This project aims to develop a standardized mouse EEG approach, similar to a human standardized system, with defined electrode positions and methodology to facilitate comparisons between data from different studies and mouse strains. This aims for effective, comprehensive sensory phenotyping of transgenic mouse lines, especially for multisensory testing and a topographic overview of activity. As a stand alone, it allows to assess sensory capabilities before more complex experiments.
Topographical information is useful for testing auditory, visual or somatosensory cross-modal changes in the cortex, for example in deaf or blind mice strains, in order to study cross-modal plasticity. Further, this potentially allows to establish useful neural EEG markers for the use in mice, as a tool to better understand variability and effects of genetic and pharmacological influences. Recently, we demonstrated the feasibility for measuring visual evoked potentials with mouse EEG (Land et al. 2019).
Mouse EEG with different configurations shows after re-referencing that this is usable for testing visual evoked potentials on different mouse strains (Land et al. 2019)
Auditory brainstem Response - The P-wave
Mouse EEG can be used to assess biomarkers of different conditions, specifically often used to assess hearing status by measuring ABR waves. This provides an objective measure for the integrity of the auditory pathway along in the auditory brainstem. However, it is necessary to know the origin of the ABR waves, and this origin is still not perfectly clear for the later waves. One important structure is the inferior colliclus as a most important relay station of all auditory information to the cortex. One can identify a specific marker for IC activity in the ABR response when filtering the signal adequately. This slow component provides a non-invaisve measure of IC activity in the mouse, and correlates well with activity recorded within the IC (Land et al. 2016).
By combining invasive recrodings with surface recordings different components can be established in more detail, especially the contribution of the IC to the ABR activity in the mouse. This can then be used to phenotype more effciently, when testing auditory function in transgenic mouse strains.
Mouse ABR and measured responses within the mouse inferior colliculus with a 32-channel multielectrode array. Latency help to determine possible generators for the ABR waves (Land et al. 2016)
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References
Land, R., Kapche, A., Ebbers, L. & Kral, A. 32-channel mouse EEG: Visual evoked potentials. J. Neurosci. Methods 108316 (2019).
Land, R., Burghard, A. & Kral, A. The contribution of inferior colliculus activity to the auditory brainstem response (ABR) in mice. Hear. Res. 341, 109–118 (2016).