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Somatosensory System

開催日 2014/9/12
時間 14:00 - 15:00
会場 Poster / Exhibition(Event Hall B)

Physiological properties of motor thalamic nucleus during sensory stimulation in mice

  • P2-170
  • 厚美 佑輔 / Yusuke Atsumi:1,2 小田川 摩耶 / Maya Odagawa:1 太田 桂輔 / Keisuke Ota:1,3 村山 正宜 / Masanori Murayama:1 
  • 1:理化学研究所 / Lab for Behav Neurophysiol, BSI, RIKEN, Saitama, Japan 2:東京工業大学大学院 / Department of Biological Information, Tokyo Institute of Technology 3:日本学術振興会特別研究員PD / JSPS Research Fellow 

Top-down input from a higher-order cortical area toward a sensory area is essential for sensory perception and behavior execution. Our previous studies in mice have shown that sensory-motor circuits consist of a long-range recurrent horizontal projection from secondary motor cortex (M2) to hindlimb somatosensory cortex (S1HL), called the cortical direct pathway, which works during hind limb stimulation. However, other studies have shown that each cortical region forms thalamic connections that relay information from one cortical area to the other through the thalamus, called indirect pathways. Little is known about the physiological property of these indirect pathways in sensory perception. Here, we focused on the S1HL-M2 circuit through the thalamus and investigated its functions. In order to locate the projection from M2 to the thalamus anatomically, we labeled M2 axons by injecting adeno-associated virus-green fluorescent protein (AAV-GFP), an anterograde tracer, into M2. To find the thalamic neurons projecting to S1HL, we labeled somata of the thalamic region by injecting cholera toxin subunit-B (CT-B), which is a retrograde tracer, into S1HL. We found that AAV-GFP-labeled M2 axons and CT-B-labeled thalamic neurons projecting into S1HL coexisted mainly in the motor thalamus. This anatomical finding suggests that the motor thalamus possibly relays top-down signals from M2 to S1HL. To test this hypothesis, we recorded the extracellular neural firing activity from the sensory and motor thalamus, S1HL, and M2. The motor thalamus is functionally divided into two parts, namely, basal ganglia recipient zone (BZ) and cerebellar recipient zone (CZ). Hence, we also characterized the axonal distribution of M2 neurons in BZ and CZ and evaluated the correlation between neural activities of M2 and of these two areas. Here, we present the results of this study and discuss the functions of the indirect pathway within the motor thalamus in sensory perception.

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