Biomedical subjects

J Vincent Filoteo

Publications and source records attributed to J Vincent Filoteo.

25 records · Page 2Linked to original sources

PubMed2003

Semantic and cross-case identity priming in patients with Parkinson's disease.

Semantic and cross-case identity priming were investigated in nondemented patients with Parkinson's disease (PD) and controls using the Lexical Decision Task. Three conditions were administered that consisted of the presentation of prime and target word pairs. In the semantic priming condition the word pairs were semantically related (e.g., table-CHAIR), in the cross-case identity priming condition the word pairs consisted of the same word (e.g., noise-NOISE), and in the unrelated condition the word pairs were not related semantically (e.g., guns-DEEP). A fourth condition was also administered that consisted of the presentation of a prime word and a pronounceable nonword target (e.g., starved-FORVE). Participants were asked to indicate whether the target was a real word or a nonword. The prime and target were separated by either a short or long (250 ms or 1000 ms) stimulus onset asynchrony (SOA). Results indicated that PD patients displayed normal semantic priming (i.e., faster responding to the target in the semantic condition as compared to the unrelated condition) at both the short and long SOA. Similarly, PD patients displayed normal cross-case identity priming (i.e., faster responding to the target in the identity condition relative to the unrelated condition) at the long SOA. At the short SOA, however, PD patients displayed hyper identity priming relative to controls (134 ms vs. 50 ms). These results suggest that semantic processes are normal in nondemented PD patients but that the processes involved in accessing lexical information may be overly activated in these patients.

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PubMed2003

Category learning deficits in Parkinson's disease.

Sixteen patients with Parkinson's disease (PD), 15 older controls (OCs), and 109 younger controls (YCs) were compared in 2 category-learning tasks. Participants attempted to assign colored geometric figures to 1 of 2 categories. In rule-based tasks, category membership was defined by an explicit rule that was easy to verbalize, whereas in information-integration tasks, there was no salient verbal rule and accuracy was maximized only if information from 3 stimulus components was integrated at some predecisional stage. The YCs performed the best on both tasks. The PD patients were highly impaired compared with the OCs, in the rule-based categorization task but were not different from the OCs in the information-integration task. These results support the hypothesis that learning in these 2 tasks is mediated by functionally separate systems.

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PubMed2002

Visual perception without awareness in a patient with posterior cortical atrophy: impaired explicit but not implicit processing of global information.

A patient with progressive posterior cortical atrophy (PCA) was examined on several tests of visual cognition. The patient displayed multiple visual cognitive deficits, which included problems identifying degraded stimuli, attending to two or more stimuli simultaneously, recognizing faces, tracing simple visual stimuli, matching simple shapes, and copying objects. The patient was also impaired in identifying visual targets contained at the global level within global-local stimuli (i.e., smaller letters that compose a larger letter). Although the patient denied any conscious awareness of the global form, he nevertheless displayed a normal pattern of global interference when asked to identify local level targets. Thus, the patient processed the global information despite not being consciously aware of such information. These results suggest that global-local processing can take place in the absence of awareness. Possible neurocognitive mechanisms explaining this dissociation are discussed.

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PubMed2002

Lateralized perceptual organization deficits on the global-local task in schizotypal personality disorder.

Right and left hemisphere contributions to perceptual organization functions were examined using a divided-attention version of the global-local task in a sample of 21 unmedicated participants diagnosed with schizotypal personality disorder (SPD) and 20 controls. The SPD participants showed an abnormal global processing advantage. When the visual angle of the hierarchical stimuli was increased from 3 degrees to 9 degrees, the controls showed an increasing local processing advantage, but the SPD participants continued to show an abnormal global processing advantage. These findings suggest a local processing deficit on divided-attention versions of the global-local task in schizophrenia spectrum disorders. Female SPD participants, who had less severe interpersonal deficit symptoms, showed a more abnormal global processing advantage. Hemispheric and processing resource mechanisms that might explain these findings are discussed.

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PubMed2002

Negative priming in patients with Parkinson's disease: evidence for a role of the striatum in inhibitory attentional processes.

Patients with Parkinson's disease (PD) and normal controls (NCs) performed a negative priming task. NCs displayed the normal pattern of negative priming in that relative to a control condition they were slower to identify a target within a stimulus array when it had been a distractor in the previous array. PD patients did not display any evidence of negative priming. In contrast, both PD patients and NCs displayed statistically the same level of spatial priming and response repetition cost. Regression analyses indicated that although symptom severity, symptom characteristics, and global cognitive functioning were not reliable predictors of negative priming or spatial priming in PD patients, greater symptom severity and poorer global cognitive functioning were associated with less response repetition cost. The possible role of the striatum in negative priming, spatial priming, and response repetition cost is discussed.

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PubMed2002

Divergent findings regarding negative priming in Parkinson's disease: A comment on Filoteo et al. (2002) and Wylie and Stout (2002).

This commentary discusses divergent findings in 2 articles published in this issue of Neuropsychology. The studies used negative priming (NP) to probe the associations between basal ganglia function and cognition in Parkinson's disease (PD) and tested different predictions about NP in PD. Different NP tasks were used, and although the subject samples appeared to have similar clinical features, results were quite different. This commentary, written jointly by the authors of the 2 studies (J. V. Filoteo, L. M. Rilling, & D. L. Strayer, 2002; S. A. Wylie & J. C. Stout, 2002), describes a process by which their disparate results may be used to facilitate the design of new studies that may determine how specific features of NP tasks lead to different findings in PD. The results are a more systematic account of how task features, such as specific response demands, interact with the response selection processes that are implemented by the basal ganglia.

Basal Ganglia↗

PubMed1999

Hemispheric and attentional contributions to perceptual organization deficits on the global-local task in schizophrenia.

Right and left hemisphere hypotheses have been proposed to account for cognitive deficits in schizophrenia. To examine these hypotheses, perception of global-local patterns was studied in 22 patients with schizophrenia and 28 normal comparison participants. The patients with schizophrenia showed an abnormally exaggerated global processing advantage when attention was divided between global and local levels but not when participants were instructed to attend to either the local or global level. This finding suggested a local processing (left hemisphere) deficit, which was overcome through strategic attentional allocation (instructional set). When the stimulus visual angle was reduced from 9 degrees to 3 degrees, the normal participants showed a shift from a local to a global processing advantage, but the patients did not. This finding suggested a more subtle deficit in strategic attentional processes that develop through exposure to stimulus context.

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