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Biomedical subjects

M Pantev

Publications and source records attributed to M Pantev.

6 recordsLinked to original sources
PubMed1996

The use of diurnal vigilance changes in the EEG to verify vigilance-enhancing effects of memantine in a clinical pharmacological study.

In elderly subjects there is a vigilance decrease from morning to noon which was used in a clinical pharmacological model as a state condition to verify vigilance-enhancing effects of an antidementia drug. In this model the effects of Memantine (20 mg, single-dose application) on the quantified EEG were investigated in 16 elderly (mean age: 65 +/- 5 years), healthy subjects (10 females, 6 males) in a randomised, twofold cross-over design vs. placebo under double-blind conditions. EEG was recorded before medication, and 2 and 4 h after medication under reaction time (RT) and resting (RS) conditions. EEG data were subjected to spectral analysis and the topographic distribution of the amplitude values was mapped. The results show that a time-dependent decrease (from morning to noon) in vigilance (indicated by an increase in average EEG amplitudes caused by increased synchronisation in the alpha and beta range and an increase in delta) occurred under placebo which was counteracted by Memantine. The diurnal variations of the EEG and their compensation by a pharmacological agent represent an effective model for investigating the vigilance-enhancing effects of antidementia drugs.

Aged↗
PubMed1985

Frequency-specific contributions to the auditory brain stem response derived by means of pure-tone masking.

The pure-tone masking technique has been employed to determine the contributions of neural activity from different cochlear regions to the click-evoked auditory brain stem response (compound ABR). ABR to broad-band clicks were recorded without and with simultaneous presentation of pure tones of frequencies ranging from 8 to 0.5 kHz. Derived ABRs for individual frequency bands were obtained by subtracting the masked responses from the unmasked ones. To determine the contributions to the compound ABR, masked and derived ABRs were compared with unmasked responses. The frequency specificity of the contributions was more distinct at lower rather than at higher stimulus intensities. Independent of stimulus intensity, the 8- to 2-kHz regions turned out to be the main sources of waves I-V in the compound ABR, whereas waves VI and VII seem to be predominantly generated by contributions from regions specific for 1 and 0.5 kHz. The main advantage of the pure-tone masking technique as compared with the tone pip stimulation is that contributions from the low-frequency regions become more clearly detectable. The validity of this technique has been proved by comparing the compound ABR with the sum of the derived ABRs. The comparison of ABRs derived by pure-tone masking with those derived by conventional high-pass noise masking did prove the validity of the technique as well.

Acoustic Stimulation↗
PubMed1982

Derived brain stem responses by means of pure-tone masking.

In order to demonstrate the possibility of deriving narrow-band responses, investigations using simultaneous pure-tone masking at frequencies of 1 and 0.5 kHz were carried out. Constant and reproducible derived responses were obtained at both masker frequencies within the following latency ranges: w6 (masker frequency 1 kHz) from 7.7 to 9.9 msec and w7 (masker frequency 0.5 kHz) from 9.2 to 11.2 msec at intensities of 70-20 dBSL. The agreement of our results with those obtained with the high-pass noise-masking technique permits us to ascribe our narrow-band responses (w6, w7) to the corresponding frequency regions around 1 and 0.5 kHz along the cochlear partition. This method is suitable for deriving frequency-specific responses without any sophistication.

Adult↗