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Recent research in comparative psychology suggests that similarities between the behaviour of two individuals may not be the consequence of imitation only, but also of nonimitative social-learning processes. In the present study we aimed to investigate whether these alternative learning processes can take place in human adults, specifically in patients whose ability to imitate has been reduced by brain damage. Left (LBD) and right (RBD) brain-damaged patients were asked to perform four tool use tasks in three experimental conditions: exposure to the apparatus (N); demonstration of the correct solution (C); and demonstration of a failed attempt followed by the correct solution to the problem (I + C). Results suggest that the left hemisphere is indeed critical for action and that selective neuropsychological deficits can affect action imitation and selection of goal-directed movements, independently from each other. Findings also indicate that when the ability to imitate actions is lowered emulation may become available. [ABSTRACT FROM AUTHOR]

We report the case of OTM who presented with dynamic aphasia following a stroke that occurred in the left basal ganglia. He showed drastically reduced spontaneous speech in the context of well preserved naming, repetition and comprehension skills. OTM was particularly impaired in generating words, sentences and phrases when cued by a stimulus allowing many response options. By contrast, when a single response was strongly suggested by a stimulus, he could generate verbal responses adequately. OTM's non-verbal response generation abilities varied across tasks. He performed in the normal range in a motor movement generation test and he produced as many figures as controls when tested on a figural fluency task. He showed, however, many perseverations on this test. Moreover in a random number generation task he produced more responses that were part of ascending and descending series of numbers. The patient's impairments are interpreted as a consequence of two deficits. The first of these consists of an inability to generate verbal responses particularly in situations of high competition and involves the function of left frontal regions. The second deficit is one of impaired novel thought generation as evidenced by perseverations. This second deficit has been proposed to be a function of basal ganglia damage. [ABSTRACT FROM AUTHOR]