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Sensorimotor Control

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

Sensory input to the forelimb motor areas in rat: an in vivo optical imaging study

  • P2-116
  • 九里 信夫 / Nobuo Kunori:1,2 高島 一郎 / Ichiro Takashima:1 
  • 1:産業技術総合研究所 システム脳科学研究グループ / Neurosci.Res.Inst., National Inst. of Advanced Industrial Sci. & Techonol, Ibaraki, Japan 2:筑波大学大学院 / Grad. Sch. Of Comp. Human Sci., Univ. of Tsukuba, Ibaraki, Japan 

In the rodent motor cortex, two distinct forelimb motor areas have been identified: caudal forelimb area (CFA) and rostral forelimb area (RFA). The CFA and RFA are thought to be equivalent to the hand area in primary motor area and premotor/supplementary motor area in primates, respectively. Although anatomical connectivity and firing property of neurons are different between these forelimb motor areas, one of the major difference is responsiveness to the somatosensory input. Sievert et al., (1986) performed single-unit recording in the forelimb areas in awake rats, and showed that almost no neurons in the RFA responded to sensory stimulus (1 / 117 neurons) while 30% of the CFA neurons (n=114) received somatosensory input. In contrast to the rodent, somatosensory stimulus evoked neural firing in both premotor and supplementary motor areas in primate (Wiesendanger et al., 1985). It is still unknown whether the above difference reflects species difference between rats and primates. In the present study, we re-evaluated the neural response in both the CFA and the RFA regions after somatosensory stimulation. In vivo voltage sensitive dye (VSD) imaging was performed over the motor area with electrical pulse stimulation (0.2-0.6mA, 1ms) to the forelimb in isoflurane-anesthetized rat. After VSD imaging, motor representation was confirmed by intracortical microstimulation. We also applied electrical pulse stimulation (0.1mA, 0.2ms) directly to the CFA, and evoked-response in the RFA was recorded by VSD imaging. Results showed that not only the CFA but also the RFA was activated by electrical stimulation to the forelimb. The direct activation of the CFA also induced cortical activation in the RFA. In addition, the forelimb stimulation-evoked RFA response was disappeared after pharmacological inactivation of the CFA. These results suggest that the RFA receives sensory input through the CFA.

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