Abstract
Recent research has suggested that the pontomesencephalic tegmentum might be an important part of a network underlying sustained attention. The largest structure of the pontomesencephalic tegmentum is the pedunculopontine tegmental nucleus, which has ascending connections to thalamus and with corticostriatal systems. In this experiment we examined the performance of rats following bilateral excitotoxic lesions of the pedunculopontine tegmental nucleus on a test of sustained attention previously used to examine frontal cortical function. After an initial period of darkness, the rats had to attend continuously to a dim stimulus light that would, at unpredictable intervals, become transiently brighter. During this period of increased stimulus brightness the rats could press a lever to obtain a food reward. Rats were trained to a criterion level of performance before lesions were made. After surgery, sham lesioned rats (n=7) resumed accurate responding, with an average successful detection rate of ∼70%. Pedunculopontine lesioned rats (n=7), however, only achieved a successful detection rate of ∼40%. When the duration of the bright target stimulus was increased from 1.5 to 4 s, the performance of the pedunculopontine lesioned rats significantly improved. The observation that an increase in brightness duration caused a marked improvement in lesioned rats' performance suggests strongly that the impairment was in attention rather than motor ability or simple sensory processing. These data are taken to be consistent with the hypothesis that the pedunculopontine tegmental nucleus is an important part of a network maintaining attention.
Original language | English |
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Pages (from-to) | 257-264 |
Number of pages | 8 |
Journal | Experimental Brain Research |
Volume | 162 |
Issue number | 2 |
Early online date | 19 Nov 2004 |
DOIs | |
Publication status | Published - 30 Apr 2005 |
Funding
Acknowledgements This work was supported by UK BBSRC project grant no. 49/S10196. We thank the staff of the School of Psychology Animal Unit for their care of our rats, and Drs. Morag Farquhar and Helen Alderson for their critical assessment. A preliminary report of these data was made at the 31st Annual Meeting of the Society for Neuroscience, San Diego, 2001.
Keywords
- acetylcholine
- ascending reticular activating system
- basal forebrain
- corticostriatal
- executive function
- pontomesencephalic tegmentum
- thalamus