Biomedical subjects

R E Gur

Publications and source records attributed to R E Gur.

At least 91 records · Page 5Linked to original sources

PubMed1995

Normative neuropsychological test performance: effects of age, education, gender and ethnicity.

Normative data on neuropsychological test performance for a sample of 131 adults (ages 18-49) is presented. All subjects were native speakers of English screened for past or present medical, neurological and psychiatric disorders, including substance abuse. A broad-based battery including measures of intellectual skills, memory and learning, receptive and expressive language, auditory and visual information processing and attention, sensory processing, motor skills, and self-reported anxiety and depression was administered. Means, standard deviations and percentile rankings for all tests are reported. Regression analyses were computed to consider the concurrent influence of sociodemographic factors on all tests. Significant effects of age (M=27.1 yrs), education (M=14.6 yrs), gender (58% male), and ethnicity (62% white) were observed for relatively few test scores. Younger age at testing was associated with better continuous performance test scores. Higher education levels were associated with higher vocabulary and reading scores. Males had higher WAIS-R Information scores and faster Finger Tapping scores compared to females Ethnicity was associated with Full-scale IQ, and additional tests with a verbal component, e.g., Boston Naming Tests, and non-verbal component, e.g., Drawing Tests. We conclude that sociodemographic factors infrequently account for more than 10% of the variance for many neuropsychological test scores.

Journal Article↗

PubMed1995

Regional cerebral function determined by FDG-PET in healthy volunteers: normal patterns and changes with age.

UNLABELLED: The main objective of this study was to determine patterns of regional brain metabolic activity utilizing high-resolution PET in normal healthy volunteers and variations in different age groups. METHODS: High-resolution [18F]FDG PET images of the entire brain were obtained in 120 healthy normal volunteers (64 men, 56 women), age range from 19 to 79 yr. Each anatomic region was assessed using a qualitative rating scale with a score ranging from 1 to 6 (1 = definitely normal and 6 = definitely abnormal). Local metabolic activity was also estimated as showing increased (+) or decreased (-) compared to normal (0) states. RESULTS: The most consistent finding in normal aging was decreased cortical metabolism, particularly in the frontal lobes. Temporal, parietal and occipital lobe metabolism varied considerably among subjects within the same age group as well as over decades. Basal ganglia, hippocampal area, thalami, cerebellum, posterior cingulate gyrus and visual cortex remained metabolically unchanged with advancing age. CONCLUSION: These data indicate that qualitative interpretation of FDG-PET images allows accurate assessment of regional metabolic activity of the brain in normal subjects similar to those described with quantitative techniques. Adequate knowledge of normal variations and changes related to normal aging is necessary for optimal assessment of pathologic states.

Adult↗

PubMed1994

Cerebral blood flow in schizophrenia: effects of memory processing on regional activation.

Regional cerebral blood flow (rCBF) was measured with the 133Xenon clearance technique and a high resolution (254 detectors) scanner during the performance of a verbal and a facial memory task in 18 patients with schizophrenia and 18 sociodemographically matched controls. Patients and controls had comparable resting rCBF, but differed in global and hemispheric rCBF changes induced by the memory tasks. Patients had less global increase, which was relatively higher in the left hemisphere, and this was more pronounced for the verbal task. Although controls showed appropriate laterality changes (L > R for verbal and R > L for facial memory) in the midtemporal region, patients failed to show such a focal pattern. They did not show appropriate laterality change in the midtemporal region, but instead showed such changes in other regions. Patients showed greatest impairment in specificity of verbal recognition performance, and this correlated with severity of hallucinations and delusions. This supports a model of left temporal lobe dysfunction in schizophrenia.

Adult↗

PubMed1994

Neuropsychological deficits in neuroleptic naive patients with first-episode schizophrenia.

BACKGROUND: Medication and chronicity have complicated past attempts to characterize the neuropsychological performance of patients with schizophrenia. There have been inconsistencies regarding the pattern, selectivity, and sources of observed deficits. Our objective was to comprehensively examine neuropsychological function in patients with schizophrenia who had never been exposed to neuroleptic medication, and who were experiencing their first episode (FE) of psychosis. METHODS: Subjects were consecutive recruitments that included 37 patients with FE schizophrenia who were never exposed to neuroleptics. These subjects were compared with 65 unmedicated, previously treated (PT) patients and 131 healthy controls. RESULTS: The patients groups had nearly identical profiles showing generalized impairment, particularly in verbal memory and learning, attention-vigilance, and speeded visual-motor processing and attention. Verbal memory and learning accounted for most of the variance between patients and controls and removing this effect substantially attenuated all other differences. By contrast, both the FE group and PT group continued to show highly significant deficits in verbal memory and learning after controlling for attention, abstraction, and all other functions. Some functions not typically implicated in schizophrenia (spatial cognition, fine motor speed, and visual memory) were more impaired in the PT group than in the FE group. CONCLUSIONS: Verbal memory, as a primary neuropsychological deficit present early in the course of schizophrenia, implicates the left temporal-hippocampal system. Neuropsychological evaluations before treatment permit differentiation of primary deficits from changes secondary to medication or chronicity. This is essential for developing a neurobehavioral perspective on schizophrenia.

Adult↗

PubMed1994

Neuropsychological functioning in siblings discordant for schizophrenia and healthy volunteers.

OBJECTIVE: To determine whether schizophrenics and their nonschizophrenic siblings have a similar pattern of neuropsychological deficit when compared with normal controls. DESIGN AND PARTICIPANTS: Fifteen probands with schizophrenia, 16 of their nonschizophrenic siblings, and 31 unrelated, demographically balanced, normal individuals underwent evaluation with a comprehensive neuropsychological test battery. All subjects were screened for history of head injury, neurologic illness, major medical conditions, substance use, and axis I psychiatric disorders other than schizophrenia. Probands underwent evaluation twice: once at intake when half had never received neuroleptic medication and the other half had received none for a minimum of 2 weeks, and again at the 2- to 4-week follow-up, after stabilization with neuroleptic medications. RESULTS: Both schizophrenics and their nonschizophrenic siblings were impaired neuropsychologically compared with normal controls, with the nonschizophrenic siblings' performance intermediate between that of the schizophrenic siblings and the normal controls on all measures of functioning. The shapes of the deficit profiles of schizophrenic patients and their siblings were similar; in patients, verbal memory, abstraction, attention, and language functions were significantly more affected compared with spatial abilities, spatial memory, and sensory-motor functions, with a nonsignificant trend in the same direction in siblings. Cognitive functioning in patients was found to be stable across changes in medication status and clinical state. Four fifths of patients obtained more deviant scores than their nonschizophrenic siblings. Among the sibling group, those with probable and certain diagnoses of schizotypal personality disorder were more impaired compared with those without schizophrenia-spectrum symptoms. CONCLUSION: These results support the hypothesis that impaired information processing aggregates in the family members of schizophrenics and may serve as an indicator of genetic vulnerability to the disorder. Further work is needed to establish whether particular areas of functioning are selectively impaired in relatives and to determine whether the performance deficits are mediated by structural and/or metabolic disturbances in specific brain regions.

Adult↗

PubMed1994

Lateralized increases in cerebral blood flow during performance of verbal and spatial tasks: relationship with performance level.

Physiologic neuroimaging studies have shown lateralized regional increase in brain activity during cognitive tasks, but the hypothesis that such changes are correlated with task performance has not been tested directly. We examined cerebral blood flow (CBF) changes induced by cognitive tasks in relation to performance. CBF was measured with the 133Xenon clearance method in 34 normal right-handed young (age < 30) volunteers during resting baseline and during the performance of a verbal analogies and a spatial line orientation test. Performance measures included "speed" and "power" estimates of both activation tasks. Resting CBF was moderately correlated with performance. The correlations were slightly higher with activated CBF for verbal but not spatial performance. The degree of increase (task-baseline) did not correlate with performance for either task. The highest and topographically specific correlations were obtained between laterality of CBF and verbal performance. Higher left hemispheric activation was correlated with verbal performance, and this correlation was significantly higher in the angular gyrus region. For the spatial task the correlations were with relatively higher right hemispheric activation but without regional specificity. The results underscore the importance of integrating behavioral performance data with physiologic measures in neuroimaging activation studies.

Adolescent↗

PubMed1994

Effects of emotional discrimination tasks on cerebral blood flow: regional activation and its relation to performance.

Facial discrimination tasks were applied as activation probes during physiologic neuroimaging ("neurobehavioral probes"). The stimuli pictured professional actors and actresses, posing degrees of happy and sad emotion. Cortical cerebral blood flow (CBF) was determined using the 133Xenon inhalation method during resting baseline, two emotional (happy from neutral and sad from neutral faces) and one nonemotional discrimination task (age). The three tasks produced CBF increase over baseline, which was greater in the right hemisphere (Task x Hemisphere interaction, p = .0001). There were regionally specific effects (Task x Region x Hemisphere interaction, p = .022). Relative to the age discrimination task, both emotion discrimination tasks were associated with greater right parietal activation. In addition, the happy discrimination task induced greater left frontal activation relative to the sad discrimination task. While overall magnitude of CBF increase did not show regionally specific correlations with performance, laterality did show such specificity. Sad discrimination performance correlated with greater right parietal activation, while performance on the happy discrimination task correlated with left frontal activation. Age discrimination performance correlated with higher activated right temporal CBF. These results support the hypothesis of right hemispheric involvement in facial processing and further suggest regionally specific hemispheric participation in happy and sad emotional discrimination. The study underscores the utility of performance measures for understanding the behavioral significance of activation effects in physiologic neuroimaging studies.

Adult↗

PubMed1994

The stability of tachistoscopic measures of hemispheric specialization.

Two-week test-retest reliabilities were determined for two tachistoscopic tasks, consonant-vowel-consonant trigrams and dot location, in 48 right-handed university students. Both visual field and laterality scores were examined. Analysis of variance showed no significant main effects or interactions of session for either task, indicating stability of mean performance and laterality scores. Likewise, grouping subjects as "high" or "low" by median laterality scores showed concordance across sessions for both tasks. Test-retest correlations were moderately high for all verbal task measures and for visual field scores for the dot location test. However, laterality indices for dot location showed low stability despite comparable within-session reliabilities of laterality scores for the two tasks. These findings suggest stability of group means and subgroups for verbal and dot location tachistoscopic measures. However, the degree to which individual scores are predictable from one session to the next differs between the two tasks.

Adult↗

PubMed1994

Standardized mood induction with happy and sad facial expressions.

The feasibility of applying ecologically valid and socially relevant emotional stimuli in a standardized fashion to obtain reliable mood changes in healthy subjects was examined. The stimuli consisted of happy and sad facial expressions varying in intensity. Two mood-induction procedures (happy and sad, each consisting of 40 slides) were administered to 24 young healthy subjects, who were instructed to look at each slide (self-paced) and try to feel the happy or sad mood expressed by the person in the picture. On an emotional self-rating scale, subjects rated themselves as relatively happier during the happy mood-induction condition and as relatively sadder during the sad mood-induction condition. Conversely, they reported that they were less happy during the sad mood-induction condition and less sad during the happy mood-induction condition. The effects were generalized to positive and negative affect as measured by the Positive and Negative Affect Scale. The intraindividual variability in the effect was very small. In a retest study after 1 month, the mood-induction effects showed good stability over time. The results encourage the use of this mood-induction procedure as a neurobehavioral probe in physiologic neuroimaging studies for investigating the neural substrates of emotional experience.

Adult↗

PubMed1994

Differential effects of mood on cortical cerebral blood flow: a 133xenon clearance study.

Studies of healthy and clinical populations have suggested valence-specific cortical and subcortical neural systems regulating emotions. In a study of 12 normal volunteers, the 133xenon clearance method for measuring regional cerebral blood flow (CBF) was used to study the effects of experimentally controlled mood states on regional brain activity within superficial cortex. CBF was measured with 254 detectors and bolus infusion during a happy mood induction task, a sad mood induction task, a sex differentiation task, and a resting baseline condition. CBF increased during sad and decreased during happy mood induction, relative to the activated (sex differentiation) and the nonactivated (resting) nonemotional control conditions. Increased CBF during sad mood induction was correlated with greater negative mood changes. Conversely, increased CBF was associated with a stronger subjective experience of positive affect during happy mood induction. This suggests that cortical arousal may serve to intensify the conscious experience of emotion. Heart rate accelerated during happy and sad mood induction and during sex differentiation relative to a pretask baseline condition. Some regional specificity of effects was also observed. The occipital temporal region showed higher overall CBF during sad mood induction than during happy mood induction. The only region that showed specific lateralized changes in CBF which differentiated sad from happy states was the frontal pole, with left CBF being higher during sad and lower during happy mood induction relative to right CBF. For sad mood induction, there were significant regional differences among correlations between CBF and self-ratings. These were attributable to higher negative correlations (i.e., higher CBF correlates with negative self-rating) in midtemporal, occipital temporal, and postcentral regions. These correlations did not vary across the 15 regions for happy mood induction. For sad mood induction, heart rate correlated positively with CBF increase and with negative affect. Correlations were opposite for happy mood induction. The results suggest high cortical and autonomic arousal during negative/sad mood and low cortical and high autonomic arousal during positive/happy mood. They underscore the value of integrating emotional experience with physiologic measures in neuroimaging activation studies.

Adult↗

PubMed1994

Effects of medication history on midlatency auditory evoked responses in schizophrenia.

The recovery cycle of the P1 component of the auditory evoked potential (50-70 ms latency) has been reported as abnormal in both unmedicated and medicated patients with schizophrenia when a paired stimuli protocol is used to examine recovery. However, findings have been mixed when a stimulus train protocol is used. This study examined the effects of medication history on P1 abnormalities in schizophrenia assessed by a stimulus train protocol. Auditory evoked potentials were recorded from 14 normal controls, 14 neuroleptic naive patients with schizophrenia and 14 previously medicated patients in response to binaural clicks presented at three stimulus rates: 1/s, 5/s and 10/s. Neuroleptic naive patients showed a smaller P1 at the baseline rate (1/s) and greater recovery (less amplitude suppression) at faster rates than did normal controls or previously medicated patients. Additional analyses suggested that this latter effect was not due to smaller baseline P1 amplitudes. Greater recovery in neuroleptic naive patients was not associated with clinical symptomatology contrary to previous findings of the authors for a mixed sample of neuroleptic naive and previously medicated patients. Medication status appears to account for some of the variability in P1 abnormalities in schizophrenia although identification of the underlying mechanism responsible requires further study.

Adolescent↗

PubMed1994

Magnetic resonance imaging in schizophrenia: relationship with clinical measures.

Relationships were examined between clinical features of schizophrenia and cerebrospinal fluid (CSF) volume in brain obtained by magnetic resonance imaging (MRI) in a sample of 59 patients. The volumes of the cerebral hemispheres and CSF were measured with a computer program designed to separate reliably neural tissue from CSF. The CSF to cranial volume ratios were related to history, symptom profile and outcome functioning. Earlier age of onset was associated with higher sulcal CSF ratio, r = -0.40. The anatomic measures were unrelated to symptom severity. However, patient subtypes differed in the laterality of measures. Higher left hemispheric ratios were seen in patients with severe negative symptoms, and left predominance of ventricular relative to sulcal ratios was associated with the presence of hallucinations and delusions. The results suggest that while higher CSF is related to earlier age of onset, the clinical symptoms are more related to its lateralization. This is consistent with the hypothesis that schizophrenia is a lateralized brain disease.

Adolescent↗

PubMed1994

Clinical subtypes of schizophrenia: differences in brain and CSF volume.

OBJECTIVE: Investigations of the relation of clinical features of schizophrenia to neuroanatomic measures have produced inconclusive results. The purpose of this study was to examine measures of whole-brain volume in men and women and relate them to clinical subtypes of schizophrenia. METHOD: Magnetic resonance imaging measures of cranial, brain, and ventricular and sulcal CSF volume were examined in 81 patients with schizophrenia (50 men and 31 women), divided into subgroups based on their symptom profiles, and 81 demographically matched healthy comparison subjects. RESULTS: The men had higher cranial and brain volumes than the women. The patients had smaller cranial and brain volumes than the comparison subjects; they also had higher ventricular CSF volumes and thus higher ventricle-brain ratios (VBRs). Ratio elevations were larger for the female than for the male schizophrenic patients. The patients with predominantly negative symptoms of schizophrenia had higher VBRs and sulcal CSF-brains ratios than the comparison subjects, although the component volumes did not differ. The patients with predominantly Schneiderian symptoms had higher VBRs than the comparison subjects but showed reduced cranial and brain volumes. The paranoid patients had normal VBRs, reduced sulcal CSF-brain ratios, and lower cranial and sulcal CSF volumes. CONCLUSIONS: The results suggest two patterns of neuroanatomic whole-brain abnormalities that differ in severity according to the relative prominence of negative, Schneiderian, and paranoid symptoms. These patterns may reflect differential involvement of dysgenic and atrophic pathophysiological processes. Sex moderates abnormalities in the neuroanatomic features of schizophrenia.

Adolescent↗

PubMed1994

MMPI characteristics in adults diagnosed with ADD: a preliminary report.

Characterization of Attention Deficit Disorder (ADD) in adults has been hampered by an absence of well-defined clinical profiles on objective personality measures. A sample of 22 ADD adults completed personality testing (MMPI) in conjunction with cognitive assessment. A sample of 30 normal controls and 20 patients diagnosed with schizophrenia, who had completed the MMPI as part of a larger research protocol, were utilized as comparison groups. Validity and clinical scales revealed multiple elevations in the ADD group which were similar in nature but not to the same degree as elevations observed in the schizophrenia group. Harris-Lingoes subscales identified the sources of clinical scale elevations indicating a pattern of specific and nonspecific symptomatology which differentiated the three groups. The results may aid in identifying ADD in adults.

Adult↗

PubMed1994

Sex differences in aging of the human frontal and temporal lobes.

This study investigated effects of age and sex on regional brain structure in humans, focusing on the frontal and temporal lobes. Hemispheric volumes were obtained from magnetic resonance images (MRIs) of 96 young (53 men, 43 women; aged 18-40 years) and 34 older (17 men, 17 women; aged 41-80) healthy volunteers. Images (5 mm axial spin-echo, repetition time of 3000 msec and echo times of 30 and 80 msec) were resliced along the anterior commissure-posterior commissure (AC-PC) axis to standardize for difference in head tilt, and imported into a computer program where borders of the frontal and temporal lobes were delineated. The program calculated regional brain volumes based on slice data from which CSF was segmented out. An age x sex x hemisphere x region interaction indicated that age-related reductions in brain volume were sexually dimorphic, lateralized, and region specific. Greater decrements in brain volume occurred with age in the frontal lobe than in the temporal lobe. Age-related reductions in both regions were greater in men than in women, demonstrating that sexual dimorphisms in human neuroanatomy are not fixed, but continue to change throughout adulthood. The possibility that gonadal hormones play a role in the promotion and/or prevention of neural atrophy with aging is discussed.

Adolescent↗

PubMed1993

Effects of hypnosis on regional cerebral blood flow during ischemic pain with and without suggested hypnotic analgesia.

Using 133Xe regional cerebral blood flow (CBF) imaging, two male groups having high and low hypnotic susceptibility were compared in waking and after hypnotic induction, while at rest and while experiencing ischemic pain to both arms under two conditions: attend to pain and suggested analgesia. Differences between low and highly-hypnotizable persons were observed during all hypnosis conditions: only highly-hypnotizable persons showed a significant increase in overall CBF, suggesting that hypnosis requires cognitive effort. As anticipated, ischemic pain produced CBF increases in the somatosensory region. Of major theoretical interest is a highly-significant bilateral CBF activation of the orbito-frontal cortex in the highly-hypnotizable group only during hypnotic analgesia. During hypnotic analgesia, highly-hypnotizable persons showed CBF increase over the somatosensory cortex, while low-hypnotizable persons showed decreases. Research is supportive of a neuropsychophysiological model of hypnosis (Crawford, 1991; Crawford and Gruzelier, 1992) and suggests that hypnotic analgesia involves the supervisory, attentional control system of the far-frontal cortex in a topographically specific inhibitory feedback circuit that cooperates in the regulation of thalamocortical activities.

Adult↗

PubMed1993

Neuroimaging in schizophrenia research.

Neuroimaging has advanced the study of brain structure and function in schizophrenia. Magnetic resonance imaging provides measures of whole brain and regional anatomy and cerebrospinal fluid volume. Functional methods have included the Xenon-133 technique for measuring cerebral blood flow (CBF); positron emission tomography for assessing metabolism, CBF, and neuroreceptor functioning; and single photon emission computed tomography for studying CBF and neuroreceptors. Despite heterogeneity of patient samples, and studies which differed in the methodologies applied, there is converging evidence implicating three brain systems: frontal, temporolimbic, and basal ganglia. Current emphasis is aimed at probing specific regions across imaging modalities. Now these findings and research paradigms in neuroimaging must be integrated with phenomenological, neurobehavioral, and neuropathological investigations. The application of this technology is already helping to elucidate the neurobiology of schizophrenia, and further important advances can be anticipated.

Brain↗

PubMed1993

Asymmetrical visual deprivation: a technique to differentially influence lateral hemispheric function.

This article describes a contact-lens method to sustain asymmetry in visual deprivation and the use of this method to test the general hypothesis that asymmetry in input deprivation can shift activation balance in the integrated brain, differentially influencing lateral hemispheric function. Effects of asymmetrical visual deprivation were as predicted on lateral asymmetry of EEG theta, producing more theta over the deprived hemisphere. Cross-modal influence of such visual deprivation was found in the perception of pleasantness of odors. An interaction was found between side of visual deprivation and performance on verbal reasoning and spatial orientation tasks. A line-bisection test of visual attention was not sensitive to the effects. Fatigue as rated on the Profile of Mood States was greatest when the left hemisphere was deprived.

Adolescent↗