Increasing the speed of an internal clock: The effects of nicotine on interval timing

✍ Scribed by Sean C. Hinton; Warren H. Meck

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 654 KB
• Volume: 38
• Category: Article
• ISSN: 0272-4391
• DOI: 10.1002/(sici)1098-2299(199607/08)38:3/4<204::aid-ddr9>3.0.co;2-q

✦ Synopsis

This experiment assessed the effects of nicotine on the ability of rats to time short intervals. Ten rats were trained to discriminate 20 and 60 s signals and were then tested using the peak-interval timing procedure for their ability to reproduce these intervals. Testing continued for 33 days on a weekly schedule in which five saline-injection days were followed by two nicotineinjection days. When they were administered 0.2 mg/kg nicotine on the first day after saline, the rats showed a proportional leftward shift in their timing functions. When the rats were given nicotine again on the subsequent day, their timing functions renormalized. On the following saline-injection day, the rats' timing functions showed a rebound in the opposite direction. This pattern of data implies that nicotine is speeding up the internal clock. Nicotinic interactions with the nigrostriatal dopamine system suggest a possible physiological mechanism for the observed increase in clock speed.