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Signal Transduction and Modulation

開催日 2014/9/13
時間 14:00 - 15:00
会場 Poster / Exhibition(Event Hall B)

Frequency dependent specialization of dendritic processing in auditory coincidence detector neurons of birds

  • P3-002
  • 山田 玲 / Rei Yamada:1 久場 博司 / Hiroshi Kuba:1,2 
  • 1:名古屋大院医細胞生理 / Dept Cell Physiol, Nagoya Univ Grad Sch Med, Aichi, Japan  2:JSTさきがけ / JST PRESTO, Saitama, Japan 

Neurons in nucleus laminaris (NL) of birds are the coincidence detector of binaural inputs and involved in processing of interaural time differences (ITDs) for sound localization. Importantly, NL neurons are tuned to a specific frequency of sound (characteristic frequency, CF) and change their dendritic structure depending on CF; neurons with low tuning frequency (low-CF neurons) have dendrites 7-20 times longer than higher CF neurons have. However, the functional roles of frequency specific variation of dendritic length for the ITD processing still remain elusive. This is partly because the distribution of synaptic inputs along the dendrites is poorly understood in the low-CF neurons. In this study, we analyzed the distribution of glutamate receptors along the NL dendrites with the focal uncaging of MNI-glutamate in the chicken brain slices. We found that the density of glutamate receptors was heterogeneous in the low-CF neurons and large receptor currents were generated at thin distal dendrites. On the other hand, the currents were uniform along the dendrites in higher CF neurons. In the low-CF neurons, the properties of focal-evoked mEPSCs showed no clear differences between the proximal and distal dendrites, suggesting that the type and density of receptors under the synaptic release site is similar along the dendrites. Therefore, the excitatory synapses might concentrate at the distal and thin dendrites of low-CF neurons. We will further examine the voltage responses generated at the focal dendrites to address the functional roles of heterogeneous distribution of excitatory synapses along the dendrites in the low-CF neurons of NL.

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