Functional localisation of motor processes in the human cortex.
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Brain Mapping↗
Biomedical subjects
G Lindinger
Publications and source records attributed to G Lindinger.
Supplementary motor area activation while tapping bimanually different rhythms in musicians.
In 15 musicians, cortical DC-potentials were recorded from the scalp before and during the execution of bimanual motor sequences. Subjects (Ss) either tapped with their two index fingers in synchrony (quavers against quavers; "2 against 2") or they tapped quavers against triplets ("2 against 3"). Either the right or the left finger started tapping the quavers (onset time t1), after about 4 s the other finger joined in (t2) either with quavers as well (easy rhythm) or with triplets (difficult rhythm). Ss were free to start the sequences, i.e. to determine the onset times t1 and t2. Shifts of cortical DC potentials were averaged twice; (1) time-locked to t1 and (2) time-locked to t2. When moving in synchrony (easy rhythm) DC-potential shifts and maps of radial current densities across the scalp indicated activations of the two primary motor cortices (MI). When bimanually tapping different rhythms, there was not only an activation of MI cortices, but in addition a very large activation of the mesial, central cortex was observed. It is suggested that this cortical area which mainly contains the supplementary motor area (SMA) has the function of controlling the initiations of movements in the difficult sequence which have to fit into a very precise timing plan. Interestingly, activation of the mesial, central cortex preceded the actual performance of the difficult rhythm by about 4 s. This finding indicates that the preparatory set differs between the two tasks.
Adult↗
Movement-related potentials accompanying unilateral and bilateral finger movements with different inertial loads.
The present study was aimed at investigating the effect of inertial loading on movement-related potentials (MRPs) recorded from the scalps of normal subjects while performing finger movements. Two experiments were performed. Experiment 1. MRPs preceding and accompanying the execution of voluntary, unilateral finger movements were investigated in 8 subjects under the 3 experimental conditions of: no inertial load, small inertial load (250 g), and large inertial load (400 g). A significant effect of the inertial load on Bereitschaftspotential (BP) amplitude was observed for the 100 msec period preceding movement onset (BP -100 to 0) at precentral electrode sites and following movement onset (N0 to 100) at both precentral and parietal electrode sites. Pairwise comparisons revealed that significant effects were due to differences between the loading and non-loading conditions and not for different amounts of loading. No significant differences were observed for BP onset or early BP amplitudes, indicating that scalp negativity immediately prior to, and during, movement onset is primarily influenced by conditions of inertial loading. Experiment 2. This experiment examined the effect of inertial loading on MRPs for bilateral, simultaneous voluntary finger movements in 10 subjects under conditions of: no inertial load, inertial load applied separately to the left and right fingers, and with identical inertial loads applied to both fingers. No significant effect of inertial load on MRP amplitude was observed. These results are contrasted with those of experiment 1 which show significant effects of inertial loading for unilateral movements and are interpreted in terms of the hypothesis that bilateral movement organization involves 'higher' aspects of motor control than those reflecting adjustment to conditions of inertial loading.
Adult↗
Cerebral correlates of imagining colours, faces and a map--II. Negative cortical DC potentials.
Cortical activation patterns as measured by negative shifts of the scalp-recorded cortical steady potential ("DC shifts") were assessed in 28 normal subjects during imagining colours, faces, and a spatial map. Imaging resulted in sustained negative DC shifts at temporal, parietal and particularly at occipital sites. The topographic distributions of such DC shifts was modulated as a function of whether spatial or visual imagery was performed. During imaging the spatial map, a parietal maximum was observed, as opposed to a distribution in favour of temporal and occipital sites during imagining faces and colours. Results suggest a neuroanatomical dissociation between visual and spatial imagery. Since a similar visual-spatial dichotomy exists in perception, the finding is interpreted as further evidence of a shared cerebral substrate for images and percepts. The results are discussed in conjunction with the joint blood flow study.
Adult↗
Elaborative strategies in word pair learning--DC-potential correlates of differential frontal and temporal lobe involvement.
Cortical DC potentials were recorded while subjects were learning word pairs. The use of an elaborative mnemonic strategy resulted in a left frontal sustained negative shift. Its amplitude was independent of whether imagery mnemonics or semantic mnemonics were used. By contrast, posterior temporal potentials differed according to strategy: with imagery mnemonics, subjects had more symmetrical potentials over posterior temporal areas whereas with a semantic strategy, there was a left hemispheric preponderance of the DC potential. An interpretation within Stuss and Benson's theory on the frontal lobes is given.
Adult↗
[Microcomputer-assisted 64-channel EEG amplifier (DC-2kHz) with digital filter and 16 bit resolution].
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Brain↗
Negative cortical DC shifts preceding and accompanying simple and complex sequential movements.
Negative cortical DC shifts preceding and accompanying the execution of four different motor tasks were analysed in 18 subjects (Ss): Repetitive flexions and extensions of the forefinger had to be performed either by the right (1) or the left (2) hand. This simple motor task was compared to a complex one in which flexions and extensions of forefinger and hand had to be alternated in a fixed sequence. The complex task had either to be performed by the right (3) or the left (4) hand. Thus, the four conditions differed in the side of the performing hand (right/left) and in task-complexity (simple/complex). After its voluntary initiation, each task had to be performed for at least a period of six seconds. A Bereitschaftspotential (BP) preceded the voluntary initiation of the movement. Task-performance was accompanied by a negative DC shift called a performance-related negativity (N-P). Amplitudes of BP and N-P were compared by analysis of variance (ANOVA) using the factors "performing hand" (right/left) and "task-complexity" (simple/complex). "Performing hand" had significant effects on N-BP and N-P in C3* and C4* (positioned over the primary motor cortex) but did not influence mid-central (Cz*), frontal (F3, Fz, and F4) or parietal (P3, Pz, P4) recordings. "Task-complexity" had significant effects on N-P in mid-central (Cz*, C1*, C2*) and parietal (P3, Pz) recordings with higher negativity for complex movements. Recordings in C3* and C4* did not vary with "task complexity".(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
[Dynamic EEG mapping--an imaging procedure for studying perceptive, motor and cognitive brain performance].
The spatial pattern and time course of cortical activation can be studied when the event-related desynchronization in 30 EEG recordings is being quantified, averaged over about 60 events and displayed in form of maps with integration times of 125 ms (8 maps/s). This method was named dynamic mapping and used for investigating cortical activation pattern during the following tasks: Planning and execution of voluntary self-paced thumb movements, tactile stimulation of the foot sole and recognition of words, displayed shortly on a computer terminal. All these experiments resulted in localized activation pattern.
Cognition↗
[Concanavalin A- Sepharose affinity chromatography for routine microanalysis of gamma-glutamyltransferase (author's transl)].
The separation of two molecular forms of liver gamma-glutamyltransferase is achieved by Con A-Sepharose chromatography, an adult type with high affinity to Con A and a fetal type without binding capacity to this lectin. Now we present a new method using micro-columns for affinity chromatography (gel volume 2 ml). By this rapid and inexpensive procedure it is possible to study this enzyme separation for its use in the diagnosis of liver diseases.
Chromatography, Affinity↗
[Detection of multiple molecular forms of the gamma-glutamyltransferase by concanavalin A affinity chromatography (author's transl)].
The separation of several forms of gamma-glutamyl-transferase was achieved by using concanavalin A-Sepharose columns. The enzyme of the adult liver was bound totally to the lectin, whereas only 5% of the kidney enzyme and 50% of the pancreas gamma-glutamyltransferase was adsorbed by concanavalin A. Due to a higher content of N-acetylneuraminic acid, the enzyme of the fetal liver does not show any affinity to concanavalin A. Within 8 days after birth the N-acetylneuraminic acid-rich fetal gamma-glutamyltransferase is substituted by the adult form.
Animals↗
Somatotopy of human hand somatosensory cortex as studied in scalp EEG.
We recorded somatosensory evoked potentials (SEPs) in scalp EEGs during stimulation of the median nerve, the ulnar nerve and the individual digits in 3 normal subjects and in 1 epilepsy patient. In this patient we also measured SEPs from chronically indwelling subdural grid electrodes during electrocorticography (ECoG). We applied dipole modelling technique to study the 3-dimensional intracerebral locations and time activities of the neuronal sources underlying stimulation of different peripheral receptive fields. The sources underlying median nerve SEPs were located an average of 10.8 mm lateral inferior to those underlying ulnar nerve SEPs. Digit SEP sources showed a somatotopic arrangement from lateral inferior to medial superior in the order thumb, index finger, middle finger, ring finger and little finger, with some overlap or reversal for adjacent digits. The average distance between thumb and little finger was 12.5 mm. Thumb, index finger and middle finger were clustered around median nerve cortical representation, whereas ring finger and little finger were arranged around ulnar nerve cortex. In the epilepsy patient, the source localizations obtained in scalp EEGs showed good agreement with those on ECoGs. We conclude that SEPs recorded in scalp EEGs can be used to study functional topography of human somatosensory cortex non-invasively.
Adult↗