Journal article
Reductions in cortical alpha activity, enhancements in neural responses and impaired gap detection caused by sodium salicylate in awake guinea pigs
The European journal of neuroscience, Vol.45(3), pp.398-409
02/2017
DOI: 10.1111/ejn.13474
PMCID: PMC5763375
PMID: 27862478
Abstract
Tinnitus chronically affects between 10–15% of the population but, despite its prevalence, the underlying mechanisms are still not properly understood. One experimental model involves administration of high doses of sodium salicylate, as this is known to reliably induce tinnitus in both humans and animals. Guinea pigs were implanted with chronic electrocorticography (ECoG) electrode arrays, with silver‐ball electrodes placed on the dura over left and right auditory cortex. Two more electrodes were positioned over the cerebellum to monitor auditory brainstem responses (ABRs). We recorded resting‐state and auditory evoked neural activity from awake animals before and 2 h following salicylate administration (350 mg/kg; i.p.). Large increases in click‐evoked responses (> 100%) were evident across the whole auditory cortex, despite significant reductions in wave I ABR amplitudes (in response to 20 kHz tones), which are indicative of auditory nerve activity. In the same animals, significant decreases in 6–10 Hz spontaneous oscillations (alpha waves) were evident over dorsocaudal auditory cortex. We were also able to demonstrate for the first time that cortical evoked potentials can be inhibited by a preceding gap in background noise [gap‐induced pre‐pulse inhibition (PPI)], in a similar fashion to the gap‐induced inhibition of the acoustic startle reflex that is used as a behavioural test for tinnitus. Furthermore, 2 h following salicylate administration, we observed significant deficits in PPI of cortical responses that were closely aligned with significant deficits in behavioural responses to the same stimuli. Together, these data are suggestive of neural correlates of tinnitus and oversensitivity to sound (hyperacusis).
Tinnitus, the perception of a phantom auditory sensation, can be reliably induced by sodium salicylate. However, the underlying mechanisms are poorly understood. Using a chronic ECoG implant, we demonstrate clear changes in awake neural and behavioural activity in guinea pigs following salicylate administration, including poorer gap detection, enhanced evoked potentials and reductions in alpha band activity. These data highlight possible combined neural and behavioural correlates of tinnitus and enhanced sound sensitivity (hyperacusis).
Details
- Title: Subtitle
- Reductions in cortical alpha activity, enhancements in neural responses and impaired gap detection caused by sodium salicylate in awake guinea pigs
- Creators
- Joel I. Berger - MRC Institute of Hearing ResearchBen Coomber - MRC Institute of Hearing ResearchMark N. Wallace - University of NottinghamAlan R. Palmer - MRC Institute of Hearing ResearchJohn Foxe
- Resource Type
- Journal article
- Publication Details
- The European journal of neuroscience, Vol.45(3), pp.398-409
- DOI
- 10.1111/ejn.13474
- PMID
- 27862478
- PMCID
- PMC5763375
- ISSN
- 0953-816X
- eISSN
- 1460-9568
- Number of pages
- 12
- Grant note
- Action on Hearing Loss (G62)
- Language
- English
- Date published
- 02/2017
- Academic Unit
- Neurosurgery
- Record Identifier
- 9984618636802771
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