The effects of clinically relevant doses of amphetamine and methylphenidate on signal detection and DRL in rats.
Low dose amphetamine (AMPH) and methylphenidate (MPH, Ritalin(®)) are the most widely prescribed and most effective pharmacotherapy for attention-deficit/hyperactivity disorder (ADHD). Certain low, clinically relevant doses of MPH improve sustained attention and working memory in normal rats, in contrast to higher doses that impair cognitive ability and induce locomotor activity. However, the effects of AMPH of MPH on sustained attention and behavioral inhibition remain poorly characterized. The present experiments examined the actions of AMPH (0.1 and 0.25 mg/kg) and MPH (0.5 and 1.0 mg/kg) in a rat model of 1) sustained attention, where signal and blank trials were interspersed randomly and occurred at unpredictable times, and 2) behavioral inhibition, using a differential reinforcement of low rate (DRL) schedule. In a signal detection paradigm, both 0.5 mg/kg and 1.0 mg/kg MPH and 0.25 mg/kg AMPH improve sustained attention, however neither AMPH nor MPH improve behavioral inhibition on DRL. Taken together with other recent studies, it appears that clinically-relevant doses of AMPH and MPH may preferentially improve attention-related behavior while having little effect on behavioral inhibition. These observations provide additional insight into the basic behavioral actions of low-dose psychostimulants and further suggest that the use of sustained attention tasks may be important in the development of novel pharmacological treatments for ADHD.
Department of Psychology, University of Wisconsin-Whitewater, 800 W. Main St., Whitewater, WI 53190, United States. Electronic address: andrzejm@uww.edu.
Matthew E
ME
Andrzejewski
Department of Psychology, University of Wisconsin-Madison, Madison, WI, United States.
Robert C
RC
Spencer
Department of Psychology, University of Wisconsin-Madison, Madison, WI, United States.
Rachel L
RL
Harris
Department of Psychology, University of Wisconsin-Madison, Madison, WI, United States.
Elizabeth C
EC
Feit
Biological Sciences, Edgewood College, Madison, WI, United States.
Brenda L
BL
McKee
Department of Psychology, University of Wisconsin-Madison, Madison, WI, United States.
Craig W
CW
Berridge
D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D001288:Attention / Q000187:drug effects*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D007266:Inhibition, Psychological; D008297:Male; D008774:Methylphenidate / Q000494:pharmacology*; D009483:Neuropsychological Tests; D011619:Psychotropic Drugs / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012055:Reinforcement Schedule; D017603:Signal Detection, Psychological / Q000187:drug effects
D000697:Central Nervous System Stimulants; D011619:Psychotropic Drugs; D008774:Methylphenidate; D000661:Amphetamine
Amphetamine; Attention; Behavioral inhibition; DRL; Methylphenidate; Rats; Signal detection