Biomedical subjects

Gregory P Crucian

Publications and source records attributed to Gregory P Crucian.

At least 19 recordsLinked to original sources

PubMed2007

Laterality, region, and type of motor dysfunction correlate with cognitive impairment in Parkinson's disease.

We studied the relationship between two screening cognitive measures and off motor Unified Parkinson's Disease Rating Scale (UPDRS) scores in 108 Parkinson's disease patients. Multiple regressions were conducted to examine the UPDRS subscores' unique contributions to cognitive function. When including bradykinesia, rigidity, and postural/gait instability subscores, only bradykinesia predicted Mini Mental Status Examination (MMSE), normalized beta = -0.57, t(104) = -3.31, P < 0.01, and Dementia Rating Scale-2 (DRS-2), normalized beta = -0.45, t(104) = -2.55, P < 0.05. Tremor was not included in the regression analyses because it did not correlate with cognitive function. When including axial and appendicular subscores, only the axial subscore predicted MMSE, normalized beta = -0.39, t(105) = -3.19, P < 0.01, and DRS-2 scores, normalized beta = -0.40, t(106) = -3.28, P < 0.01. When including left-sided and right-sided subscores, only the right-sided symptoms predicted DRS-2 scores, normalized beta = -0.28, t(105) = -2.45, P < 0.05, and showed a trend toward predicting MMSE scores, normalized beta = -0.22, t(105) = -1.95, P = 0.054. We therefore found that right-sided symptoms (for laterality), axial symptoms (for region), and bradykinesia (for type of symptoms) were the best predictors of cognitive function.

Aged↗

PubMed2006

Posture recognition in Alzheimer's disease.

BACKGROUND: Apraxia is neurologically induced deficit in the ability perform purposeful skilled movements. One of the most common forms is ideomotor apraxia (IMA) where spatial and temporal production errors are most prevalent. IMA can be associated Alzheimer's disease (AD), even early in its course, but is often not identified possibly because the evaluation of IMA by inexperienced judges using performance tests is unreliable. The purpose of this study, therefore, is to learn if the Postural Knowledge Test (PKT), a praxis discrimination test that assesses knowledge of transitive (PKT-T subtest) and intransitive (PKT-I subtest) postures and does not require extensive training, is as sensitive and specific as the praxis performance tests. METHODS: We studied 15 subjects with probable AD as well as 18 age-matched controls by having them perform transitive and intransitive gestures to command and imitation, as well as having them discriminate between correct and incorrect transitive and intransitive postures. RESULTS: Overall on all tests, the control subjects performed better than those with AD. In addition all subjects had more trouble with transitive than intransitive gestures. Using a stepwise discriminative analysis, 81.8% of the subjects could be classified according to Group (94.4% of Controls, 66.7% of AD subjects). In this analysis, the PKT-T (transitive posture subtest) was the only measure that contributed to the discrimination of subjects. CONCLUSION: We found that having subjects select the correct transitive hand postures in this "booklet test" was more sensitive than grading their praxis performances even when using judges with extensive training. This suggests that this discrimination test might be an excellent means for diagnosing and screening patients for AD. The reason why recognition of transitive postures is relatively more difficult for our AD subjects is not known. Two possibilities are that the representations for intransitive movements are stronger than those for transitive movements, and hence, more resistant to degradation, or that intransitive acts are stored in parts of the brain not affected by AD.

Aged↗

PubMed2006

Lewy body dementia and creativity: case report.

BACKGROUND: We studied a visual artist with Lewy body dementia (LBD) to learn how this disease influenced his paintings during the course of the disease. METHODS: Study 1 evaluated two paintings of the same subject matter, one that the patient painted before his illness and the other after the onset of this disease. Study 2 evaluated a collection of his paintings from the time before he was ill (1994) until the time he stopped painting when he was suffering with LBD (2002). To learn how the onset and progression of LBD affected his paintings we had judges score the following qualities: aesthetic-beauty, closure completeness, evocative impact, novelty, technique and representational quality. RESULTS: In Study 1 we found that the representational ratings for the picture he painted when he had LBD was significantly lower than the picture he painted before he developed LBD. In Study 2, we found that all the artistic qualities measures temporally declined except novelty. We also found that the paintings that were judges as having the highest quality representations were significantly more novel than those that had poorer representations. In addition, we conducted a forward stepwise regression analysis using quality measures as predictor of year. This analysis revealed that only representational quality significantly predicted painting year. CONCLUSIONS: Our results suggest that as LBD progresses, except for novelty there is a gradual degradation of the ability to visually express artistic subject matter. It possible that the preserved ability to paint novel picture is related to relative preservation of frontal lobe function, but the degradation of other artistic qualities might be related to deterioration of the parietal lobes which either impairs the brain's iconic representations or the knowledge needed to portray these representations.

Adult↗

PubMed2006

The right arm likes to be close.

A prior study revealed that the left (vs. right) hemisphere has a visual attentional bias toward the body, a finding that is consistent with the observation that most of the visual cognitive activities performed by the left hemisphere (e.g., reading) take place in proximal (peripersonal) space. In addition, when right-handed people perform bimanual motor tasks their right hand is often held more proximal to the body than their left hand. In this study, we wanted to test the hypothesis that the right hand is also more biased toward the body than is the left hand. Thus, we had blindfolded right-handed subjects attempt to draw straight horizontal lines (at the junction of the transverse and coronal planes), with their left and right hands, on sheets of paper placed in front of them and then measured their deviation from the coronal plane. We found that these subjects' right hands deviated closer to their body than did their left hands. These results support the postulate that in addition to an attentional bias, the left hemisphere-right hand has a proximal motor bias. This bias might account for means by which right-handed people position their hands when using both hands on tools and implements.

Adult↗

PubMed2006

Ipsilesional attentional-approach neglect or crossover effect.

Patients with ipsilateral neglect (IN) bisect lines toward contralesional space. It has been posited that IN might be induced by an attempt at compensation, as part of the crossover effect, where patients with an ipsilesional bias when bisecting long lines, cross over and develop a contralesional bias on short lines or as a release of an approach (grasp) behavior that might be attentional or intentional. To test these alternative hypotheses we had a patient with IN from a right medial frontal lesion bisect lines that contained no cue, a left-sided cue, a right-sided cue, and bilateral cues. If this patient had ipsilateral neglect (IN) because of a crossover effect or compensation, right-sided cues should have influenced bisection more than left-sided cues. We, however, found that only left-sided cues induced a significant change (left-sided deviation) providing support for the attentional-approach (grasp) hypothesis. Further support of this contralesional attentional grasp hypothesis comes from the observation that this patient also had ipsilesional extinction to simultaneous stimuli.

Attention↗

PubMed2006

Finger agnosia in Alzheimer disease.

BACKGROUND AND OBJECTIVE: The purpose of this study was to learn if a deficit of finger naming (finger agnosia or anomia) is a sensitive test for Alzheimer disease (AD) and the best means of testing for finger agnosia. METHODS: The subjects were 38 patients with AD and 10 matched normal controls. All subjects were asked to name the thumb, index, and pinky fingers. RESULTS: No control subject had trouble naming any of these fingers, but 37% of the AD subjects did. When AD patients had difficulty with finger naming, they always had trouble naming the index finger. CONCLUSIONS: In the absence of stroke, the inability to name the index finger seems as an indicator of dementia. Although brief, this test is not extremely sensitive test for AD.

Agnosia↗

PubMed2006

Distribution of attention in normal people as a function of spatial location: right-left, up-down.

The spatial allocation of attention influences estimates of stimulus magnitude, including line length and the line bisection task has been used to assess the asymmetrical allocation of spatial attention. The purpose of this study is to learn if normal subjects' allocation of attention changes as a function of the trunk-head centered spatial position of the line stimuli. Normal subjects were asked to bisect lines placed in five different head-trunk centered special positions (central, right up-distal, left up-distal, right down-proximal, left down-proximal). When compared with the central condition, deviations in the right or left lateral conditions were only significant in the down-proximal conditions, such that the bisection bias significantly shifted direction to the left of the objective midline in left hemispace and to the right of the objective midline in right hemispace, suggesting that stimuli presented in lateral hemispace primarily activate the contralateral hemisphere's attentional systems. The finding that the lines presented in down-proximal lateral hemispace induce a greater spatial bias than lines in up-distal lateral space suggests that the portion of the brain's dorsal visual system, which processes stimuli in down-proximal space, influences the horizontal (right-left) spatial allocation of attention more than does the brain's ventral visual system.

Adult↗

PubMed2004

Eye patching biases spatial attention after thalamic hemorrhage in a patient without spatial neglect: a case report.

Monocular patching has been advocated as a treatment for spatial neglect. Eye patching, however, is also reported to increase spatial bias. Thus, patching brain injury patients for ocular conditions may also impair their attention. To learn if an eye patch may induce asymmetric attention in a patient without spatial neglect, we tested a woman with diplopia after a left thalamic-intraventricular hemorrhage. She had no spatial neglect on bedside attention tasks. Using a laser pointer, she bisected a blank space at near (279 mm) and far (914 mm) distances under 3 conditions: unpatched and wearing a right or left eye patch. Unpatched, she showed no bias. She erred further leftward with right patching at both distances. Right eye patching appeared to induce neglect of right space when the patient performed this task. With left patching, leftward error tended to increase in near space only. Clinicians prescribing eye patches to patients with brain injury even for purely ocular indications, should evaluate them for spatial neglect once the patch is in place.

Adult↗

PubMed2004

Novel treatments for expressive aprosodia: a phase I investigation of cognitive linguistic and imitative interventions.

This study investigated two mechanism-based treatments for expressive aprosodia, a disturbance in emotional prosody thought to be governed by the right hemisphere. The 3 participants all suffered right CVA's resulting in expressive aprosodia. Presence of expressive aprosodia was determined by performance on two batteries of emotional communication. A single subject ABAC design was employed in which two treatments, one imitative and one cognitive linguistic, were assigned in random order. All participants in this study were randomly assigned to begin with the cognitive linguistic treatment. Probes of treated and untreated emotions were completed during baseline and therapy phases. Probe items were judged by a reliable, trained rater blind to time of testing. Visual and statistical analyses were completed. These analyses confirmed that both treatments were active. For example, effect size calculations confirmed modest to substantial treatment effects for both treatments in all 3 patients. Replication to increase confidence about treatment effect and enhance understanding of the neuromechanisms underlying aprosodia is underway.

Aged↗

PubMed2003

Visual-spatial ability in Parkinson's disease.

Parkinson's Disease (PD) has traditionally been viewed as primarily a disturbance of motor functioning, typically involving tremor, rigidity, hypokinesia, gait disturbance, and postural instability. More recently, decline in cognitive function has been recognized as a feature of PD. One prominent cognitive symptom of PD involves deficits on tasks of spatial ability. However, findings of visual-spatial deficits in individuals with PD have been inconsistent. There are several methodological issues in this area of research that potentially confound the interpretation of data and need to be taken into consideration, including subject characteristics (e.g., age, sex and education), duration of illness, the current level of disability, the presence of emotional depression, the current level of medications, and the presence of dementia. Further, the tests that have shown visual-spatial deficits in PD are often complex, showing sensitivity to other cognitive processes as well. Another problem in this area of research is the lack of a clear understanding of the brain mechanisms that underlie visual-spatial deficits in PD. One theory of cognitive dysfunction in PD suggests that these cognitive deficits are in some way related to disruption of frontal-basal ganglia neural circuits important in executive functions. However, frontal-basal ganglionic dysfunction does not appear to account entirely for the visual-spatial cognitive deficits seen in PD. Subtle differences in performance on executive function measures appear to dissociate individuals with frontal lobe damage from individuals with PD. Findings from two recent studies indicate that PD is indeed associated with deficits in visual-spatial ability. These findings also indicate that the relationship between visual-spatial ability and frontal-executive function in PD is likely complex, and that the visual-spatial deficits in PD may be sensitive to the sex of the individual with PD.

Humans↗

PubMed2003

Mental object rotation in Parkinson's disease.

Deficits in visual-spatial ability can be associated with Parkinson's disease (PD), and there are several possible reasons for these deficits. Dysfunction in frontal-striatal and/or frontal-parietal systems, associated with dopamine deficiency, might disrupt cognitive processes either supporting (e.g., working memory) or subserving visual-spatial computations. The goal of this study was to assess visual-spatial orientation ability in individuals with PD using the Mental Rotations Test (MRT), along with other measures of cognitive function. Non-demented men with PD were significantly less accurate on this test than matched control men. In contrast, women with PD performed similarly to matched control women, but both groups of women did not perform much better than chance. Further, mental rotation accuracy in men correlated with their executive skills involving mental processing and psychomotor speed. In women with PD, however, mental rotation accuracy correlated negatively with verbal memory, indicating that higher mental rotation performance was associated with lower ability in verbal memory. These results indicate that PD is associated with visual-spatial orientation deficits in men. Women with PD and control women both performed poorly on the MRT, possibly reflecting a floor effect. Although men and women with PD appear to engage different cognitive processes in this task, the reason for the sex difference remains to be elucidated.

Aged↗

PubMed2003

Age-dependent recall bias for material of internal versus external origin.

OBJECTIVE: To learn whether young and aged subjects exhibit different recall biases for internally derived (Internal) versus externally supplied (External) material. BACKGROUND: Internally derived knowledge, prized by educators and therapists, can bring about dramatic behavioral change. Such information, seldom assessed on formal memory testing, may be preferentially recalled compared with external-origin material. Under some circumstances, however, subjects may demonstrate a recall advantage for externally supplied over internally generated material. METHOD: We compared Internal and External word recall in young and aged subjects with and without explicit intent to remember. RESULTS: Although overall the young and aged subjects recalled the same number of words, we did find a word-origin recall bias. This recall bias differed by age group (P = 0.005). When not instructed to remember words, the young subjects tended to remember more External words, while aged subjects remembered more Internal words. CONCLUSIONS: The differences in the brain mechanisms mediating Internal versus External recall bias are unknown. However, aging may modify an Internal-External memory bias.

Adult↗

PubMed2002

Is the middle between both halves?: midpoint location and segment size estimation in neglect.

BACKGROUND: Line bisection errors in neglect are attributed to perceptual size distortions. In order to compare the two segments of the line to determine if they are equal, one might first estimate the location of a midpoint that defines the two line segments to be compared. OBJECTIVES: The authors attempted to determine whether estimating a line's midpoint can be dissociated from comparing the two segments of this line, and if so, what the relative contribution of each of these tasks is to the perceptual bias in neglect. METHODS: The authors studied two patients with hemispatial neglect from right hemisphere lesions by asking them where bisection marks were placed on prebisected lines and whether the two adjacent line segments were equal. RESULTS: There was a stronger bias judging the position of the bisecting marks ("where" determination) than comparing the size of two adjacent line segments. CONCLUSIONS: These results suggest that perceptual size distortion of line segments alone cannot explain the subjects' line bisection bias, but postperceptual deficits in "where" computations may better account for their errors locating the midpoint. "Where" determinations might require more attentional capacity, depend more heavily on viewer-centered allocation of attention, and be mediated by the right hemisphere's "where" dorsal stream. In contrast, comparing the length of two segments might be mediated by the left hemisphere's "what" ventral stream.

Aged↗

PubMed2002

Far bias on the radial line bisection task: measuring perceptual-attentional and motor-intentional bias in normal subjects.

Normal subjects usually err distally when bisecting radial lines below eye level in midsagittal space (far bias). To learn if a radial line bisection bias may be characterized as primarily perceptual-attentional or primarily motor-intentional, we had subjects bisect lines while watching their hand and the line under two video monitoring conditions. In the DIRECT condition, proximal (near) and distal (far) on the video monitor corresponded with the workspace where subjects bisected lines. In the INDIRECT condition, we reversed proximal and distal as they appeared on the monitor. Thus, in the indirect condition, distal hand movement appeared proximal, and vice versa. In the DIRECT condition, subjects erred toward far space (mean 2.075 mm). In the INDIRECT condition, however, subjects erred proximally (mean 1.59 mm, near bias). Distal-proximal reversal of errors over the group of subjects is consistent with a primarily perceptual-attentional bias. In lower body space, normal visual-perceptual-attentional systems may be more biased toward far space than are kinesthetic-motor systems.

Adolescent↗

PubMed2002

Spatial bias: effects of early reading direction on Korean subjects.

Spatial bias may occur in subjects performing a number of cognitive and visual-motor tasks. These include coordinate visuospatial computations (e.g. bisecting a line) and categorical representations of syntactic information (e.g. drawing a picture depicting the action of a sentence). Readers of European languages scan from left-to-right and this learned visual scanning may contribute to leftward spatial bias. In 30 subjects who first learned to read in a top-to-bottom, right-to-left direction (right-left vertical readers, RL), we tested spatial-syntactic bias by reading sentences to subjects, who drew pictures depicting the actions. We noted whether the subject of the sentence was located leftward or rightward of the object. We assessed visual-spatial bias by measuring subjects' accuracy at bisecting lines, and by measuring how closely their drawings on the house-tree-person test were centered on the page. On the spatial-syntactic task, the RL were not right- or left-biased (P=0.581). Korean controls (left-right horizontal readers, LR) also showed no significant spatial-syntactic bias. RL only tended to bisect lines leftward, but displaced house-tree-person drawings left of page center (P<0.001). LR erred leftward on line bisection, and had a smaller magnitude leftward bias on drawing tasks. We conclude that a leftward spatial-syntactic bias may not be innate and does not appear to be influenced by learned reading direction. In contrast, the leftward visual-spatial bias may occur in subjects whose cultural and reading background is neither western nor left-to-right.

Adult↗

PubMed2002

Postural knowledge of transitive pantomimes and intransitive gestures.

Patients with apraxia are more impaired when performing transitive pantomimes than intransitive gestures. This dissociation might be related to the differences in movement complexity. Alternatively, the programs for intransitive gestures might be better defined, more widely distributed, or easier to activate than are those for transitive pantomimes. The purpose of this study was to test the complexity versus representational hypotheses. Twenty right-handed normal subjects both performed and discriminated correct from incorrect transitive pantomimes and intransitive gestures. The discrimination was performed by having subjects point at illustrations of hand postures. The subjects performed better when discriminating postures than when performing gestures or pantomimes. On both the production and discrimination tests, subjects performed better with intransitive gestures than transitive pantomimes. Although the finding that even normal subjects had more difficulty performing transitive pantomimes than intransitive gestures might appear to support the complexity hypothesis, that subjects also had more difficulty discriminating transitive than intransitive postures supports the representational activation hypothesis.

Adult↗

PubMed2002

Emotional experience and perception in the absence of facial feedback.

The facial feedback hypothesis suggests that facial expressions are either necessary or sufficient to produce emotional experience. Researchers have noted that the ideal test of the necessity aspect of this hypothesis would be an evaluation of emotional experience in a patient suffering from a bilateral facial paralysis; however, this condition is rare and no such report has been documented. We examined the role of facial expressions in the determination of emotion by studying a patient (F.P.) suffering from a bilateral facial paralysis. Despite her inability to convey emotions through facial expressions, F.P. reported normal emotional experience. When F.P. viewed emotionally evocative slides her reactions were not dampened relative to the normative sample. F.P. retained her ability to detect, discriminate, and image emotional expressions. These findings are not consistent with theories stating that feedback from an active face is necessary to experience emotion, or to process emotional facial expressions.

Adult↗

PubMed2002

Cerebral blood flow changes in depressed patients after treatment with repetitive transcranial magnetic stimulation: evidence of individual variability.

OBJECTIVE: To elucidate the neural mechanisms of depression. BACKGROUND: Despite extensive study, the neurophysiology of the brain's state(s) corresponding to depression remains uncertain. METHODS: HMPAO single photon emission computed tomographic (SPECT) scans were obtained from eight adults diagnosed with major depression resistant to medication (average age 51 years; 4 men) before and immediately after 10 days of 20 Hz repetitive transcranial magnetic stimulation (rTMS) (2000 stimuli/daily 30' treatment). To maximize the likelihood that SPECT scans reflected the state of depression, rather than uncontrolled responses of patients to poorly constrained environments, HMPAO was administered while subjects performed a simple task involving continuous monitoring of the direction of a large arrow on a computer screen and continuously tapping with the left or right index finger according to the direction of the arrow. Mean baseline Beck Depression Inventory (BDI) score was 27.4 (SD = 8.3) and mean posttreatment BDI score was 17.5 (SD = 8.5). RESULTS: Treatment responders (defined by reduction in BDI score of > or = 30%) had significantly less pretreatment blood flow in the left amygdala compared with nonresponders. Responders demonstrated two patterns of change in regional blood flow with treatment: a reduction in orbitofrontal blood flow and/or a reduction in anterior cingulate blood flow. Nonresponders did not demonstrate any regional changes in blood flow with treatment. CONCLUSIONS: These results suggest that there may be either more than one state of depression, or that depression may be associated with more than one pattern of psychologic activity, which in turn defines the depressive experience for individual patients.

Adult↗