Investigating the Effects of Aging on Spatial Memory Processes

Associate Professor Dori Derdikman

Associative memory is known to be comprised of two major components: pattern completion and pattern separation. In the aging individual, it has been demonstrated both in animal models and in humans that there is a tendency to perform more processes related to pattern completion at the expense of pattern separation processes. In other words, there is a tendency to perform less categorization, and rather to “lump things together” in larger conceptual groups. For example, the feeling that we have already seen certain things, and that nothing could surprise us, is typical as we grow older.

 In my lab, we research spatial perception in animal models, recording from nerve cells that are part of the brain’s cognitive map of space (our internal navigation circuit, a kind of natural “GPS”), which allows us to orient ourselves in the environment. It is known that such processes are vulnerable in old age, and that many times our cognitive capacities related to navigation and spatial perception are the first to falter.

We will research the function of memory in brain circuits of older rats in comparison to younger rats, and try to understand the nature of memory deficits related to old age. Specifically, we will record hippocampal nerve-cell activity from normal animals at different ages, and from Alzheimer’s disease model animals. We will also record activity from the main cortical afferent to the hippocampus: the entorhinal cortex. These structures contain place cells, grid cells, head-direction cells and border cells, all part of the brain’s GPS system, and we would like to check how these different types of cells are affected in such animals. We will also perform targeted stimulations in these regions, using modern optogenetic techniques, in order to check the effect of such manipulations on the function of the normal and aging brain.

The results of such investigations are expected to aid our understanding of neural processes of memory deterioration, and will perhaps aid us with diagnostic tools to understand the time course of such deterioration at different ages.Dori Derdikman