Random motor generation in a finger tapping task: influence of spatial contingency and of cortical and subcortical hemispheric brain lesions

Abstract

Objective-To test the hypothesis that, during random motor generation, the spatial contingencies inherent to the task would induce additional preferences in normal subjects, shifting their performances farther from randomness. By contrast, perceptual or executive dysfunction could alter these task related biases in patients with brain damage. Methods-Two groups of patients, with right and left focal brain lesions, as well as 25 right handed subjects matched for age and handedness were asked to execute a random choice motor task-namely, to generate a random series of 180 button presses from a set of 10 keys placed vertically in front of them. Results-In the control group, as in the left brain lesion group, motor generation was subject to deviations from theoretical expected randomness, similar to those when numbers are generated mentally, as immediate repetitions (successive presses on the same key) are avoided. However, the distribution of button presses was also contingent on the topographic disposition of the keys: the central keys were chosen more often than those placed at extreme positions. Small distances were favoured, particularly with the left hand. These patterns were influenced by implicit strategies and task related contingencies. By contrast, right brain lesion patients with frontal involvement tended to show a more square distribution of key pressesthat is, the number of key presses tended to be more equally distributed. The strategies were also altered by brain lesions: the number of immediate repetitions was more frequent when the lesion involved the right frontal areas yielding a random generation nearer to expected theoretical randomness. The frequency of adjacent key presses was increased by right anterior and left posterior cortical as well as by right subcortical lesions, but decreased by left subcortical lesions. Conclusions-Depending on the side of the lesion and the degree of corticalsubcortical involvement, the deficits take on a diVerent aspect and direct repetions and adjacent key presses have diVerent patterns of alterations. Motor random generation is therefore a complex task which seems to necessitate the participation of numerous cerebral structures, among which those situated in the right frontal, left posterior, and subcortical regions have a predominant role.

Brain fMRI Activation Associated with Self‐Paced Finger Tapping in Chronic Alcohol‐Dependent Patients

“…Most efferent neurons from the cerebellum to the spinal cord do not cross in the brainstem but those to the motor cortex cross in the medulla (Goetz and Pappert, 1999). These classically accepted neuroanatomic principles have recently received support from fMRI studies (Annoni and Pegna, 1997;Desmond et al, 1997;Rao et al, 1993). Therefore, our findings may be interpreted as supporting the so-called "right hemisphere hypothesis" of alcohol-induced brain injury, a notion that has received only equivocal support from the literature (Oscar-Berman, 2000).…”

Changes in artistic style after minor posterior stroke

“…16 The role of the thalamus and posterior brain structures in executive functions has been reported [33][34][35] and is supported by data from functional imaging studies. 36 Simplification of drawing and attention to detail have both been described in some patients with frontal dementia.…”

A computer program for testing and analyzing random generation behavior in normal and clinical samples: The Mittenecker Pointing Test

“…Since the development of the original MPT, other authors have suggested alternatives to the classical verbal random generation tasks, also involving motor responses (e.g., Annoni & Pegna, 1997;Baddeley, 1996;Hoffmann et al, 2003;Schneider, Joppich, van der Lugt, Däuper, & Münte, 2004). We prefer the MPT because it does not use labeled response sets, which may confound random number generation with random motor generation.…”