PubMed Health⌕ Search

Biomedical subjects

E Szelag

Publications and source records attributed to E Szelag.

At least 19 recordsLinked to original sources
PubMed2006

Auditory perception of temporal order in humans: the effect of age, gender, listener practice and stimulus presentation mode.

The temporal order (TO) of two auditory stimuli can be reported correctly when they are separated by a gap of approximate 30 ms. Since no clear evidence on individual differences in human sequencing abilities exists, we tested the effect of subjects' age and gender, as well as physical properties of presented stimuli and listener practice on the perception of TO. In two experiments, young and elderly listeners reported the TO of two clicks or tones. The TO threshold (i.e. the minimum temporal gap required to report the stimulus order at 75% correctness) was lower in young than elderly listeners, in men than women and for tones than clicks. Age-related deterioration depended on the physical properties of presented stimuli, remaining resistant to both gender and practice.

Acoustic Stimulation↗
PubMed2004

Deficits of non-verbal auditory perception in postlingually deaf humans using cochlear implants.

Temporal integration in the time domain of a few seconds was investigated with a subjective accentuation paradigm in 11 monochannel cochlear implant users, who showed auditory comprehension deficits. While listening to metronome beats generated at various frequencies, patients were asked to accentuate mentally every n-th beat and create an individual rhythmic pattern. The extent of temporal integration was defined as the duration of perceptual units consisting of subjectively grouped beats at particular metronome frequencies. The results indicate that there is reduced capacity for temporal integration in implant recipients, particularly for lower metronome frequencies, in comparison to normally hearing. These observations point to the coincidence of specific temporal processing disorders and deficits in auditory comprehension after cochlear implantation.

Acoustic Stimulation↗
PubMed2001

Hemispheric specialisation for self-paced motor sequences.

Temporal aspects of motor control were investigated in patients with infarction to the brain with two finger-tapping tests. In the self-paced tapping task patients with cortical left-hemispheric lesions were slowed down and patients with left-hemispheric subcortical injuries were consistently faster as compared with control subjects and patients with right hemispheric cortical lesions. The results point to the dominant control of the left-hemisphere in voluntarily timed action and to a special time range of 250-300 ms involved in motor behaviour.

Adult↗
PubMed1999

Auditory temporal-order judgement is impaired in patients with cortical lesions in posterior regions of the left hemisphere.

Auditory temporal-order judgement was investigated in patients suffering from unilateral focal brain lesions, localized in anterior or posterior regions of the left hemisphere (LH) (resulting in non-fluent or fluent aphasia, respectively), or in predominantly subcortical regions of this hemisphere (without aphasic syndromes) and in anterior or posterior regions of the right hemisphere. The temporal order threshold was measured as the minimum time interval between two clicks presented consecutively and binaurally via headphones (one to each ear) that was necessary for a subject to indicate the temporal order of the two stimuli. Only the patient group with fluent aphasia showed a significantly increased mean temporal-order threshold as compared to the controls. Our results indicate that fine temporal resolution for auditory stimuli is predominantly associated with posterior regions of the LH.

Aphasia↗
PubMed1998

Temporal integration in a subjective accentuation task as a function of child cognitive development.

We have previously shown that temporal integration in the domain of a few seconds may be studied using a subjective accentuation paradigm. Here we report developmental effects on the limits of this temporal integration in 9-10-year-olds in comparison with 13-14-year-olds. The task was to listen to a string of identical metronome beats and mentally bind the presented beats by subjectively accentuating every second, third or nth beat. The integration interval length was defined as the number of stimuli mentally connected multiplied by the temporal interval between two successive beats. For the lowest stimulus frequency integration intervals were approximately 3 s for the older and 2.2 s for the younger children. For higher frequencies integration intervals got systematically shorter, but being always longer for the older age group. It is suggested that the prefrontal region is responsible for this developmental effect. The expansion of temporal integration correlates with cognitive development in the investigated phase of ontogenesis.

Adolescent↗
PubMed1997

Temporal processing disorders in patients with Broca's aphasia.

We report an association between a language deficit following brain lesion and a new strategy in temporal integration. Patients with different brain lesions mentally grouped sequences of identical acoustic stimuli generated at various frequencies. They were asked while listening to the stimuli to accentuate every second, third or other stimulus to create an individual rhythmic pattern. After each sequence patients reported how many stimuli they had united into a perceptual unit. The integration interval was defined as the number of reported stimuli multiplied by the temporal interval between two successive stimuli. Results indicate different integration strategies depending on the lesion site, i.e. Broca's aphasics behaving differently than all other patient groups. At lower frequencies they showed longer, at higher frequencies they displayed shorter integration. From this observation we conclude that the Broca's patients acquired a new strategy because of the lesion; they relied on mental counting and less on automatic temporal integration, which is usually the case.

Adult↗
PubMed1997

Hemispheric asymmetries in stutterers: disorder severity and neuroticism?

This study tests the hypothesis that there is atypical brain asymmetry in stuttering children. In particular the association of both severity of stuttering and neuroticism with cerebral laterality in perception of visuospatial material is tested. Subjects were asked to recognize faces presented laterally in the left or right visual field and point to the exposed stimuli on response cards containing three different faces. Recognition errors committed in the left and right field presentations were analyzed. In fluent speakers and in moderately neurotic stutterers, fewer errors were found for the right hemisphere independently of their neuroticism score; in contrast, stutterers with a high neuroticism score showed fewer errors for the left hemisphere. The latter was true regardless of severity of stuttering. The study suggests a close link between atypical hemispheric dominance in the face recognition test and the emotional state in stutterers as defined by their neuroticism score. This characteristic may be related to the negative emotional reactions demonstrated relatively often by stuttering individuals. In highly neurotic stutterers, the negative affective states might be associated with disturbances of right hemisphere functioning and related to an atypical asymmetry pattern in the processing of right-hemispheric stimuli. These results illustrate the importance of controlling for subject-related factors while conducting and interpreting investigations on stutterers.

Adolescent↗
PubMed1996

The effect of auditory experience on hemispheric asymmetry in a post-lingually deaf child: a case study.

We have previously shown that cerebral asymmetry in congenitally deaf children differs from that observed in normal hearing children. The effect of early auditory experiences on this process was investigated in a 14 year-old boy who had completely lost his hearing at the age of 5 due to meningitis. His recognition of laterally projected words and faces was compared with that of 18 congenitally deaf and 18 normal hearing children. In the word recognition test, a right hemisphere advantage was found in the patient and in congenitally deaf subjects and a left hemisphere advantage in normal hearing subjects. In the face recognition test, the left hemisphere was more proficient in the patient and the right hemisphere in normal hearing subjects. There was no hemispheric difference in the congenitally deaf. While hemispheric asymmetry has an ontogenetic base, these findings suggest that the degree and nature of such asymmetries can be influenced by environmental factors during development.

Adolescent↗
PubMed1996

Temporal constraints in processing of nonverbal rhythmic patterns.

This study investigates the effect of a mental content of presented stimuli, normal aging and individual differences in cognitive abilities on temporal limits of an integration mechanism. Younger and older subject grouped together the beats generated by a metronome. Subjects were asked to listen to the beats of a metronome and to accentuate mentally every second, third, fourth...etc. beat, to create a subjective rhythm. This rhythm exists, in fact, only in subjects' mind and not objectively. Subjects reported verbally how many clicks they were able to integrate into a perceptual unit. On this basis, the time interval during which subjects were able to integrate temporally separated stimuli was calculated (number of beats reported as being integrated x time distance between beats) for different metronome frequencies. The results show, firstly, that the length of integration periods significantly depends on the frequency of presented metronome beats. When the frequency of metronome beats is high, the time interval during which the subjects integrate beats into a single perceptual unit is shorter. Secondly, older adults integrate information during a longer time interval than younger ones. Thirdly, the length of an integration period is related to a subjects' level of cognitive ability. These results suggest that the length of an integration period is not a constant, stable feature, but varies across the life span depending on the mental content of the information presented and individual factors.

Acoustic Stimulation↗
PubMed1994

Individual differences in the functional asymmetry of the human brain.

Standard models of hemispheric asymmetry assume the dychotomous division of functional competence between the two hemispheres. Individual subjects, however, often do not fit such prototypical patterns and show great variation with respect to the functional differentiation of their hemispheres. The present paper reviews the results of some of our investigations on the effect of various subject related factors on brain lateralization. Among these individual experience, gender and handedness seem to be of most significance.

Dominance, Cerebral↗
PubMed1993

Brain lateralization and severity of stuttering in children.

Cerebral lateralization in visual perception was investigated in 9 severe stuttering, 11 mild stuttering and 48 fluent speakers. The subjects were asked to identify words presented in the left or right visual field for 20 ms. Children responded by pointing to the exposed test word on a response card which contained four different words. Errors committed in the left and right visual fields were analyzed. The data showed a left hemisphere superiority in the processing of words in both the mild stutterers and the fluent speakers, but a right hemisphere advantage in the severe stutterers. The results suggest a close relationship between the severity of stuttering and functional brain organization.

Child↗
PubMed1992

The effect of congenital deafness on cerebral asymmetry in the perception of emotional and non-emotional faces.

Functional hemispheric specialization in recognizing faces expressing emotions was investigated in 18 normal hearing and 18 congenitally deaf children aged 13-14 years. Three kinds of faces were presented: happy, to express positive emotions, sad, to express negative emotions, and neutral. The subjects' task was to recognize the test face exposed for 20 msec in the left or right visual field. The subjects answered by pointing at the exposed stimulus on the response card that contained three different faces. The errors committed in expositions of faces in the left and right visual field were analyzed. In the control group the right hemisphere dominated in case of sad and neutral faces. There were no significant differences in recognition of happy faces. The differentiated hemispheric organization pattern in normal hearing persons supports the hypothesis of different processing of positive and negative emotions expressed by faces. The observed hemispheric asymmetry was a result of two factors: (1) processing of faces as complex patterns requiring visuo-spatial analysis, and (2) processing of emotions contained in them. Functional hemispheric asymmetry was not observed in the group of deaf children for any kind of emotion expressed in the presented faces. The results suggest that lack of auditory experience influences the organization of functional hemispheric specialization. It can be supposed that in deaf children, the analysis of information contained in emotional faces takes place in both hemispheres.

Adolescent↗
PubMed1992

Hemispheric differences in the perception of words and faces in deaf and hearing children.

The purpose of this study was to investigate hemispheric functional asymmetry in 18 normal hearing children and 18 congenitally deaf children aged 13-14 years. The task was identification of a visual stimulus (3-letter word or photograph of a face) presented in either the left or right visual field. The children responded by pointing to the target stimulus on a response card which contained four different words or three different faces. The percentage of errors for presentations to the two visual fields were analysed to determine hemispheric dominance. The pattern of hemispheric differences for the hearing children was consistent with that from previous investigations. The results for the deaf children differed from those of the normals. In word perception we observed a right hemisphere advantage and in the face recognition a lack of hemispheric differences. These results point to a lack of auditory experiences which is affecting the functional organization of the two hemispheres. It is suggested that the necessity to make use of visuo-spatial information in the process of communication causes right hemisphere dominance in verbal tasks. This may influence the perception of other visuo-spatial stimuli which may yield a lack of hemispheric asymmetry in face recognition.

Adolescent↗
PubMed1991

Recognition of faces expressing emotions in patients with unilateral brain damage.

The experiment concerned the functional specialization of brain hemispheres in recognizing faces expressing emotions in patients with focal brain damage of the left and right hemispheres and in persons without damage of the central nervous system. Three types of faces were presented: happy i.e. expressing positive emotions, sad i.e. expressing negative emotions and neutral. The task of the subject was to recognize the test face exposed for 20 ms in the left or right visual field and point to the correct face on the response-card which contained three different faces. The errors made in recognizing of faces exposed in the right visual field (addressing the left hemisphere) and in the left one (addressing the right hemisphere) were analyzed. The patients with left hemisphere damage showed a similar pattern of hemispheric differences to that observed in the controls. In case of neutral and sad faces fewer errors were made in the left visual field exposures, in case of happy faces no significant differences between the two fields were stated. The results in patients with right hemispheric damage were different from both the other groups. In processing all the three types of faces, fewer errors were made in the left visual field presentations independently of the localization of the damage within the right hemisphere. Similar recognition level of different types of faces was also found in patients with left or right hemisphere damage as well as in controls. The above results suggest the crucial role of the right hemisphere in processing both positive and negative emotions expressed in faces.

Adult↗
PubMed1986

Measurement of lateral differences for faces in a two-response paradigm.

The experiments illustrated the effect of procedural factors in reaction time measurements on lateral differences between visual fields for faces in two-reaction paradigm. The subjects were instructed to decide whether two faces presented successively in the left or right visual field were the same or different. The two experiments differed in the situation of response buttons in horizontal line left-right (Experiment I), or in vertical line further-closer to the subject (Experiment II). Both experiments showed advantage of the right hemisphere, though in the Experiment I the differences between the left and right visual fields depended on the configuration of buttons applied. The results point to fact, that even slight procedural changes may effect the results.

Dominance, Cerebral↗
PubMed1985

Hemispheric asymmetry in processing of verbal material by left-handers.

In our experiments we studied the laterality differences in a word-matching task for 16 strongly right-handed and 10 strongly left-handed female subjects. The results showed the right visual-field advantage for left-handers. Right-handed subjects performed the task faster than left-handed subjects. For both tested groups mean reaction times for the "same" responses were shorter than for "different" responses.

Adult↗