Memory encoding and storage in cortical circuits: electrophysiological studies

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A new memory requires the formation of a new memory trace, or "engram", in the brain. Memory traces are thought to consist of networks of simultaneously activated neurons, and a major mechanism through which new networks can be formed is through long-lasting increases (or decreases) in the strength of synaptic connections between neurons. My research is aimed at understanding how new memory traces are formed through long-lasting changes in the strength of synaptic connections between brain cells. The parahippocampal cortex and neocortex are regions of the brain that are crucial for normal memory formation. The parahippocampal area is thought to combine different types of sensory input during memory encoding. Memory is then thought to be stored more permanently through connections with other parts of the brain including the neocortex. To better understand the fundamental mechanisms that mediate memory formation, I use various electrophysiological and pharmacological techniques to determine how synaptic strengths can be altered in the parahippocampal and neocortical regions of the rat brain. There are two primary lines of research. The first line of research is aimed at understanding how the entorhinal cortex (an important parahippocampal area) processes and encodes sensory input. Experiments examine how temporal patterns of activity increase or decrease synaptic strength, and how activity in the entorhinal cortex can be modulated by the parasubiculum and perirhinal cortex. These experiments are important because they can indicate how sensory information is processed by neural circuits during the encoding of a new memory. The second line of research is aimed at understanding changes that occur in the neocortex during memory storage. Experiments will focus on identifying elements of the neocortical circuit that are affected by a cellular model of learning, and characterizing the cortical EEG rhythms and morphological changes in neurons that can lead to long-lasting changes in synaptic strength. This line of research may help us understand how memories can be stored in the neocortex for long periods of time.