## Project Details

### Description

The well-known extreme variability of spinal cord reflex output has

defied analysis suing classical statistics. This variability renders the

interpretation of electrophysiologic monitoring during spasticity surgery

extremely difficult. Preliminary studies have re-evaluated reflex output

data using new techniques developed for the analysis of complex

phenomena. In the normal human, it appears that reflexes fluctuate on

many different time scales: seconds, minutes, and perhaps hours.

Physical systems which fluctuate on many time scales are "self-similar",

and this is the hallmark of a "fractal" process. The results generate

the following working hypothesis: time-series of spinal cord reflex

output fluctuate with a fractal pattern. this idea will be rigorously

tested using data collected from the spinal cord of the decerebrate cat

including: 1) neuronal population response, 2) individual neuron firing

frequency and 3) the tendon force generated. Data will be obtained while

varying the frequency of stimulation and with the reflex feedback loop

opened and closed. to characterize fractal behavior, non-linear

analytical methods will be extensively used. By employing simulated data

sets as mathematical controls, these methods should help determine

whether the observed fractal patterns originate from deterministic or

stochastic processes. The results of this work are important from both

clinical and basic science perspectives. Clinically, proving that spinal

cord reflexes fluctuate on time scales far longer than the measuring

period permitted in the operating room would lead to a radical shortening

of operative time and risk. On a basic level, the results will provide

information leading to a deeper understanding of the origin of apparently

random fluctuations in a simple input-output neural circuit in the

mammalian nervous system. It is expected that the results of this study

will be applicable to more complex neural circuits in the central nervous

system.

defied analysis suing classical statistics. This variability renders the

interpretation of electrophysiologic monitoring during spasticity surgery

extremely difficult. Preliminary studies have re-evaluated reflex output

data using new techniques developed for the analysis of complex

phenomena. In the normal human, it appears that reflexes fluctuate on

many different time scales: seconds, minutes, and perhaps hours.

Physical systems which fluctuate on many time scales are "self-similar",

and this is the hallmark of a "fractal" process. The results generate

the following working hypothesis: time-series of spinal cord reflex

output fluctuate with a fractal pattern. this idea will be rigorously

tested using data collected from the spinal cord of the decerebrate cat

including: 1) neuronal population response, 2) individual neuron firing

frequency and 3) the tendon force generated. Data will be obtained while

varying the frequency of stimulation and with the reflex feedback loop

opened and closed. to characterize fractal behavior, non-linear

analytical methods will be extensively used. By employing simulated data

sets as mathematical controls, these methods should help determine

whether the observed fractal patterns originate from deterministic or

stochastic processes. The results of this work are important from both

clinical and basic science perspectives. Clinically, proving that spinal

cord reflexes fluctuate on time scales far longer than the measuring

period permitted in the operating room would lead to a radical shortening

of operative time and risk. On a basic level, the results will provide

information leading to a deeper understanding of the origin of apparently

random fluctuations in a simple input-output neural circuit in the

mammalian nervous system. It is expected that the results of this study

will be applicable to more complex neural circuits in the central nervous

system.

Status | Finished |
---|---|

Effective start/end date | 1/1/93 → 7/31/09 |