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We use behavioral and functional neuroimaging techniques to study the neural mechanisms underlying attention, language, learning and memory. Our current focus has been on aspects of experience-dependent change. In particular we are interested in neural substrates for episodic memory, procedural learning and recovery after brain injury. In episodic memory, our work has focused on areas related to episodic encoding. Many encoding tasks have been shown to activate regions in the dorsal frontal cortex These activations seem to be related to the kind of information encoded with left dorsal frontal regions active for verbal information (e.g., lists of words), and right frontal regions active for non-verbal information (e.g. unfamiliar faces). These relationships hold across many different stimulus types. For studies of procedural learning, people are asked to trace through mazes, and they are imaged during early unskilled tracing, and after they become skilled at tracing the maze. Different areas of the brain are used for unskilled (right premotor and parietal cortex, left cerebellum) than skilled performance (SMA). This is consistent with ideas from behavioral literature that skilled and unskilled performance of a task are programmed at different levels of abstraction, and might use different neural substrates. In studies of language recovery following stroke in aphasic individuals, recruitment of areas not seen in normal subjects are found. These include apparently homologous regions in the opposite hemisphere, and "peri-lesional" activations on the ipsilateral side. Current investigations focus on the both the functional and prognostic value of the abnormal activations.
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