| Over the past two decades a number of laboratories, including ours, have conducted studies of how the aging process affects cellular and molecular mechanisms of synaptic plasticity and memory in rats. These experiments have provided a framework for understanding how the brain stores and retrieves information and what biological processes may underlie the cognitive changes that are observed in mammals as they age. Alterations in brain plasticity mechanisms during aging will be reviewed. More recently our research group has developed methods for recording from many single neurons in freely behaving rats that has provided an unprecedented window into changes in neural population coding dynamics in the young and aged rodent hippocampus in relation to spatial learning and memory. With these methods we have discovered what appears to be a principal neuronal population correlate of memory retrieval failure in old rats. We propose that this age-related change in the dynamics of neural coding may provide a plausible explanation for why elderly people more frequently become spatially disoriented or lost. A new direction in this work has the potential to provide a bridge between what is known about the activity characteristics of ensembles of cells recorded during behavior, and what we know about multiple genes that are activated during these behaviors. It is possible now to envision whole brain imaging of neuronal activity at the level of individual cells, using multiple genes as markers, with discrete temporal resolution of multiple experiences. This new cellular/molecular imaging approach should complement existing functional imaging methods, and should help achieve a more complete understanding of the systems responsible for hippocampal-dependent behaviors. |
|
Cognitive Neuroscience Colloquium: Friday October 5, 2001 1:30-3:00 BSBE 2-101 |