Changes in electrocortical power and coherence in response to the selective cholinergic immunotoxin 192 IgG-saporin

Abstract

Changes in brain electrical activity in response to cholinergic agonists, antagonists, or excitotoxic lesions of the basal forebrain may not be reflective entirely of changes in cholinergic tone, in so far as these interventions also involve noncholinergic neurons. We examined electrocortical activity in rats following bilateral intracerebroventricular administration of 192 IgG-saporin (1.8 μg/ventricle), a selective cholinergic immunotoxin directed to the low-affinity nerve growth factor receptor p75. The immunotoxin resulted in extensive loss of choline acetyl transferase (ChAT) activity in neocortex (80%-84%) and hippocampus (93%), with relative sparing of entorhinalpiriform cortex (42%) and amygdala (28%). Electrocortical activity demonstrated modest increases in 1-to 4-Hz power, decreases in 20-to 44-Hz power, and decreases in 4-to 8-Hz intraand interhemispheric coherence. Rhythmic slow activity (RSA) occurred robustly in toxin-treated animals during voluntary movement and in response to physostigmine, with no significant differences seen in power and peak frequency in comparison with controls. Physostigmine significantly increased intrahemispheric coherence in lesioned and intact animals, with minor increases seen in interhemispheric coherence. Our study suggests that: (1) electrocortical changes in response to selective cholinergic deafferentation are more modest than those previously reported following excitotoxic lesions; (2) changes in cholinergic tone affect primarily brain electrical transmission within, in contrast to between hemispheres; and (3) a substantial

Interactions of Subsymptomatic Doses of Sarin with Pyridostigmine - Neurochemical, Behavioral, and Physiological Effects

“…It is possible that the observed phenomenon might be associated with EEG arousal, since a similar association has been observed previously in rats (Holschneider et al, 1998;Waite et al, 1999).…”

Donepezil effects on sources of cortical rhythms in mild Alzheimer's disease: Responders vs. Non-Responders

“…This advantage was supposed to compensate the use of odd 10.5 Hz as half-limit between alpha 1 and alpha 2 bands. Sharing of a frequency bin by two contiguous bands has been shown to be adequate by much EEG literature (Cook and Leuchter, 1996;Jelic et al, 1996;Besthorn et al, 1997;Holschneider et al, 1999). Furthermore, it follows the theoretical consideration of Klimesch and others stating that near EEG rhythms may overlap at their frequency borders (see Klimesch, 1999 for a review).…”

Stability of clinical condition in mild cognitive impairment is related to cortical sources of alpha rhythms: An electroencephalographic study

“…An important neuroanatomical substrate of alpha rhythms is the cholinergic innervation from basal forebrain to cerebral cortex, including a gross branch connecting visual occipital regions. This innervation would be targeted by neurodegenerative processes in AD [Helkala et al, 1996;Holschneider et al, 1999;Mesulam et al, 2004;Ricceri et al, 2004;Teipel et al, 2005], especially in AD patients not responding to long-term cholinergic therapy [Tanaka et al, 2003]. Instead, brainstem cholinergic innervation of the thalamus would be relatively spared [Geula and Mesulam, 1989, 1996, 1999Mash et al, 1985;Mesulam et al, 2004].…”