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Biomedical subjects

K Hugdahl

Publications and source records attributed to K Hugdahl.

At least 55 records · Page 3Linked to original sources
PubMed1996

Event-related potentials (ERPs) to deviant auditory stimuli during sleep and waking.

Using an oddball paradigm with two tones differing in pitch and probability, event-related potentials (ERPs) were compared during wake and two sleep stages. REM and NREM sleep stages were identified in nine subjects using the Nightcap which continuously records eye and body movements. The N1 occurred later and the P2 was larger during sleep than when awake. The N1 to the infrequent tones was larger during both sleep stages. A late negative wave was significantly larger to infrequent tones during REM sleep. It is concluded that representations of auditory stimuli occur in sleep, and most prominently during the REM phase. The prolonged latency of the ERP components indicates that processing of external sensory stimuli may be delayed.

Acoustic Stimulation↗
PubMed1996

Cognitive influences on human autonomic nervous system function.

Recent studies of human autonomic nervous system function have challenged the traditional view that the parasympathetic and sympathetic branches have opposite effects. In addition, studies of autonomic activity that accompanies attention, orienting and learning have demonstrated that the autonomic nervous system is not simply a 'non-cognitive' and automatic part of brain function. The autonomic and central nervous systems are intimately related, and new research is beginning to link brain function with autonomic function in a dynamic way.

Attention↗
PubMed1996

Left-handedness and age: comparing writing/ drawing and other manual activities.

The percentage of individuals who use the left hand for writing/drawing, brushing teeth, and throwing a ball was compared in 3229 subjects ranging in age from 8 to 96 years. The "elimination" versus "modification" hypotheses were tested as explanations of prior observations that there are fewer left-handers among the elderly. These hypotheses predict different numbers of left-handed elderly individuals when measured by activities not influenced by social pressure. The results suggest that there are age-related patterns among different measures of left-handedness. However, a significant decline in left-handedness among the elderly was also found when measured by less culturally determined activities.

Journal Article↗
PubMed1996

Cognitive function in patients with Parkinson's disease undergoing stereotaxic thalamotomy.

OBJECTIVE: To determine whether thalamotomy leads to cognitive disturbances in patients with Parkinson's disease. METHODS: A total of 53 patients with Parkinson's disease undergoing stereotaxic ventrolateral thalamotomy for tremor and rigidity were tested for cognitive functions before and after surgery. The cognitive functions investigated involved visuospatial perception and memory. verbal memory, attention shift, and executive functions including set maintenance and shift. A neuropsychological test battery was used that contained the Wisconsin card sorting test, Street completion test, Stroop test, a dichotic memory listening test, and a facial recognition test. RESULTS: Clinically, a good or moderately good effect on parkinsonian symptoms was obtained in 50 patients. The neuropsychological investigations showed that the patients were impaired compared with healthy age matched control subjects on most tests, showing slight improvement postoperatively on verbal memory and visuospatial perception. No major differences were found between tests before and after operation, and there were no significant differences between patients undergoing surgery in the right or in the left thalamus. CONCLUSION: The study indicates that ventrolateral thalamotomy does not reduce the cognitive capacity in this group of patients.

Adult↗
PubMed1996

Peripheral cuing of covert spatial attention before and after emotional conditioning of the cue.

Spatial cuing of attentional shifts were investigated before and after the visual cue had acquired emotional significance through a classical conditioning procedure. The study consisted of three phases; an attention preconditioning phase, the conditioning phase and an attention postconditioning (extinction) phase. In the attention phases, subjects participated in a trial-by-trial cuing task, in which the location of the target was validly or invalidly cued by either a frame-lit or a completely lit rectangle. During conditioning half the subjects (Conditioning group) had a 90 dB white noise unconditioned stimulus (UCS) presented together with one of the two attentional cues. This cue was, thus, turned into a conditioned stimulus (CS+), while the other cue became a CS-. The Control group received the noise uncontingent upon presentations of these stimuli. The Conditioning group showed greater skin conductance responses (SCRs) to the CS+ compared to the CS-, reflecting that a conditioned response was established. When the CS+ served as attentional cue, there was no difference in RTs between validly and invalidly cued targets, while responses to invalidly cued targets were delayed on all other trials. This suggests that the CS+ reduced the cognitive cost of shifting attention from the cued to the uncued location.

Adult↗
PubMed1996

Implicit memory during anaesthesia attempt at replication.

The present study investigated implicit memory during general anaesthesia in patients with elective surgery on the cervical or lumbar spine. A total of 37 patients were investigated, together with 59 healthy control subjects. The patients were divided into two groups. One group heard repeated presentations of common words (animals, flowers, countries) during anaesthesia. The other patient group heard only pink noise during anaesthesia. After surgery, all patients were asked spontaneously to name three countries, flowers, and animals. The healthy control subjects were simply asked "on the street" to spontaneously name three countries, flowers and animals. The results showed no statistically significant differences in frequency of hits for the three categories for the three groups. However, the highest hit rate was for the patient group who had heard the words during surgery (35% hits), with no difference between the other two groups (29% hits). The finding of no difference between the groups is discussed in the context of methodological issues when studying memory in anesthesia. It is, furthermore, argued that a healthy nonanesthesized control group is necessary when comparing hit rates between various anesthesized patient groups.

Adult↗
PubMed1995

Brain mechanisms in human classical conditioning: a PET blood flow study.

Five healthy male subjects participated in a classical conditioning experiment, and positron emission tomography (PET) was used to compare regional cerebral blood flow before and after conditioning. The subjects participated in three different experimental phases. In the first (habituation) phase they listened to 24 repetitions of a tone with random intervals. In the second (acquisition) phase, the tone was paired with a brief shock to the wrist. In the third (extinction) phase, the tone was presented alone again. 15OPET scans were taken during the habituation and extinction phases. Because the habituation and extinction phases were similar, any difference in blood flow to the tones presented during extinction probably reflected conditioning that occurred during the acquisition phase. Statistical parametric mapping (SPM) analysis of the PET data showed significantly increased activation in the right hemisphere in the orbito-frontal cortex, dorsolateral prefrontal cortex, inferior and superior frontal cortices, and inferior and middle temporal corticies. The only activated areas in the left hemisphere were area 19 and the superior frontal cortex. The results are interpreted as evidence for the involvement of cortical areas in human classical conditioning.

Acoustic Stimulation↗
PubMed1995

Attentional effects in dichotic listening.

This study addresses attentional effects in dichotic listening (DL) to consonant-vowel syllables. Previous research has shown that ear advantages in DL are modulated by biased attention to either the left or the right ear. Attentional effects in DL can be the result of two processes: facilitation of reports from the attended ear, or suppression of intrusions from the nonattended ear. Sixty-two students were tested with DL under three different task instructions: nonforced (divided) attention, attention forced to the right ear, and attention forced to the left ear. The main finding was inhibition of intrusions from the nonattended ear, combined with the facilitation of the correct reports from the attended ear during the two forced-attention conditions, compared with the nonforced condition. The results are discussed in relation to right hemisphere processing of dichotic input, and that attention may activate subcortically biased asymmetries which suppress input from the nonattended channel.

Acoustic Stimulation↗
PubMed1995

Absence of ear advantage on the consonant-vowel dichotic listening test in adolescent and adult dyslexics: specific auditory-phonetic dysfunction.

The present study investigated auditory-phonetic processing in a group of adolescent and adult reading disabled subjects. Right- and left-handed dyslexic subjects were compared with an age, sex, and handedness matched control group. All subjects were studied with a consonant-vowel version of the dichotic listening task with repeated presentations of dichotically presented pairs of CV-syllables. Left and right ear correct scores were compared for ear advantage in each of the different subgroups of subjects. The main finding was the absence of an expected right-ear advantage (REA) in the right-handed dyslexic group as compared to the right-handed normal readers. Both the dyslexic and normal left-handed groups did not show a REA. The findings are discussed within a theoretical framework that focuses on a basic auditory-phonetic processing dysfunction in developmental dyslexia that persists into adulthood.

Adult↗
PubMed1995

Immune disorders and handedness in dyslexic boys and their relatives.

Thirty dyslexic and 30 control boys aged 7-11 years were compared for frequency of immune disorders and handedness as well as for family history of immune disorders and learning disabilities (dyslexia and stuttering). They were also compared for neurological status and for history of speech and language difficulties. There were no significant differences between the two groups in the frequency of immune disorders and in handedness. The results showed significantly more dyslexic boys with soft neurological signs and signs of speech and language disorders. The frequency of dyslexia was significantly higher in the relatives of the dyslexic boys. Also significantly more mothers of the dyslexic boys reported difficulties during pregnancy and complications at delivery. The results are discussed in terms of Geschwind's hypothesis and neuromaturational delay as possible determinants of developmental dyslexia.

Autoimmune Diseases↗
PubMed1995

Arachnoid cysts of the left temporal fossa: impaired preoperative cognition and postoperative improvement.

Thirteen adult patients were operated on for symptomatic arachnoid cysts in the left temporal fossa; seven with an internal shunt procedure during local anaesthesia, and five with a craniotomy with fenestration of the cyst to the basal cisterns. In one patient, an initial internal shunt was transformed to a cystoperitoneal shunt. After surgery, all patients experienced relief of symptoms. Reduction of cyst volume occurred in 11 patients. The patients were tested for brain asymmetries related to language and verbal memory before and after operation, with a dichotic listening technique with simultaneous presentation of different auditory stimuli to the two ears. In the preoperative memory test, the patients showed impaired total recall compared with healthy control subjects, and recall from the right ear was significantly impaired. The patients also performed poorly in a forced attention task consisting of dichotic presentations of consonant-vowel syllables. In addition to clinical improvement, the surgical procedures led to improvements in both dichotic perception and memory. Overall memory performance was enhanced, mainly because of improved recall from the right ear. This normalisation of memory function was found as early as four hours after the operation. The results indicate that arachnoid cysts in the left temporal fossa may impair cognitive function, that neuropsychological tests are necessary to disclose these impairments, and that cognitive improvement occurs after surgery.

Arachnoid Cysts↗
PubMed1995

Functional magnetic resonance imaging of primary visual processing using a 1.0 Tesla scanner.

Recent advances in functional magnetic resonance imaging (fMRI) at > or = 1.5 T magnetic field strength and with high speed single-shot echo planar imaging techniques have made it possible to monitor local changes in cerebral blood volume, cerebral blood flow, and blood oxygenation level in response to sensory stimulation, simple motor activity, and possibly also to more complex cognitive processing. However, fMRI has also been accomplished on conventional MR scanners of medium field strength (approximately 1.0 T) using special pulse sequences and appropriate methods for image analysis. We present results from six subjects on photic stimulation using a standard 1.0 T MR scanner together with special software for off-line image analysis. Continuous serial T2-weighted imaging were performed for 6 minutes in the plane of the calcarine fissure. There were 3 repetitions of 1 minute resting state of darkness (OFF) and 1 minute activated state (ON) with 8 Hz flicker stimulation. To directly map these functional images to the underlying anatomy we also acquired a high resolution T1-weighted image from the same axial slice. The results demonstrated that stimulus-related signals can be obtained from primary visual cortex with a conventional 1.0 T MR scanner. Further methodological improvements are discussed and related to present and future possibilities for the use of fMRI within psychophysiology.

Adult↗
PubMed1994

Auditory neglect and the ear extinction effect in dichotic listening: a reply to Beaton and McCarthy (1993).

In our reply to Beaton and McCarthy (1993), we argue that the issue of ear extinction in dichotic listening also should take into account lesion site and lesion extension. When the lesion is primarily affecting the auditory pathways, the resulting dichotic dysfunction may be an ear extinction effect. However, when the lesion is outside of the auditory system, the absence of reports from one ear may be part of a larger cognitive deficit, involving more complex processes, like orientation and attention. Thus, by constraining the definition of an "ear extinction effect" to a perceptual deficit, Beaton and McCarthy confounds the issue of ear extinction with auditory neglect. In our reply we also present some new data from a patient with a left-sided thalamic pulvinar lesion, contrasting his dichotic listening performance with the patient reported in our original 1991 study.

Adult↗
PubMed1994

Normal lateralization for handedness and ear advantage in a verbal dichotic listening task in women with congenital adrenal hyperplasia (CAH).

Functional cerebral asymmetry was studied in 22 women, 17-34 years old, with prenatal virilization due to congenital adrenal hyperplasia (CAH) (21-hydroxylase deficiency) and 22 matched, healthy controls. The theory of an androgen influence on cerebral lateralization has been supported by the observation of sex differences in cognitive performance, anatomical cerebral differences between the sexes and atypical patterns of functional asymmetry in certain anomalous hormonal states. The result of the present study did however not show a significantly different pattern of functional asymmetry for women with CAH and prenatal exposure to high levels of androgens. No significant differences with the controls were found for the Finger Tapping Test (FTT), Edinburgh Handedness Inventory (EHI) or Dichotic Listening (Consonant-Vowel) Test (DL). The CAH group included four non-right-handers (18%) vs two (9%) in the control group. As sex differences generally are small, the present result, may have been influenced by the limited size of the sample.

Adolescent↗
PubMed1994

Electrophysiological correlates to cued attentional shifts in the visual and auditory modalities.

Reaction time (RT) is usually speeded and slowed to correctly and incorrectly cued target stimuli, respectively, in experiments on attention shift (Posner, 1988). When targets occur in a spatial location different from the cue, shifting attention from the cued location to the target location involves interrupt of ongoing activity, move attention to the new location, and reengage attention. The present study investigated whether the cognitive operations involved in cued vs uncued attentional shifts also were detectable in the event-related potentials (ERPs). Two experiments are reported, one with visual and one with auditory stimuli. In the visual modality, the cue and target were a lit-up square and an asterisk, respectively, shown on a computer screen. In the auditory modality, the cue was a tone in either the left or right ear, followed by the target noise in either the same or the opposite ear. The results from the visual experiment showed shorter RTs to correctly cued (Valid) targets and longer RTs to incorrectly cued (Invalid) targets. Invalidly cued targets elicited enhanced P3 amplitudes, with a frontocentral distribution. Reduced P3 amplitudes were observed on Valid trials, largest reduction for parietooccipital leads. The auditory experiment showed P3 enhancement frontally and reduced amplitudes at temporal and parietal leads. No RT differences were seen to Valid and Invalid trials. The existence of an anterior attention system involved in interrupt and disengage of attention, and a posterior attention facilitation system related to cue presentation is discussed.

Adult↗
PubMed1994

Dichotic listening and focused attention in children with hemiplegic cerebral palsy.

Dichotic listening data are reported from children with left and right hemiplegia, compared with a normal, age-matched, control group. The dichotic listening test was performed under two different attentional instructions. The aim of the study was to investigate whether lateral injury to one hemisphere also affects the capacity to direct attention in a laterality task because of inattention. The dichotic task consisted of consonant-vowel syllables that were presented with two different instructions, to attend to the left- or right-ear stimulus. The results showed that the control children had a right-ear advantage during the forced-right attention instruction, and a small left-ear advantage during the forced-left instruction. The two hemiplegia groups, however, showed the same ear advantage irrespective of attentional instruction. The results are discussed in terms of hemi-inattention and hypoarousal of the lesioned hemisphere in children with hemiplegia.

Adolescent↗
PubMed1994

Cardiovascular conditioning and anticipatory nausea and vomiting in cancer patients.

Explanations of individual differences in susceptibility to learning of anticipatory nausea and/or vomiting (AN/V) in cancer patients have focused mainly on the patients who develop AN/V. On the basis of conditioning theory, however, one would expect that all patients who experience post-treatment nausea and/or vomiting (PN/V) should develop AN/V. Consistent with findings demonstrating that conditioned responses are more easily established in autonomic-reactive individuals, we have previously reported that patients who do not develop AN/V (noAN/V) are less autonomic reactive than the AN/V patients. Thus, we hypothesized that the noAN/V patients might not show classical conditioning to the same degree and extent as the AN/V patients and that conditioning may be the mediating mechanism in AN/V. This study presents data from 36 patients. Among the 28 patients who experienced PN/V, 16 developed AN/V. We found no systematic group differences in severity of PN/V or antiemetic treatment. Before chemotherapy, all patients were tested in a signaled reaction-time paradigm. We used two different tones (CSs), one of which was always followed by a noise (UCS) as a button-press signal. The patients who later developed AN/V demonstrated significantly shorter reaction times, and also showed enhanced cardiovascular reactivity to the tone followed by the UCS (CS+) in comparison with the nonsignal tone (CS-). The noAN/V patients did not show differential cardiovascular responses to the CS+ and CS-.

Adolescent↗