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Abstract
The present study tested if lesions of the nucleus basalis magnocellularis (NBM) affect
prepulse inhibition (PPI) of the acoustic startle response and latent inhibition (LI)
of fear-potentiated startle. The NBM is known to play an important role in learning
and memory. Recently, the interest of research focused on its role in attentional
and response selection processes. We here tested the effect of excitotoxic NBM-lesions
on PPI, a phenomenon of sensorimotor gating that occurs at early stages of information
processing. We also assessed the lesion effects on LI, a phenomenon of reduced conditioning
after stimulus preexposure that can be used to measure selective attention. Bilateral
infusions into the NBM of 80 nmol of quinolinic acid markedly reduced the number of
choline acetyltransferase immunopositive neurons in the NBM and lead to a pronounced
reduction of acetylcholine esterase in the cortex and the amygdala. However, no effects
on PPI, fear-conditioning, or LI of fear-potentiated startle were found. Therefore,
we conclude that there is no NBM-driven attentional or response selection process
involved in PPI. Furthermore, the simple association learning in the classical conditioning
paradigm used for fear-potentiated startle or LI is unaffected by NBM-lesions.