Recognition of category-related visual stimuli in Parkinson's disease: before and after pharmacological treatment.
Visual-sensory dysfunctions and semantic processing impairments are widely reported in Parkinson's disease (PD) research. The present study investigated the category-specific deficit in object recognition as a function of both the semantic category and spatial frequency content of stimuli. In the first experiment, the role of dopamine in object-recognition processing was assessed by comparing PD drug naïve (PD-DN), PD receiving levodopa treatment (PD-LD), and control subjects. Experiment 2 consisted of a retest session for PD drug naïve subjects after a period of pharmacological treatment. All participants completed an identification task which displayed animals and tools at nine levels of filtering. Each object was revealed in a sequence of frames whereby the object was presented at increasingly less-filtered images up to a complete version of the image. Results indicate an impaired identification pattern for PD-DN subjects solely for animal category stimuli. This differential pharmacological therapy effect was also confirmed at retest (experiment 2). Thus, our data suggest that dopaminergic loss has a specific role in category-specific impairment. Two possible hypotheses are discussed that may account for the defective recognition of semantically different objects in PD.
Dipartimento di Psicologia, Università degli Studi di Firenze, Via s. Niccolò 93, 50125 Firenze, Italy. srighi@unifi.it
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Righi
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Viggiano
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Paganini
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Ramat
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Marini
D000368:Aged; D000704:Analysis of Variance; D000978:Antiparkinson Agents / Q000627:therapeutic use*; D016022:Case-Control Studies; D002965:Classification; D015350:Contrast Sensitivity / Q000187:drug effects / Q000502:physiology*; D004298:Dopamine / Q000502:physiology; D005260:Female; D005556:Form Perception / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000188:drug therapy* / Q000503:physiopathology / Q000523:psychology; D010775:Photic Stimulation; D021641:Recognition, Psychology / Q000187:drug effects* / Q000502:physiology; D012016:Reference Values; D018709:Statistics, Nonparametric
D000978:Antiparkinson Agents; D007980:Levodopa; D004298:Dopamine