Contribution of nucleus accumbens core (AcbC) to behavior control during a learned resting period: introduction of a novel task and lesion experiments.
In recent years, the study of resting state neural activity has received much attention. To better understand the roles of different brain regions in the regulation of behavioral activity in an arousing or a resting period, we developed a novel behavioral paradigm (8-arm food-foraging task; 8-arm FFT) using the radial 8-arm maze and examined how AcbC lesions affect behavioral execution and learning. Repetitive training on the 8-arm FFT facilitated motivation of normal rats to run quickly to the arm tips and to the center platform before the last-reward collection. Importantly, just after this point and before confirmation of no reward at the next arm traverse, locomotor activity decreased. This indicates that well-trained rats can predict the absence of the reward at the end of food seeking and then start another behavior, namely planned resting. Lesions of the AcbC after training selectively impaired this reduction of locomotor activity after the last-reward collection without changing activity levels before the last-reward collection. Analysis of arm-selection patterns in the lesioned animals suggests little influence of the lesion in the ability to predict the reward absence. AcbC lesions did not change exploratory locomotor activity in an open-field test in which there were no rewards. This suggests that the AcbC controls the activity level of planned resting behavior shaped by the 8-arm FFT. Rats receiving training after AcbC lesioning showed a reduction in motivation for reward seeking. Thus, the AcbC also plays important roles not only in controlling the activity level after the last-reward collection but also in motivational learning for setting the activity level of reward-seeking behavior.
Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama, Saitama, Japan.
Chika
C
Sato
Honda Research Institute Japan Co., Ltd., Wako, Saitama, Japan.
Masato
M
Hoshino
Laboratory for Brain-Operative Expression, RIKEN Brain Science Institute, Wako, Saitama, Japan; Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama, Saitama, Japan.
Naori
N
Ikumi
Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama, Saitama, Japan.
Kentarou
K
Oba
Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama, Saitama, Japan.
Akiko
A
Koike
Laboratory for Brain-Operative Expression, RIKEN Brain Science Institute, Wako, Saitama, Japan; Honda Research Institute Japan Co., Ltd., Wako, Saitama, Japan.
Osamu
O
Shouno
Honda Research Institute Japan Co., Ltd., Wako, Saitama, Japan.
Tatsuhiko
T
Sekiguchi
Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama, Saitama, Japan.
Tetsuya
T
Kobayashi
Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama, Saitama, Japan.
Takeo
T
Machida
Laboratory for Brain-Operative Expression, RIKEN Brain Science Institute, Wako, Saitama, Japan.
Gen
G
Matsumoto
Laboratory for Brain-Operative Expression, RIKEN Brain Science Institute, Wako, Saitama, Japan; Area of Regulatory Biology, Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama, Saitama, Japan.
Hiroyuki
H
Furudate
Laboratory for Brain-Operative Expression, RIKEN Brain Science Institute, Wako, Saitama, Japan; Laboratory for Alzheimer's Disease, RIKEN Brain Science Institute, Wako, Saitama, Japan; Department of Aging Neurobiology, National Center for Geriatrics and Gerontology, Obu, Aichi, Japan.
Tetsuya
T
Kimura
D000818:Animals; D001481:Basal Metabolism / Q000502:physiology*; D001522:Behavior, Animal / Q000502:physiology*; D005106:Exploratory Behavior / Q000502:physiology; D008297:Male; D008568:Memory / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology; D009714:Nucleus Accumbens / Q000502:physiology* / Q000503:physiopathology; D051381:Rats; D012201:Reward