title: Prepulse inhibition of auditory change-related cortical responses.
abstract: BACKGROUND
  Prepulse inhibition (PPI) of the startle response is an important tool to investigate the biology of schizophrenia. PPI is usually observed by use of a startle reflex such as blinking following an intense sound. A similar phenomenon has not been reported for cortical responses.
  
  
  RESULTS
  In 12 healthy subjects, change-related cortical activity in response to an abrupt increase of sound pressure by 5 dB above the background of 65 dB SPL (test stimulus) was measured using magnetoencephalography. The test stimulus evoked a clear cortical response peaking at around 130 ms (Change-N1m). In Experiment 1, effects of the intensity of a prepulse (0.5 ~ 5 dB) on the test response were examined using a paired stimulation paradigm. In Experiment 2, effects of the interval between the prepulse and test stimulus were examined using interstimulus intervals (ISIs) of 50 ~ 350 ms. When the test stimulus was preceded by the prepulse, the Change-N1m was more strongly inhibited by a stronger prepulse (Experiment 1) and a shorter ISI prepulse (Experiment 2). In addition, the amplitude of the test Change-N1m correlated positively with both the amplitude of the prepulse-evoked response and the degree of inhibition, suggesting that subjects who are more sensitive to the auditory change are more strongly inhibited by the prepulse.
  
  
  CONCLUSIONS
  Since Change-N1m is easy to measure and control, it would be a valuable tool to investigate mechanisms of sensory gating or the biology of certain mental diseases such as schizophrenia.
authors.affiliation: Department of Integrative Physiology, National Institute for Physiological Sciences, Okazaki, 444-8585, Japan. inui@nips.ac.jp
authors.forename: Koji
authors.initials: K
authors.lastname: Inui
authors.forename: Aki
authors.initials: A
authors.lastname: Tsuruhara
authors.forename: Minori
authors.initials: M
authors.lastname: Kodaira
authors.forename: Eishi
authors.initials: E
authors.lastname: Motomura
authors.forename: Hisashi
authors.initials: H
authors.lastname: Tanii
authors.forename: Makoto
authors.initials: M
authors.lastname: Nishihara
authors.forename: Sumru
authors.initials: S
authors.lastname: Keceli
authors.forename: Ryusuke
authors.initials: R
authors.lastname: Kakigi
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D000704:Analysis of Variance; D001303:Auditory Cortex / Q000502:physiology*; D004576:Electromyography; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D011571:Psychoacoustics; D011930:Reaction Time; D013216:Reflex, Startle; D015203:Reproducibility of Results; D055139:Sensory Gating / Q000502:physiology*; D013997:Time Factors