To better understand the cortical mechanisms mediating perception and memory, this section has been examining the functional areas that comprise visual association cortex in nonhuman primates and exploring their interconnections by the use of neuroanatomical tracing techniques in combination with physiological recording of neural activity. Future studies will pursue functional brain imaging studies of perception and memory in humans and parallel single-cell recording studies in awake, behaving monkeys. A major effort will be to determine how "top-down" influences of attention and memory affect perceptual processing.
This Section is concerned with elucidating the neural structures associated with information acquisition, storage, and retrieval. Functional magnetic resonance imaging (fMRI) has been used to concentrate on three domains of memory. The first domain focuses on semantic memory, the part of long-term memory composed of general information, such as facts, ideas, and the meaning of objects and words. We are particularly interested in characterizing the neural substrate mediating object and word meaning and its role in object perception. We are also interested in understanding how abstract forms of knowledge, such as knowledge of social interactions, are represented. The second domain focuses on priming, a form of implicit learning not dependent on conscious retrieval of prior events. These studies concentrate on characterizing changes in neural activity associated with this form of learning to provide a model system for studying cortical plasticity. The third domain, episodic memory, is an explicit form of memory that involves conscious recollection of a specific event. These studies concentrate on identifying the brain structures unique to this form of information retrieval.
The Unit on Functional Imaging Methods (FIM) in the Laboratory of Brain and Cognition has four themes, all aimed at increasing the utility and interpretability of functional magnetic resonance imaging (fMRI). The first theme involves quantitative characterization of the neuronal, physiologic, and biophysical processes that contribute to blood oxygenation level dependent (BOLD) and perfusion-based contrast in fMRI. The second theme involves tailoring specific neuroscience questions to unique characteristics of fMRI processing and acquisition. The third theme involves the development of pulse sequences, hardware, and processing techniques toward the direction of increased fMRI utility. The fourth theme involves the exploration of the measurement and quantification of previously unmeasured neuronal or physiological processes by MRI.
The aim of the Unit on Learning and Plasticity is to better understand how the structure, function and selectivity of the cortex change with experience or impairment, even in adulthood. Toward this goal, there are two main avenues of research, principally using brain-imaging techniques. The first avenue concerns how experience and learning change the neural and cognitive representations of sensory stimuli with a current focus on vision. For example, what are the neural changes underlying our enormous capacity to learn to recognize new objects and to make fine-grained discriminations among those objects. The second avenue concerns how the cortex adapts following damage to the nervous system (either peripheral or central). For example, what is the impact of macular degeneration (loss of foveal vision and consequent deprivation of corresponding cortex) on the cortical processing of visual stimuli? Elucidating the nature and extent of cortical plasticity is critical for understanding brain function throughout life.
Last modified March 31, 2006