Switching between top-down and bottom-up attention in a patient with right MFG tumor resection

Monday, September 22, 2014 — Poster Session I
12:00 p.m. – 2:00 p.m.	FAES Academic Center	NIMH	NEURO-9

Authors

• K.A. Holiday
• S.A. Japee
• M.D. Satyshur
• I Mukai
• L.G. Ungerleider

Abstract

Previous research on neural mechanisms of visual attention (Corbetta et al., 1998) has identified a top-down system, which acts in a goal-directed endogenous manner, and a bottom-up system, which responds in an involuntary exogenous manner. In this study, we examined the contribution of the right middle frontal gyrus (rMFG) to both endogenous and exogenous attention by comparing performance on a Gabor patch orientation discrimination task of a patient with a rMFG resection and 10 healthy controls. Valid endogenous cues facilitated faster reaction times (RT) compared to invalid cues. Exogenous cues, for shorter inter-stimulus intervals (ISIs), showed the expected facilitatory effect on subsequent stimulus processing. However, the patient exhibited faster RTs compared to controls at longer ISIs such that the patient was unable to withhold his response during the longer ISIs and often responded before the Gabor patch stimuli appeared. Results indicate that the rMFG may be involved in the process of reorienting from an exogenous to an endogenous mode of attention. Taken together, these results suggest that the rMFG frontal cortex plays a role in top-down reorienting of attention, but that reorganization of the brain after surgery may help to diminish the impact of the lost tissue in this region.

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