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Mapping of EEG activity during mental training of isometric leg contractions
135 tion, and extinction phases of classical conditioning. Two tones served as CS ÷ and C S - while a loud noise served as the US. Some subjects could not report the C S + / U S relationship and were designated 'unaware'. Across acquisition, CNV increased to both CS + and C S - for both aware and unaware subjects, N100 was larger to CS + than to C S - for both aware and unaware subjects, and P300 was smaller to CS + than to C S - for aware subjects only. Since awareness did not affect the CNV and N100 changes, these waves may reflect procedural learning. In contrast, P300 may reflect declarative learning. A second experiment will be reported in which the aversiveness and response requirements to the US were manipulated. Although more research is needed, it seems likely that E R P s can enhance our understanding of the cognitive processes involved and the types of knowledge acquired within the conditioning paradigm.
S P Y G H M O M A N O M E T R Y VS. T H E P E N A Z M E T H O D F O R M O N I T O R I N G B L O O D P R E S S U R E D U R I N G ACTIVATION J. Kugler, N. Schmitz, W. N e u m a n n and G. Kriiskemper D e p a r t m e n t of Medical Psychology, Ruhr-University Bochum, Bochum, Germany Over the last years, a technique introduced by Penaz makes it feasible to monitor blood pressure (BP) non-invasively and continuously from the finger artery. A high correlation with intra-arterial BP, usually r > 0.90, demonstrates its validity. For clinical and research purposes, however, BP is mostly measured non-invasively using sphygmomanometry. In this study, we compared sphygmomanometry and the Penaz method in an activation experiment. 46 healthy individuals (age 19 to 28) were randomly assigned to two groups: The treatment group worked on a reaction time task for six intervals of 6 min. Before and after the intervals, BP was measured by sphygmomanometry (S&K, Germany). In addition, BP was monitored by the FINAPRES-system (Ohmeda, USA) at the middle or ring finger of the left hand. The control group was instructed to relax, but had the same blood pressure measuring protocol. The results indicate that (a), sphygmomanometry underestimated variability of short- and long-term BP changes; (b), during occlusion of the brachial artery, systolic blood pressure showed a pattern of increase and decrease. It can be stated that the Penaz method appears to be the more appropriate if dynamic aspects of blood pressure are of interest.
Mental training of voluntary isometric contraction (VIC) was chosen as a model to investigate CNS activation related to motor processes. E E G background activity was registrated in 12 male Ss during real and imagined VIC (80% and maximal VIC; extension of both legs; sitting position) and analysed by m e a n s of FFT. During real VIC (80% Fmax) m e a n theta- and alpha-power during VIC decreased above parietal cortex, whereas alpha frequency increased in all 14 E E G channels compared to initial rest. Parameter maps and probability maps are demonstraded. Motor imagination caused similar changes in EEG, the power in the betal-band decreased also in central und frontal areas. 3 7 - C H A N N E L M A G N E T I C R E C O R D I N G OF P300 ACTIVITY Burkhard MaeB a, Lutz T r a h m s b and Angela Friederici a a Freie Universitgt, Institut fiir Psychologie, Berlin, Germany and b Physikalisch Technische Bundesanstalt, Berlin, Germany Data recordings were taken on 37 magnetic channels and 5 electric channels simultaneously. The magnetic channels picture the N100 and P300 activities known from the electrical recordings. The field strength maps taken at the time points of m a x i m u m activity about 100 and 300 ms after stimulus onset show field strength maxima in nearly the same distance but in different positions. Hence, the distance between both sources of activity in the brain and the sensor system appears to be approximately equal; their position, however, is different. The measurements were carried out using a 37-channel device, built by the Physikalisch Technische Bundesanstalt, employed in the Berlin Magnetically Shielded Room. The sensors were arranged in a plane in concentric circles with diameters of 7, 14 and 21 cm, respectively. We used a sampling rate of 500-Hz and an antialiasing filter of 64 Hz. The subjects were acoustically stimulated in the right ear. They heard 200 tones of 100 ms duration and 500/1000 Hz with a constant interval of 2000 ms. The task was to count the 40 500-Hz tones. The magnetic sensors were positioned centrotemporal over the left hemisphere. Mean values were calculated over single subjects after neglecting distorted sweeps due to eye blinks or other artefacts. RELATION BETWEEN THE TRANSIENT S T E A D Y - S T A T E 40-Hz RESPONSES
AND
MAPPING OF EEG ACTIVITY DURING MENTAL TRAINING OF ISOMETRIC LEG CONTRACTIONS
J.P. Miikelii Low T e m p e r a t u r e Laboratory, Helsinki University of Technology, Espoo, Finland
B. Leutert, L. Beyer, Th. Weig, E. Hansen, R. Rost and M. Sust Institute of Physiology, FSU Jena, G e r m a n y
With proper filtering, auditory-evoked potentials and magnetic fields to single tones, measured outside the brain, show periodic oscillations at about 40 Hz. Trains of auditory 40-Hz
S P Y G H M O M A N O M E T R Y VS. T H E P E N A Z M E T H O D F O R M O N I T O R I N G B L O O D P R E S S U R E D U R I N G ACTIVATION J. Kugler, N. Schmitz, W. N e u m a n n and G. Kriiskemper D e p a r t m e n t of Medical Psychology, Ruhr-University Bochum, Bochum, Germany Over the last years, a technique introduced by Penaz makes it feasible to monitor blood pressure (BP) non-invasively and continuously from the finger artery. A high correlation with intra-arterial BP, usually r > 0.90, demonstrates its validity. For clinical and research purposes, however, BP is mostly measured non-invasively using sphygmomanometry. In this study, we compared sphygmomanometry and the Penaz method in an activation experiment. 46 healthy individuals (age 19 to 28) were randomly assigned to two groups: The treatment group worked on a reaction time task for six intervals of 6 min. Before and after the intervals, BP was measured by sphygmomanometry (S&K, Germany). In addition, BP was monitored by the FINAPRES-system (Ohmeda, USA) at the middle or ring finger of the left hand. The control group was instructed to relax, but had the same blood pressure measuring protocol. The results indicate that (a), sphygmomanometry underestimated variability of short- and long-term BP changes; (b), during occlusion of the brachial artery, systolic blood pressure showed a pattern of increase and decrease. It can be stated that the Penaz method appears to be the more appropriate if dynamic aspects of blood pressure are of interest.
Mental training of voluntary isometric contraction (VIC) was chosen as a model to investigate CNS activation related to motor processes. E E G background activity was registrated in 12 male Ss during real and imagined VIC (80% and maximal VIC; extension of both legs; sitting position) and analysed by m e a n s of FFT. During real VIC (80% Fmax) m e a n theta- and alpha-power during VIC decreased above parietal cortex, whereas alpha frequency increased in all 14 E E G channels compared to initial rest. Parameter maps and probability maps are demonstraded. Motor imagination caused similar changes in EEG, the power in the betal-band decreased also in central und frontal areas. 3 7 - C H A N N E L M A G N E T I C R E C O R D I N G OF P300 ACTIVITY Burkhard MaeB a, Lutz T r a h m s b and Angela Friederici a a Freie Universitgt, Institut fiir Psychologie, Berlin, Germany and b Physikalisch Technische Bundesanstalt, Berlin, Germany Data recordings were taken on 37 magnetic channels and 5 electric channels simultaneously. The magnetic channels picture the N100 and P300 activities known from the electrical recordings. The field strength maps taken at the time points of m a x i m u m activity about 100 and 300 ms after stimulus onset show field strength maxima in nearly the same distance but in different positions. Hence, the distance between both sources of activity in the brain and the sensor system appears to be approximately equal; their position, however, is different. The measurements were carried out using a 37-channel device, built by the Physikalisch Technische Bundesanstalt, employed in the Berlin Magnetically Shielded Room. The sensors were arranged in a plane in concentric circles with diameters of 7, 14 and 21 cm, respectively. We used a sampling rate of 500-Hz and an antialiasing filter of 64 Hz. The subjects were acoustically stimulated in the right ear. They heard 200 tones of 100 ms duration and 500/1000 Hz with a constant interval of 2000 ms. The task was to count the 40 500-Hz tones. The magnetic sensors were positioned centrotemporal over the left hemisphere. Mean values were calculated over single subjects after neglecting distorted sweeps due to eye blinks or other artefacts. RELATION BETWEEN THE TRANSIENT S T E A D Y - S T A T E 40-Hz RESPONSES
AND
MAPPING OF EEG ACTIVITY DURING MENTAL TRAINING OF ISOMETRIC LEG CONTRACTIONS
J.P. Miikelii Low T e m p e r a t u r e Laboratory, Helsinki University of Technology, Espoo, Finland
B. Leutert, L. Beyer, Th. Weig, E. Hansen, R. Rost and M. Sust Institute of Physiology, FSU Jena, G e r m a n y
With proper filtering, auditory-evoked potentials and magnetic fields to single tones, measured outside the brain, show periodic oscillations at about 40 Hz. Trains of auditory 40-Hz