Effects of pre-training pedunculopontine tegmental nucleus lesions on delayed matching- and non-matching-to-position in a T-maze in rats.
Lesions of the pedunculopontine tegmental nucleus (PPTg) can impair spatial learning tasks, but it is not clear whether those detrimental effects depend on the specific training conditions (for example, number of response choices available) or are secondary to enhanced anxiety. In the present work, rats with either bilateral excitotoxic (ibotenate) lesions of the PPTg (lesion group) or with vehicle infusions (control group) were tested in an elevated plus-maze, in order to measure anxiety-like behaviours and spontaneous locomotion. Subsequently, they were trained in a delayed matching-to-position (DMTP) task in a T-maze (a two-response choice task). After reaching a predefined learning criterion, or after a maximum of 30 training sessions, the animals were trained in a delayed non-matching-to-position (DNMTP) task. Lesioned animals made less grooming episodes, stretch-attend postures and closed arm entries than controls in the elevated plus-maze, suggesting slightly lower anxiety levels. None of the lesioned rats reached the learning criterion for the DMTP, and overall accuracy levels were significantly lower in those rats, compared to controls. In the DNMTP task, lesioned animals showed lower accuracy levels and higher side bias than controls in some of the sessions, but there were no significant differences between the two groups in the proportion of animals reaching the learning criterion. It is concluded that spatial learning deficits induced by damage to the PPTg are not secondary to enhanced anxiety. Instead, those deficits seem to be influenced by several conditions that modify task demands, the number of response choices being only one of such conditions.
Satorra-Marín
Núria
N
Institut de Neurociències, Departament de Psicobiologia i de Metodologia de les Ciències de la Salut, Edifici B, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
Núria
Satorra-Marín
SM
Homs-Ormo
Sandra
S
Sandra
Homs-Ormo
HO
Arévalo-García
Rosa
R
Rosa
Arévalo-García
AG
Morgado-Bernal
Ignacio
I
Ignacio
Morgado-Bernal
MB
Coll-Andreu
Margalida
M
Margalida
Coll-Andreu
CA
D000704:Analysis of Variance; D000818:Animals; D001007:Anxiety / Q000503:physiopathology; D001522:Behavior, Animal; D001930:Brain Injuries / Q000139:chemically induced / Q000503:physiopathology*; D002755:Choice Behavior / Q000187:drug effects / Q000502:physiology; D018690:Excitatory Amino Acid Agonists; D007051:Ibotenic Acid; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D045042:Pedunculopontine Tegmental Nucleus / Q000293:injuries / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar; D012054:Reinforcement, Psychology; D013028:Space Perception / Q000502:physiology*; D013997:Time Factors
D018690:Excitatory Amino Acid Agonists; D007051:Ibotenic Acid