György Buzsáki
Center for Molecular and Behavioral Neuroscience
Rutgers University, Newark, NJ

INHIBITION, OSCILLATIONS AND SELF-ORGANIZATION: TREASURES INHERITED FROM GRASTYÁN

Endre Grastyán was among the pioneers to propose a role for brain oscillators. Oscillations allow for packaging of neuronal information in manageable quanta for transferring and storing information. The brain contains a system of oscillators that spans five orders of magnitude. Mixture of the various oscillators express a 1/f form, known as self-organized critical state in physics. Brain states constantly shift from the critical state (which allows maximum perturbation with the weakest inputs) to oscillation-dominant state which allows for prediction in time. Oscillations emerge from single neuron constituents but once a self-organized form of activity is formed at the cell assembly level, individual neurons become 'enslaved' to group activity ("circular causation"). Grastyan's hippocampal theta oscillations (5-10 per second) serve to "compress" information learned over seconds and minutes into 10 to 25 millisecond neuronal assemblies, necessary for encoding and retrieving episodic memories. The rules of self-organized, oscillatory assembly sequences explain the well-known contiguity and time-forward features of learned episodes, linking Grastyan's physiological studies to Ranschburg's psychophysical observations.