RT Journal Article
SR Electronic
T1 Mammalian octopus cells are direction selective to frequency sweeps by synaptic sequence detection
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2021.11.29.470040
DO 10.1101/2021.11.29.470040
A1 Lu, Hsin-Wei
A1 Smith, Philip
A1 Joris, Philip
YR 2021
UL http://biorxiv.org/content/early/2021/11/30/2021.11.29.470040.abstract
AB Octopus cells are remarkable projection neurons of the mammalian cochlear nucleus, with extremely fast membranes and wide frequency tuning. They are considered prime examples of coincidence detectors but are poorly characterized in vivo. We discover that octopus cells are selective to frequency sweep direction, a feature that is absent in their auditory nerve inputs. In vivo intracellular recordings reveal that direction selectivity does not derive from cross-channel coincidence detection but hinges on the amplitudes and activation sequence of auditory nerve inputs tuned to clusters of “hotspot” frequencies. A simple biophysical model of octopus cell excited with real nerve spike trains recreates direction selectivity through interaction of intrinsic membrane conductances with activation sequence of clustered inputs. We conclude that octopus cells are sequence detectors, sensitive to temporal patterns across cochlear frequency channels. The detection of sequences rather than coincidences is a much simpler but powerful operation to extract temporal information.Competing Interest StatementThe authors have declared no competing interest.