title: Memory impairment and alterations in prefrontal cortex gamma band activity following methamphetamine sensitization.
abstract: BACKGROUND
  Repeated methamphetamine (MA) use leads to increases in the incentive motivational properties of the drug as well as cognitive impairments. These behavioral alterations persist for some time following abstinence, and neuroadaptations in the structure and function of the prefrontal cortex (PFC) are particularly important for their expression. However, there is a weak understanding of the changes in neural firing and oscillatory activity in the PFC evoked by repeated drug use, thus complicating the development of novel treatment strategies for addiction.
  
  
  OBJECTIVE
  The purpose of the current study was to assess changes in cognitive and brain function following MA sensitization.
  
  
  METHODS
  Sensitization was induced in rats, then temporal and recognition memory were assessed after 1 or 30 days of abstinence. Electrophysiological recordings from the medial PFC were also acquired from rats whereupon simultaneous measures of oscillatory and spiking activity were examined.
  
  
  RESULTS
  Impaired temporal memory was observed after 1 and 30 days of abstinence. However, recognition memory was only impaired after 1 day of abstinence. An injection of MA profoundly decreased neuronal firing rate and the anesthesia-induced slow oscillation (SO) in both sensitized (SENS) and control (CTRL) rats. Strong correlations were observed between the SO and gamma band power, which was altered in SENS animals. A decrease in the number of neurons phase-locked to the gamma oscillation was also observed in SENS animals.
  
  
  CONCLUSIONS
  The changes observed in PFC function may play an integral role in the expression of the altered behavioral phenotype evoked by MA sensitization.
authors.affiliation: Department of Psychology, Indiana University-Purdue University Indianapolis, 402 N. Blackford, LD 124, Indianapolis, IN, 46202, USA, sjanetsi@iupui.edu.
authors.forename: Sarine S
authors.initials: SS
authors.lastname: Janetsian
authors.forename: David N
authors.initials: DN
authors.lastname: Linsenbardt
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Lapish
mesh_terms: D000818:Animals; D016739:Behavior, Addictive / Q000523:psychology; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003071:Cognition / Q000187:drug effects; D004569:Electroencephalography / Q000187:drug effects*; D008297:Male; D008569:Memory Disorders / Q000139:chemically induced* / Q000523:psychology*; D008694:Methamphetamine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects; D009474:Neurons / Q000187:drug effects; D017397:Prefrontal Cortex / Q000166:cytology / Q000187:drug effects*; D051381:Rats; D021641:Recognition, Psychology / Q000187:drug effects; D013239:Stereotyped Behavior / Q000187:drug effects
chemical_list: D000697:Central Nervous System Stimulants; D008694:Methamphetamine