Auditory ERP components and mismatch negativity in dysphasic children.

Auditory event-related potentials (ERPs) and especially the mismatch negativity component (MMN) were examined in 14 dysphasic and 12 normal children (aged 7-13). The ERPs were elicited by sine tone stimuli using the passive oddball paradigm and short ISI (350 msec). We measured the peak latency and peak amplitude of MMN responses to frequency (500/553 Hz) and duration (50/110 msec or 50/500 msec) differences. In the dysphasic group the peak amplitude of the frequency MMN was significantly attenuated. The duration MMN showed a significant difference between the two groups only for stimuli with highly contrasting values (50/500 msec). In normal subjects we found a negative correlation between the peak latency of the frequency MMN and age. The maturational changes of long-latency ERPs were non-significant in dysphasic children. Evidence of differences in hemispheric asymmetry between the two groups was observed.

Nerve conduction velocity in juvenile rheumatoid arthritis.

Motor and sensory nerve conduction velocities (NCV) were recorded in several nerves of a total of 99 patients with juvenile rheumatoid arthritis (JRA), and the results were compared to those obtained for two reference groups, one consisting of healthy children and the other of 30 children with different articular manifestations. The JRA and the affected reference group were not found to differ significantly from each other. NCV values were systematically slightly higher and the distal median nerve latencies slightly shorter in the patients with JRA than in the healthy reference group. Several measurement values differed from each other significantly. Some patients with JRA showed slightly decreased NCVs in individual nerves, but manifest mononeuropathy was not found. The results show that complications of peripheral nervous system origin do not typically occur in association with JRA.

Quantitative vibration perception thresholds in patients under prolonged antiepileptic treatment.

Quantitative vibration perception threshold (VPT) measurements were performed on 134 healthy subjects and 147 epileptics undergoing prolonged (more than one year) antiepileptic treatment, 28 patients received diphenylhydantoin, 71 carbamazepine and 11 some other drug. 37 subjects received a combination of drugs, which included diphenylhydantoin and/or carbamazepine. VPT was measured quantitatively at the dorsum of the right foot with a device vibrating at 100 Hz. The mean of the four successive threshold values was calculated. VPTs of the epileptic groups treated with diphenylhydantoin, carbamazepine or combined medication were all significantly (P less than 0.001) higher than those of the control group. The group receiving other medication showed no difference in this respect. The percentage of patients with abnormal thresholds was about the same (10-16) in the epileptic groups. An exception was the group taking other medication, in which no abnormal VPTs were found. It is suggested that such quantitative measurement may be a useful screening method for detecting dysfunction in the peripheral nervous system due to prolonged antiepileptic treatment. It will, however, be necessary to test the clinical validity of the method for diagnosing manifest or subclinical polyneuropathies.

The maltose-inducible 43 kDa major outer membrane protein in Vibrio cholerae is immunogenic and common to different isolates.

We have previously demonstrated the presence of a maltose-inducible major outer membrane protein of 43 kDa in an El Tor Inaba strain of Vibrio cholerae. The occurrence of similar proteins was examined in several isolates of V. cholerae 01. The results indicate that the 43 kDa protein is common to all of the isolates as evidenced by Western blotting analysis with antiserum raised against this protein. The 43 kDa protein was maltose-inducible in most isolates although some strains exhibited a constitutive production of the protein. This protein was present also on V. cholerae 01 organisms harvested directly from the small intestine of rabbits with experimental cholera and it gave rise to specific antibodies after immunization with in vivo grown vibrios.

Evolution of nerve conduction velocity in later childhood and adolescence.

Sensory and/or motor nerve conduction velocities (NCVs) were measured in median, radial, sural, and peroneal nerves of 54 healthy girls and 75 healthy boys aged 3-19 years. Independent of the nerve and sex, both motor and sensory NCVs increased in the upper extremities and decreased in the lower ones as a function of age/growth in length. NCV increased in the upper limbs on an average 3.17 m/sec in the boys and in the girls 1.47 m/sec per 10 years of life. As for the nerves of the lower extremities, NCV slowed down on the average 1.81 m/sec in the boys and in the girls 3.62 m/sec per 10 years of age. The change varied in different nerves. A highly significant one (P less than 0.001) was found in both the motor and sensory NCVs of peroneal nerve in the girls and in the sensory NCV of radial nerve in boys. On the average NCV was in most nerves faster in the girls than in boys of the same age. According to these results, changes occur in the function---and thus probably also in the morphology---of peripheral nerves even in later childhood and adolescence. These changes pertain to general maturation, growth in length of the limbs, and possibly also sex.

Vibratory perception thresholds in shipyard workers exposed to solvents.

Vibratory perception thresholds were determined for 90 subjects working at a shipyard with industrial solvents. The duration of exposure varied from 1 to 44 years (mean 19.6 years). Four of the men but none of women had bilaterally significantly increased thresholds in the lower limbs. In addition, seven subjects had increased thresholds in the upper extremities only. Fifteen subjects were further examined at a neurophysiological laboratory to determine the degree of possible peripheral polyneuropathy. The following measurements were made at the laboratory: motor and sensory conduction velocities, electromyography and heart rate variation during normal and forced breathing. The laboratory investigations revealed abnormalities in most of the subjects with increased vibratory perception thresholds in the lower limbs. On the other hand the laboratory measurements were normal for all subjects with increased thresholds in the upper limbs only. It is concluded that when peripheral polyneuropathy is suspected, quantitative vibratory perception threshold measurement is an easily applicable screening method for selecting subjects for further laboratory investigations.

Automatic auditory word perception as measured by 40 Hz EEG responses.

OBJECTIVES: Here we report the existence of automatic speech perception in man, revealed by 40 Hz EEG responses. METHODS: We presented to Finnish subjects the Finnish word /tu:li/(wind) as the standard stimulus and another Finnish word /tuli/(fire) as the deviant stimulus using a passive auditory oddball task. The experiment was also conducted with pseudowords as stimuli. RESULTS: We observed a global significant increase in 40 Hz EEG power at 600 ms after stimulus onset for words, but not for pseudowords. CONCLUSIONS: Our results indicate that the memory representation of the standard verbal stimuli, even if unattended, might not merely be based on the physical features of the stimuli: if a semantic representation exists, then the brain processes it pre-attentively.

Event-related desynchronization evoked by auditory stimuli.

Event-Related Desynchronization (ERD) and Synchronization (ERS) of several EEG alpha frequencies was studied in 19 subjects during the presentation of linguistic and/or melodic auditory stimuli. The stimulus length was 1300 msec (+/-100 msec) and the interstimulus interval was 2000 msec. A significant ERD was found during auditory stimulation in the 8-10 Hz and 10-12 Hz alpha frequency bands, and there were also significant differences in the spatiotemporal pattern of the ERD between these frequency bands. Significant ERD was elicited also in the 10-11 and 11-12 Hz frequency bands by auditory stimulation. There were no significant differences between these one-hertz frequency bands. The subjects were assigned to two analysis groups according to their individual alpha peak frequency (10-11 or 11-12 Hz) at rest. The ERD in these groups reached statistical significance and there were significant differences between the groups. The ERD of the two groups differed significantly also when their EEG data was studied in the 10-12 Hz frequency band. The results from this study show that ERD is not modality-specific, i.e., it can be elicited also by auditory stimuli. Moreover, they indicate that it is important to control over interindividual variation in the EEG when studying the ERD phenomenon.