Article abstract

Nature Neuroscience 11, 1100 - 1108 (2008)
Published online: 24 August 2008 | doi:10.1038/nn.2177

Interhemispheric correlations of slow spontaneous neuronal fluctuations revealed in human sensory cortex

Yuval Nir1, Roy Mukamel2, Ilan Dinstein3, Eran Privman4, Michal Harel1, Lior Fisch1, Hagar Gelbard-Sagiv1, Svetlana Kipervasser5,6, Fani Andelman7, Miri Y Neufeld5,6, Uri Kramer5,7, Amos Arieli1, Itzhak Fried2,5,7 & Rafael Malach1

Animal studies have shown robust electrophysiological activity in the sensory cortex in the absence of stimuli or tasks. Similarly, recent human functional magnetic resonance imaging (fMRI) revealed widespread, spontaneously emerging cortical fluctuations. However, it is unknown what neuronal dynamics underlie this spontaneous activity in the human brain. Here we studied this issue by combining bilateral single-unit, local field potentials (LFPs) and intracranial electrocorticography (ECoG) recordings in individuals undergoing clinical monitoring. We found slow (<0.1 Hz, following 1/f-like profiles) spontaneous fluctuations of neuronal activity with significant interhemispheric correlations. These fluctuations were evident mainly in neuronal firing rates and in gamma (40–100 Hz) LFP power modulations. Notably, the interhemispheric correlations were enhanced during rapid eye movement and stage 2 sleep. Multiple intracranial ECoG recordings revealed clear selectivity for functional networks in the spontaneous gamma LFP power modulations. Our results point to slow spontaneous modulations in firing rate and gamma LFP as the likely correlates of spontaneous fMRI fluctuations in the human sensory cortex.

  1. Department of Neurobiology, Weizmann Institute of Science, 240 Herzl Street, Rehovot 76100, Israel.
  2. Division of Neurosurgery, David Geffen School of Medicine, and Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, Los Angeles, California 90095, USA.
  3. Center for Neural Science, New York University, 4 Washington Place, New York, New York 10003, USA.
  4. School of Computer Science, Sackler Faculty of Exact Sciences, Tel Aviv 69978, Israel.
  5. Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
  6. Electroencephalography and Epilepsy Unit, Department of Neurology, Tel Aviv Medical Center, 6 Weizmann Street, Tel Aviv 64239, Israel.
  7. Functional Neurosurgery Unit, Tel Aviv Medical Center, 6 Weizmann Street, Tel Aviv 64239, Israel.

Correspondence to: Rafael Malach1 e-mail:


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