サル大脳皮質における長期増強と長期抑圧

村山雄亮、藤田一郎、加藤誠

19回日本神経科学大会プログラム・抄録集p.80

1996711日〜13 神戸

 シナプスの伝達効率が変化する長期増強・抑圧が、学習・記憶能力に長けた霊長類脳に備わっているかはよく分かっていない。長期増強・抑圧の発現を麻酔下サル大脳皮質を用いて検討した。皮質23層に記録電極と刺激電極を設置し、細胞外電場電位を記録した。皮質内水平軸索への同様な高頻度刺激によりTE野では長期増強が、V1では長期抑圧が誘発された。これらは、霊長類脳での長期増強・抑圧の存在を証明し、サル大脳皮質の可塑的性質は領野間で異なることを示唆する。

Long-term potentiation and depression in the adult monkey neocortex.

  Long-term potentiation(LTP) and depression(LTD) of synaptic transmission are possible cellular bases for learning and memory.  It remains unclear, however, whether LTP and LTD can be elicited in primates, the animal group having the most developed learning abilities.  In adult Japanese monkeys anesthetized with N2O, we recorded extracellular field potentials in layer 2/3 of the inferior temporal cortex(TE) and of the striate cortex(V1).  Stimulating electrodes were placed lateral to the recording site to activate horizontal axons.  After a high-frequency conditioning stimulus, the amplitude of field potentials evoked by a single stimulus in the TE gradually increased over 50-70 min up to a maximum, and this potentiation lasted for more than 3 hours.  An identical stimulus protocol did not potentiate field potentials in V1, but caused a depression which developed over 5-10 min and remained stable throughout the remaining recording period.  In both areas, field potentials evoked from an unconditioned pathway were not changed in their amplitude and wave form.  LTP and LTD could thus be elicited in the adult primate neocortex, and the TE and V1 differed from each other in their synaptic plasticity.


Back