Physiological and pathological spindling phenomena have similar regional EEG power distributions.
Sleep spindles in human and in rat are known to have a thalamocortical substrate. It has also been suggested that absence epilepsy spike and wave discharges may be generated by a similar mechanism. In addition, we have previously reported a possible thalamocortical origin of the EEG spindling rhythmic discharges associated with myoclonic jerks in the picrotoxin rat model of primary generalised epilepsy. To investigate whether pathological and physiological brain rhythms have common mechanisms of generation, we analysed four electroencephalographic (EEG) spindling activities in the rat. These were the non-convulsive spindle discharges induced by picrotoxin (picrotoxin spindles), naturally occurring absence epilepsy spike and wave discharges (absence spindles), spindle discharges during natural sleep (sleep spindles) and spindling activity that occurs under barbiturate anaesthesia (barbiturate spindles). We used power spectral analysis to define and compare the strength and brain distribution of EEG power during the spindling activities in 12 forebrain and 7 brainstem regions. There were brain-wide differences in power for each of the different spindle types with the pathological rhythms of the epilepsies containing more power than the physiological rhythms. There were also similar differences in the expression of spindles related to the region examined and no thalamic emphasis. These results provide evidence for a similar regional EEG power distribution for all four types of spindling activity and thus for the different spindles being expressions of a single phenomenon.
Mackenzie
Lorraine
L
Department of Medicine and Centre for Neuroscience, Flinders University and Medical Centre, Adelaide, G.P.O. Box 2100, Adelaide, SA 5001, Australia.
Pope
Kenneth James
KJ
Willoughby
John Osborne
JO
D000704:Analysis of Variance; D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology; D001921:Brain / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology*; D003292:Convulsants / Q000494:pharmacology; D004567:Electrodes, Implanted; D004569:Electroencephalography; D004829:Epilepsy, Generalized / Q000503:physiopathology*; D008297:Male; D010634:Phenobarbital / Q000494:pharmacology; D010852:Picrotoxin / Q000494:pharmacology; D051381:Rats; D011921:Rats, Inbred WKY; D017207:Rats, Sprague-Dawley; D012815:Signal Processing, Computer-Assisted; D012890:Sleep / Q000502:physiology*; D013045:Species Specificity
D000927:Anticonvulsants; D003292:Convulsants; D010634:Phenobarbital; D010852:Picrotoxin