Modulation of the acoustic startle response by the level of arousal: comparison of clonidine and modafinil in healthy volunteers
Modulation of the acoustic startle response by the level of arousal: comparison of clonidine and modafinil in healthy volunteers
A sudden loud sound evokes an electromyographic (EMG) response from the orbicularis oculi muscle in humans together with an auditory evoked potential (AEP) and an increase in skin conductance (SC). Startle responses are inhibited by weak prepulses (prepulse inhibition, (PPI)) and may also be modified by the level of alertness. We compared the sedative drug clonidine and the alerting drug modafinil on sound-evoked EMG, AEP, and SC responses, on the PPI of these responses and on level of arousal and autonomic functions. Sixteen healthy male volunteers participated in four weekly sessions (clonidine 0.2 mg, modafinil 400 mg, their combination, placebo) in a double-blind, cross-over, balanced design. Responses were evoked by sound pulses of 115 and 85 dB (PPI) for 40 ms and recorded conventionally. Level of alertness, autonomic functions (pupil diameter, blood pressure, heart rate, salivation, temperature) and the plasma levels of the hormones prolactin, thyroid-stimulating hormone and growth hormone were also measured. Data were analyzed with analysis of variance with multiple comparisons. Both prepulses and clonidine attenuated all three startle responses and modafinil antagonized clonidine's effects on the EMG and AEP responses. None of the drugs affected PPI. Clonidine showed sedative and sympatholytic effects, and modafinil showed alerting and sympathomimetic effects. In conclusion, startle responses were susceptible not only to PPI but also to the level of arousal.
acoustic startle response, auditory evoked potential, skin conductance, prepulse inhibition, clonidine, modafinil
2405-2421
Samuels, Ebony R.
aefe49d3-bf1d-4389-8cb8-14fc5921f045
Hou, Ruihua H.
470bdcbc-93a9-4dad-aac5-26d455c34376
Langley, Robert W.
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Szabadi, Elemer
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Bradshaw, Christopher M.
cb3e1129-7215-44a6-bb47-d0f1ea448795
October 2007
Samuels, Ebony R.
aefe49d3-bf1d-4389-8cb8-14fc5921f045
Hou, Ruihua H.
470bdcbc-93a9-4dad-aac5-26d455c34376
Langley, Robert W.
727f09d4-4fab-4e10-980d-d75157e1da4b
Szabadi, Elemer
04ad8033-490b-43f6-a860-bf42367a6eff
Bradshaw, Christopher M.
cb3e1129-7215-44a6-bb47-d0f1ea448795
Samuels, Ebony R., Hou, Ruihua H., Langley, Robert W., Szabadi, Elemer and Bradshaw, Christopher M.
(2007)
Modulation of the acoustic startle response by the level of arousal: comparison of clonidine and modafinil in healthy volunteers.
BMC Psychiatry, 32 (11), .
(doi:10.1038/sj.npp.1301363).
Abstract
A sudden loud sound evokes an electromyographic (EMG) response from the orbicularis oculi muscle in humans together with an auditory evoked potential (AEP) and an increase in skin conductance (SC). Startle responses are inhibited by weak prepulses (prepulse inhibition, (PPI)) and may also be modified by the level of alertness. We compared the sedative drug clonidine and the alerting drug modafinil on sound-evoked EMG, AEP, and SC responses, on the PPI of these responses and on level of arousal and autonomic functions. Sixteen healthy male volunteers participated in four weekly sessions (clonidine 0.2 mg, modafinil 400 mg, their combination, placebo) in a double-blind, cross-over, balanced design. Responses were evoked by sound pulses of 115 and 85 dB (PPI) for 40 ms and recorded conventionally. Level of alertness, autonomic functions (pupil diameter, blood pressure, heart rate, salivation, temperature) and the plasma levels of the hormones prolactin, thyroid-stimulating hormone and growth hormone were also measured. Data were analyzed with analysis of variance with multiple comparisons. Both prepulses and clonidine attenuated all three startle responses and modafinil antagonized clonidine's effects on the EMG and AEP responses. None of the drugs affected PPI. Clonidine showed sedative and sympatholytic effects, and modafinil showed alerting and sympathomimetic effects. In conclusion, startle responses were susceptible not only to PPI but also to the level of arousal.
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Published date: October 2007
Keywords:
acoustic startle response, auditory evoked potential, skin conductance, prepulse inhibition, clonidine, modafinil
Identifiers
Local EPrints ID: 62567
URI: http://eprints.soton.ac.uk/id/eprint/62567
ISSN: 1471-244X
PURE UUID: 786c028b-c642-45b0-bee5-357b0785be67
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Date deposited: 06 Apr 2009
Last modified: 16 Mar 2024 03:55
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Author:
Ebony R. Samuels
Author:
Robert W. Langley
Author:
Elemer Szabadi
Author:
Christopher M. Bradshaw
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