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Frontal lobe neglect in monkeys
K M Heilman1, E Valenstein, A Day
1Department of Neurology, University of Florida College of Medicine, Gainesville, USA.
Neurology
|June 1, 1995
Summary
Monkeys with frontal lesions show motor neglect, not sensory neglect. A new task revealed ipsilateral arm errors, termed "allokinesia," suggesting a disinhibition defect.
Area of Science:
- Neuroscience
- Primate Behavior
Background:
- Unilateral frontal lesions in primates can induce neglect.
- Previous tasks suggested motor rather than sensory neglect, but might not detect subtle sensory deficits.
Purpose of the Study:
- To investigate sensory neglect after frontal lesions using a perceptually complex task.
- To characterize motor deficits and unusual ipsilateral arm responses.
Main Methods:
- Two monkeys underwent unilateral frontal (arcuate gyrus) ablation.
- A perceptually complex crossed-response task was employed to assess sensory and motor neglect.
- Behavioral responses and errors were meticulously recorded.
Main Results:
- No contralateral perceptual disorders or sensory neglect were observed.
- Both monkeys exhibited contralateral arm motor neglect.
- Increased incorrect responses with the ipsilateral arm were noted, termed 'allokinesia'.
Conclusions:
- Frontal lesions primarily cause motor neglect, not sensory neglect, in this task.
- The ipsilateral arm errors ('allokinesia') represent a disinhibition defect, not a compensatory strategy.
- This finding refines our understanding of neglect after arcuate gyrus lesions.