title: Habituation and dishabituation of P300.
abstract: OBJECTIVE
  We aimed to see the consequences of habituation and posthabituation by means of repeatedly measuring the effects over a longer period.
  
  
  METHODS
  The study was performed on 27 healthy volunteers. The event-related potentials were recorded from the Fz, the Cz, and the Pz electrode sites. The rare tone-frequent tone probability ratio was 20%. All subjects were asked to press a button when they heard a rare tone. The test was continued until 20 artifact-free rare tones were averaged, which was accepted as 1 trial block. After 10 trial blocks were obtained in a sequential manner, the test was completed.
  
  
  RESULTS
  This study has indicated that P300 amplitudes decrease with repeated stimulations, that is, there is a habituation period. As the test continues, the speed of amplitude decrease slows down and after a while it even starts to increase: that is, a dishabituation occurs.
  
  
  CONCLUSIONS
  It is very likely that this habituation relates to a period of learning and dishabituation relates to a period of mental fatigue. In these processes, changes of amplitude and latency values reflect changes in amount of neuronal activation.
authors.affiliation: Department of Neurology, Duzce Medical School, Turkey. hulusikececi@ttnet.net.tr
authors.forename: Hulusi
authors.initials: H
authors.lastname: Kececi
authors.forename: Yildiz
authors.initials: Y
authors.lastname: Degirmenci
authors.forename: Selcuk
authors.initials: S
authors.lastname: Atakay
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000704:Analysis of Variance; D002540:Cerebral Cortex / Q000502:physiology*; D004192:Discrimination, Psychological / Q000502:physiology*; D018913:Event-Related Potentials, P300 / Q000502:physiology*; D005260:Female; D006185:Habituation, Psychophysiologic / Q000502:physiology*; D006801:Humans; D007858:Learning / Q000502:physiology*; D008297:Male; D012016:Reference Values; D013997:Time Factors