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.
Righi
S
S
Dipartimento di Psicologia, Università degli Studi di Firenze, Via s. Niccolò 93, 50125 Firenze, Italy. srighi@unifi.it
Viggiano
M P
MP
Paganini
M
M
Ramat
S
S
Marini
P
P
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