1	Chaos and Dipole Analysis of Brain Electrical Activity Samuel Koszer MD Associate Professor of Neurology Albany Medical Center
2	Normal Brain = Chaos Music; Tuning up vs. a symphony The subtle shift from the normal, disorderly, chatter of neurons into a more synchronized pattern can be a step toward the uncontrolled electrical activity of a seizure.
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4	Neuronal function. Determinism or Chaos ? Determinism is the philosophical belief that every event or action is the inevitable result of preceding events and actions. Thus, in principle at least, every event or action can be completely predicted in advance, or in retrospect.
5	"Determinism can be traced as..." Determinism can be traced as least as far back as the time of Ancient Greece Incorporated into modern science around the year 1500 A.D. with the establishment of the idea that cause-and-effect rules completely govern all motion and structure on the material level.
6	Modern View of Determinism Isaac Newton, who lived in England about 300 years ago. the values of the measurements at a given starting time are called the initial conditions for that system.
7	Complexity of Neocortex 10 billion cells 10-20,000 synapses / Cell 10¹⁴(100 trillion)connections
8	Organization Columnar 80-110 cells per column Diameter 30-50 um Depth 3-6 mm They are believed to function as modules. A cortical column is a complex processing and distributing unit that links a number of inputs to a number of outputs via overlapping internal processing chains" (Mountcastle, 1998).
9	Cortical Layers Supragranular Layers: Layers I - III - Layer III receives input from other cortical columns - Cells of layers II and III project to other parts of the cortex Granular Layer: Layer IV - Receives inputs from the thalamus - Sends signals to the rest of the column (primarily up to layers II and III) Infragranular Layers: Layers V - VI - Receive input from the supragranular cells of adjacent columns - Send signals mainly to extracortical structures (thalamus, other subcortical structures)
10	States of complexity in EEG
11	"It is important to remember..." It is important to remember that the uncertainty in the dynamical outcome does not arise from any randomness in the equations of motion--since they are completely deterministic--but rather from the lack of the infinite accuracy in the initial conditions.
12	"dynamical instability," dynamical instability, which to most physicists is the same in meaning as chaos. Dynamical instability refers to a special kind of behavior in time found in certain physical systems and discovered around the year 1900, by the physicist Henri Poincaré.
13	"Poincaré was a physicist interested..." Poincaré was a physicist interested in the mathematical equations which describe the motion of planets around the sun. That these mathematical orbit equations are deterministic means, of course, that by knowing the initial conditions---in this case, the positions and velocities of the planets at a given starting time---you find out the positions and speeds of the planets at any time in the future or past.
14	"The astronomical systems which did..." The astronomical systems which did not obey the rule typically consisted of three or more astronomical bodies with interaction between all three. For these types of systems, Poincaré showed that a very tiny imprecision in the initial conditions would grow in time at an enormous rate.
15	"That is," That is, for these systems, even if you could specify the initial measurements to a hundred times or a million times the precision, etc., the uncertainty for later or earlier times would not shrink, but remain huge.
16	"The extreme "sensitivity to..." The extreme "sensitivity to initial conditions" mathematically present in the systems studied by Poincaré has come to be called dynamical instability, or simply chaos. in a chaotic system, using the laws of physics to make precise long-term predictions is impossible, even in theory. Making long-term predictions to any degree of precision at all would require giving the initial conditions to infinite precision. The mathematics inside Lorenz's model of atmospheric currents was widely studied in the 1970's. Gradually it came to be known that even the smallest imaginable discrepancy between two sets of initial conditions would always result in a huge discrepancy at later or earlier times, the hallmark of a chaotic system, of course. the weather as a whole is a chaotic system This means that in order to make long-term weather forecasts with any degree of accuracy at all, it would be necessary to take an infinite number of measurements
17	Recognizing a seizure Patterns Clinical EEG Change in frequency Change in amplitude Voltage depression Change in interictal spikes
18	Fast Seizure Detection Systems Gotman, Qu 1997 Gold Standard, 9 sec delay (0.02 fp/hr) Estellar et al, 1999 Fractal dimension, 1.8 sec delay (0-1 fp/hr)
19	Predicting Seizures Patterns Clinical (in dogs) Psychics Intuition Chemical EEG Chaos Theory
20	Single Feature Prediction Iasemedis/Sackellares (1990) Lyaponev measurements 20 mins to 1 hour before clinical/eeg onset Martinerie, Le-Van-Quyen et Al (1994) Correlation density Dynamical similarity Others; neural networks,wavelet nn, fuzzy clustering, implanted detectors
21	Stopping a seizure Medications Vagus Nerve Stimulation Transcranial magnetic stimulation
22	What is Chaos Theory and how can it predict seizures ?
23	"In terms of weather forecasts" In terms of weather forecasts, the "Butterfly Effect" refers to the idea that whether or not a butterfly flaps its wings in a certain part of the world can make the difference in whether or not a storm arises one year later on the other side of the world.
24	"Because of the "Butterfly..." Because of the "Butterfly Effect," it is now accepted that weather forecasts can be accurate only in the short-term, and that long-term forecasts, even made with the most sophisticated computer methods imaginable, will always be no better than guesses
25	"Because of this fact," Because of this fact, some scientists have begun to question whether or not it is meaningful at all to say that the universe is deterministic in its behavior.
26	"A chaotic system can actually..." A chaotic system can actually evolve in a way that appears to be smooth and ordered, however. Chaos refers to the issue of whether or not it is possible to make accurate long-term predictions of any system if the initial conditions are known to an accurate degree.
27	Systems with low chaos
28	Systems with medium chaos
29	Systems with lots of chaos
30	Attractor
31	EEG associated with a seizure – 8 dimensions of complexity
32	Chaos Analysis of EEG
33	Mandelbrot
34	Stopping a seizure Medications Vagus Nerve Stimulation Transcranial magnetic stimulation
35	Dipole Analysis Mathematical reconstruction of the source of brain electrical activity Epileptic spikes Evoked potentials Normal activity EEG/MEG
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39	Magnetoencephalography Tangential Magnetic Fields Less blurring of recording No secondary induced currents Sees deeper sources Within sulci or deep within gyri
40	SQUID Superconducting Quantum Interference Device PicoTesla (10^-12 Tesla)
41	The Squid
42	Lesional Epilepsy
43	Mesial Temporal Epilepsy
44	Mesial Temporal Epilepsy
45	Temporal Lobe Epilespy
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