Selective and long-term learning impairment following neonatal hypoxic-ischemic brain insult in rats

• Published in: Behavioural brain research Vol. 118; no. 1; pp. 17 - 25
• Main Authors: Ikeda, Tomoaki, Mishima, Kenichi, Yoshikawa, Tetsuya, Iwasaki, Katsunori, Fujiwara, Michihiro, Xia, Yi X, Ikenoue, Tsuyomu
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier B.V 08.01.2001; Elsevier Science
• Subjects: Animal; Animals; Biological and medical sciences; Choice Behavior; Choice reaction time task; Eight-arm radial maze task; Female; Fundamental and applied biological sciences. Psychology; Hypoxia-ischemia; Hypoxia-Ischemia, Brain - psychology; Learning; Learning Disorders - physiopathology; Learning impairment; Learning. Memory; Levine's model; Male; Maze Learning; Memory; Models, Neurological; Neonatal rat; Plus-maze task; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Rats; Rats, Wistar; Space life sciences; Water maze task; Learning impairment; Eight-arm radial maze task; Choice reaction time task; Levine's model; Plus-maze task; Water maze task; Neonatal rat; Hypoxia-ischemia; Vigilance; Animal model; Oxygen; Rat; Memory; Rodentia; Attention; Environmental factor; Spatial ability; Cognition; Experimental study; Learning; Vertebrata; Mammalia; Acquisition process; Ischemia; Choice reaction time; Animal; Problem solving; Hypoxia; Measurement method
• ISSN: 0166-4328; 1872-7549
• DOI: 10.1016/S0166-4328(00)00287-4

We examined four different learning and memory tasks in rats which had been subjected to left carotid artery ligation followed by 2 h hypoxia (8% oxygen) when they were 7 days old. The examination began on the 4th week after insult and continued to 18 weeks post-insult. Compared with the control group, the hypoxic-ischemic group showed significant learning impairments in choice reaction time tasks relating to the attention process, and in plus-maze tasks and water maze tasks which examine long-term reference memory. In eight-arm radial maze tasks representing both short-term working memory and long-term reference memory, inferiority of the hypoxic-ischemic group was transient. Results of the sensorimotor test were normal in the hypoxic-ischemic group although slight flexion and twisting in the right forelimb was observed in 30% of the hypoxic-ischemic group when suspended by the tail. These abnormalities did not affect the results of learning tests. Findings of the study indicate that left-side brain damage produced by hypoxia-ischemia at 7 days of age resulted in selective and long-lasting learning and memory impairment.