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Psychophysiological significance of temporal order in brain chaos
151 T H E O R G A N I Z A T I O N OF M E M O R Y Larry R. Squire Studies of animals with complex nervous systems, including humans, have provided continuing insights about how memory is organized in the brain. O n e major new idea is that there are multiple forms of memory. Thus, a distinction can be made between declarative (explicit) memory and nondeclarative (implicit) memory. Declarative memory refers to information about previously encountered facts and events, the kind of information that is ordinarily available as conscious recollections. Nondeclarative (implicit) memory is a heterogeneous collection of nonconscious abilities, which support skill learning, the development of dispositions or habits and the phen o m e n o n of priming. Parallel studies in monkeys have identified the anatomical components of the declarative memory system in the hippocampus and related cortex. This system is essential for the formation and storage of declarative memory, and for its retrieval during a lengthy period of consolidation and reorganization. As time passes, the role of this system in memory diminishes and a more p e r m a n e n t memory gradually develops elsewhere, probably in neocortex. A n o t h e r new development is the possibility of studying the anatomy of memory in h u m a n s using magnetic resonance imaging and positron emission tomography. These technologies have provided direct evidence of hippocampal damage in patients with circumscribed memory impairment and direct evidence for the activation of the hippocampal region in normal subjects performing memory tasks.
PSYCHOPHYSIOLOGICAL SIGNIFICANCE OF TEMPOR A L O R D E R IN B R A I N C H A O S W.S. Tirsch, M. Keidel and G. Sommer Three h u m a n neurobiological signals such as EEG, tremor and muscle vibrations (VMG) were investigated. In contrast to conventional, consecutive analysis, a sliding or 'running' computation of (1), spectral density; (2), fractal dimension and (3), dimensional complexity of the recorded time series was performed, using a time-shift of 1 s and epoch length of 10 s. To get an insight into the chaotic behaviour of the time-series, phase-space trajectories of the underlying dynamical system were reconstructed. To measure the self-similar structure of such 'strange' attractors, their correlation dimension or complexity was computed. The temporal pattern of systematic cyclic changes in complexity with transients from 'high-' to 'low-dimensional' brain chaos may indicate a temporal ordered transition from a rather parallel information processing mode to a more central mode. The temporal pattern of complexity shows also an inverse relationship with simultaneously computed spectral power changes; i.e., the spectral density of the signals increases with decreasing dimensional complexity and vice versa. Consequently, we assume that the 'network' of the CNS may be more ordered and, thus, less
complex in case of high spectral peak density (and low fractal dimensionality) and vice versa, which may be caused by an underlying increase in synchronisation or coupling strength of neuronal elements generating the derived signals. The results indicate that the CNS periodically alters the level of activity, complexity and degree of synergy between different processing structures and subsystems and is not maintained on a static level.
S Y M P A T H O V A G A L I N T E R A C T I O N IN STRESS A N D R E L A X A T I O N ; H E A R T R A T E V A R I A B I L I T Y IN H O M E NURSES H. Toivanen, E. L~insimies and O. H~inninen University of Kuopio, Kuopio, Finland The interaction of parasympathetic and sympathetic nervous systems was tested in stress and relaxation. Age-matched home nurses (n = 64), as representatives of a group with stressful occupation, were randomly alloted to control and intervention groups. A 15-min long daily exercise consisted of deep breathing (including forced contractions of abdominal muscles, yogic bandhas) and relaxation. The intervention period lasted for 6 months. The effect of the intervention on cardiac autonomic functions was tested by recording the R-R-interval variations as a response to quiet breathing, Valsalva manoeuvre, deep breathing test and active orthostatic test. Imbalance was observed in the indices of both parasympathetic and sympathetic autonomic nervous systems. The measured values of the intervention group normalized significantly by the daily practising of relaxation for 6 months. It was concluded that stress-related dysfunction of the autonomic nervous system can be manifested either in the parasympathetic pituitary-adrenal-cortical or the sympathetic adrenal-medullary axis, or in both of them, and relaxation is characterized by balanced autonomic function.
MENTAL WORKLOAD AFTER-EFFECTS OF PAPER/ PENCIL VS. C O M P U T E R I Z E D TASKS I N D I C A T E D BY P300 Michael Trimmel, Raul H u b e r and Manfred Haider Institute of Environmental Hygiene, Vienna, Austria 49 Ss took part in a 4 (groups: experts, users, beginners and novice) × 2 (computer vs. non-computer) x 3 (tasks: text editing, problem solving (IQ test, learning DOS or programming, and answering a questionnaire or playing Tetris)) A N O V A design with repeated measures on the last two factors. Sequence of the 6 conditions was balanced across Ss in each group. After each (15 min lasting) task, Ss performed an acoustic discrimination task for which the P300 (at F3, F4, C z, P3 and P4 referred to linked mastoids) was analyzed.
PSYCHOPHYSIOLOGICAL SIGNIFICANCE OF TEMPOR A L O R D E R IN B R A I N C H A O S W.S. Tirsch, M. Keidel and G. Sommer Three h u m a n neurobiological signals such as EEG, tremor and muscle vibrations (VMG) were investigated. In contrast to conventional, consecutive analysis, a sliding or 'running' computation of (1), spectral density; (2), fractal dimension and (3), dimensional complexity of the recorded time series was performed, using a time-shift of 1 s and epoch length of 10 s. To get an insight into the chaotic behaviour of the time-series, phase-space trajectories of the underlying dynamical system were reconstructed. To measure the self-similar structure of such 'strange' attractors, their correlation dimension or complexity was computed. The temporal pattern of systematic cyclic changes in complexity with transients from 'high-' to 'low-dimensional' brain chaos may indicate a temporal ordered transition from a rather parallel information processing mode to a more central mode. The temporal pattern of complexity shows also an inverse relationship with simultaneously computed spectral power changes; i.e., the spectral density of the signals increases with decreasing dimensional complexity and vice versa. Consequently, we assume that the 'network' of the CNS may be more ordered and, thus, less
complex in case of high spectral peak density (and low fractal dimensionality) and vice versa, which may be caused by an underlying increase in synchronisation or coupling strength of neuronal elements generating the derived signals. The results indicate that the CNS periodically alters the level of activity, complexity and degree of synergy between different processing structures and subsystems and is not maintained on a static level.
S Y M P A T H O V A G A L I N T E R A C T I O N IN STRESS A N D R E L A X A T I O N ; H E A R T R A T E V A R I A B I L I T Y IN H O M E NURSES H. Toivanen, E. L~insimies and O. H~inninen University of Kuopio, Kuopio, Finland The interaction of parasympathetic and sympathetic nervous systems was tested in stress and relaxation. Age-matched home nurses (n = 64), as representatives of a group with stressful occupation, were randomly alloted to control and intervention groups. A 15-min long daily exercise consisted of deep breathing (including forced contractions of abdominal muscles, yogic bandhas) and relaxation. The intervention period lasted for 6 months. The effect of the intervention on cardiac autonomic functions was tested by recording the R-R-interval variations as a response to quiet breathing, Valsalva manoeuvre, deep breathing test and active orthostatic test. Imbalance was observed in the indices of both parasympathetic and sympathetic autonomic nervous systems. The measured values of the intervention group normalized significantly by the daily practising of relaxation for 6 months. It was concluded that stress-related dysfunction of the autonomic nervous system can be manifested either in the parasympathetic pituitary-adrenal-cortical or the sympathetic adrenal-medullary axis, or in both of them, and relaxation is characterized by balanced autonomic function.
MENTAL WORKLOAD AFTER-EFFECTS OF PAPER/ PENCIL VS. C O M P U T E R I Z E D TASKS I N D I C A T E D BY P300 Michael Trimmel, Raul H u b e r and Manfred Haider Institute of Environmental Hygiene, Vienna, Austria 49 Ss took part in a 4 (groups: experts, users, beginners and novice) × 2 (computer vs. non-computer) x 3 (tasks: text editing, problem solving (IQ test, learning DOS or programming, and answering a questionnaire or playing Tetris)) A N O V A design with repeated measures on the last two factors. Sequence of the 6 conditions was balanced across Ss in each group. After each (15 min lasting) task, Ss performed an acoustic discrimination task for which the P300 (at F3, F4, C z, P3 and P4 referred to linked mastoids) was analyzed.