PT  - JOURNAL ARTICLE
AU  - Edward J. Schicatano
AU  - Kavita R. Peshori
AU  - Ramesh Gopalaswamy
AU  - Eva Sahay
AU  - Craig Evinger
TI  - Reflex Excitability Regulates Prepulse Inhibition
AID  - 10.1523/JNEUROSCI.20-11-04240.2000
DP  - 2000 Jun 01
TA  - The Journal of Neuroscience
PG  - 4240--4247
VI  - 20
IP  - 11
4099  - http://www.jneurosci.org/content/20/11/4240.short
4100  - http://www.jneurosci.org/content/20/11/4240.full
SO  - J. Neurosci.2000 Jun 01; 20
AB  - Presentation of a weak stimulus, a prepulse, before a reflex-evoking stimulus decreases the amplitude of the reflex response relative to reflex amplitude evoked without a preceding prepulse. For example, presenting a brief tone before a trigeminal blink-eliciting stimulus significantly reduces reflex blink amplitude. A common explanation of such data are that sensory processing of the prepulse modifies reflex circuit behavior. The current study investigates the converse hypothesis that the intrinsic characteristics of the reflex circuit rather than prepulse processing determine prepulse modification of trigeminal and acoustic reflex blinks.Unilateral lesions of substantia nigra pars compacta neurons created rats with hyperexcitable trigeminal reflex blinks but normally excitable acoustic reflex blinks. In control rats, presentation of a prepulse reduced the amplitude of both trigeminal and acoustic reflex blinks. In 6-OHDA-lesioned rats, however, the same acoustic prepulse facilitated trigeminal reflex blinks but inhibited acoustic reflex blinks. The magnitude of prepulse modification correlated with reflex excitability.Humans exhibited the same pattern of prepulse modification. An acoustic prepulse facilitated the trigeminal reflex blinks of subjects with hyperexcitable trigeminal reflex blinks caused by Parkinson's disease. The same prepulse inhibited trigeminal reflex blinks of age-matched control subjects. Prepulse modification also correlated with trigeminal reflex blink excitability. These data show that reflex modification by a prepulse reflects the intrinsic characteristics of the reflex circuit rather than an external adjustment of the reflex circuit by the prepulse.