Multisite silicon probes enable simultaneous recording of spontaneous and evoked activity in multiple isolated C-fibres in rat saphenous nerve

Anna C Sales, Graeme W T Newton, Anthony E Pickering, Jim Dunham*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

Abstract

Background
Recordings of electrical activity in nerves have provided valuable insights into normal function and pathological behaviours of the nervous system. Current high-resolution techniques (e.g. teased fibre recordings) typically utilise electrodes with a single recording site, capturing the activity of a single isolated neurone per recording.

New Method
We conducted proof-of-principle C-fibre recordings in the saphenous nerve of urethane-anaesthetised adult Wistar rats using 32-channel multisite silicon electrodes. Data was acquired using the OpenEphys recording system and clustered offline with Kilosort 2.5.

Results
In single recordings in 5 rats, 32 units with conduction velocities in the C-fibre range (<1 m/s) were identified via constant latency responses and classified using activity dependent slowing. In two animals, 6 C-fibres (5 classified as nociceptors) were well isolated after clustering. Their activity could be tracked throughout the recording – including during periods of spontaneous activity. Axonal conduction velocities were calculated from spontaneous activity and/or low frequency electrical stimulation using only the differences in action potential latency as it propagated past multiple probe sites.

Comparison with Existing Methods
Single electrode approaches have a low data yield and generating group data for specific fibre types is challenging as it requires multiple experimental subjects and recording sessions. This is particularly true when the experimental targets are the small, unmyelinated C-fibres carrying nociceptive information.

Conclusions
We demonstrate that multisite recordings can greatly increase experimental yields and enhance fibre identification. The approach is of particular utility when coupled with clustering analysis. Multisite probes and analysis approaches constitute a valuable new toolbox for researchers studying the peripheral nervous system.
Original languageEnglish
Article number109419
JournalJournal of Neuroscience Methods
Early online date17 Nov 2021
DOIs
Publication statusE-pub ahead of print - 17 Nov 2021

Keywords

  • peripheral nervous system
  • multisite probes
  • nociception
  • c-fibers
  • clustering

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