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Biomedical subjects

F Jagla

Publications and source records attributed to F Jagla.

At least 19 recordsLinked to original sources
PubMed2006

Limbic irritability and chaotic neural response during conflicting stroop task in the patients with unipolar depression.

According to recent findings activation of anterior cingulate cortex (ACC) is related to detecting cognitive conflict. This conflict related activation elicits autonomic responses which can be assessed by psychophysiological measures such as heart rate variability calculated as beat to beat R-R intervals (RRI). Recent findings in neuroscience also suggest that cognitive conflict is related to specific nonlinear chaotic changes of the signal generated by neural systems. The present study used Stroop word-color test as an experimental approach to psychophysiological study of cognitive conflict in connection with RRI measurement, psychometric measurement of limbic irritability (LSCL-33), depression (BDI-II) and calculation of largest Lyapunov exponents in nonlinear data analysis of RRI time series. Significant correlation 0.61 between largest Lyapunov exponents and LSCL-33 found in this study indicate that a defect of neural inhibition during conflicting Stroop task is closely related to limbic irritability. Because limbic irritability is probably closely related to epileptiform abnormalities in the temporolimbic structures, this result might represent useful instrument for indication of anticonvulsant treatment in depressive patients who are resistant to antidepressant medication.

Adult↗
PubMed2006

Chaotic EEG patterns during recall of stressful memory related to panic attack.

Chaotic transitions likely emerge in a wide variety of cognitive phenomena and may be linked to specific changes during the development of mental disorders. They represent relatively short periods in the behavior of a system, which are extremely sensitive to very small changes. This increased sensitivity has been suggested to occur also during retrieval of stressful emotional experiences because of their fragmentary, temporally and spatially disorganized character. To test this hypothesis we recorded EEG during retrieval of fearful memories related to panic attack in 7 patients and retrieval of anxiety-related memories in 11 healthy controls. Nonlinear data analysis of EEG records showed a statistically significant increase in degree of chaotic dynamics after retrieval of stressful memories in majority of patients as well as in control subjects. This change correlated with subjective intensity of anxiety induced during the memory retrieval. The data suggest a role of nonlinear changes of neural dynamics in the processing of stressful anxiety-related memories, which may play an important role in the pathophysiology of panic disorder.

Adult↗
PubMed2001

Modulation of evoked potentials by interfering mental activity.

BACKGROUND: Non-specific influences (attention, mental set, mental imagery) take part in modulation of information processing in the human central nervous system at various levels of central hierarchy. OBJECTIVES: To broaden knowledge concerning the conjunction of motor control and cognition as well as to discuss some possible psychophysiological mechanisms. METHODS: Somatosensory evoked potentials, motor related cortical potentials and the saccadic eye movement related potentials were recorded over frontal and parietal cortices in the control condition and compared with those registered under the influence of a mental imagery task introduced as a modulatory factor. Special focus was devoted to their early components. MAIN RESULTS: Early components of the above potentials, which are assumed to represent the coding of physical characteristics of evoking stimuli, are changed under the influence of mental activity. Frontal evoked potentials are markedly modulated as compared to those recorded parietally. In general, the results support the view that the preparation for both, real movements and mentally simulated movements share probably some common mechanisms at the cortical level. CONCLUSIONS: Modulatory effects of mental activity upon the used evoked potentials point to the possible participation of the central gating mechanism, attention focussing and some other psychophysiological mechanisms related to internal representation of sequence of events. The results suggest that experimental conditions need to be exactly specified and examined subjects must be properly instructed. (Fig. 3, Ref. 12.)

Evoked Potentials↗
PubMed1996

Attention level oscillations during visual perception of moving stimuli.

Optokinetic nystagmus (OKN) pursuit phase velocity oscillations were studied in seven undergraduates during repeated 4 min presentation of optokinetic stimuli. The following variable parameters of the stimuli motion were used with each subject: horizontal direction, angular velocity (AV), and frequency-to-velocity ratio. AV of the OKN pursuit phases was found to decrease markedly within the first 30 sec of stimuli presentation with its successive increase and variously marked oscillations. Gradual decrease of the AV of OKN pursuit phases was observed at the end of the whole examination as compared to its beginning already within 4 min presentation of the moving stimuli. The results are discussed from the point of view of the arousal, and the activation components of visual attention.

Adult↗
PubMed1994

Differences in saccadic eye movement-related potentials under regular and irregular intervals of visual stimulation.

The saccadic eye movement-related potentials (SEMRPs) were recorded over various brain areas in a group of righthanders while they performed saccades to visual stimuli appearing either at regular or at irregular time intervals. The premotion positivity, motion execution component and lambda responses were of shorter latencies and lower amplitudes over the parietal areas as compared to the occipital ones. This finding did not depend on the regularity of intervals. With regular intervals, the positive wave starting before and peaking at the end of a saccade was found over the frontal eye fields. With irregular intervals, the premotion negativity was registered over the motor and frontal cortices. With saccades at regular intervals, the oculomotor components in the SEMRPs were less pronounced as compared to the irregular ones. These results are in accordance with the presumption that visual stimuli, appearing at irregular intervals, require higher attention and readiness to the oculomotor reaction, respectively, and also with the supposed role of the right hemisphere of righthanders in processing visual information.

Adult↗
PubMed1992

[The accuracy of saccadic eye movements is associated with their horizontal and vertical direction].

Electro-oculagraphic, photo-oculographic, and magnetoelectro-oculographic methods were used to study and to compare the accuracy of 10 degrees saccadic movements of the eyes in dependence on their direction to the right, to the left, upwards and downwards. Leftward saccades in right-handers and rightward saccades in left-handers proved to be more accurate compared to saccades in the opposite direction. This finding may be related to the functional asymmetry of the cerebral hemispheres. Downward saccades are inaccurate in comparison to upward saccades. Their inaccuracy is caused by overshooting the target. In the case of vertical saccades, the existence of different generators in the brain for triggering upward and downward saccades may play a role, along with a potential preprogramming of the change in the downward look into a sequence of two saccades. The obtained results emphasize the requirement of calibrating the electro-oculogram by saccades in that direction in which the analyzed eye movements are recorded.

Adult↗
PubMed1990

[Characteristics of evoked potentials related to saccadic eye movements in man].

The exactness of saccadic eye movements to the right and to the left and changes in evoked potentials related to these eye movements were analyzed in 50 university students with marked righthandedness and normal vision, aged from 18 to 24 years (18 males, 32 females). The saccades to the left were found to be more exact than those to the right, which overshot the target in a significantly higher number of instances. In subjects with exact refixations the premotion activity in evoked potentials is of shorter duration, the spike potential has a lower amplitude and the lambda response a shorter latency in saccades to the left. The given changes are more pronounced above the right occipital region. In subjects with a higher number of correction saccades the differences between the two sides disappear in saccade related evoked potentials. The obtained results support the presumed important role of the right hemisphere or the left half of the visual field in organizing eye movements and in the integration mechanisms of eyemotion-visual perception in righthanded subjects.

Adolescent↗
PubMed1978

Effect of the distance of optokinetic stimuli from the eyes on certain parameters of the optokinetic nystagmus.

The above effect was studied in 65 subjects with normal vision (mean age 20 years) in investigations in which the following factors were successively changed: distance of optokinetic stimuli from the eyes; this distance and angular velocity of stimuli; distance and frequency of stimuli or finally distance and accommodation level. The angular velocity of the pursuit nystagmus phase was found to be by far the highest and simultaneously the closest to the angular velocity of optokinetic stimuli when the latter are 1.5m from the eyes. With shorter distances, the velocity of the pursuit movements lags steadily behind that of stimulus velocity. This change is conditioned by changes in OKN amplitude since its frequency as a whole does not change. Even though the accommodation level significantly affects the velocity of the pursuit nystagmus phase, the dependence on the distance of optokinetic stimuli from the eyes persists even after atropinization. The interpretation of these findings must take into account sepcifically the demands on accommodation, convergence, and on visual attention which are increased with shorter distances.

Accommodation, Ocular↗