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Brain stem circuits mediating prepulse inhibition of the startle reflex

Authors
  • Fendt, Markus
  • Li, Liang
  • Yeomans, John S.
Type
Published Article
Journal
Psychopharmacology
Publisher
Springer-Verlag
Publication Date
Jun 22, 2001
Volume
156
Issue
2-3
Pages
216–224
Identifiers
DOI: 10.1007/s002130100794
Source
Springer Nature
Keywords
License
Yellow

Abstract

Rationale: Prepulse inhibition (PPI) of the startle reflex occurs when brief, non-startling tactile, acoustic or visual stimuli are presented 20–500 ms before the startling stimulus. Objective: To review information about PPI-mediating brain stem circuits and transmitters, and their functions. Results: Midbrain systems are most critical for the fast relay of these PPI stimuli. Acoustic prepulses for PPI are relayed through the inferior colliculus (IC). The superior colliculus (SC) is important for acoustic PPI, and may be important for the mediation of tactile and visual prepulses. This collicular activation for PPI is quickly relayed through the pedunculopontine tegmental nucleus (PPTg), with lesser contributions to PPI from the laterodorsal tegmental nucleus (LDTg) and substantia nigra, pars reticulata (SNR). The transient activation of midbrain nuclei by PPI stimuli is converted into long-lasting inhibition of the giant neurons of the caudal pontine reticular nucleus (PnC). We propose that muscarinic and GABAB inhibitory receptors (both metabotropic receptors) on PnC giant neurons combine to produce the long-lasting inhibition of startle. Activation of mesopontine cholinergic neurons leads to cortical arousal, turning and exploratory approach responses. Conclusion: PPI is mediated by a circuit involving the IC, SC, PPTg, LDTg, SNR and PnC. By reducing startle, PPI allows the execution of approach responses and perceptual processing following salient stimuli.

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