Biological control systems

How do neuronal connectivity and the dynamics of distributed brain networks process
information during bimanual coordination? Contemporary brain theories of cognitive
function posit spatial, temporal and spatiotemporal network reorganization as mechanisms
for neural information processing. In this dissertation, rhythmic bimanual coordination is
studied as a window into neural information processing and subsequently an investigation of
underlying network reorganization processes is performed. Spatiotemporal reorganization
between effectors (limbs) is parameterized in a theoretical model via a continuously varying
cross-talk parameter that represents neural connectivity. Thereby, effector dynamics during
coordinated behavior is shown to be influenced by the cross-talk parameter and time delays
involved in signal processing. In particular, stability regimes of coordination patterns
as a function of cross-talk, movement frequency and the time delays are derived. On the
methodological front , spatiotemporal reorganization of neural masses are used to simulate
electroencephalographic data. A suitable choice of experimental control conditions is used
to derive a paradigmatic framework called Mode Level Cognitive Subtraction (MLCS) which
is demonstrated to facilitate the disambiguation between spatial and temporal components
of the reorganization processes to a quantifiable degree of certainty. In the experimental
section, MLCS is applied to electroencephalographic recordings during rhythmic bimanual
task conditions and unimanual control conditions. Finally, a classification of reorganization
processes is achieved for differing stability states of coordination: inphase (mirror) primarily
entails temporal reorganization of sensorimotor networks localized during unimanual
movement whereas spatiotemporal reorganization is involved during antiphase (parallel)
coordination.

This study is a pilot concerning the relationship between acute pain management and biofeedback training. The population studied included patients from a local community hospital undergoing coronary artery bypass graft surgery. The study applied theories of the mind/body connection and stress frameworks for exploring the correlation between patients' hand temperatures and their reported levels of pain pre-operatively and post-operatively. Study findings indicated that there was significant within-subjects effect in hand temperature after biofeedback treatment across three points in time. But the study also found no difference between-subjects in hand temperature after biofeedback treatment across three points in time. Therefore, the sample proved to be heterogeneous. Further study was indicated with larger samples to demonstrate the analgesic effects of biofeedback in the management of acute pain.

In this thesis the transition region between two modes of behavior is explored using a novel technique, delayed feedback, and a variety of dynamical systems measures. In a previous study, Engstrom, Kelso, and Holroyd (to appear) established the existence of a transition between anticipatory and reactive behavior in a sensorimotor coordination task as a control parameter (frequency) was varied. Here, in order to explore the hypothesis that the behavioral dynamics during this transition are intermittent in character, subjects were asked to synchronize with a metronome that was actually a delayed copy of their own response pattern. The use of delayed feedback was expected to destabilize the behavioral dynamics enough to allow the observation of hypothesized intermittent phenomena. Use of delayed feedback was shown to destabilize synchronization, resulting in the emergence of a new behavioral pattern in the transition region that exhibited complex "bursting" dynamics. Analysis revealed that this bursting behavior displays many of the characteristics common to intermittency, which supports the idea that the anticipation-reaction transition is the result of a neurobehavioral dynamical system losing stability. Living in the vicinity of instabilities may be an important mechanism for biological organisms to maintain both flexibility and stability.