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A delay in the movement initiation was shown to entail an augmentation of the N2 wave ascending front and a delay in the ERPs P3 wave in frontal leads in healthy subjects and in parkinsonian patients. The modulation of the N2 wave seems to reflect inhibitory processes in frontal areas of the brain.
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The auditory mismatch negativity (MMN) event-related brain potential (ERP) reflects the storage of information in acoustic sensory memory. Thirteen patients with probable Alzheimer's disease (AD), 6 receiving treatment with the cholinesterase inhibitor (ChEI) tacrine (tetrahydroaminoacridine, THA) and 7 receiving no treatment, were administered 2 mg of nicotine polacrilex and placebo. MMNs were recorded with 1- and 3-s interstimulus intervals pre- and postplacebo/nicotine administration. In nontreated patients, amplitudes were decreased from pre- to postplacebo recordings but remained stable in THA-treated patients. Comparison of pre- and postnicotine MMNs found amplitude increases with nicotine in nontreated but not THA-treated patients. MMN latencies were shortened by nicotine in both treatment groups. These exploratory findings suggest that nicotine-improved strength of acoustic sensory memory traces and speed of acoustic sensory discrimination in AD are differentially affected by chronic ChEI treatment.
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During the pain-free interval migraine patients display increased negative amplitudes in recordings of slow cortical potentials compared to healthy controls. This fact can be linked to diminished or absent habituation during the recording session. This difference in amplitude and habituation is at its maximum the day before the migraine attack. After the attack, amplitudes and habituation course are comparable with those of healthy controls. This observation enables the migraine patient to predict the next migraine attack and to become acquainted with other symptoms which indicate an imminent attack and which can be present one or two days before it. During this period, when the attack has begun but the pain has not yet developed, novel therapeutic strategies for preventing the full-blown attack can be introduced. These "pre-emptive" strategies--which may include intake of tranquillizers to reduce the high cortical arousal, but also non-medical relaxation methods--constitute neither acute treatment (because there is no acute pain) nor prophylaxis.
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Bit-mapped multicomponent CNV complex and reaction time (RT) were recorded and measured in 24 presenile patients with initial symptoms of very mild to moderately severe primary mental deterioration without depression, and in 10 age-matched controls. All patients underwent CT and MRI examinations, EEG spectral analysis and a battery of psychometric test. Significant group differences were obtained for measures of some post-S1 ERP and CNV components, particularly of the post-S1 N1b, P300 and early and late pre-S2 CNV. P300 with increased latency, no significant CNV activity, very prolonged RTs, EEG slowing down and diffuse brain atrophy were observed in the majority of patients with probable presenile Alzheimer's dementia. These results suggest that CNV/RT and EEG activity changes similar to those observed in our patients may constitute a valuable clue for the study of brain dysfunction in the early stage of presenile idiopathic cognitive impairment.
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The gait of 31 hemiplegics is analyzed with a multiplecomponents force-plate. The healthy and paretic side differ in 5 of 7 parameters. The difference betwen the left and right side is bigger in the right hemiplegic, because in the left hemiplegic, the healthy side is more disturbed as in the right hemiplegic. That makes less differences between healthy and paretic side. The variability of the single steps is bigger in subjects with a bad gait. The method is suitable to screen the change of the gait and its progress.
Seven normal young men were submitted to standard and target paired auditory stimuli. The warning stimulus of paired tones informed subjects whether or not the impending unconditional stimulus implied a motor response. Subjects were instructed to execute the motor response at less one second after the unconditional stimulus occurrence, and were informed that the standard warning stimulus was always followed by an additional stimulus which confirmed its detection. Components of target warning and imperative stimuli responses presented a significant increase in amplitude with regard to evoked potential components elicited by standard warning and unconditional tones. P3 waves observed in response to standard warning and unconditional stimuli culminated over fronto-central cortex, while P3 of target warning and imperative tone responses peaked over centro-parietal cortex. These results suggest that manipulating warning stimulus significance by assigning to it a discriminative function, can modify processing of the information carried out by paired stimuli.
The sensitivity of the CNV and somatosensory evoked potentials (SEP) was assessed in shoe industry workers suffering from neurotoxic effects of adhesive solvents. We have examined 21 patients with clear electroneuromiographic and clinical signs of polyneuropathy as well as EEG signs of diffuse brain damage. 10 normal volunteers served as a control group. The maximal motor conduction velocity (MMCV) was considerably reduced in all patients. The maximal sensory conduction velocity (MSCV) was in the lower normal range (or borderline) in 12 patients, whereas in 9 or more severe decrement was detected. In comparison with normal subjects, none of the patients showed clear differences in latency or amplitude of SEP components (p always greater than .2). It was very easy to elicit CNVs over all areas explored and all the 10 patients showed normal characteristics. These results, therefore, suggest that CNV and SEP are not helpful for an early diagnosis of toxic effects of the solvents on the function of the central and peripheral nervous system.
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This paper is concerned with the relation of two components of the late positive complex, P300 and slow wave, to parameters of signal detection theory. In the first experiment, basically a replication of Squires et al., signal probability was 50% and a six point rating scale was used for subjects' answers. Whereas for the P300 the well known relation to subjective confidence (and thus to response criteria) was confirmed, a similar relation could not be found for the slow wave. In the second experiment the local signal probability was varied from 25% to 75% on a trial to trial basis. Under these conditions neither the P300 nor the slow wave exhibited a relation to signal-probability, whilst the relation to decision-confidence was preserved.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.