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Dynamics of magnetic, auditory evoked steady-state responses in Alzheimer patients
S12h These findings indicate that the N20 latency and amplitude are strongly affected by the non-REM stages of sleep and chloral hydrate in some cases potentiates these changes. These findings should be taken into account m the performance and interpretation of somatosensory evoked potentials in children, to avoid false positive results.
IN NORMAL SUBJECTS ARE LONG-LOOP RESPONSES MODIFIED BY COGNITIVE SET. M.P. Remler and D.J. Beckley (University
of California
Davis, Martinez,
CA. USA)
The influence of cognitive set on long-loop responses in normals subjected to rotational perturbations of various amplitudes was studied. EMG recordings were obtained from 3 muscles in the left leg in 10 normal adults (age range = 25-41, mean 34.3 years: 5 females, 5 males). Stimuli consisted of 3 sets of 20 trials of sudden toe-up ramp movements of preselected amplitudes (pure 4”, pure lo”, and mixed 4O/lO o at a constant velocity of 35 O. Latencies for the short, middle and long latency responses showed no significant differences. Mean normalized long latency tibialis anterior (TA) amplitudes of both the pure and random loo displacements were increased in comparison to the pure 4O displacements. Random 4O TA mean amplitudes were similar to random and pure 10” responses. We concluded that scaling of the amplitude of the TA long latency response, and not changes in response latencies, represents the major postural adjustment mechanism in this paradigm and favors a large response in situations where perturbation size cannot be reliably predicted in advance.
DYNAMICS OF MAGNETIC, STEADY-STATE RESPONSES TIENTS. U. Ribary, Ferris
R. Llinas,
(New York University
A. Kluger,
Medical
AUDITORY EVOKED IN ALZHEIMER PA-
J. Cappell,
Center,
in a continuous phase shift manner over parietal. temporal and frontal areas. The largest amplitudes for this acticitv were found over temporal cortex. Source localization indicates that this magnetic wave reflects a complex. time locked sequence 01 network activations involving most probably thalamu-corticothalamic pathways. In Alzheimer patients. decreased magnetic fields and a distortion of the dynamtcs of their response was observed, largely due to increased phase shifts over the hemisphere and to a lower activity in fronto-parietotemporal area,. In addition. source localization indicates an overall reduction in cortical activity and of the synchronization of 40 Hz. activity over the sensory area in these patients. These MEG data illustrate a new approach to monitoring the dynamics of pathological brain function in psychiatry.
BLINK-REFLEX EXCITABILITY CURVE IN PATIENTS WITH BLEPHAROSPASM TREATED WITH LOCAL INJECTION OF BOTULINUM TOXIN. C. Ribera. J. Valls, M.J. Marti, (Hospital
Clinic,
Barcelona.
M. PUJOI and E. Tolosa
Spain)
Local injections of botulinurn toxin are widely used as a symptomatic treatment for dystonic blepharospasm (DBS). Such treatment gives rise to a temporary decrease in the intensity and frequency of the spasms. Little is known about the etiology of DBS. However, the neurophysiological finding of an enhanced recovery curve of the blink-reflex R2 response, which probably .reflects an enhanced excitability of the brainstem interneurons (Tolosa et al., Movement Disorders. 1988, 3: 61), may be related with the physiopathology of the disease. In the present study, we examined whether or not the clinical improvement of these patients during the course of the botulinurn-toxin treatment is related to changes in the blmk-reflex recovery curve. We have found that while there was a decrease in the amplitude of the direct and reflex facial responses, there was no change in the excitability curve of the blink-reflex. which was abnormally enhanced before as well as after the treatment with botulinum toxin.
J. Suk and S.H.
New York, NY, USA)
A 14-multichannel neuromagnetic measuring system (BTi) was used to map the distribution of magnetic (MEG) fields in 10 Alzheimer patients and 10 control subjects (60-75 years). The activity, evoked during a 40 Hz continuous auditory stimulation was recorded over the right hemisphere. The stimuli consisted of a 12 msec duration 250 Hz tone pulse, presented binaurally at approximately 60 dB at repetition rates of 40 Hz. Our MEG data show that the 40 Hz response involves more than one generator, which are more in phase in controls than in patients. The MEG data in control subjects, and analyzed at 1 msec steps, indicate a stereotyped temporal pattern of magnetic activity over the hemisphere. It consisted of a positivenegative field sequence, demonstrating a rotation-like pattern
CORRELATION BETWEEN EMG BIOFEEDBACK AMOUNT OF ALPHA RHYTHM. F. Rragm (Hospital
AND
and L. Crispino Italiano,
Montevideo,
Uruguay)
The use of biofeedback as a treatment of tension headache led us to the observation that in most patients, disappearance of headache occurred along with other manifestations of general improvement, probably related to a better control of autonomic functions. In that sense, patients reported better sleep, better digestive tract and other functions. Many authors have suggested that the increase of alpha rhythm activity has beneficial effects upon behavioral state reducing anxiety. for instance, and on autonomic functions as well.
IN NORMAL SUBJECTS ARE LONG-LOOP RESPONSES MODIFIED BY COGNITIVE SET. M.P. Remler and D.J. Beckley (University
of California
Davis, Martinez,
CA. USA)
The influence of cognitive set on long-loop responses in normals subjected to rotational perturbations of various amplitudes was studied. EMG recordings were obtained from 3 muscles in the left leg in 10 normal adults (age range = 25-41, mean 34.3 years: 5 females, 5 males). Stimuli consisted of 3 sets of 20 trials of sudden toe-up ramp movements of preselected amplitudes (pure 4”, pure lo”, and mixed 4O/lO o at a constant velocity of 35 O. Latencies for the short, middle and long latency responses showed no significant differences. Mean normalized long latency tibialis anterior (TA) amplitudes of both the pure and random loo displacements were increased in comparison to the pure 4O displacements. Random 4O TA mean amplitudes were similar to random and pure 10” responses. We concluded that scaling of the amplitude of the TA long latency response, and not changes in response latencies, represents the major postural adjustment mechanism in this paradigm and favors a large response in situations where perturbation size cannot be reliably predicted in advance.
DYNAMICS OF MAGNETIC, STEADY-STATE RESPONSES TIENTS. U. Ribary, Ferris
R. Llinas,
(New York University
A. Kluger,
Medical
AUDITORY EVOKED IN ALZHEIMER PA-
J. Cappell,
Center,
in a continuous phase shift manner over parietal. temporal and frontal areas. The largest amplitudes for this acticitv were found over temporal cortex. Source localization indicates that this magnetic wave reflects a complex. time locked sequence 01 network activations involving most probably thalamu-corticothalamic pathways. In Alzheimer patients. decreased magnetic fields and a distortion of the dynamtcs of their response was observed, largely due to increased phase shifts over the hemisphere and to a lower activity in fronto-parietotemporal area,. In addition. source localization indicates an overall reduction in cortical activity and of the synchronization of 40 Hz. activity over the sensory area in these patients. These MEG data illustrate a new approach to monitoring the dynamics of pathological brain function in psychiatry.
BLINK-REFLEX EXCITABILITY CURVE IN PATIENTS WITH BLEPHAROSPASM TREATED WITH LOCAL INJECTION OF BOTULINUM TOXIN. C. Ribera. J. Valls, M.J. Marti, (Hospital
Clinic,
Barcelona.
M. PUJOI and E. Tolosa
Spain)
Local injections of botulinurn toxin are widely used as a symptomatic treatment for dystonic blepharospasm (DBS). Such treatment gives rise to a temporary decrease in the intensity and frequency of the spasms. Little is known about the etiology of DBS. However, the neurophysiological finding of an enhanced recovery curve of the blink-reflex R2 response, which probably .reflects an enhanced excitability of the brainstem interneurons (Tolosa et al., Movement Disorders. 1988, 3: 61), may be related with the physiopathology of the disease. In the present study, we examined whether or not the clinical improvement of these patients during the course of the botulinurn-toxin treatment is related to changes in the blmk-reflex recovery curve. We have found that while there was a decrease in the amplitude of the direct and reflex facial responses, there was no change in the excitability curve of the blink-reflex. which was abnormally enhanced before as well as after the treatment with botulinum toxin.
J. Suk and S.H.
New York, NY, USA)
A 14-multichannel neuromagnetic measuring system (BTi) was used to map the distribution of magnetic (MEG) fields in 10 Alzheimer patients and 10 control subjects (60-75 years). The activity, evoked during a 40 Hz continuous auditory stimulation was recorded over the right hemisphere. The stimuli consisted of a 12 msec duration 250 Hz tone pulse, presented binaurally at approximately 60 dB at repetition rates of 40 Hz. Our MEG data show that the 40 Hz response involves more than one generator, which are more in phase in controls than in patients. The MEG data in control subjects, and analyzed at 1 msec steps, indicate a stereotyped temporal pattern of magnetic activity over the hemisphere. It consisted of a positivenegative field sequence, demonstrating a rotation-like pattern
CORRELATION BETWEEN EMG BIOFEEDBACK AMOUNT OF ALPHA RHYTHM. F. Rragm (Hospital
AND
and L. Crispino Italiano,
Montevideo,
Uruguay)
The use of biofeedback as a treatment of tension headache led us to the observation that in most patients, disappearance of headache occurred along with other manifestations of general improvement, probably related to a better control of autonomic functions. In that sense, patients reported better sleep, better digestive tract and other functions. Many authors have suggested that the increase of alpha rhythm activity has beneficial effects upon behavioral state reducing anxiety. for instance, and on autonomic functions as well.