Robert Knight

Research Interests

My laboratory studies the contribution of subregions of human prefrontal cortex to the control of cognitive and social behavior. We employ electrophysiological, MRI and behavioral techniques in neurological patients with frontal lobe damage in an effort to understand the neural mechanisms of cognitive processing.

Research Summary

The laboratory employs neuroanatomical, electrophysiological, blood flow, neuropsychological and behavioral techniques to study attention and memory mechanisms in humans. A long standing interest has centered on behavioral and physiological study of human dorsolateral prefrontal cortex. Ongoing work in this area includes studies of sensory gating, working memory, sustained attention, language and novelty detection. Experimental subjects are typically neurological patients with CT or MRI scan defined damage in subregions of prefrontal cortex and age matched controls. Lesions are further defined by high resolution 3-D MRI scanning. The contribution of prefrontal cortex to age related changes is also an active ongoing topic of inquiry. Converging evidence from experiments in neurological patients in the visual , auditory and somatosensory modalities has documented a critical regulatory role of dorsolateral prefrontal cortex in multiple tasks. Prefrontal cortex modulates both inhibitory and excitatory activity in distributed neural networks with apparent differential contributions from dorsal and ventral prefrontal subregions. In addition to a role in modulation of sensory processing, a prefrontal-hippocampal network is also selectively engaged by novel events and this phenomena is currently being investigated in several studies. Although dorsal and ventral prefrontal cortex has been the main area of research, more recently we have begun to examine patients with discrete orbito-frontal damage with additional interests in the neural control of emotion. Over the last few years, the laboratory has also begun investigation of mesial temporal function with a particular emphasis on the relationship of novelty detection, and the influence of prefrontal-hippocampal interactions on subsequent memory for distinct unusual events. Other studies are investigating the role of subregions of the mesial temporal region in familiarity and recognition memory and in memory binding. The experimental subjects in the mesial temporal experiments include patients with unilateral infarction of the posterior hippocampus and adjacent structures due to posterior cerebral artery occlusion and patients with CA1 hypoxic damage.

Selected Publications

Chao, L.L. and Knight, R.T. Contribution of human prefrontal cortex to delay performance. Journal of Cognitive Neuroscience , 10 (2): 167-177, 1998.

Stone, V.E., Baron-Cohen, S. and Knight, R.T. Does Frontal Lobe Damage Produce Theory of Mind Impairment? Journal of Cognitive Neuroscience , 10:5, 1998.

Alain, C., Woods, D.L. and Knight, R.T. A distributed cortical network for auditory sensory memory in humans. Brain Research, 812:23-37, 1998.

Knight, R.T., Staines, W.R., Swick, D. and Chao, L.L. Prefrontal cortex regulates inhibition and excitation in distributed neural networks. Acta Psychologia , 101:159-178, 1999.

Nielsen-Bohlman, L.C. and Knight, R.T. Prefrontal cortex involvement in visual working memory. Cognitive Brain Research, 8:299-310, 1999.

Haaland, K.Y., Harrington, D.L.and Knight, R.T. Neural representations of skilled movements. Brain, 123:2306-2313, 2000.