Prepulse inhibition

Prepulse inhibition: preceding stimulus attenuates the startle response.

Prepulse inhibition (PPI) is a neurological phenomenon in which a weaker prestimulus (prepulse) inhibits the reaction of an organism to a subsequent strong reflex-eliciting stimulus (pulse), often using the startle reflex. The stimuli are usually acoustic, but tactile stimuli (e.g. via air puffs onto the skin)[1] and light stimuli[2] are also used. When prepulse inhibition is high, the corresponding one-time startle response is reduced.

The reduction of the amplitude of startle reflects the ability of the nervous system to temporarily adapt to a strong sensory stimulus when a preceding weaker signal is given to warn the organism. PPI is detected in numerous species including mice and humans. Although the extent of the adaptation affects numerous systems, the most comfortable to measure are the muscular reactions, which are normally diminished as a result of the nervous inhibition.

Deficits of prepulse inhibition manifest in the inability to filter out the unnecessary information; they have been linked to abnormalities of sensorimotor gating. Such deficits are noted in patients with conditions like schizophrenia and Alzheimer's disease, and in people under the influence of drugs, surgical manipulations, or mutations. Human studies of PPI have been summarised in reviews by Braff et al. (2001)[3] and Swerdlow et al. (2008).[4]

PPI and startle reflex apparatus for mice
  1. ^ Braff DL, Grillon C, Geyer MA (March 1992). "Gating and habituation of the startle reflex in schizophrenic patients". Archives of General Psychiatry. 49 (3): 206–15. doi:10.1001/archpsyc.1992.01820030038005. PMID 1567275.
  2. ^ Weber M, Swerdlow NR (January 2008). "Rat strain differences in startle gating-disruptive effects of apomorphine occur with both acoustic and visual prepulses". Pharmacology Biochemistry and Behavior. 88 (3): 306–11. doi:10.1016/j.pbb.2007.08.014. PMC 2266874. PMID 17900675.
  3. ^ Braff DL, Geyer MA, Swerdlow NR (July 2001). "Human studies of prepulse inhibition of startle: normal subjects, patient groups, and pharmacological studies". Psychopharmacology. 156 (2–3): 234–58. doi:10.1007/s002130100810. PMID 11549226. S2CID 37231909.
  4. ^ Swerdlow NR, Weber M, Qu Y, Light GA, Braff DL (August 2008). "Realistic expectations of prepulse inhibition in translational models for schizophrenia research". Psychopharmacology. 199 (3): 331–88. doi:10.1007/s00213-008-1072-4. PMC 2771731. PMID 18568339.