Neuron. Volume 50, Issue 2 , 20 April 2006, Pages 329-339

When the Brain Loses Its Self: Prefrontal Inactivation during Sensorimotor Processing

Ilan I. Goldberg1, Michal Harel1 and Rafael Malach1, ,

1Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel

Received 29 July 2005; revised 15 December 2005; accepted 1 March 2006. Published: April 19, 2006. Available online 19 April 2006.

Summary

A common theme in theories of subjective awareness poses a self-related “observer” function, or a homunculus, as a critical element without which awareness can not emerge. Here, we examined this question using fMRI. In our study, we compared brain activity patterns produced by a demanding sensory categorization paradigm to those engaged during self-reflective introspection, using similar sensory stimuli. Our results show a complete segregation between the two patterns of activity. Furthermore, regions that showed enhanced activity during introspection underwent a robust inhibition during the demanding perceptual task. The results support the notion that self-related processes are not necessarily engaged during sensory perception and can be actually suppressed.