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Amphetamine Enhances Impulsive Behavior in Rats Responding under a Stop Signal Procedure
Author(s) -
Maguire David Richard,
France Charles P
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.1184.8
Subject(s) - impulsivity , timeout , stop signal , stimulant , psychology , amphetamine , audiology , developmental psychology , medicine , psychiatry , neuroscience , statistics , mathematics , dopamine , electrical engineering , engineering , latency (audio)
Impulsivity might contribute to the persistence of stimulant (e.g., amphetamine) abuse and stimulant use can enhance impulsivity. The dynamic relationship between stimulant use and impulsivity has been well‐documented; however, the exact nature of the relationship remains unclear, in part, because of the multidimensionality of impulsivity. This study examined effects of amphetamine in rats (n=9) responding under a stop signal procedure which measured two different aspects of motor impulsivity: 1) responding before presentation of a go signal; and 2) responding after presentation of a stop signal. Rats were trained to press one lever (e.g., left) and then another lever (e.g., right) in order to obtain food. On 80% of trials (go trials), completion of the second response within a limited hold delivered food; failure to complete the second response initiated a timeout. On the remaining 20% of trials (stop trials), a tone was presented after the first response signaling that food would be presented only if the second response was withheld; responses after presentation of the tone initiated a timeout. Trials were separated by an inter‐trial interval; responses during the inter‐trial interval initiated a timeout, and responses during a timeout extended the timeout. Responding on stop trials (false alarms) and during the inter‐trial interval (premature responses) were measures of motor impulsivity. Under baseline conditions, rats responded on at least 90% of go trials and on no more than 10% of stop trials, while making fewer than 10 premature responses per session. Amphetamine (0.1–1.78 mg/kg) impaired response accuracy by significantly decreasing responses during go trials and increasing responses during stop trials. Amphetamine also significantly increased premature responding but did not impact timeout responding. Increased premature responding occurred with doses of amphetamine (0.32 and 1.0 mg/kg) smaller than the dose (1.78 mg/kg) that significantly increased false alarms. These data indicate that amphetamine enhances two types of motor impulsivity as measured with a stop signal procedure. However, increased premature responding occurred with doses of amphetamine that were 5‐fold smaller than the smallest dose that increased stop trial responding. Taken together, these data suggest that although amphetamine increases different behaviors thought to reflect motor impulsivity, sensitivity to amphetamine differs across measures. Thus, the impact of stimulant use on impulsivity might depend upon which aspect is being measured. Support or Funding Information Supported, in part, by NIH grant K05DA017918 (CPF).