The temporal fluctuations in quasi-periodic motor activities and autonomic physiological processes exhibit a strong fractal pattern in healthy individuals. These fractal or self-similar patterns are very robust, persistent for hundreds and thousands of event cycles.
Interestingly, these patterns decay in the presence of pathological conditions, such as neurological impairments. Our lab has been interested in fractal dynamics in a variety of functional activities. These include those listed below.
In children with cerebral palsy, we have discovered that stride dynamics are diminished significantly when compared to children without neurological impairments. The measurement of walking dynamics may serve as an objective quantitative outcome measure. Further, it may be possible to develop interventions to restore healthy neuromotor dynamics.
Handwriting and drawing are key occupations in school-aged children, necessary for language development, communication, expressing ideas and completion of homework. We have found that in able-bodied adults, repetitive graphomotor activities exhibit strong fractal temporal dynamics. Perhaps, this information may be useful as a diagnostic indicator of handwriting difficulties and as an outcome measure for targeted interventions.
Interbeat intervals of the heart and interbreath intervals of the lungs have been shown to be fractal. Using the multifractal formalism, it may be possible to detect subtle subconscious modulation of heart and breathing dynamics due for example to the mental selection of a desired option or systemic cardiovascular changes due to kidney dialysis.
This research endeavours to:
1. Develop multifractal analytical methods to detect dynamical changes in temporal processes as indication of the onset of pathological events, specific cognitive activity or physiological response to certain stimuli.
2. Better understand the high-order factorial interactions which contribute to the observed fractal dynamics. This knowledge may suggest means of restoring dynamics in instances where they have been diminished by pathological conditions.
3. Relate fractal measures to conventional functional and physiological assessments. Establishing these relationships may set the stage for fractal outcome measures in rehabilitation.
Dr. Desiree Maltais (Laval)
Dr. Chris Chan (UHN)