| Research Abstract |
The purpose of this project is to clarify the relationship between neuroactive molecules and cognitive functions in the aged monkey prefrontal cortex. We investigated the changes of brain-derived neurotrophic factor (BDNF)-immunoreactive structures in the prefrontal cortex and the hippocampal formation of aged macaques (Macaca fuscata fuscatd). At the adult stages (5, 10 and 12 years), BDNF-immunoreactivity was observed in the pyramidal neurons in layers II, III, V and VI of the prefrontal cortex. In the hippocampal formation, BDNF immunoreactivity occurred in the neurons of the dentate gyrus, the pyramidal neurons in the CA1, CA2, CA3 subfields and the subiculum. In aged monkeys (26, 30 and 32 years), the intensity of the BDNF-immunoreactivity declined significantly in cell bodies and dendrites of neurons in the prefrontal cortex and the hippocampal formation (Brain Res. 918 : 191-196, 2001). In addition, we examined aged (25, 27 and 28 years) and young monkeys (6 and 10 years) using a multiple position reversal task to investigate declines in cognitive functions with aging. Aged monkeys showed a poorer performance than the young monkeys in this task. According to our response analysis, the poor performance of aged monkeys in the reversal learning was not caused mainly by repetition of error responses, but rather by the impairment of an understanding of the association between stimulus and reward. We are now investigating changes in BDNF-immunoreactivity of the prefrontal cortex of these aged and young monkeys. We also found that transitions in the dimerization of TrkB subtypes with BDNF occurred during aging of the monkey prefrontal cortex (J. Neurosci. Res. 65 : 463-469, 2001).
|
