The analysis of the neuronal circuit of the inferior colliculus using optogentics.

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K11200
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Otorhinolaryngology
• Research Institution: Kanazawa Medical University
• Principal Investigator: ONO Munenori 金沢医科大学, 医学部, 准教授 (30422942)
• Co-Investigator(Kenkyū-buntansha): 伊藤 哲史 金沢医科大学, 医学部, 准教授 (90334812)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 下丘 / 興奮性ニューロン / 抑制性ニューロン / 光遺伝学

Outline of Final Research Achievements

Using the novel optogenetics recording method, we compared the activities of the excitatory and inhibitory neurons in the inferior colliculus (IC). We found that responses of both inhibitory and excitatory classes of neurons were similar in their response to sound. In the local circuit, the excitatory and inhibitory neurons shared the similar frequency response areas. The activity level of the IC neurons was profoundly affected by anesthesia. In contrast to the response to sound, the inhibitory neurons had higher spontaneous firing rates than the excitatory neurons. Interestingly, this relationship was altered by the hearing loss. In the noise exposed mice, the spontaneous activities of the excitatory neurons were enhanced, while those of the inhibitory neurons did not change, These results showed that the IC transform the afferent inputs in to the excitatory and inhibitory output, and its balance is dynamically modified depending on the strength of the afferent inputs.

Free Research Field

神経生理学

Academic Significance and Societal Importance of the Research Achievements

興奮性及び抑制性の情報伝達は脳内の感覚情報の伝達に極めて重要な役割を持つことがよく知られている。本研究の結果から下丘は大脳皮質に代表される他の脳領域とは異なる独自の音情報処理機能を持つことを示唆しており、その学術的意義は高い。また抑制性ニューロンと興奮性ニューロンの活動レベルが内耳からの入力レベルに応じて可塑的に変化していることから下丘が、耳鳴のような難聴に対する不適応から生じる疾患に関わっていることが強く示唆された。耳鳴は現在治療不可能な疾患であるため、その治療に向けた基礎的な知見を本研究が与えたことの意義は大きい。