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R C Gur

Publications and source records attributed to R C Gur.

At least 19 recordsLinked to original sources
PubMed2006

Are neurologic examination abnormalities heritable? A preliminary study.

BACKGROUND: Neurologic examination abnormalities (NEA) are more prevalent among patients with schizophrenia as well as their unaffected relatives when compared with healthy controls, suggesting that NEA may be endophenotypes for schizophrenia. We estimated the heritability of NEA in moderately sized pedigrees. We also evaluated correlations between NEA and cognitive performance in order to examine their construct validity. METHODS: Members of eight extended families, each consisting of two first degree relatives with schizophrenia/schizoaffective disorders, as well as available first- to fifth-degree relatives were examined (n=96 participants). A modification of the Neurological Evaluation Scale (NES) was employed, augmented with localizing signs. Where feasible, we used untransformed data such as error counts and completion time, rather than ordinal measures. Heritability was estimated using the variance component method, implemented in SOLAR. RESULTS: Statistically significant heritability (h2) estimates were obtained for several measures (p<0.05, h2+/-standard error: rapid alternating movements, right-sided completion time, 0.99+/-0.19; alternating fist-palm test, completion time, 0.77+/-0.19 s, errors, 0.70+/-0.32; fist-ring test, right-sided completion time, 0.53+/-0.23 s, left-sided completion time, 0.70+/-0.21 s; go-no go task, correct responses, 0.93+/-0.33; audio-visual integration, correct responses, 0.79+/-0.54). For most items, heritability analysis was hampered by insufficient data variability (infrequent errors). Correlational analyses show some degree of divergence among types of NEA, repetitive motor tasks being associated with most domains of cognitive functioning other than executive functioning, and cognitive-perceptual tasks being associated with memory and executive functioning. CONCLUSIONS: Significant familial influences on certain aspects of neurologic performance were detected. These heritable measures were also correlated with heritable neurocognitive measures.

Adolescent↗
PubMed2005

Classifying spatial patterns of brain activity with machine learning methods: application to lie detection.

Patterns of brain activity during deception have recently been characterized with fMRI on the multi-subject average group level. The clinical value of fMRI in lie detection will be determined by the ability to detect deception in individual subjects, rather than group averages. High-dimensional non-linear pattern classification methods applied to functional magnetic resonance (fMRI) images were used to discriminate between the spatial patterns of brain activity associated with lie and truth. In 22 participants performing a forced-choice deception task, 99% of the true and false responses were discriminated correctly. Predictive accuracy, assessed by cross-validation in participants not included in training, was 88%. The results demonstrate the potential of non-linear machine learning techniques in lie detection and other possible clinical applications of fMRI in individual subjects, and indicate that accurate clinical tests could be based on measurements of brain function with fMRI.

Adult↗
PubMed2004

Cognitive performance of male adolescents is lower than controls across psychiatric disorders: a population-based study.

OBJECTIVE: Psychiatric patients, as well as humans or experimental animals with brain lesions, often concurrently manifest behavioral deviations and subtle cognitive impairments. This study tested the hypothesis that as a group, adolescents suffering from psychiatric disorders score worse on cognitive tests compared with controls. METHOD: As part of the assessment for eligibility to serve in the military, the entire, unselected population of 16-17-year old male Israelis undergo cognitive testing and screening for psychopathology by the Draft Board. We retrieved the cognitive test scores of 19 075 adolescents who were assigned any psychiatric diagnosis, and compared them with the scores of 243 507 adolescents without psychiatric diagnoses. RESULTS: Mean test scores of cases were significantly poorer then controls for all diagnostic groups, except for eating disorders. Effect sizes ranged from 0.3 to 1.6. CONCLUSION: As group, adolescent males with psychiatric disorders manifest at least subtle impairments in cognitive functioning.

Adolescent↗
PubMed2002

Brain activity during simulated deception: an event-related functional magnetic resonance study.

TheGuilty Knowledge Test (GKT) has been used extensively to model deception. An association between the brain evoked response potentials and lying on the GKT suggests that deception may be associated with changes in other measures of brain activity such as regional blood flow that could be anatomically localized with event-related functional magnetic resonance imaging (fMRI). Blood oxygenation level-dependent fMRI contrasts between deceptive and truthful responses were measured with a 4 Tesla scanner in 18 participants performing the GKT and analyzed using statistical parametric mapping. Increased activity in the anterior cingulate cortex (ACC), the superior frontal gyrus (SFG), and the left premotor, motor, and anterior parietal cortex was specifically associated with deceptive responses. The results indicate that: (a) cognitive differences between deception and truth have neural correlates detectable by fMRI, (b) inhibition of the truthful response may be a basic component of intentional deception, and (c) ACC and SFG are components of the basic neural circuitry for deception.

Adult↗
PubMed2001

Comparison of the continuous performance test with and without working memory demands in healthy controls and patients with schizophrenia.

The Penn Continuous Performance Test (PCPT), a measure of sustained visual attention developed for use in functional neuroimaging studies, was compared with a standard CPT developed by Gordon Diagnostic Systems (GDS; Vigilance subtest). The PCPT and the GDS CPT were administered with a standard neuropsychological battery to 68 healthy adults to assess reliability and construct validity. The test had adequate internal consistency, and convergent validity was established through significant correlations between measures of efficiency on the PCPT and the GDS CPT. With the exception of a significant correlation between efficiency measures on the GDS CPT and a measure of auditory sustained attention, neither version of the CPT correlated significantly with other measures in the battery. Factor analysis showed that the PCPT loaded with the GDS CPT. In 39 patients with schizophrenia and 39 matched, healthy controls, equivalent impairment was evident on the two CPT tasks. Neither version correlated significantly with symptom measurements. These results support previous conclusions that sustained visual attention in schizophrenia is a core information processing deficit, not directly related to symptomatology.

Adult↗
PubMed2001

Computerized neurocognitive scanning: I. Methodology and validation in healthy people.

Neuropsychological testing batteries are applied in neurobehavioral evaluations of brain disorders, including neuropsychiatric populations. They are lengthy, require expert administrators and professional scorers, and are prone to data handling errors. We describe a brief computerized neurocognitive "scan" that assesses similar domains with adequate reliability. The scan and a traditional battery were administered to a sample of 92 healthy individuals (44 men, 48 women) in a counterbalanced order. Both approaches showed a significant "sex-typical" gradient, with women outperforming men in verbal memory relative to spatial tasks. Both methods also yielded similar profiles of sex differences, with the additional computerized measure of face memory showing better performance in women. Age effects were evident for both methods, but the computerized scan isolated the effects to speed rather than accuracy. Therefore, the computerized scan has favorable reliability and construct validity and can be applied efficiently to study healthy variability related to age and gender.

Adult↗
PubMed2001

Computerized neurocognitive scanning: II. The profile of schizophrenia.

Cognitive dysfunction in schizophrenia is well established with neuropsychological batteries, which have assessed multiple domains indicating diffuse deficits especially in processing related to frontotemporal systems. Two studies are reported examining the feasibility of the computerized neurocognitive scan to assess differential deficits in schizophrenia. In Study 1, we tested 53 patients and 71 controls with the traditional and computerized assessments counterbalanced in order. Both showed comparable generalized impairment in schizophrenia with differential deficits in executive functions and memory. The profile was replicated in Study 2 in a new sample of 68 patients and 37 controls, receiving only the computerized scan. The combined sample showed robust correlations between performance on both speed and accuracy measures of the neurocognitive scan and clinical variables, including premorbid adjustment, onset age, illness duration, quality of life, and severity of negative symptoms. These correlations were higher and more prevalent in women than men, who showed correlations predominantly for speed rather than accuracy. Neuroleptic exposure was associated with poorer performance only for speed of memory processing, and in men, this association was seen only for typical neuroleptics. We conclude that the computerized neurocognitive scan can be applied reliably in people with schizophrenia, yielding data that support its construct and criterion validity.

Adult↗
PubMed2001

Approaches to cognitive remediation of neuropsychological deficits in schizophrenia: a review and meta-analysis.

A review and critique of the literature pertaining to the use of cognitive remediation techniques in patients with schizophrenia is presented. The review is organized into three sections, according to the neuropsychological deficit targeted for remediation: 1) executive-function, 2) attention, and 3) memory. With regards to executive-function, despite an initial report suggesting that Wisconsin Card Sorting Test performance cannot be remediated, subsequent studies suggest that performance can be improved on a variety of dependent measures including perseverative errors, categories achieved, and conceptual level responses. These observations were confirmed by a meta-analytic investigation that revealed large mean effects sizes (d+ = 0.96) for these studies. Effect sizes were homogenous across discrepant remediation strategies and dependent measures. With regards to attention, serial scanning can be improved with instruction and reinforcement, whereas there is mixed evidence suggesting that practice-based attention drills can improve performance on measures of sustained attention in schizophrenia. With regards to memory, relatively simple semantic and affective elaborate encoding strategies elevates verbal list-learning memory in patients with schizophrenia to levels consistent with controls. A similar encoding procedure, combined with vigilance training, produces substantial improvement in social cue recognition. Avenues for future research are discussed.

Attention↗
PubMed2001

Age-related volumetric changes of brain gray and white matter in healthy infants and children.

To date there is little information about brain development during infancy and childhood, although several quantitative studies have shown volume changes in adult brains. We performed three-dimensional magnetic resonance imaging (3D-MRI) in 28 healthy children aged 1 month to 10 years. We examined the volumes of whole brain and frontal and temporal lobes with an advanced method for segmenting images into gray matter (GM), white matter (WM) and cerebrospinal fluid (CSF) compartments. Growth spurts of whole brain and frontal and temporal lobes could be seen during the first 2 years after birth. During this period the frontal lobes grew more rapidly than the temporal lobes, the right--left asymmetry was more noticeable in the temporal lobes than in the frontal lobes and the increase in GM was larger than that in WM in the temporal lobes. Subsequently, WM volume increased at a higher rate than GM volume throughout childhood. Quantitative information on normal brain development may play a pivotal role in clarifying brain neurodevelopmental abnormalities.

Age Factors↗
PubMed2001

Effect of schizophrenia on frontotemporal activity during word encoding and recognition: a PET cerebral blood flow study.

OBJECTIVE: Neuropsychological studies have shown that deficits in verbal episodic memory in schizophrenia occur primarily during encoding and retrieval stages of information processing. The current study used positron emission tomography to examine the effect of schizophrenia on change in cerebral blood flow (CBF) during these memory stages. METHOD: CBF was measured in 23 healthy comparison subjects and 23 patients with schizophrenia during four conditions: resting baseline, motor baseline, word encoding, and word recognition. The motor baseline was used as a reference that was subtracted from encoding and recognition conditions by using statistical parametric mapping. RESULTS: Patients' performance was similar to that of healthy comparison subjects. During word encoding, patients showed reduced activation of left prefrontal and superior temporal regions. Reduced left prefrontal activation in patients was also seen during word recognition, and additional differences were found in the left anterior cingulate, left mesial temporal lobe, and right thalamus. Although patients' performance was similar to that of healthy comparison subjects, left inferior prefrontal activation was associated with better performance only in the comparison subjects. CONCLUSIONS: Left frontotemporal activation during episodic encoding and retrieval, which is associated with better recognition in healthy people, is disrupted in schizophrenia despite relatively intact recognition performance and right prefrontal function. This may reflect impaired strategic use of semantic information to organize encoding and facilitate retrieval.

Adult↗
PubMed2001

Striatal dopamine transporters and cognitive functioning in healthy men and women.

OBJECTIVE: There is growing interest in distinguishing the biological bases of sex differences in behavior from environmental influences. Sex hormone levels seem to be related to some cognitive abilities, particularly memory, and the dopaminergic system participates in the mediation of memory. The dopamine transporter is the primary indicator of dopaminergic tone. This study investigated the relationship between cognition and dopamine transporter availability in healthy men and women. METHOD: Dopamine transporter levels were measured with a technetium-99m radiolabeled analog of cocaine, TRODAT-1, in 66 healthy volunteers (30 men and 36 women). A neuropsychological battery designed to target functions associated with dopaminergic activity was administered during the uptake interval between the radiopharmaceutical injection and image acquisition. RESULTS: Women and younger participants had higher dopamine availability in the caudate nucleus, and these groups also performed better on verbal learning tasks. Furthermore, dopamine transporter availability was correlated with learning performance within groups. Relationships between dopamine availability in the caudate and putamen and executive and motor functioning were observed in women, but not in men. CONCLUSIONS: The results provide further evidence for age effects and sex differences in the neuromodulatory influences of dopamine on behavior in humans.

Adolescent↗
PubMed2001

Effectiveness of an attention- and memory-training program on neuropsychological deficits in schizophrenia.

The effect of two cognitive remediation procedures developed for closed head injury, Attention Process Training (APT) and Prospective Memory Training (PROMT), on neuropsychological deficits in schizophrenia was investigated. Six patients with schizophrenia, varying in baseline intellectual function and symptoms, were studied; three in a remediation condition and three in a nonremediated control condition. Results were evaluated individually for each of the three treated patients. Two of three remediation-treated subjects showed marked improvement on tests of sustained and divided attention. Untreated patients showed little evidence of change in neuropsychological test performance across a similar time interval, when tested on a subset of the measures administered to remediation-treated patients. The results of this study are discussed with a view toward future studies using larger sample sizes with homogeneous subject populations.

Adult↗
PubMed2001

Neuropsychological differences among empirically derived clinical subtypes of schizophrenia.

Neuropsychological profile differences between empirically derived clinical subtypes of schizophrenia were examined. Two hundred five patients and 209 demographically matched controls were administered a neuropsychological battery examining 8 domains. Subtypes included negative, disorganized, paranoid, Schneiderian, and mild. All subtypes displayed a neuropsychological profile of generalized impairment with greater deficits in learning, memory, and attention. Results were suggestive of diffuse cognitive dysfunction in schizophrenia with more severe deficits in learning and memory relative to executive skills. This pattern of greater learning and memory impairment was pronounced for disorganized patients. In contrast, paranoid patients outperformed disorganized and negative patients in several domains. These findings reflect bilateral frontal-temporal dysfunction, particularly in disorganized and negative patients. Subtype differences highlight the importance of conceptualizing schizophrenia as a multifocal disorder.

Adolescent↗
PubMed2001

Controlled and automatic processing during animal word list generation in schizophrenia.

Controlled and automatic aspects of semantic-associative functioning in schizophrenia were investigated by evaluating performance on animal word list generation (WLG). Responses from control (n = 47) and patient (n = 38) participants were subjected to multidimensional scaling (MDS), cluster analysis (CA), and indices on the basis of number of shared attributes (SA) between consecutive responses. Patient MDS results accounted for less variance and contained more error than control data. CA results yielded fewer and less clear animal-response subgroups among patients yet demonstrated intact associations among strongly related exemplars. The SA indices revealed better clustering and more effective switching among response clusters in controls than patients. Results suggest that animal WLG in schizophrenia is compromised both by aberrant automatic semantic-associative network activation and by controlled processes such as search, access, and selection. This pattern is consistent with prominent frontotemporal pathology evident in the disorder.

Adult↗
PubMed2000

Emotion recognition deficit in schizophrenia: association with symptomatology and cognition.

BACKGROUND: Previous investigations have found impaired recognition of facial affect in schizophrenia. Controversy exists as to whether this impairment represents a specific emotion recognition deficit when compared with other face recognition control tasks. Regardless of whether the emotion processing deficit is differential, it may uniquely influence other manifestations of schizophrenia. We compared patients and healthy control subjects on computerized tasks of emotion and age recognition. Performances on emotion and age recognition tasks were correlated with cognitive functioning and with symptomatology. METHODS: Thirty-five patients with schizophrenia and 45 healthy people underwent computerized testing for emotion and age recognition. Participants were assessed neuropsychologically, and patients were rated for positive and negative symptoms. RESULTS: The patients with schizophrenia performed worse than control subjects on emotion and age recognition without differential deficit. In both groups, we found higher error rates for identification of emotion in female faces and for identification of sad versus happy faces. In schizophrenic patients, emotion but not age recognition correlated with severity of negative and positive symptoms. In healthy control subjects, neither task correlated with cognitive functions. In schizophrenic patients, emotion but not age recognition correlated with attention, verbal and spatial memory, and language abilities. CONCLUSIONS: This study did not reveal a specific deficit for emotion recognition in schizophrenia; however, our findings lend support to the concept that emotion recognition is uniquely associated in schizophrenia with core symptomatology and cognitive domains.

Adult↗
PubMed2000

Emotional processing in schizophrenia across cultures: standardized measures of discrimination and experience.

Schizophrenia appears quite similar across a range of cultures. However, variability has been noted, and understanding the variant and invariant features of the disorder is necessary for elucidating its biological and environmental basis. Evidence of prominent emotion processing deficits in schizophrenia, including perceptual and experiential aspects, led us to extend the paradigm of standardized measures cross-culturally. We assessed performance of American, German, and Indian patients with schizophrenia and healthy controls on standardized emotion discrimination and experience (mood induction) procedures using happy, sad, and neutral facial expressions of Caucasian actors. Participants were 80 Americans (40 patients; 40 controls), 48 Germans (24 patients; 24 controls), and 58 Indians (29 patients; 29 controls). Face discrimination performance was impaired across patient groups, but was most impaired in those of Indian origin. Lower performance was also found in Indian controls, relative to their American and German counterparts. Mood induction produced weaker effects in all patient groups relative to their respective controls. The results supported the feasibility of cross-cultural comparisons and also emphasized the importance of poser ethnic background for facial affect identification, while poser ethnicity was less consequential for mood induction effects. Emotion processing deficits in schizophrenia may add to the clinical burden, and merit further examination.

Adult↗
PubMed2000

Working memory constrains abstraction in schizophrenia.

BACKGROUND: Abstraction has long been considered an area of differential cognitive deficit in schizophrenia, primarily because of patients' poor performance on the Wisconsin Card Sorting Test (WCST). Yet, the complexity and multidimensional nature of the WCST increases the likelihood that several different cognitive processes, perhaps mediated by different neural systems, are being tapped. METHODS: In the current study, the Abstraction and Working Memory (AIM) task was designed to disentangle abstraction and working memory so that the effects of each cognitive domain could be independently analyzed. The AIM task and a battery of neuropsychological tests were administered to 62 patients with schizophrenia and 62 matched healthy volunteers. RESULTS: Whereas patients with schizophrenia demonstrated deficits in simple abstraction, they were disproportionately impaired with the addition of a minimal memory requirement. CONCLUSIONS: Group differences on WCST performance appear to be attributable to patients' inability to maintain information over a short delay, before that information is used for more complex cognitive operations.

Adolescent↗