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Left-right asymmetry defect in the hippocampal circuitry impairs spatial learning and working memory in iv mice.

Goto K, Kurashima R, Gokan H, Inoue N, Ito I, Watanabe S - PLoS ONE (2010)

Bottom Line: Although left-right (L-R) asymmetry is a fundamental feature of higher-order brain function, little is known about how asymmetry defects of the brain affect animal behavior.To investigate the effects of hippocampal laterality defects on higher-order brain functions, we examined the capacity of reference and working memories of iv mice using a dry maze and a delayed nonmatching-to-position (DNMTP) task, respectively.These results suggest that the L-R asymmetry of hippocampal circuitry is critical for the acquisition of reference memory and the retention of working memory.

View Article: PubMed Central - PubMed

Affiliation: Japan Society for the Promotion of Science, Tokyo, Japan. kgoto@psy.flet.keio.ac.jp

ABSTRACT
Although left-right (L-R) asymmetry is a fundamental feature of higher-order brain function, little is known about how asymmetry defects of the brain affect animal behavior. Previously, we identified structural and functional asymmetries in the circuitry of the mouse hippocampus resulting from the asymmetrical distribution of NMDA receptor GluR ε2 (NR2B) subunits. We further examined the ε2 asymmetry in the inversus viscerum (iv) mouse, which has randomized laterality of internal organs, and found that the iv mouse hippocampus exhibits right isomerism (bilateral right-sidedness) in the synaptic distribution of the ε2 subunit, irrespective of the laterality of visceral organs. To investigate the effects of hippocampal laterality defects on higher-order brain functions, we examined the capacity of reference and working memories of iv mice using a dry maze and a delayed nonmatching-to-position (DNMTP) task, respectively. The iv mice improved dry maze performance more slowly than control mice during acquisition, whereas the asymptotic level of performance was similar between the two groups. In the DNMTP task, the iv mice showed poorer accuracy than control mice as the retention interval became longer. These results suggest that the L-R asymmetry of hippocampal circuitry is critical for the acquisition of reference memory and the retention of working memory.

Show MeSH
Schematic illustration of apparatus and experimental procedure.(A) The front and back panel of the operant conditioning chamber, and (B) the delayed nonmatching-to-position task sequence.
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pone-0015468-g002: Schematic illustration of apparatus and experimental procedure.(A) The front and back panel of the operant conditioning chamber, and (B) the delayed nonmatching-to-position task sequence.

Mentions: An operant-conditioning chamber (ENV-307A; Med Associates, Georgia, VT), 21.6 cm long×17.8 cm wide×12.7 cm high (internal dimensions) was used for this task. The chamber was housed in a sound-attenuating box in a test room, and equipped with three retractable levers (ENV-312M): two on the front wall and one on the back (Figure 2A). A 1.0-A house light was positioned above the back lever; two 1.0-A lights, which were not used in the experiment, were positioned above the front levers. A food well was positioned in the center of the front panel; a 25-mg food pellet was delivered into the well by a dispenser (ENV-203-20) to reinforce correct responses. Masking noise was provided by 75-db white noise, which persisted throughout experimental sessions. A Pentium IV computer (Optiplex; Dell, Round Rock, TX) situated outside the testing room controlled and recorded all experimental events and responses via an interface.


Left-right asymmetry defect in the hippocampal circuitry impairs spatial learning and working memory in iv mice.

Goto K, Kurashima R, Gokan H, Inoue N, Ito I, Watanabe S - PLoS ONE (2010)

Schematic illustration of apparatus and experimental procedure.(A) The front and back panel of the operant conditioning chamber, and (B) the delayed nonmatching-to-position task sequence.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2984506&req=5

pone-0015468-g002: Schematic illustration of apparatus and experimental procedure.(A) The front and back panel of the operant conditioning chamber, and (B) the delayed nonmatching-to-position task sequence.
Mentions: An operant-conditioning chamber (ENV-307A; Med Associates, Georgia, VT), 21.6 cm long×17.8 cm wide×12.7 cm high (internal dimensions) was used for this task. The chamber was housed in a sound-attenuating box in a test room, and equipped with three retractable levers (ENV-312M): two on the front wall and one on the back (Figure 2A). A 1.0-A house light was positioned above the back lever; two 1.0-A lights, which were not used in the experiment, were positioned above the front levers. A food well was positioned in the center of the front panel; a 25-mg food pellet was delivered into the well by a dispenser (ENV-203-20) to reinforce correct responses. Masking noise was provided by 75-db white noise, which persisted throughout experimental sessions. A Pentium IV computer (Optiplex; Dell, Round Rock, TX) situated outside the testing room controlled and recorded all experimental events and responses via an interface.

Bottom Line: Although left-right (L-R) asymmetry is a fundamental feature of higher-order brain function, little is known about how asymmetry defects of the brain affect animal behavior.To investigate the effects of hippocampal laterality defects on higher-order brain functions, we examined the capacity of reference and working memories of iv mice using a dry maze and a delayed nonmatching-to-position (DNMTP) task, respectively.These results suggest that the L-R asymmetry of hippocampal circuitry is critical for the acquisition of reference memory and the retention of working memory.

View Article: PubMed Central - PubMed

Affiliation: Japan Society for the Promotion of Science, Tokyo, Japan. kgoto@psy.flet.keio.ac.jp

ABSTRACT
Although left-right (L-R) asymmetry is a fundamental feature of higher-order brain function, little is known about how asymmetry defects of the brain affect animal behavior. Previously, we identified structural and functional asymmetries in the circuitry of the mouse hippocampus resulting from the asymmetrical distribution of NMDA receptor GluR ε2 (NR2B) subunits. We further examined the ε2 asymmetry in the inversus viscerum (iv) mouse, which has randomized laterality of internal organs, and found that the iv mouse hippocampus exhibits right isomerism (bilateral right-sidedness) in the synaptic distribution of the ε2 subunit, irrespective of the laterality of visceral organs. To investigate the effects of hippocampal laterality defects on higher-order brain functions, we examined the capacity of reference and working memories of iv mice using a dry maze and a delayed nonmatching-to-position (DNMTP) task, respectively. The iv mice improved dry maze performance more slowly than control mice during acquisition, whereas the asymptotic level of performance was similar between the two groups. In the DNMTP task, the iv mice showed poorer accuracy than control mice as the retention interval became longer. These results suggest that the L-R asymmetry of hippocampal circuitry is critical for the acquisition of reference memory and the retention of working memory.

Show MeSH