title: Transient decline in rats' hippocampal theta power relates to inhibitory stimulus-reward association.
abstract: The hippocampus is important in learning during a discrimination-reversal task. In this task, animals first learn to emit the go response to one stimulus and the no-go response to another stimulus (S1+, S2-) during the discrimination phase, and then they learn to reverse these relationships between stimulus and response during the reversal phase (S1-, S2+). To emit a no-go response for non-reinforced trial during the reversal phase, animals needed to inhibit the previously learned response pattern. This study examined the relationship between the reversal phase of the discrimination-reversal task and hippocampal electric activity in operant conditioning. The results revealed that hippocampal theta power transiently declined during the non-reinforced trial in the reversal phase compared with that during the discrimination phase. This decrease was observed during the 400-600-ms epoch after the onset of stimulus presentation. This study suggested that transient decline in hippocampal theta power is related to negative memory retrieval.
authors: Graduate School of Medicine, Yamaguchi University, Yamaguchi, Japan.
authors: Yuya
authors: Y
authors: Sakimoto
authors: Kozue
authors: K
authors: Takeda
authors: Kana
authors: K
authors: Okada
authors: Minoru
authors: M
authors: Hattori
authors: Shogo
authors: S
authors: Sakata
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D003216:Conditioning, Operant / Q000502:physiology*; D004193:Discrimination Learning / Q000502:physiology*; D004569:Electroencephalography; D005583:Fourier Analysis; D006624:Hippocampus / Q000502:physiology*; D007266:Inhibition, Psychological; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012201:Reward; D013826:Theta Rhythm / Q000502:physiology*