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Biomedical subjects

K Hugdahl

Publications and source records attributed to K Hugdahl.

At least 19 recordsLinked to original sources
PubMed1992

Pathological left-handedness revisited: dichotic listening in children with left vs right congenital hemiplegia.

Thirty-one children with right (n = 18) and left (n = 13) congenital hemiplegia were compared for incidence of hand- and foot-preference, eye-dominance, and familial sinistrality. In addition, they were tested with dichotic listening for correct reports of consonant-vowel syllables. The two groups of children were closely matched on IQ and sensory functioning. Children with mental retardation, or epileptic seizures were not included. The results showed that 89% of the left hemisphere impaired (LHI) children were left-handed, all of them preferred the left foot, and 72% were left eye-dominant. In the right hemisphere impaired (RHI) group, everyone (100%) preferred the right hand and foot, and 62% were right eye dominant. The dichotic listening results showed a significant right ear advantage (REA) in the RHI-group, and a significant left ear advantage (LEA) in the LHI-group. The results are discussed in the framework of pathological handedness and shifts in hemisphere control of language in children with early brain injury. It is argued that the homogeneous samples, except for the site of lesion, provides an interesting possibility to compare cognitive effects of left and right hemisphere impairment in children.

Adolescent↗
PubMed1992

Dichotic listening performance in subtypes of developmental dyslexia and a left temporal lobe brain tumor contrast group.

This study examined dichotic listening performance in three subtypes of developmental dyslexia and in children with left temporal lobe brain tumors (clinical contrast group). Each child was administered a free-recall CV syllable dichotic paradigm (30 pairs). Analysis of variance and Tukey-HSD pairwise follow-up comparison indicated that the dichotic listening performance of the left temporal lobe brain tumor contrast group (strong LEA/right ear suppression) was significantly different from those of the visual-spatial/dyseidetic (strong REA/left ear depression) and mixed (moderate REA/bilateral ear suppression) dyslexic subtypes. The language disorder/dysphonetic dyslexic subtype demonstrated a REA with right ear depression. Closer inspection of the individual performances of the language disorder/dysphonetic dyslexic subtype revealed a bimodal distribution with 12 subjects demonstrating a strong LEA/right ear suppression and 8 subjects exhibiting a strong REA/left ear depression. These results lend support for the contention that the dyslexic population is heterogeneous in nature with each subgroup exhibiting (1) a distinct neuropsychological test profile and reading pattern and (2) a pattern of performance on the dichotic listening task which is consistent with what would be expected based upon the pattern of dysfunction exhibited on neuropsychological evaluation.

Adolescent↗
PubMed1992

Manipulations of subjects' level of arousal in dichotic listening.

The effects of manipulation of the subject's level of arousal on the right ear advantage (REA) in dichotic listening to CV-syllables were investigated. There were three different arousal manipulations under high and low incentive levels. Negative manipulations involved threat of electric shock (high incentive) or noise (low incentive) for incorrect answers. Positive manipulations involved the possibility to earn a substantial (high incentive) or small (low incentive) sum of money for correct answers. A third, neutral, condition involved no specific instructions about consequences for correct or incorrect answers. Thirty-six females participated in the study. Heart rate was recorded as an independent measure of change in level of arousal as a function of the experimental instructions. The results showed that the high negative condition abolished the REA effect, with a non-significant difference between ears. This was caused by both an increase in correct left ear reports and a decrease in correct right ear reports. The other arousal conditions had no effect on the REA. The results are discussed in terms of right hemisphere dominance for aversive emotional processing in dichotic listening.

Acoustic Stimulation↗
PubMed1992

Hemispheric asymmetry effects in children studied by dichotic listening and visual half-field testing.

Dichotic listening (DL) and visual half-field (VHF) testing were used to study hemisphere asymmetry in a developmental perspective. Five-, 8-, and 11-year-old children were presented lists of fused words using a DL technique in Experiment 1, and 8- and 11-year-old children were presented pictures of common objects using a VHF technique in Experiment 2. In both experiments, measures of identification, free recall, and recognition of the words/pictures were employed. The results revealed effects of ear input (right-ear advantage) and half-field presentation (right visual half-field advantage) for all age groups, although the magnitude of this lateralization effect differed between the three memory measures. The results are discussed in relation to developmental aspects of language laterality, and in relation to the clinical utility of non-invasive lateralization techniques.

Child↗
PubMed1992

Hemisphere differences in event-related potentials (ERPS) to monaural presentations of simple speech sounds.

The aim of the present study was to compare ERPs over the left and right hemispheres to monaural consonant-vowel (CV) syllables. It was predicted that, if the contralateral auditory representation is stronger than the ipsilateral one, then ERPs over the left hemisphere should be larger for right-ear stimulus input. Furthermore, if the hemispheres differ in efficiency in processing of speech sounds, then ERPs recorded at any given site should vary as a function of the ear to which the sound is presented. Twelve right-handed subjects participated. The CV-syllables used were /Ba/ and /Pa/ with 15 presentations of each syllable to each ear in a randomized order. EEG was recorded from F3, Fz, and F4 with linked ears as reference. The results showed no significant asymmetry in the ERP-leads. N1- and N2-amplitudes were, however, larger at Fz than at F3 and F4, and N1-latency was shorter for right-ear presentations, which also interacted with the /Pa/-syllable presentations. P3-latency was longer to the /Pa/-syllable compared to the /Ba/-syllable, while N4-latency was longer to the /Ba/-syllable. N4-amplitude was more negative for the /Pa/-syllable presented to the left ear. The results are discussed in terms of phonemic differences between the unvoiced /Pa/ and voiced /Ba/, and early versus late stages of processing. The results are also seen in relation to ear differences in dichotic listening.

Adult↗
PubMed1992

Dichotic listening studies of hemispheric asymmetry in brain damaged patients.

In the present paper we review the empirical evidence for structural versus attentional explanations of the right ear advantage (REA) phenomenon in dichotic listening (DL). The ear advantage in DL is a behavioral "marker" of language function in the cerebral hemispheres. Dichotic listening data from four brain-lesioned patients are presented. The patients had a tumor or cyst in the left Sylvian region (2 cases); hemorrhage in the left frontotemporal region (1 case); and severe destruction of the left hemisphere (1 case). The results from all four patients showed marked reductions in correct recall of the right ear items, while left ear recall was left unaffected. In two of the cases, the DL data showed an immediate reinstatement of the REA after neurosurgery. It is concluded that the results favor a structural/anatomical explanation of the ear advantage phenomenon in DL, rather than an attentional bias explanation.

Adult↗
PubMed1991

Auditory neglect after right frontal lobe and right pulvinar thalamic lesions.

Auditory unilateral neglect or extinction to simultaneous stimulation is reported in a right-handed male with a lesion in the right frontal lobe and in the right thalamic pulvinar area. The patient was submitted to stereotactic thalamotomy for a post-traumatic intentional ataxia in the left extremities. He was subjected to repeated tests with dichotic listening to consonant-vowel syllables under three different attentional instructions. He was also tested monaurally with the same stimulus materials as used in the dichotic test. The results showed almost complete extinction of the left ear input during dichotic presentations, despite normal hearing when tested with audiometer screening. The left ear extinction effect was independent of instructions to attend to the left or right ear input. However, during monaural presentation, correct left ear reports increased to about 85%. The results are interpreted as showing an auditory attentional neglect caused by the right frontal and pulvinar lesions.

Adult↗
PubMed1991

Hemisphere differences in conditional learning: an ERP-study.

The present ERP-experiment investigated brain asymmetry in encoding and representation of the formation of conditional associations in a Pavlovian framework. Two consonant-vowel syllables were used as conditional stimuli, one of them paired with an unconditional noise during the acquisition phase (CS+), the other never paired with noise (CS-). During a subsequent test phase, both CS cues were presented dichotically i.e. at the same time. Half of the subjects had the CS+ probe presented to the right ear (contralateral to the left hemisphere). The other half of the subjects had the CS+ presented to the left ear (contralateral to the right hemisphere). ERPs from F3, Fz and F4 leads were recorded. The paradigm used was an adaptation of the standard dichotic listening technique for the study of learned associations. The results showed that conditional associative learning occurred during the acquisition phase in both "groups". The P235 latency was furthermore delayed over the left hemisphere to the CS+ probe. During the dichotic test phase, there was a clear laterality or asymmetry effect between the groups for both the N125 and N450 components, possibly supporting an interpretation of asymmetry in encoding and cortical representation of a conditional association, although alternative interpretations remain open.

Adult↗
PubMed1991

Anticipatory nausea and vomiting in cancer patients.

The present study reports on a mediating mechanism for anticipatory nausea and vomiting (ANV) in cancer chemotherapy. ANV is usually explained as a classically conditioned response. However, conditioning models have failed to explain individual variation in ANV susceptibility. On the basis of the positive correlation between degree of autonomic reactivity (AR) and conditionability, it is proposed that individual AR is predictive of ANV development. Of the 31 patients who participated in the study, 74% experienced postinfusion nausea and vomiting (PNV). Of the 23 patients who experienced PNV, 52% developed ANV. AR was recorded in a habituation paradigm before chemotherapy treatment was initiated. The patients in the ANV group showed significantly increased sympathetic reactivity as compared with the no-ANV group, implying that AR is a mediator of ANV development.

Adolescent↗
PubMed1991

Hemispheric asymmetry in conditioning to facial emotional expressions.

In the present experiment, we report a right hemisphere advantage for autonomic conditioning to facial emotional expressions. Specifically, angry, but not happy, facial expressions showed significantly more resistance to extinction when presented initially to the right as compared to the left hemisphere. Slides of happy and angry faces were used as conditioned stimuli (CS+ and CS-) with shock as the unconditioned stimulus (UCS). Half of the subjects (n = 15) had the angry face as CS+ (and the happy face as CS-), the other half had the happy face as CS+ (and the angry face as CS-). During acquisition, the CSs were presented foveally. During extinction, using the Visual Half-Field (VHF) technique, half of the CS+ and CS- trials were randomly presented in the right visual half-field (initially to the left hemisphere), and half of the trials were presented in the left half-field (initially to the right hemisphere). Stimuli were presented for 210 ms during acquisition, and for 30 ms during extinction. Bilateral skin conductance responses (SCRs) were recorded. The results showed effects of acquisition only for the angry CS+ group. During extinction, there was a significant Conditioning X Half-field interaction which was due to greater SCRs to the CS+ angry face when it was presented in the left half-field. It is concluded that the present results reveal hemisphere asymmetry effects in facial emotional conditioning.

Adult↗
PubMed1991

Dichotic listening during forced-attention in a patient with left hemispherectomy.

A young left-handed girl with an extensive posttraumatic lesion in the left hemisphere was tested with dichotic listening (DL) under three different attentional instructions. The major aim of the study was to evaluate a structural vs attentional explanation for dichotic listening. As both her expressive and receptive language functions were intact after the lesion, it was assumed that the right hemisphere was the language-dominant one. In the free-report condition, she was free to divert attention to and to report from both ear inputs. In the forced-right condition, she was instructed to attend to and report only from the right ear input. In the forced-left condition, she was instructed to attend to and to report only from the left-ear input. Her performance was compared with data from a previously collected sample of normal left-handed females. Analysis showed that the patient, in contrast to the normal sample, revealed a complete right-ear extinction phenomenon, irrespective of attentional instruction. Furthermore, she showed superior correct reports from the left ear, compared with those of the normal sample, also irrespective of attentional instruction. It is concluded that these results support a structural, rather than attentional explanation for the right-ear advantage (REA) typically observed in dichotic listening. The utility of validating the dichotic listening technique on patients with brain lesions is discussed.

Adolescent↗
PubMed1991

Asymmetries in classically conditioned head movements and cingulate cortex slow potentials in cats.

Presuming that conditioned head movements in the cat indicate a preference for a specific direction, asymmetries were also expected to be found in bilaterally recorded cingulate cortex slow potentials to a symmetrical tone stimulus during discriminative conditioning. Conditioned stimuli (CS, 1000 and 2500 Hz tones) were delivered through two miniature loudspeakers fitted to the head in front of both ears. The unconditioned stimulus (US) was an electrical stimulation of either the left or right lateral hypothalamus yielding, in addition to its rewarding effects, an unconditioned head turning response (UR) either to the left, right, forwards or upwards. Discrimination learning appeared as more extended and more rapid headturns and greater negativity in the cingulate cortex to the CS+ than to the CS-. The preferred conditioned behavioral response (CR) was a headturn to the left in 11 of 12 cats accompanying increased negativity in evoked slow potentials in the right cingulate cortex during the 128-324 ms period after the CS onset. No differences in the movements and in the cingulate potentials were found between the left versus right US stimulations. The results showed that regardless of the direction of the original unconditioned head movement, the direction of the CR was at the end of the training period to the left in 11 out of the 12 cats. Larger evoked slow potentials observed in the right cingulate cortex which were not present in the baseline measurements suggest a population bias between the hemispheres.

Animals↗
PubMed1990

Immune and autoimmune diseases in dyslexic children.

One hundred and five dyslexic and 105 control children were compared for frequency of immune diseases, autoimmune diseases, and non-right-handedness in the light of the Geschwind-Behan (1982) "testosterone hypothesis". The results showed significantly more immune- and autoimmune-diseases int he dyslexic group. There were no differences between the groups in the frequency of non-right-handedness. There were no interactions with gender, although there were more non-right-handed boys than girls in the total sample. Mothers of children who were dyslexic experienced significantly more negative life-events during pregnancy, they also experienced the pregnancy as more difficult, and they had more spontaneous abortions. In conclusion, the results support some aspects of the "testosterone hypothesis", but they also point to a more complex pattern of interaction between the factors that still remain unanswered.

Adolescent↗
PubMed1990

The role of the left and right thalamus in language asymmetry: dichotic listening in Parkinson patients undergoing stereotactic thalamotomy.

Fourteen patients with Parkinson's disease (rigidity and unilateral tremor as main symptoms) were treated with stereotactic thalamotomy. The operation was performed in either the left or right ventrolateral thalamus, depending on which hand (or foot) was most affected with tremor. Nine patients were operated on the left side and four on the right side. All patients were tested for asymmetry of language functioning with dichotic presentations of consonant-vowel (CV) syllables. The patients had to indicate which of the two syllables he/she heard on each trial. Dichotic listening was performed before and after the operation, as well as during electrical stimulation of the VL nucleus just before the lesion was carried out. The results revealed essentially three things: an overall reduced right ear advantage (REA) in the patient group compared to what is known from studies of healthy individuals; an increase in REA during left-sided stimulations; and a marked reduction in REA after left-sided lesions. It is concluded that the present data support the notion put forward by Ojemann (e.g., 1975) of a lateralized activating gating mechanism in the left VL nucleus that gates access for language information to the appropriate cortical areas. The gating mechanism seems to be activated by stimulation, and deactivated after lesions. Dichotic listening may thus be a heuristic instrument in assessment of language functions in Parkinson patients.

Adult↗
PubMed1990

The effects of head and eye turns on the right ear advantage in dichotic listening.

The aim of the present experiment was to investigate the effects of head and eye turns on the ear advantage in dichotic listening (DL) to CV-syllables. Since head and eye turns also mean focusing attention to either the left or right side in space, a second aim was to evaluate recent arguments that ear advantages seen in DL are caused by the perceived position in space of the sound source. Forty right-handed females had 36 trials of CV-syllables under four different instructions. One group (n = 20) was instructed to turn their head (but not their eyes) to the right, the left, or straight ahead during stimulus presentations. The fourth condition was a standard (no instruction) condition. A second group (n = 20) had the same instructions but were told to turn their eyes instead of their heads. Conditions were pseudo-counterbalanced across subjects. Consistent with other studies, results showed a right ear advantage (REA) in both groups during all conditions. However, the REA was largest for the standard condition. Also, more subjects showed a REA during the standard condition, and especially compared to the turn-right condition. It is concluded that dichotic performance is not caused by selective attention to either side in space, and that lateral turns of the head and the eyes contralateral to the left hemisphere have an inhibitory (if anything) effect on the REA.

Adult↗
PubMed1990

Effects of habituation and classical conditioning on reflex modification.

Reflex modification is the inhibition or facilitation of a reflex by a stimulus (S1) occurring prior to a reflex-eliciting stimulus (S2). Two experiments were conducted that investigated the effects of habituation of the orienting response (OR) and classical conditioning on reflex modification of skin conductance responses (SCRs). During the first phase of Expt. 1 two groups (Group S1 and the Control group) received pre-presentations of S1 (200 Hz). Another group (Group S3) received pre-presentations of a different tone (S3, 3000 Hz). During the second phase, Groups S1 and S3 received pairings of S1 with S2 (white noise), whereas the Control group received pairings of S2 with S1. The predictions were: if the OR to S1 produces reflex modification of the response to S2, then Group S1 and the Control group will display larger SCRs on the first trial of the second phase of the experiment compared to Group S3, in which the OR to S1 will produce reflex modification. However, if conditioned diminution of the unconditioned response (UR) elicited by S1 produces reflex modification of the response to S2, then there should be no initial differences between the groups in the second phase of the experiment. The results showed that SCRs in Group S1 were significantly larger in the second phase compared to Group S3. This result favors an OR explanation of reflex modification. In Expt. 2, the effect of conditioned diminution of the UR on reflex modification was further investigated.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗
PubMed1990

Reflex modification in the electrodermal system: conceptual and methodological issues.

Reflex modification (RM) is the inhibition or facilitation of a reflex response by a stimulus (S1) occurring prior to a reflex-eliciting stimulus (S2). The present experiment investigated two issues: (1) whether RM may be confounded by orienting generated by changes in the experimental procedure, or habituation generated by repeated stimulus presentations; (2) whether the strength of RM is influenced by repeated pairing of S1 and S2, that is, classical conditioning. Two groups of subjects were given two series of stimulus presentations. Group A received first 10 S2-alone presentations, before 10 S1-S2 presentations. Group B received the stimuli in reversed order, that is, first 10 S1-S2 presentations, and then 10 S2-alone presentations. This design permits a comparison of unconfounded with confounded RM, as well as assessment of influences of learning. The results showed RM to be influenced by orienting caused by changes in the experimental procedure. The strength of RM tended to be gradually reduced as a function of the number of S1-S2 pairing, indicating that the orienting response to S1 habituated across trials. It is concluded that RM may be useful in the objective investigation of more complex cognitive processes.

Adult↗