Table of Contents

Enhanced Category Tuning Revealed by Intracranial Electroencephalograms in High-Order Human Visual Areas

  1. Rafael Malach3
  1. 1School of Computer Science, Sackler Faculty of Exact Sciences and
  2. 2Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel,
  3. 3Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel,
  4. 4Electroencephalography and Epilepsy Unit, Department of Neurology, and
  5. 5Functional Neurosurgery Unit, Tel Aviv Medical Center, Tel Aviv 64239, Israel, and
  6. 6Ahmanson Lovelace Brain Mapping Center and
  7. 7Division of Neurosurgery, David Geffen School of Medicine and Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, Los Angeles, California 90095
  1. Correspondence should be addressed to Prof. Rafael Malach, Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel. rafi.malach{at}weizmann.ac.il

Abstract

The functional organization of human sensory cortex was studied by comparing intracranial EEG (iEEG) recordings of local field potentials in neurosurgical patients with functional magnetic resonance imaging (fMRI) obtained in healthy subjects. Using naturalistic movie stimuli, we found a tight correlation between these two measures throughout the human sensory cortex. Importantly, the correlation between the iEEG and fMRI signals was site-specific, exhibiting neuroanatomically specific coupling. In several cortical sites the iEEG activity was confined strictly to one object category. This site selectivity was not limited to faces but included other object categories such as houses and tools. The selectivity of the iEEG signals to images of different object categories was remarkably higher when compared with the selectivity of the corresponding fMRI signals. A plausible interpretation of the fMRI and iEEG results concerns cortical organization in which object categories are organized in a mosaic of narrowly tuned object-selective clusters.