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Board of Honors Tutors
Howard Eichenbaum
Professor of Psychology (Boston University), Director (Cognitive Neurobiology Laboratory, http://www.bu.edu/cogneuro/)
hbe@bu.edu
The research in my laboratory concerns the neurobiological bases of memory. We are particularly interested in how the brain mediates a higher form of memory called declarative or explicit memory, rather than simple facts and events that can be brought to conscious recollection. While it would obviously be very useful to understand how the brain mediates this kind of memory, it is difficult to create valid animal models of "episodic memory" and "conscious recall" so that brain processes active during such memory be studied with biological tools. So far we have identified structures of the cerebral cortex and other structures, particularly the hippocampus, that play key roles in this kind of memory. Our research efforts are now focused in two directions of study. One direction involves psychological testing of animals with experimental damage to specific cortical and hippocampal areas. These studies inform us about what aspects of memory rely on particular brain areas. This work is guided by neuroanatomical work that allow us to model the flow of information through the brain, and has given us a good behavioral model of declarative memory in animals. An example of this work is our recent study of how memory breaks down after experimental damage to the hippocampus in rats. The hippocampus is critical to declarative memory in humans. This kind of memory involves associations among items or events that can be accessed flexibly to guide memory expression in various and even novel situation. In animals, there has been controversy about whether the hippocampus is specialized for spatial memory or whether it mediates a general memory function, as it does in humans. To address this issue we trained normal rats and rats with hippocampal damage on a variety of tasks that involve episodic memory and involve the creation of memory networks that are accessible by many routes of expression. Normal rats demonstrate rather amazing capacities for learning and making inferences from memory that indicate they have the capacity to form episodic memories and can express their memory in ways consistent with conscious recollection. Rats with damage to the hippocampus fail to show these capacities, indicating that declarative processing depends specifically on the hippocampus in animals as it does in humans. The other major direction of our research involves electrophysiological recordings of single brain cells (neurons) and large neuronal ensembles in these same brain regions while animals perform memory tasks. These studies have allowed us a window on the brain, a sort of interview of the brain, that tells us how information is processed and stored in different areas. The results of this work confirm our working hypothesis that the cerebral cortex encodes highly specific facts and events, whereas the hippocampus mediates the organization of episodic-like representations into a memory network that supports the properties of declarative memory. Students would ideally have relevant course and laboratory work, and computer skills are also very useful.
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