School or College:
Traditional accounts of memory and visual perception have theorized that these are separate cognitive processes that operate in separate areas of the human brain—memory in the hippocampus and perception in a brain pathway called the ventral visual stream. When visual information enters the brain, the first cells in the ventral visual stream process basic visual features (lines and colors); at the next station in the pathway, neurons process combinations of simple features (e.g., conjoining two lines into a corner); finally, neurons at the highest stations respond to whole objects. The theory behind my study proposes that the hippocampus can be understood as an extension of the ventral visual stream, combining whole objects with temporal, spatial, and contextual information: the stuff of “episodic memories.” The hippocampus is then not specialized “for memory,” but specialized for performing any cognitive feat, including memory or perception, that involves complex, high-dimensional information.
According to this theory, it is not the cognitive process (e.g., recollection of a memory or visual perception of a scene) that engages a given brain region, but the type of information content being processed. A brain region will be important for a cognitive task if it is equipped to handle the kind of information that the task involves. Thus, both memory and perception can operate in both the ventral visual stream and the hippocampus; these cognitive functions are “spread out” in the brain. My project tests this theory by examining changes in memory with age. The hippocampus is known to suffer age-related deterioration earlier than the ventral visual stream. Thus, I am asking whether recollection is impaired by aging (i.e., by presumed hippocampal damage) as a function of the type of information that a person is asked to recollect. This novel viewpoint not only offers insight into the contributions of the different structures of the human brain to memory, but could have important implications for our understanding of Alzheimer’s Disease and dementia.