title: Excitotoxic lesions of the pedunculopontine tegmental nucleus in rats impair performance on a test of sustained attention.
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 approximately 70%. Pedunculopontine lesioned rats (n=7), however, only achieved a successful detection rate of approximately 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.
authors.affiliation: Department of Psychology, Ohio State University, 27 Townshend Hall, 1885 Neil Avenue, Columbus, OH 43210-1222 , USA.
authors.forename: Rouba
authors.initials: R
authors.lastname: Kozak
authors.forename: Eric M
authors.initials: EM
authors.lastname: Bowman
authors.forename: Mary P
authors.initials: MP
authors.lastname: Latimer
authors.forename: Claire L
authors.initials: CL
authors.lastname: Rostron
authors.forename: Philip
authors.initials: P
authors.lastname: Winn
mesh_terms: D000818:Animals; D001288:Attention / Q000187:drug effects / Q000502:physiology*; D018690:Excitatory Amino Acid Agonists / Q000633:toxicity*; D008297:Male; D045042:Pedunculopontine Tegmental Nucleus / Q000187:drug effects / Q000502:physiology*; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology*; D051381:Rats
chemical_list: D018690:Excitatory Amino Acid Agonists