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Olfaction, Taste, Chemical Senses

開催日 2014/9/13
時間 11:00 - 12:00
会場 Poster / Exhibition(Event Hall B)

Transformation of taste responses from the rostral nucleus of the solitary tract to the parabrachial nucleus in rats

  • P3-143
  • 横田 たつ子 / Tatsuko Yokota:1 平場 勝成 / Katsunari Hiraba:1 
  • 1:愛知学院大学 / Aichi-Gakuin Univ. 

Recent genetic engineering studies have provided clear evidence of "labeled-line" pathways in the periphery. In the central gustatory pathway, it is increasingly important to understand the transformation of neuronal activity from the lower to the higher relay nuclei. The parabrachial nucleus (PBN) of the pons, the second-order taste relay, receives abundant projections from the rostral nucleus of the solitary tract (rNST) in the medulla oblongata, the first-order taste relay. We have reported that the rNST neurons were classified into NaCl (N)-best, NaCl/HCl (NH)-best, HCl (H)-best and sucrose (S)-best. The NH-best neurons could be distinguished from the N-best neurons not only by the taste profile and response duration, but also by their distribution along the rostrocaudal axis. In the present study, we recorded extracellular single unit activities in the rNST and the PBN neurons using multi-barrel glass micropipettes while under urethane anesthesia. Taste solutions were applied to the tongue and the oral cavity. In both the rNST and the PBN, the NaCl response in the N-best neurons was significantly larger than that in the NH-best neurons, and the response duration in the former was significantly longer than that in the latter. These response properties seem to be transferred in the neurons with the same best-stimulus from the rNST to the PBN. The taste response magnitudes to the four basic tastants did not significantly differ between the rNST and the PBN, although the magnitudes in the PBN were somewhat larger than those in the rNST. To investigate the fidelity of taste responses, the coefficient of variation (CV) was calculated from the taste responses in individual trials. The mean CV of the N-best neurons was significantly smaller in the PBN than that in the rNST. The fidelity of taste responses of the N-best neurons may be enhanced in the PBN. The steady responsiveness in the PBN may be advantageous in transmitting taste information to the central gustatory regions.

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