Active mechanisms of vibration encoding and frequency filtering in central mechanosensory neurons

Summary

Date: 
April 26, 2017 - 1:00pm - 2:00pm
Location: 
Northwest 243/ Lunch at 12:45pm
About the Speaker
Name: 
Rachel I. Wilson
Speaker Title: 
Martin Family Professor of Basic Research in the Field of Neurobiology
Speaker Affiliation: 
Harvard Medical School

Peripheral cells of the auditory, vestibular, somatosensory, and
proprioceptive systems are all specialized to encode time-varying
displacements. In vertebrates, these peripheral signals are then relayed to the
brain stem or spinal cord, which are difficult to access for intracellular
electrophysiological recording in vivo, particularly in an awake organism. For
this reason, the early stages of central mechanosensory processing are poorly
understood. My lab has recently been studying central mechanosensory processing
in Drosophila, where we can readily perform genetically-targeted in vivo
whole-cell recordings. In particular, we have been studying processing
downstream from the largest mechanosensory organ in Drosophila (Johnston's
organ) which resides in the antenna and encodes antennal movements on a wide
range of temporal and spatial scales. I will focus on our recent work on cells
in the brain that are postsynaptic to the specialized vibration-detector-cells
of Johnston's organ. Some of these cells are particularly interesting because
they use graded potentials to track antennal vibrations cycle-by-cycle, with
opponent populations responding in an anticorrelated fashion on each cycle.

Different cells prefer different vibration frequencies, largely due to
differences in their active (voltage-gated) conductances. Na+ and K+ channels
actively suppress low-frequency synaptic inputs to these cells, making these
cells bandpass filters, with different cells having different intrinsic
passbands. Our results illustrate how central neurons can deploy diverse ion
channel combinations to extract specific temporal features from their synaptic
inputs.