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Alterations of micromotoric tonus regulation during paroxysmal EEG activity
FREE COMMUNICATIONS IN EEG activity was never observed in the presence of this rhythm during wakefulness and both the slowwave and REM patterns of sleep, and (d) that facilitation of the SMR in the waking state resulted in a related enhancement of sensorimotor cortex spindle-burst activity during sleep. Subcortical EEG recordings obtained during conditioned SMR activity disclosed corresponding electrical patterns in the VPL, VPM, and VL nuclei of the thalamus. Late cortical evoked potentials elicited by stimulation of these nuclei were suppressed during both the SMR and slow-wave sleep spindles, the suppression being probably of thalamic origin. These and other neurophysiological findings stress the role of proprioceptive feedback and fusimotor activity in the regulation of phasic m o t o r behavior. Preliminary studies suggegt, also, that modification of these mechanisms through manipulation of the SMR can alter susceptibility to drug-induced motor seizures.
69.
The advantages of brain signal reconstitution within a resistive analog of the skuU.-G. Schuler and E. W. Peterson (Ottawa, Canada).
A variety of EEG signals reconstituted within an electrically resistive volume permits electrical exploration of the volume to provide a sensitive and selective means to study signals arising from discrete areas within the brain. In theory, EEG signals may arise from such spatially discrete areas as non-propagating epileptic foci, or from temporally discrete areas such as the individual generators of complex brain activity. Such signals travel routes with various conductive properties, but appear almost simultaneously upon all areas of the scalp. If many scalp electrodes pass these signals to low-noise amplifiers connected in a common-average-reference configuration, the resuiting amplified signals may be impressed upon corresponding areas of a simple resistive analog of the head. With the scalp voltage pattern reproduced upon the periphery of the resistive analog, the resulting signals within the analog may be profitably studied since parallel averaging provides 'low-noise', and maximal signal areas give spatial information. In theoretical operation, a low-level epileptic focus could impart submicrovolt spikes to large areas of the scalp, but be undetected by present day EEG techniques. If these submicrovolt spikes were processed by 100 electrode-amplifier units and combined in a resistive analog, the resultant parallel averaging could provide a I 0-fold improvement in signal/noise ratio and aid detection. The locus of maximal spike activity within the analog would exactly correspond to the epileptic focus were the animal head electrically homogeneous, but with this not so, the correspondence is
679
imperfect but nevertheless useful. In practice, a somewhat similar technique has selectively acquired fetal EKG signals and a special 20 channel EEG amplifier and resistive analog of the human skull has been built and tested. The EEG apparatus, tests and results will be presented.
70.
Alterations of micromotoric tonus regulation during paroxysmal EEG activity.-H. D. Weigeldt (Bremen, W. Germany).
During the last seven years, the recording of the "micromotoric tonus" (MMT) in and during traumatic and alcoholic delirious processes has produced more qualified and measurable data about the extent of cerebral functional disorders than the EEG. This has been especially so with the late sequelae of cerebral injuries. The method has also been very useful for controlling the anticonvulsive treatment of epileptics as it can be used as often as necessary without losing its diagnostic validity for the recognition and determination of positive or negative psychotropic drug effects or intoxications. We, therefore, studied the direct influence of spike-wave bursts on the writing pressure records by simultaneous registration of the EEG and the MMT. Various degrees of curve inhibition (retardation, perseveration, interruption of records) were dependent only to a minor degree on the mode, localization and duration of the paroxysms. No direct simple relation was found between the records, especially if the EEG and MMT were compared for longer periods. Not only the writing speed as an approximate measure of the psychomotor velocity but also various symptoms of the p r e s s u r e course-also one mode of tonus r e g u l a t i o n - p e r m i t better recognition of the fluctuations of subcortical regulation and counterregulation than the conventional EEG. Often from a few up to more than 20 sec before a spike-wave discharge a period of increased lability with pathological symptoms is observed. The writing speed before and after the bursts frequently increases, probably by pre- and postparoxysmal arousal reactions. It is also noted that simultaneous EEG and MMT recording reveals that similar EEG phenomena may have different clinical meanings, possibly due to brain stem and/or cortical effects. Simultaneous comparisons with the H-reflex, with DC shifts and data on the autonomic system might permit more certain correlation of the phenomena described with subcortical functions. 71.
Alterations micromotorie tonus regulation in cerebral disorders.-F. Steinwachs (Aachen, W. Germany).
69.
The advantages of brain signal reconstitution within a resistive analog of the skuU.-G. Schuler and E. W. Peterson (Ottawa, Canada).
A variety of EEG signals reconstituted within an electrically resistive volume permits electrical exploration of the volume to provide a sensitive and selective means to study signals arising from discrete areas within the brain. In theory, EEG signals may arise from such spatially discrete areas as non-propagating epileptic foci, or from temporally discrete areas such as the individual generators of complex brain activity. Such signals travel routes with various conductive properties, but appear almost simultaneously upon all areas of the scalp. If many scalp electrodes pass these signals to low-noise amplifiers connected in a common-average-reference configuration, the resuiting amplified signals may be impressed upon corresponding areas of a simple resistive analog of the head. With the scalp voltage pattern reproduced upon the periphery of the resistive analog, the resulting signals within the analog may be profitably studied since parallel averaging provides 'low-noise', and maximal signal areas give spatial information. In theoretical operation, a low-level epileptic focus could impart submicrovolt spikes to large areas of the scalp, but be undetected by present day EEG techniques. If these submicrovolt spikes were processed by 100 electrode-amplifier units and combined in a resistive analog, the resultant parallel averaging could provide a I 0-fold improvement in signal/noise ratio and aid detection. The locus of maximal spike activity within the analog would exactly correspond to the epileptic focus were the animal head electrically homogeneous, but with this not so, the correspondence is
679
imperfect but nevertheless useful. In practice, a somewhat similar technique has selectively acquired fetal EKG signals and a special 20 channel EEG amplifier and resistive analog of the human skull has been built and tested. The EEG apparatus, tests and results will be presented.
70.
Alterations of micromotoric tonus regulation during paroxysmal EEG activity.-H. D. Weigeldt (Bremen, W. Germany).
During the last seven years, the recording of the "micromotoric tonus" (MMT) in and during traumatic and alcoholic delirious processes has produced more qualified and measurable data about the extent of cerebral functional disorders than the EEG. This has been especially so with the late sequelae of cerebral injuries. The method has also been very useful for controlling the anticonvulsive treatment of epileptics as it can be used as often as necessary without losing its diagnostic validity for the recognition and determination of positive or negative psychotropic drug effects or intoxications. We, therefore, studied the direct influence of spike-wave bursts on the writing pressure records by simultaneous registration of the EEG and the MMT. Various degrees of curve inhibition (retardation, perseveration, interruption of records) were dependent only to a minor degree on the mode, localization and duration of the paroxysms. No direct simple relation was found between the records, especially if the EEG and MMT were compared for longer periods. Not only the writing speed as an approximate measure of the psychomotor velocity but also various symptoms of the p r e s s u r e course-also one mode of tonus r e g u l a t i o n - p e r m i t better recognition of the fluctuations of subcortical regulation and counterregulation than the conventional EEG. Often from a few up to more than 20 sec before a spike-wave discharge a period of increased lability with pathological symptoms is observed. The writing speed before and after the bursts frequently increases, probably by pre- and postparoxysmal arousal reactions. It is also noted that simultaneous EEG and MMT recording reveals that similar EEG phenomena may have different clinical meanings, possibly due to brain stem and/or cortical effects. Simultaneous comparisons with the H-reflex, with DC shifts and data on the autonomic system might permit more certain correlation of the phenomena described with subcortical functions. 71.
Alterations micromotorie tonus regulation in cerebral disorders.-F. Steinwachs (Aachen, W. Germany).