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2. Influence of physiological changes of glycemia on VEPs and visual ERPs
- Creator:
- Kubová, Z., Chlubnová, J., Szanyi, J., Kuba, M., and Kremláček, J.
- Type:
- article, model:article, and TEXT
- Subject:
- Hypoglycemia, Visual event related potentials, Cognitive potentials, Evoked potentials, Fasting, and Exertion
- Language:
- English
- Description:
- Since hypoglycemia is known to influence cognitive functions, we checked whether the physiological changes in glycemia (after fasting or exertion) can explain the rather high intra-individual variability of event-related potentials (ERPs). Besides the ERPs to “change in coherence of a moving pattern” with reaction time (RT) recording, binocular pattern reversal VEPs and motion-onset VEPs (to linear and radial motion) were also examined in 14 healthy subjects prior to and after 24-h fasting that decreased glycemia from 5.3 to 3.9 mmol/l on the average. We only found one significant change in the latencies and amplitudes of VEPs and ERPs (with no change of RT). The N160 peak in the motion-onset VEPs to radial (expansive) motion (EM-VEPs) showed a larger amplitude at lower glycemia. For evaluation of the exertion influence, we tested glycemia prior to and after 90 min long exercise – bicycle ergometry with the load set to 2 W/kg in women and 2.5 W/kg in men (average age-related values for W170/kg index). The changes of glycemia to exertion were, however, less distinct than those to fasting. We conclude that in healthy subjects the glycemia decrease due to 24-h fasting or intensive time-limited exercise never reaches the critical value to change the VEP, ERPs and RTs.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3. Motion-reversal visual evoked responses
- Creator:
- Kuba, M., Toyonaga, Naoto, and Kubová, Z.
- Type:
- article, model:article, and TEXT
- Subject:
- visual evoked responses, VEPs, visual motion stimulation, and motion-reversal
- Language:
- English
- Description:
- Motion-reversal visual evoked responses (VERs) have remarkable waveform variability. In our opinion this is caused by the alternative predominance of either motion or pattem-onset/offset related components. The motion dependent component of motion-reversal VER closely resembles motion-onset VER (main negative peak with the latency of about 170 ms), the first positive peak (with the latency of about 100 ms) corresponds to the pattern-onset component and the second non-constant positive peak (with the latency of about 130 ms) seems to be identical with the pattern-offset positivity. The differences in expression of these components are dependent on some stimulus characteristics (mainly on the contrast of a structure, velocity of motion, retinal localization of the stimulus) and on substantial differences in the sensitivity of subjects to motion stimulation.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4. Visual evoked potential evidence for magnocellular system deficit in dyslexia
- Creator:
- Kubová, Z., Kuba, M., Peregrin, J., and Nováková, V.
- Type:
- article, model:article, and TEXT
- Subject:
- dyslexia, visual evoked potentials, motion, and magnocellular system
- Language:
- English
- Description:
- Some recent studies on dyslexia have suggested a selective abnormality in the magnocellular visual pathway. To verify this hypothesis, we investigated motion-onset visual evoked potentials (VEPs) (predominantly testing the magnocellular system) as well as pattern-reversal VEPs (presumably testing the parvocellular system) in 20 dyslexics and 16 controls (both groups with a mean age of 10.0 years). Although the latencies and amplitudes of the main positive peak of pattern-reversal VEPs did not differ between the dyslexic and control group, the motion specific negative peak of motion-onset VEPs was significantly delayed (p<0.001) in dyslexics. Our results confirm a selective magnocellular pathway disorder in dyslexics and indicate that the motion-onset VEPs might serve as an objective method for early diagnosis of dyslexia.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
5. Visual Evoked Potentials and Event Related Potentials in Congenitally Deaf Subjects
- Creator:
- Chlubnová, J., Kremláček, J. , Kubová, Z., and Kuba, M.
- Type:
- article, model:article, and TEXT
- Subject:
- sign language, Pattern-reversal VEPs, Motion VEPs, Event related potentials, and Deaf subjects
- Language:
- English
- Description:
- The purpose was to test parameters of visual evoked potentials (VEPs) and of event-related potentials (ERPs) in deaf subjects to verify visual and cognitive CNS functions in a handicapped group of the population. Three types of visual stimuli (with dominating parvocellular or magnocellular system activation or with cognitive tasks) were used in the study. Six deaf persons (4 women, 2 men, mean age 17 years) and 6 persons with normal hearing (sex- and age-matched) were included in this pilot study. In all types of stimulation, latencies and amplitudes of main VEPs and ERPs components were evaluated. No significant latency differences were found. However, significantly reduced amplitudes were found in the occipital area for responses to motion and cognitive stimuli which might be interpreted as a part of functional reorganization of the extrastriate and cognitive cortical areas of deaf subjects.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public