Sara N. Burke, Ph.D.
Department of Neuroscience
University of Florida
1149 Newell Drive
PO Box 100244
Gainesville, FL 32611-0244
Office Phone: (352) 294-4979
Aging, Entorhinal Cortex, Hippocampus, Memory, Neurophysiology, Perirhinal Cortex
At the turn of this century, the net balance of the world’s elderly population grew by more than 795,000 people each month reaching over 420 million by the beginning of 2011. Declining birthrates and an increased life expectancy have resulted in a population age distribution with a larger proportion of elderly individuals than has ever occurred in recorded history. Even in the absence of significant neuropathology, many of these individuals will experience memory impairments that interfere with their instrumental activities of daily living. Increasing our understanding of how advanced age impacts neurophysiological function is therefore essential for facilitating the development of potential therapeutics and behavioral interventions that will promote positive health outcomes for this growing demographic sector.
The principal aim of my research is to investigate how medial temporal lobe and frontal cortical structures involved in memory and high-level sensory perception are altered by advanced age and how nutrition and fitness can circumvent possible network impairments. Age-associated cognitive impairments do not result from alterations to brain structures in isolation. To fully understand cognitive aging, it is therefore imperative to examine how brain areas interact. A powerful tool for pin-pointing disruptions in the complex neural systems that produce cognitive dysfunction during normal aging is the careful analysis of behavior. Therefore, all of my research projects begin with an extensive cognitive test battery, including tests of spatial memory, working memory, stimulus recognition and sensory perception. Following, a careful characterization of behavior, the primary methods I use to assay the neurobiological basis of age-associated cognitive decline are single-cell imaging techniques and in vivo high-density recordings of single neurons from behaving rats. A strength of this approach is that the neurobiology of age-related memory loss is examined at multiple levels. Behavioral analysis along with advanced imaging and physiological techniques provides a multiplicative understanding of the loci of circuit disruptions by linking specific physiological features to cognitive performance.
Research Focus & Aims:
Although damage to different medial temporal lobe structures can have dissociable behavioral effects, the dense interconnectivity between the hippocampus, lateral entorhinal and perirhinal cortices suggest that these areas cooperatively support memory. Moreover, it is known that the prefrontal cortex modulates functional interactions among medial temporal lobe structures. We have obtained behavioral and electrophysiological data indicating that the perirhinal cortex is compromised with age. Moreover, recent neural recordings from young rats have revealed that stimuli known to modulate perirhinal neuron activity also lead to alterations in the firing properties of hippocampal neurons. Little is known, however, regarding the necessity of interactions between brain areas for memory and if this is vulnerable to the aging process. In order to understand the neural circuits critical for memory, and to promote the design of targeted interventions for treating cognitive aging, it is vital to determine the dynamic relationships between the brain regions that govern this aspect of cognition. Currently, the experiments in my lab are aimed at better characterizing age-associated changes in the intrinsic properties of the perirhinal cortex that lead to behavioral deficits, and defining the interactions between medial temporal lobe structures and the prefrontal cortex that are associated with memory formation and retrieval.