Yigal Agam, Ph.D.

Instructor in Psychiatry
Massachusetts General Hospital, Harvard Medical School

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I am a cognitive neuroscientist interested in neural mechanisms of learning, memory and attention. I take a multimodal approach that combines different brain imaging methods such as EEG, MEG, fMRI and DTI. A major goal of my research is to understand the neural basis of error processing. Learning from errors is critical for adaptive behavior and, unfortunately, impaired in many neuropsychiatric disorders. My recent work has focused on two well-established neural markers of errors: The error-related negativity (ERN), an EEG potential seen after errors, and fMRI activation in the dorsal anterior cingulate cortex (dACC). Using multimodal neuroimaging, we have shown that contrary to the widely-held assumption, these two signals likely index distinct underlying mechanisms, and that the generator of the ERN is in the dorsal posterior cingulate cortex (dPCC) and not dACC. We proposed a model in which dPCC detects errors, giving rise to the ERN, whereas dACC activation reflects later processes related to error correction and to increased cognitive control following errors. If confirmed, this model could have profound implications for theoretical models of error processing and, in turn, for our understanding of how humans adjust their behavior according to outcomes and why this ability might go awry in some populations.

The left column shows the ERN and its combined EEG/MEG source localization. The right column shows error-related dACC activation in the same subjects and its hemodynamic time course. See Agam et al. (2011): Multimodal functional imaging dissociates hemodynamic and electrophysiological correlates of error processing. PNAS, 108(42):17556-61.