Inter-individual variability of oscillatory responses to subject's own name. A single-subject analysis.

In previous studies event-related potentials and oscillations in response to subject's own name have been analyzed extensively on group-level in healthy subjects and in patients with a disorder of consciousness. Subject's own name as a deviant produces a P3. With equiprobable stimuli, non-phase-locked alpha oscillations are smaller in response to subject's own name compared to other names or subject's own name backwards. However, little is known about replicability on a single-subject level. Seventeen healthy subjects were assessed in an own-name paradigm with equiprobable stimuli of subject's own name, another name, and subject's own name backwards. Event-related potentials and non-phase locked oscillations were analyzed with single-subject, non-parametric statistics. No consistent results were found either for ERPs or for the non-phase locked changes of oscillatory activities. Only 4 subjects showed a robust effect as expected, that is, a lower activity in the alpha-beta range to subject's own name compared to other conditions. Four subjects elicited a higher activity for subject's own name. Thus, analyzing the EEG reactivity in the own-name paradigm with equiprobable stimuli on a single-subject level yields a high variance between subjects. In future research, single-subject statistics should be applied for examining the validity of physiologic measurements in other paradigms and for examining the pattern of reactivity in patients.

EEG frequency analysis of responses to the own-name stimulus.

OBJECTIVE: The neuronal response to hearing a subject's own (SON) compared with other names has been examined in healthy subjects as well as in patients with disorders of consciousness. So far, on electroencephalographic data, only event-related potentials (ERPs) were considered. In this study, we examined the frequency properties of SON. METHODS: Data of 17 healthy subjects were processed for equiprobable stimuli of SON, other- and own-name backwards by calculating ERPs, evoked and induced activity for a period of 2000 ms from stimulus onset in the delta, theta, lower and upper alpha bands and averaging for four consequent temporal segments of 500 ms each. RESULTS: For SON, the N1 component's amplitude was larger, while induced activity in the alpha band decreased in the second temporal segment (of 500-1000 ms). No differences between other- and own-name backwards were found. CONCLUSIONS: The late reactivity may indicate responses to a stimulus after having recognised it. Alpha is known to play a role in attention and alertness. The results may reflect the fact that the SON stimulus enhances alertness. SIGNIFICANCE: The findings correlate previous work about alertness and alpha activity with those about attention capturing of the SON stimulus. We suggest using frequency analysis in research on disorders of consciousness.

Functional involvement of the cerebral cortex following paramedian bithalamic infarction.

To investigate further the functional mechanisms underlying the so-called 'loss of psychic self-activation' following paramedian bithalamic lesions, we used transcranial magnetic stimulation (TMS) in a patient who presented with this clinical picture after paramedian bithalamic infarction due to arterial occlusion. The patient showed higher motor thresholds than the controls; the cortical silent period and intracortical inhibition to paired-pulse stimulation, two different forms of inhibition that are believed to reflect GABAergic mechanisms, were significantly increased; short latency afferent inhibition (SAI), a technique that may give direct information about the function of some cholinergic circuits in the human brain, was significantly reduced. This study first demonstrates that there are changes in the intracortical excitatory and inhibitory circuits in this neurobehavioral syndrome, that lead to cortical hypoexcitability. The modulation in GABAergic activity may result in excitability changes in those cholinergic cortical networks that are involved in SAI. TMS may provide important information on connections between the thalamus and cortex and may help in better understanding the role of the thalamo-cortical relationship in behavioural changes associated with thalamic stroke.

Magnetic resonance spectroscopy of memory and frontal brain region in early multiple sclerosis.

In vivo proton magnetic resonance spectroscopy (1H-MRS) has been used to assess biochemical changes that occur in demyelinating lesions and in normal appearing white matter (NAWM) in multiple sclerosis (MS) patients. N-acetylaspartate (NAA) levels in MS patients may indicate neural viability. In early stages of MS, patients may suffer from slight cognitive impairment. The objective of this study was to investigate memory function in relation to biochemical properties of frontal brain areas of MS patients. Twenty-one patients with relapsing-remitting MS and 21 healthy comparison subjects were examined psychometrically using the Wechsler Memory Scale (WMS) and the Multiple Sclerosis Functional Composite (MSFC) scale, and (1H-MRS) was used to examine frontal deep white matter (left hemisphere) and the frontal cingulate gyrus (Brodmann areas 24/32, bihemispheric). A significant reduction of the NAA/Creatine (Cr) ratio in the frontal cingulate gyrus among the MS patient group was detected when compared to healthy subjects. A significant decrease in the NAA/Cr ratio was also found in volumes of cerebral deep white matter, including plaques, in the MS patients. No NAA/Cr ratio changes were found in NAWM. Differences in MSFC results did not reach statistical significance, but the WMS general memory score showed a significant statistical difference between the patient group and healthy subjects. Regression analysis showed the gray matter NAA/Cr ratio of the frontal cingulate gyrus to be significantly related to distinct memory functions. The authors conclude that (1H-MRS) of gray matter in early stages of MS may be pertinent in the detections of early metabolic disturbances, particularly in subjects with or without minor neurological impairment. Findings suggest a general relationship between the metabolic status of the frontal cortices and memory function.

Stimulating music increases motor coordination in patients afflicted with Morbus Parkinson.

The present study measured the short-term effect of special stimulating music on motor coordination in Parkinson patients. Eleven patients with a dominant akinetic Parkinson syndrome as well as ten healthy persons (age-matched control group) participated in this study. In the Parkinson group, the measurement of fine motor coordination with the 'Vienna Test System' showed an improvement in two (aiming, line tracking) of the four subtests after listening to the music. The patients improved their performance with the right arm significantly in the subtest aiming-error-time. No statistical differences were found in the other two subtests (steadiness, tapping) in both groups. There was also no improvement in frequency of tapping movement on the power-force-working-plate. Accordingly, music effects more the precision of a movement than the speediness. The measurements on the power-force-working-plate showed a significant improvement in two of five measured parameters: contact time, variability coefficient for total step and impact maximum changed significantly. This study gives evidence that specific music can improve the precision of arm and finger movements.