ms-Scale temporal coding in the thalamus predicted by whisker dispersive vibrational transduction

Ding, Yu

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https://hdl.handle.net/2142/129657 Copy

Description

Title

ms-Scale temporal coding in the thalamus predicted by whisker dispersive vibrational transduction

Author(s)

Ding, Yu

Issue Date

2024-12-20

Director of Research (if dissertation) or Advisor (if thesis)

Vlasov, Yurii

Doctoral Committee Chair(s)

Aksimentiev, Alek

Committee Member(s)

• Kleinfeld, David
• Llano, Daniel

Department of Study

Physics

Discipline

Physics

Degree Granting Institution

University of Illinois Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Biophysics modeling
• Neuroscience
• Somatosensation
• In vivo study
• Temporal coding

Abstract

Whether stimulus information is encoded in the whisker system has been a question of debate. Considering the remarkable temporal precision in the whisker system with spike timing as small as 10μs, there is potential for ultrahigh capacity information channel in kb/s. To study temporal structures in the stimuli that could be encoded by this information channel, highly sensitive acoustic methods were used to listen to fast whisker vibrations up to 10kHz. The observed whisker vibrations were separated into distinct eigenmodes, with the high-frequency vibrations above 1kHz occupying as much as 80% of the energy during whisker interaction with texture. We predicted that the whisker could act as a preneuronal processor by converting a shockwave at the whisker tip into separate energy packets arriving at the whisker base at different times, thus potentially generating temporally precise spiking in the mechanoreceptors. This dispersive vibrational transduction (DVT) predicts temporal code with information capacity as high as 700bits/s [1]. To verify the hypothesis, we conducted in-vivo recording from multielectrode array placed in the mouse thalamus (VPMdm), while simultaneously recording vibrations at the whisker tip. We discovered that firing of 99 VPMdm neurons across 8 animals is triggered by high-frequency vibrations with jitters below 0.4ms. Some of these VPMdm neurons with short latency below 4ms exhibit strong modulation of firing rate at the ms scale. This ms-scale non-stationary firing rate (FR) modulation is present even after accounting for bursting of the neurons, which suggests that the FR modulation reflects temporal structure of the stimuli, potentially encoding rapid changes in the whisker micromotions. Established information theory metrics were used to quantify the amount of information contained in the FR modulations. We found that all VPMdm neurons that are responsive to high-frequency vibrations convey information through spike time, not only spike count. Additionally, most of that information is carried in the first peristimulus spike. Looking at the contribution to the carried information for various peristimulus time, the accumulation of information increases in increments corresponding to individual peaks in FR. For the FR modulated neurons, the additional peaks in FR after the first peak contain as much as 39% of total information. Experiments found FR modulations that could serve as additional information channels carrying ms-scale temporal information from the stimulus, as predicted by the DVT hypothesis. To see how well DVT hypothesis could explain the observed information channel, spike trains predicted from the DVT model is compared against those predicted from a traditional viscoelastic model (VEM) considering the bending moment at the whisker base [2]. The DVT model, not the VEM model, predicts non-stationary FR modulation on the order of ms, as well as the accumulation of information in peaks in FR. Our results indicate that fast whisker vibrations are dispersed by the whisker as wavepackets arriving at the whisker base, with its ms difference in arrival time likely encoded as non-stationary FR modulations in VPMdm neurons.

Graduation Semester

2025-05

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/129657

Copyright and License Information

Copyright 2024 Yu Ding

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