D. Verdier et Rw. Dykes, Long-term cholinergic enhancement of evoked potentials in rat hindlimb somatosensory cortex displays characteristics of long-term potentiation, EXP BRAIN R, 137(1), 2001, pp. 71-82
Pairing a cutaneous electrical stimulus of the hind-paw with stimulation of
the basal forebrain produces long-term cholinergic enhancement of the resp
onsiveness to a tactile stimulus. A short period of pairing (20 trials) inc
reased the area of the two main components of the evoked potential by 37.1/-13.5% (+/-SEM) and 37.9+/-6.8%, respectively. The effects lasted for the
duration of the experiment (>2 h). The enhancement could be blocked by eith
er MK-801, an NMDA receptor antagonist or by L-NAME, a nitric-oxide-synthas
e inhibitor when they were given prior to pairing. Control experiments with
Skin stimulation alone and basal forebrain stimulation alone had only smal
l long-term effects (similar to 10%) on the size of the evoked potential. T
hus, long term cholinergic enhancement, attributable to disinhibition and i
ncreased release of acetylcholine in the cortex during neuronal excitation
by other sources, and so named because it is blocked by atropine, may be a
form of long-term potentiation. The existence of such a mechanism for the c
ontrol of cortical neuronal plasticity identifies the basal forebrain as a
powerful modulator of long-lasting changes in cortical neuronal excitabilit
y.