title: New learning and memory related pathways among the hippocampus, the amygdala and the ventromedial region of the striatum in rats.
abstract: BACKGROUND
  The hippocampus, central amygdaloid nucleus and the ventromedial region (marginal division) of the striatum have been reported to be involved in the mechanism of learning and memory. This study aimed elucidating anatomical and functional connections among these brain areas during learning and memory.
  
  
  RESULTS
  In the first part of this study, the c-Fos protein was used to explore functional connections among these structures. Chemical stimulation of either hippocampus or central amygdaloid nucleus results in dense expression of c-Fos protein in nuclei of neurons in the marginal division of the striatum, indicating that the hippocampus and the central amygdaloid nucleus might be functionally connected with the marginal division. In the second part of the study, the cholera toxin subunit B-horseradish peroxidase was injected into the central amygdaloid nucleus to observe anatomical connections among them. The retrogradely transported conjugated horseradish peroxidase was observed in neurons of both the marginal division and dorsal part of the hippocampus following the injection. Hence, neural fibers from both the marginal division and the hippocampus directly projected to the central amygdaloid nucleus.
  
  
  CONCLUSIONS
  The results implicated potential new functional and structural pathways through these brain areas during the process of learning and memory. The pathways ran from ventromedial portion (the marginal division) of the striatum to the central amygdaloid nucleus and then to the hippocampus before going back to the marginal division of the striatum. Two smaller circuits were between the marginal division and the central amygdaloid nucleus, and between the central amygdaloid nucleus and the hippocampus. These connections have added new dimensions of neural networks of learning and memory, and might be involved in the pathogenesis of dementia and Alzheimer disease.
authors.affiliation: Center of Pediatrics, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.affiliation: Center of Pediatrics, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, China.
authors.forename: Yan-chen
authors.initials: YC
authors.lastname: Chen
authors.affiliation: Department of Ear, Nose and Throat, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, China. Electronic address: jiangali6370@163.com.
authors.forename: Gang
authors.initials: G
authors.lastname: Jiang
authors.affiliation: Department of Neurology, 153 PLA Central Hospital, Zhengzhou City, Henan Province 450042, China.
authors.forename: Qun
authors.initials: Q
authors.lastname: Ning
authors.affiliation: Department of Radiology, PLA General Hospital, Beijing, 100853, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Ma
authors.affiliation: School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Wood-yee
authors.initials: WY
authors.lastname: Chan
authors.affiliation: Nanjing Junqu Hangzhou Sanatorium, 14 Ling-ying Road, Hangzhou, 310007, China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Wu
authors.affiliation: Jinan Junqu Qingdao First Sanatorium, 27 West Xianggan Road, Qingdao,266071 China.
authors.forename: Guo-qing
authors.initials: GQ
authors.lastname: Zhou
authors.affiliation: Department of Pediatrics, Sun Yet-San Hospital, Zhong-Shan University, Guangzhou, 510120, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Bao
authors.affiliation: Department of Neurosurgery, Fuzhou Central Hospital of Nanjing Junqu, Fuzhou, Fujian, 350025, China.
authors.forename: Zhao-cong
authors.initials: ZC
authors.lastname: Zheng
authors.affiliation: Jinan Junqu Qingdao First Sanatorium, 27 West Xianggan Road, Qingdao,266071 China.
authors.forename: Xin
authors.initials: X
authors.lastname: Yang
authors.affiliation: Center of Pediatrics, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, China.
authors.forename: Ji-xuan
authors.initials: JX
authors.lastname: Luo
authors.affiliation: Center of Pediatrics, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zheng
authors.affiliation: Center of Pediatrics, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, China.
authors.forename: Hai-wen
authors.initials: HW
authors.lastname: Guo
authors.affiliation: Center of Pediatrics, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Zeng
authors.affiliation: Center of Pediatrics, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, China. Electronic address: zqy8852@126.com.
authors.forename: Qi-yi
authors.initials: QY
authors.lastname: Zeng
authors.affiliation: Center of Pediatrics, Zhujiang Hospital, Southern Medical University, Guangzhou, Guangdong 510282, China. Electronic address: shusiyun@126.com.
authors.forename: Si-yun
authors.initials: SY
authors.lastname: Shu
mesh_terms: D000679:Amygdala / Q000502:physiology*; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D002772:Cholera Toxin; D003342:Corpus Striatum / Q000502:physiology*; D006624:Hippocampus / Q000502:physiology*; D006735:Horseradish Peroxidase; D007858:Learning; D008297:Male; D008568:Memory; D009434:Neural Pathways; D009474:Neurons / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D017207:Rats, Sprague-Dawley
chemical_list: D016760:Proto-Oncogene Proteins c-fos; D002772:Cholera Toxin; D006735:Horseradish Peroxidase
keywords: Basal ganglia; Dementia; Immunohistochemistry; Tract tracing; c-Fos protein