, Volume 116, Issue 1, pp 19–25 | Cite as

Unlike haloperidol, clozapine slows and dampens rats' forelimb force oscillations and decreases force output in a press-while-licking behavioral task

  • Stephen C. Fowler
  • Kristl H. Davison
  • John A. Stanford
Original Investigations


In order to detect putative differences in the behavioral effects of clozapine and haloperidol, rats were trained to use a single forelimb to exert continuous pressure on a force-sensing operandum. Behavior was maintained by presenting a water-filled dipper for consumption only as long as the force remained above a specified level (the water fountain task). Effects of clozapine (2.0, 4.0, 8.0 mg/kg) and haloperidol (0.02, 0.04, 0.08, 0.12 mg/kg) on the forelimb force oscillations manifested during the operandum pressing episodes were analyzed with power spectral analysis and other quantitative methods. All rats exhibited force oscillations with a fundamental frequency near 7 Hz. Clozapine shifted the frequency to lower values (i.e., oscillation slowing), while haloperidol shifted oscillations to slightly higher frequencies. Moreover, clozapine reduced power in the region of the spectrum above 5 Hz. In contrast, haloperidol tended to increase power in these regions. Time domain analyses of the force-time waveforms indicated that haloperidol increased force emission during the hold phase of the forelimb response, and clozapine decreased this measure. The results are congruent with the high extrapyramidal side effects of haloperidol and the lack of such effects of clozapine in the clinic. In addition, clozapine may have antitremor effects in rats as it does in humans.

Key words

Haloperidol Clozapine Neuroleptics Tremor Response force Power spectra Forelimb rat 


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Copyright information

© Springer-Verlag 1994

Authors and Affiliations

  • Stephen C. Fowler
    • 1
  • Kristl H. Davison
    • 2
  • John A. Stanford
    • 2
  1. 1.Departments of Psychology and PharmacologyUniversity of MississippiUniversityUSA
  2. 2.Department of PsychologyUniversity of MississippiUniversityUSA

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