502:physiology; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D011930:Reaction Time / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*
D015306:Biogenic Monoamines