Impaired acquisition of novel locomotor tasks in aged and norepinephrine-depleted F344 rats

Paula Bickford, Christine Heron, David A. Young, Greg A. Gerhardt, René dela Garza

Research output: Contribution to journalArticlepeer-review

71 Scopus citations

Abstract

Performance of rats on a motor learning paradigm that has been demonstrated to be dependent upon cerebellar norepinephrine (NE) was studied in 20-month-old F344 rats. The behavioral task is identical to that described by Watson and McElligott: Rats are trained on a runaway consisting of aluminum pegs arranged in a regular pattern. Rats receive a water reward at either end of the runaway. Subsequent to training, rats are tested for running times on a runway with irregularly spaced rods. The ability of rats to improve their performance (decrease their running times) on this novel motor task is diminished in young rats that have received 6-hydroxydopamine lesions. Rats at 20 months of age are known to have deficits in cerebellar noradrenergic transmission; thus, the hypothesis to be tested was to determine if aged rats demonstrated performance deficits similar to young rats depleted of central stores of NE. The rate of acquisition of the task was determined by the decrease in running times with successive days of training. The ability of 20-month-old F344 rats to acquire proficiency on the novel motor task was impaired and the rate of acquisition of the novel motor task was not different from the young 6-hydroxydopamine-lesioned rats. In an attempt to distinguish between alterations in motor coordination and motor learning, additional tests of psychomotor performance were assessed for all groups of rats. These tests included a walking on 2.5- and 5-cm rods, speed of running on the motor task, and number and types of mistakes made on the motor learning task. The data indicate that none of the above-mentioned factors correlated with the ability of an individual rat to learn the novel motor task, suggesting age-related motor performance deficits may be separable from motor learning deficits. This data is consistent with our hypothesis that age-related alterations in noradrenergic function may underlie the decline in motor learning.

Original languageEnglish
Pages (from-to)475-481
Number of pages7
JournalNeurobiology of Aging
Volume13
Issue number4
DOIs
StatePublished - 1992

Bibliographical note

Funding Information:
This work was supported by USPHS Grants AG 04418 (P.B.) and AG 06434 (G.A.G.), the Veterans Administration Medical Research Service (P.B.), and the American Federation for Aging Research (P.B.).

Copyright:
Copyright 2015 Elsevier B.V., All rights reserved.

Keywords

  • Aging
  • Cerebellum
  • Motor learning
  • Norepinephrine

ASJC Scopus subject areas

  • Neuroscience (all)
  • Aging
  • Clinical Neurology
  • Developmental Biology
  • Geriatrics and Gerontology

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