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Learning and Long-term Memory

開催日 2014/9/11
時間 16:00 - 17:00
会場 Poster / Exhibition(Event Hall B)

Memory Formation and Retrieval by Neuronal Silencing

  • P1-272
  • 原 宏士朗 / Kojiro Hara:1 野村 洋 / Hiroshi Nomura:1 池谷 裕二 / Yuji Ikegaya:1 
  • 1:東京大院・薬・薬品作用 / Lab Chem Pharmacol, Grad Sch Pharmaceut Sci, Univ Tokyo 

Sensory stimuli not only activate but also inhibit a subset of neurons in their related brain regions. The neuronal activation in the sensory cortices elicits a variety of behavior depending on the past experience; however, the significance of neuronal inhibition remains unclear. In this study, we find that the inhibition of excitatory neurons in the auditory cortex can be a cue of memory formation and retrieval in several memory tasks. To silence the neuronal activity with high temporal precision, we bilateraly injected adeno-associated viral vector (AAV) expressing archirhodopsin (Arch)-EYFP under the control of the CaMKII promoter into the mouse auditory cortex. First, we tested whether optogenetic silencing of auditory cortex neurons can be a conditioned stimulus for fear conditioning. The mice received 16 parings of footshock and delivery of green light to the auditory cortex. One day after conditioning, the mice showed freezing behavior responsive to the green light delivery. The mice receiving AAV-EYFP, instead of AAV-Arch-EYFP, showed no freezing in the test. In addition, the unpaired presentation of optogenetic silencing and foot shock did not produce freezing behavior in the test. Second, we tested whether mice can find food reward by a guide of optogenetic silencing of auditory cortex neurons. A reward pellet was placed at the end of either arm of T-maze. Green light delivery to the auditory cortex indicated the direction of the baited arm. After several days of training, mice acquired the ability to find reward based on the presence or absence of optogenetic silencing. Furthermore, brief light delivery prior to the trial was sufficient for the mice to find the reward. The mice receiving AAV-EYFP displayed chance level of performance even after training. Taken together, these results suggest that the inhibition of excitatory neurons can induce neural plasticity and elicit experience-dependent behavior.

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