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Biomedical subjects

H Nordby

Publications and source records attributed to H Nordby.

11 recordsLinked to original sources
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↗
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↗
PubMed1989

Orienting in schizophrenia: habituation to auditory stimuli of constant and varying intensity in patients high and low in skin conductance responsivity.

Groups of schizophrenics and normal controls were exposed to different series of tones of constant (80dB) and variable intensity (60, 80, and 100 dB). Measurements included bilateral skin conductance, finger pulse volume, and heart rate. Both groups were split on the common median in skin conductance response to constant intensity tones to form matched patient and control groups of low and high responsivity. The low and high responsive schizophrenic groups were more clearly separated than the two control groups in rate of spontaneous skin conductance fluctuations, skin conductance magnitudes, and skin conductance levels, primarily because of generalized hyperactivity in high responsive patients. This pattern was clearest for the most intense tone and left hand recordings. High responsive schizophrenics also showed larger response amplitudes, shorter rise and recovery times, and a smaller ratio of elicited to spontaneous responses, than high responsive controls. Finger pulse volume responses recorded from the left hand were smaller in the patient groups, whereas patients and controls did not differ in right hand recordings. High skin conductance responsive subjects showed more heart rate deceleration than low responsive subjects, and schizophrenics had more decelerative responses than controls.

Adult↗
PubMed1989

Components of type A behavior and task-induced cardiovascular activation.

The present study sought to determine whether there are subcomponents of the Type A behavior pattern that are more closely related to cardiovascular reactivity than others. The components studied were factor analytically derived subscales of the Jenkins Activity Survey denoting Irritation and Impatience, on the one hand, and Hard-Driving and Competitive, on the other. Heart rate, pulse transit time, forearm electromyography, and palmar skin conductance were measured while the subjects performed a continuous perceptual motor task, as well as during baselines before and after the task. The Irritation and Impatience dimension was consistently related to task-induced changes in heart rate, both in regression analyses and in extreme group analyses of variance. A significant relation was also observed for pulse transit time but not for electromyography. The Hard-Driving and Competitive dimension, on the other hand, was not related to any psychophysiological measures. These results were interpreted to mean that Irritable and Impatient subjects showed a cardiovascular reaction pattern indicative of active coping processes during task performance.

Adult↗
PubMed1987

The personality of the cardiac responder: interaction of seriousmindedness and type A behavior.

Forty healthy university students were recruited from a larger sample to form subgroups of seriousminded and playful Type A and Type B individuals according to their responses to the Telic Dominance Scale and Jenkins Activity Survey. The experiment made use of a factorial design and tested the hypothesis that cardiovascular reactivity during a continuous perceptual motor task is highest in individuals who are characterized by a combination of seriousmindedness and Type A behavior pattern. Relatively low levels of sympathetic reactivity were expected in playful Type B individuals. Heart rate (HR) and pulse transit time (PTT) scores from baseline and task performance periods supported the conclusions that: (1) Cardiovascular activation appeared during task performance; and that (2) seriousmindedness and Type A behavior exerted particularly significant additive effects upon HR, whereas Type A behavior showed a stronger association than did seriousmindedness with PTT scores. Analyses using pre-task score as covariate to task-scores, indicated stronger reactivity for HR in Type A than in Type B subjects.

Achievement↗
PubMed1987

Psychophysiologic response patterns in tension headache: effects of tricyclic antidepressants.

Tension headache (TH) and control subjects (n = 22, 11 in each group) were evaluated within a habituation experimental design, in which psychophysiologic responses to auditory stimulation were measured. Auditory stimuli were 20 80-dB, 1000-Hz tones, each lasting 2 sec and sounded at irregular intervals. Subjects were evaluated twice, with a 6-month interval. At the time of the first session TH subjects were being treated with tricyclic antidepressant, yielding a positive clinical effect. Medication was withdrawn 3 weeks before the second session. Phasic responses in heart rate and temporal artery pulse amplitudes and averaged EMG levels from the frontal muscles were measured. Significantly lower heart rate reactivity and significantly less pronounced left temporal artery pulse amplitude responses were found in non-medicated TH subjects than in controls. TH patients showed a pulse amplitude increase in response to stimulation, whereas control subjects showed a decrease. The pulse amplitude response pattern was normalized in medicated TH patients. EMG levels were similar in TH patients and controls when patients were receiving medication, whereas TH patients showed significantly higher frontal EMG levels than control when medication had been withdrawn.

Acoustic Stimulation↗
PubMed1987

Psychophysiologic response patterns in migraine before and after temperature biofeedback. Prediction of treatment outcome.

Psychophysiologic response patterns were studied in female migraine patients during headache-free periods (n = 16) and in controls (n = 8). Cardiovascular variables studied were heart rate (HR) and temporal artery pulse wave amplitudes (PWA). Phasic responses to 80-dB, 1000-Hz tones, each lasting 2 sec and sounded at irregular intervals, were studied within a habituation laboratory design. In addition, electromyographic (EMG) levels from the frontal muscles and hand temperature were measured. HR responses were less pronounced and PWA reduction more pronounced in migraine patients than in controls. There were no differences between migraine patients and controls in habituation pattern. Migraine patients showed lower hand temperature and higher EMG levels than controls. Migraine patients were treated with eight temperature biofeedback sessions and were evaluated clinically and psychophysiologically during and 2 months after treatment. Clinical follow-up evaluation was done 2 years after treatment. An average reduction in headache frequency of 66% was reported. A relationship between HR and PWA response pattern before treatment and treatment outcome was found. Migraine patient reporting most pronounced clinical improvement showed a "normalization" of the PWA response pattern after treatment.

Adult↗