Auditory evoked potentials from auditory cortex, medial geniculate nucleus, and inferior colliculus during sleep-wake states and spike-wave discharges in the WAG/Rij rat.
OBJECTIVE
Click auditory evoked potentials (AEP) were simultaneously recorded from the auditory cortex (ACx), the medial geniculate nucleus (MGN), and the inferior colliculus (IC) in the freely moving WAG/Rij rat, to investigate state-dependent changes of the AEP in different anatomical locations along the auditory pathway.


METHODS
AEPs obtained during active (AW) and passive wakefulness (PW), slow wave sleep (SWS), rapid-eye-movement sleep (REM) and generalized spike-wave discharges (SWD; a specific trait of the WAG/Rij rat, a genetic model for absence epilepsy), were compared.


RESULTS
The early components in ACx, MGN and IC were stable throughout the sleep-wake cycle and SWD, apart from a slight increase in the IC during SWD. At all three locations a prominent enlargement of a later component (i.e., N32 in IC, N33 in MGN, and N44 in ACx) was found during SWS and SWD.


CONCLUSIONS
The early AEP components are not modulated by the normal sleep-wake states, and are not impaired during SWD. A strong state-dependent modulation of a later AEP component occurs at all three anatomical locations investigated. This suggests that apart from the thalamic burst firing mode, additional mechanisms must exist for the enlargement of the AEP during EEG-synchronized states at the prethalamic and cortical level.
Meeren
H K
HK
Department of Comparative and Physiological Psychology, Nijmegen Institute of Cognition and Information (NICI), University of Nijmegen, P.O. Box 9104, 6500 HE, Nijmegen, The Netherlands. h.meeren@azvu.nl
van Cappellen van Walsum
A M
AM
van Luijtelaar
E L
EL
Coenen
A M
AM
D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001303:Auditory Cortex / Q000166:cytology / Q000502:physiology*; D004195:Disease Models, Animal; D004832:Epilepsy, Absence / Q000473:pathology / Q000503:physiopathology; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005829:Geniculate Bodies / Q000166:cytology / Q000502:physiology*; D007245:Inferior Colliculi / Q000166:cytology / Q000502:physiology*; D008297:Male; D009474:Neurons / Q000166:cytology / Q000502:physiology; D051381:Rats; D011922:Rats, Mutant Strains; D012890:Sleep / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology*