title: The interaction between the dopaminergic forebrain projections and the medial prefrontal cortex is critical for memory of objects: implications for Parkinson's disease.
abstract: Neuropsychological and neuroimaging studies have implicated the dopaminergic nigrostriatal pathway and the prefrontal cortex in learning and memory deficits in patients with Parkinson's disease. However, little is known about how these two brain regions interact in the processing of learning and memory. We employed a disconnection procedure to test whether interaction of these regions contributes to performance in various memory tasks. Male rats received either a unilateral injection of 6-hydroxydopamine into the nigro-striatal tract or a unilateral NMDA lesion in the medial prefrontal cortex, or both these lesions combined in either the same or opposite hemispheres. Spontaneous object exploration, spatial working memory, locomotor, emotional and sensorimotor tests were administered. Only the group with both lesions placed in opposite hemispheres failed to show object recognition memory. None of the groups treated with 6-hydroxydopamine showed intact temporal order memory, whereas only the groups that received combined lesions failed to show object-in-place and spatial recognition memory. No differences between groups were found in the spatial working memory test. Our data indicate that locomotor, emotional and sensorimotor factors are not likely to confound the results of the memory tests. Thus, the interaction between the dopaminergic forebrain projections, particularly the nigrostriatal dopamine, and the medial prefrontal cortex is critical for object recognition memory but not for spatial working memory in rats.
authors: Center for Behavioral Neuroscience, University of Düsseldorf, Universitaetstr. 1, 40225 Düsseldorf, Germany.
authors: Owen Yuan-Hsin
authors: OY
authors: Chao
authors: Martin E
authors: ME
authors: Pum
authors: Joseph P
authors: JP
authors: Huston
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D003623:Dark Adaptation / Q000187:drug effects / Q000502:physiology; D004298:Dopamine / Q000378:metabolism*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D005106:Exploratory Behavior / Q000187:drug effects / Q000502:physiology; D007839:Functional Laterality / Q000187:drug effects / Q000502:physiology; D018737:Hand Strength / Q000502:physiology; D008297:Male; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology; D008474:Medial Forebrain Bundle / Q000187:drug effects / Q000502:physiology*; D008568:Memory / Q000187:drug effects / Q000502:physiology*; D016202:N-Methylaspartate / Q000494:pharmacology; D009434:Neural Pathways / Q000502:physiology*; D016627:Oxidopamine / Q000494:pharmacology; D017397:Prefrontal Cortex / Q000502:physiology*; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D021641:Recognition, Psychology / Q000187:drug effects / Q000502:physiology; D012701:Serotonin / Q000378:metabolism; D013028:Space Perception / Q000187:drug effects; D013565:Sympatholytics / Q000494:pharmacology
chemical_list: D018690:Excitatory Amino Acid Agonists; D013565:Sympatholytics; D012701:Serotonin; D016202:N-Methylaspartate; D016627:Oxidopamine; D004298:Dopamine
keywords: 6-OHDA; Hemiparkinsonian rat; NMDA lesion; Spatial recognition memory; Spatial working memory; Temporal order memory