Hemodynamic Signals Correlate Tightly with Synchronized Gamma Oscillations
Jörn Niessing,1
Boris Ebisch,1
Kerstin E. Schmidt,1
Michael Niessing,1
Wolf Singer,1
Ralf A. W. Galuske1,2*
Functional imaging methods monitor neural activity by measuring hemodynamic signals. These are more closely related to local field potentials (LFPs) than to action potentials. We simultaneously recorded electrical and hemodynamic responses in the cat visual cortex. Increasing stimulus strength enhanced spiking activity, high-frequency LFP oscillations, and hemodynamic responses. With constant stimulus intensity, the hemodynamic response fluctuated; these fluctuations were only loosely related to action potential frequency but tightly correlated to the power of LFP oscillations in the gamma range. These oscillations increase with the synchrony of synaptic events, which suggests a close correlation between hemodynamic responses and neuronal synchronization.
1 Max Planck Institute for Brain Research, 60528 Frankfurt/M., Germany.
2 Department of Biology, Technical University of Darmstadt, 64283 Darmstadt, Germany.
* To whom correspondence should be addressed. E-mail: galuske{at}mpih-frankfurt.mpg.de
