Spatio-temporal analyses of stimulus-evoked and spontaneous stochastic neural activity observed by optical imaging in guinea pig auditory cortex.
Stimulus-evoked response in the cortex involves random neural activity besides the deterministic responses reproducible to the stimulus. Recently, we have developed a new bright optical system that enables us to investigate the spatio-temporal patterns of such stochastic activity in the guinea pig auditory cortex without averaging. We show that (1) the stochastic neural activity is evoked by a tone-stimulus in addition to the deterministic response, and spontaneous stochastic activity is also observed in a similar manner; (2) our statistical estimation of optical responses such as variance showed that the evoked stochastic activity was increased by the sound stimulus compared to the spontaneous activity; (3) both types of stochastic activity mainly display oscillatory behavior, in the frequency range of 5-11 Hz; (4) there are no significant differences between the stimulus-induced and spontaneous stochastic neural activity in our statistical analyses using the PSD (power-spectrum density) and the spatial correlation function; (5) the spatial area of the evoked stochastic activity is not strongly correlated with the tonotopical area of the deterministic response that is mainly localized in the caudal area of field A of the guinea pig auditory cortex. Thus, the stochastic neural activity existing in the stimulus response and the spontaneous activity in the auditory cortex are possibly generated by a common neural mechanism. These results were confirmed statistically using 27 animals.
Tokioka
R
R
Advanced Research Laboratory, Hitachi, Ltd., Hatoyama, Saitama, Japan. tokioka@harl.hitachi.co.jp
Kawaguchi
H
H
Fukunishi
K
K
D000161:Acoustic Stimulation; D000818:Animals; D001303:Auditory Cortex / Q000502:physiology*; D001683:Biological Clocks / Q000502:physiology*; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D006168:Guinea Pigs; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*; D013269:Stochastic Processes