Habit formation and the loss of control of an internal clock: inverse relationship between the level of baseline training and the clock-speed enhancing effects of methamphetamine.


Journal Article

Drugs that modulate the effective level of dopamine (DA) in cortico-striatal circuits have been shown to alter the perception of time in the seconds-to-minutes range. How this relationship changes as a function of repeated experience with the reinforcement contingencies and the gradual adaptation of the underlying neural circuits remains unclear.The present study examined the clock-speed enhancing effects of methamphetamine (MAP 0.5 or 1.0 mg/kg, ip) in groups of rats that received different levels of baseline training (20, 60, or 120 sessions) on a 50-s peak-interval (PI) procedure before initial drug administration.A curvilinear relationship was observed such that rats that received either minimal or intermediate levels of training (or=120 sessions) did not show this "classic" DA agonist curve-shift effect, but instead displayed a dose-dependent disruption of temporal control after MAP administration. A transition from DA-sensitive to DA-insensitive mechanisms is proposed to account for the loss of control of clock speed, as timing behaviors associated with the PI procedure gradually become learned habits through the strengthening of DA-glutamate connections.

Full Text

Cited Authors

  • Cheng, R-K; Hakak, OL; Meck, WH

Published Date

  • August 2007

Published In

Volume / Issue

  • 193 / 3

Start / End Page

  • 351 - 362

PubMed ID

  • 17464501

Pubmed Central ID

  • 17464501

Electronic International Standard Serial Number (EISSN)

  • 1432-2072

International Standard Serial Number (ISSN)

  • 0033-3158

Digital Object Identifier (DOI)

  • 10.1007/s00213-007-0783-2


  • eng