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Biomedical subjects

D Mitov

Publications and source records attributed to D Mitov.

4 recordsLinked to original sources
PubMed1991

Computer-controlled attenuator.

Various possibilities for applying electronic computer-controlled attenuators for the automation of physiological experiments are considered. A detailed description is given of the design of a 4-channel computer-controlled attenuator, in two of the channels of which the output signal can change by a linear step, in the other two channels--by a logarithmic step. This, together with the existence of additional programmable timers, allows to automate a wide range of studies in different spheres of physiology and psychophysics, including vision and hearing.

Amplifiers, Electronic↗
PubMed1991

Hemisphere asymmetry of the visually evoked potentials elicited by gratings of varying spatial frequency.

Visually evoked potentials (VEP) were recorded upon hemifield stimulation with sinusoidal gratings of varying spatial frequency (SF). Recording was bipolar from 0.1-0.2. The gratings were presented randomly in the left, in the right or in both visual hemifields. No systematic VEP asymmetry was observed at low SF. At SFs above 1.5-2 cpd, however, the early wave peaking at about 100 msec after grating onset was usually of greater amplitude when the grating was presented in the left visual field. In previous experiments of our, contrast sensitivity was almost the same in both hemifields. Thus, the VEP data suggest right-hemisphere specialization in processing high SFs and their comparison with the contrast sensitivity data suggests that this specialization occurs at a level higher than stimulus detection or is evident at suprathreshold contrast levels only.

Electroencephalography↗
PubMed1990

Hemisphere asymmetry in the detection of gratings of varying spatial frequency.

Visual field symmetry in contrast sensitivity was investigated under conditions of spatial uncertainty. The stimuli were sinusoidal gratings of varying spatial frequency (SF). They were presented randomly in the left, right or in both visual hemifields. The percent detected gratings were slightly higher than the gratings in the left visual field except for gratings of low SF (0.24-0.48 c/deg). The results suggest the existence of a slight left-field (right-hemisphere) superiority in detecting stimuli of medium and high SF. The asymmetry is too slight to allow any significant difference in the SF-content of the neural representation of the left and right halves of the images; neither might it provide an explanation of some recent data on hemispheric specialization, in particular visual tasks.

Brain↗