Aging and cholinergic modulation of the transient magnetic 40-Hz auditory response.
Cholinergic blockade by scopolamine, a central muscarinic receptor antagonist, may produce transient memory impairment in healthy subjects, and it has been used as a neurochemical model of cognitive degeneration in aged individuals. To observe the muscarinic modulation of memory and cortical auditory processing, nine cognitively intact elderly subjects (59-80 years) were studied using neuropsychological tests and 122-channel magnetoencephalography (MEG) after an administration of scopolamine hydrobromide (0.3 mg, i.v.) or glycopyrrolate (0.2 mg, i.v.), a peripheral muscarinic antagonist. A double-blind randomized crossover design was used in two sessions separated by at least 1 week. Scopolamine, but not glycopyrrolate, produced a transient impairment of verbal memory performance in the elderly subjects. MEG indicated that the auditory-evoked 40-Hz magnetic response was significantly larger after scopolamine than after glycopyrrolate administration. Furthermore, reanalysis of our earlier results in younger subjects (20-31 years), basically supporting the present MEG findings, tentatively suggests that the scopolamine effects on the 40-Hz response may be slightly pronounced with aging. In sum, the transient magnetic 40-Hz auditory response may be useful in studies on brain cholinergic deficits in elderly subjects.
Ahveninen
Jyrki
J
Cognitive Brain Research Unit, Department of Neurology, University of Helsinki, FIN-00014 Helsinki, Finland. jyrki.ahveninen@helsinki.fi
Jääskeläinen
Iiro P
IP
Kaakkola
Seppo
S
Tiitinen
Hannu
H
Pekkonen
Eero
E
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D002540:Cerebral Cortex / Q000187:drug effects / Q000502:physiology; D002799:Cholinergic Fibers / Q000187:drug effects / Q000502:physiology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005072:Evoked Potentials, Auditory / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006024:Glycopyrrolate / Q000494:pharmacology; D006801:Humans; D007262:Infusions, Intravenous; D015225:Magnetoencephalography; D008297:Male; D011939:Mental Recall / Q000187:drug effects / Q000502:physiology*; D008875:Middle Aged; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000502:physiology*; D012601:Scopolamine / Q000494:pharmacology; D014706:Verbal Learning / Q000187:drug effects / Q000502:physiology
D011976:Receptors, Muscarinic; D012601:Scopolamine; D006024:Glycopyrrolate