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Results for “Imitative Behavior”

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PubMed2004

Script generation following frontal and parietal lesions.

The purpose of this investigation was to distinguish putative effects of parietal lobe lesions on script generation, in distinction from the better known and established effects of frontal lobe lesions. Nine patients, most with excised parietal lesions, were compared to nine age, gender and education matched normal participants. Eleven patients with excised tumors of the frontal lobe were compared to twelve age, gender and education matched normal subjects. Participants were requested to generate, out loud, scripts corresponding to everyday activities. Half the scripts were relatively more demanding with respect to temporal representation (understanding the time line of events) and the other half with respect to spatial representation (understanding the layout of the actions in space). These two conditions were further broken down into conditions of high and low demands on working memory (reciting the scripts backwards versus forward). The frontal lobe patients enunciated significantly fewer actions overall. They were also significantly more impaired than the normal participants on all tasks with high demands on working memory, and more often, high temporal demands (sequencing and perseverative errors). The parietal lobe patients had significant difficulty in sequencing in all conditions, and manifested no perseveration. Though script generation tasks have been primarily associated with frontal lobe function until now, consideration should be given to the type of activity being scripted as a function of relative demands on spatial or temporal representation, as well as working memory, and the contributions of other lobes ought to be taken into consideration.

Adolescent↗
PubMed2002

A case study of successful voice imitation.

Our voices and speech behaviour give cues to the listener as to our identity. These cues make it possible for the listener to recognise a voice without seeing the speaker. A professional impersonator has to identify the salient and characteristic features of the target voice in order to succeed. The present phonetic study of a Swedish professional impersonator and one of his voice imitations compares the target voice, the voice imitation and the impersonator's own voice. The findings indicate that a successful impersonation is the result of the impersonator's ability to alter his voice in numerous ways.

Cues↗
PubMed1990

Space and movement in working memory.

Encoding seen movement of another human body requires visuo-spatial processing, and recall involves motor activity. However, encoding whole body movement patterns is affected differently by patterned and spatial secondary tasks, and this difference is reversed for encoding of spatial targets for movement (Smyth, Pearson, & Pendleton, 1988). The experiments reported here investigate the rehearsal of such movement patterns and their recall over unfilled and filled intervals. Performing, watching, or encoding a sequence of spatial positions while carrying a memory load of movement patterns did not affect recall of those movements, whereas performing, watching, or encoding a further set of patterned movements reduced the number recalled from the original set. However, memory for a series of locations in space was not affected by watching patterned movements during the interval, and only order information was affected by watching movement to a series of spatial locations during the interval. The results are discussed in terms of the independence of rehearsal mechanisms for spatial sequencing and movement patterns.

Adult↗
PubMed1982

Modality-specific and supramodal mechanisms of apraxia.

This study investigated the relation of apraxia to the nature of the stimulus which is given to elicit the gesture. Patients were required to perform a movement imitation test and to demonstrate the use of the same ten objects, once on verbal command, once with the object shown but not handled, and once with the object handled but not seen. One set of comparisons concerned the performance on two tasks involving the visual modality, movement imitation and use of objects presented visually. Although the majority of left brain-damaged patients either failed or passed both tests, there were at least 13 patients who showed an exceedingly poor performance on demonstration of use as compared to imitation. We infer that the distinction between ideational and ideomotor apraxia is warranted. Another set of comparisons concerned the performance on the use of objects presented in the verbal, visual and tactile modalities. A greater percentage of patients failed on the verbal or visual modalities than on the tactile modality. Out of 64 left brain-damaged patients who were diagnosed as apraxic in at least one modality, 23 had an exceedingly poor score on one test as compared to their score on either or both other tests. Fourteen patients selectively failed on verbal presentation, 14 on visual presentation and 2 on tactile presentation. These findings are viewed as supporting the hypothesis that apraxia results from the disconnection between the areas where information is processed and the areas where the movement is programmed.

Apraxias↗
PubMed1999

The effects of learning and intention on the neural network involved in the perception of meaningless actions.

PET was used to explore the neural network involved in the perception of meaningless action. In two conditions, subjects observed learned and unknown meaningless actions without any purpose. In two other conditions, subjects observed the same type of stimuli for later imitation. The control condition, which consisted of the presention of stationary hands, served as a baseline. Unsurprisingly, a common network that forms part of the dorsal pathway was engaged in all conditions when compared with stationary hands, and this was interpreted as being devoted to the analysis of hand movements. One of the most striking results of the present study was that some brain areas were strongly modulated by the learning level, independent of the subject's intention. Two different effects were observed: a reduced activity in posterior regions within the common network, which correlated with specific increases in the frontopolar area 10 and in the angular gyrus during the perception of learned meaningless actions compared with the perception of unknown actions. Finally, the major effect of the subject's intention to imitate was a strong increase in the dorsal pathway extending to the lateral premotor cortex and to the dorsolateral prefrontal cortex, which reflects the information processing needed for prospective action. Overall, our results provide evidence for both an effect of the visuomotor learning level and of the subject's intention on the neural network involved during the perception of human meaningless actions.

Adult↗
PubMed2004

Is Broca's area crucial for imitation?

Some neuroimaging studies have reported activation by imitation in the left Brodmann area 44 (BA 44), a part of Broca's area considered to be a neural substrate for speech production. However, in these previous studies the subjects were required to perform the same movements repeatedly so that the experimental stimuli could be viewed as cues when to do the given movements rather than a specification of what to do. Activation in the left BA 44 has also been observed in delayed motor execution tasks. This may confound the activity in BA 44 for imitation tasks used in the former studies. We tested the involvement of bilateral BA 44 and BA 45 in imitation and delayed execution tasks by functional magnetic resonance imaging with cytoarchitectonically defined BA 44 and BA 45 as volumes of interest. Our tasks required the subjects to perform a transformation from visual information (photographs of hand postures or symbolic specification of the postures) into a new hand movement in each trial. A three-way analysis of variance was performed with factors instruction, execution timing and area. The results revealed significant main effect by execution timing and by area, but not by instruction. We conclude that Broca's area does not play a pivotal role in imitation.

Adult↗
PubMed2005

The clock drawing test is an independent predictor of incident use of 24-hour care in a retirement community.

BACKGROUND: It is unclear how early cognitive impairment affects future care needs. Furthermore, the Mini-Mental State Examination (MMSE), a commonly used screening tool in the clinical setting, tends to have a ceiling effect for early cognitive decline. One of the earliest changes in cognitive function is executive impairment. We examined the relationship between executive function, measured with a clock drawing protocol (CLOX1) designed to capture executive impairment, and incident need for increased level of care and total mortality. METHODS: Residents (n = 230) in independent living at a continuing care retirement community were followed for incident need for 24-hour care (mean 2.5 years). Baseline assessment included health status and physical and cognitive function. Time to event analysis was performed to determine the association of the CLOX1 score with the outcomes. RESULTS: Forty percent of residents had a CLOX1 score <12, and 10% had an MMSE score <26. The event rate for a CLOX1 score <12 was 30 per 100 person-years (p-y) and 13 per 100 p-y for a score > or =12. Similarly, the event rate was 34 per 100 p-y versus 17 per 100 p-y for MMSE <26 and MMSE > or =26, respectively. A CLOX1 score <12 was associated with a twofold higher risk of incident use of 24-hour care (hazard ratio 2.2; 95% confidence interval: 1.5-3.4) and death (hazard ratio 2.3; 95% confidence interval: 1.1-4.8) even after controlling for age, sex, comorbidity, and MMSE scores. The MMSE score was not an independent predictor of incident use of 24-hour care or mortality. CONCLUSION: The clock drawing test, scored for executive impairment, but not the MMSE, predicted incident use of 24-hour care and mortality in this cohort of independent older adults.

Aged↗
PubMed1978

Utilization of services for preventable disease: a case study of dental care in a southern rural area of the United States.

The use made of dental services, both preventive and symptomatic, was explored in a small rural southern community in North Carolina as part of a case study illustrative of southern rural patterns of utilization of elective health services. The target population of 1689 persons in 545 households was interviewed in a household survey and in each of four follow-up panel visits over a period of one year--1974--75. Though overall utilization of dental services was low and preventive dental services even lower in both blacks and whites, blacks were at a considerable disadvantage. Unlike whites, increasing education did not increase use of services in blacks; also, unlike whites, black mothers' preventive behaviour was not associated with increased dental preventive behaviour in their children. In addition to barriers to care suffered by the poor, blacks in the south still have additional barriers to overcome: Established patterns of practice are slow to change even when legal and financial barriers are lowered.

Adolescent↗
PubMed1999

Normal movement reading in Asperger subjects.

Patients with autism and Asperger syndrome (AS) are impaired in mindreading and imitation skills. One possibility would be that their 'mirror neuron' system, which matches action execution and observation, does not function properly. To test this hypothesis we compared action-viewing related motor cortex functions in an AS group (one autistic and four AS subjects) and eight control subjects. In both groups viewing hand actions modified the neuromagnetic approximately 20 Hz oscillatory activity in the primary motor cortex to the same extent. Thus impaired mindreading and imitation skills found in AS and autism do not seem to result from dysfunction of the motor cortex part of the action execution/observation system.

Adult↗