Leslie J. Gonzalez Rothi

A cognitive neuropsychological model of limb praxis

Abstract This paper is devoted to the development of a composite model of limb praxis processing that is supported by a series of dissociations noted in the performance of apraxic patients. These dissociations include die separability of praxis production from praxis reception, the selectivity of input modalities, an “assembled” route of praxis imitation, and the possible fragmentation of semantics into an action and a nonaction system.

Apraxia : The Neuropsychology of Action

L.J.G. Rothi, K.M. Heilman, Introduction to Limb Apraxia. K.M. Heilman, L.J.G. Rothi, Limb Apraxia: A Look Back. K.M. Heilman, Handedness. L.J.G. Rothi, C. Ochipa, K.M. Heilman, A Cognitive Neuropsychological Model of Limb Praxis and Apraxia. A.M. Rayer, C. Ochipa, Conceptual Praxis. L.J.G. Rothi, A.M. Raymer, K.M. Heilman, Limb Praxis Assessment. L.M. Maher, C. Ochipa, Management and Treatment of Limb Apraxia. H. Poizner, A.S. Merians, M.A. Clark, L.J.G. Rothi, K.M. Heilman, Kinematic Approaches to the Study of Apraxic Disorders. D.L. Harrington, K.Y. Haaland, Representations of Actions in Ideomotor Limb Apraxia: Clues from Motor Programming and Control. S.Z. Rapscak, Disorders of Writing. P.A. Square, E.A. Roy, R.E. Martin, Apraxia of Speech: Another Form of Praxis Disruption. B. Crosson, Subcortical Limb Apraxia. M.K. Morris, Developmental Apraxia. M.F. Schwartz, L.J. Buxbaum, Naturalistic Action.

Role of the Right and Left Hemispheres in Recovery of Function during Treatment of Intention in Aphasia

Two patients with residual nonfluent aphasia after ischemic stroke received an intention treatment that was designed to shift intention and language production mechanisms from the frontal lobe of the damaged left hemisphere to the right frontal lobe. Consistent with experimental hypotheses, the first patient showed improvement on the intention treatment but not on a similar attention treatment. In addition, in keeping with experimental hypotheses, the patient showed a shift of activity to right presupplementary motor area and the right lateral frontal lobe from pre-to post-intention treatment functional magnetic resonance imaging (fMRI) of language production. In contrast, the second patient showed improvement on both the intention and attention treatments. During pre-treatment fMRI, she already showed lateralization of intention and language production mechanisms to the right hemisphere that continued into post-intention treatment imaging. From pre-to post-treatment fMRI of language production, both patients demonstrated increased activity in the posterior perisylvian cortex, although this activity was lateralized to left-hemisphere language areas in the second but not the first patient. The fact that the first patients lesion encompassed almost all of the dominant basal ganglia and thalamus whereas the second patients lesion spared these structures suggests that the dominant basal ganglia could play a role in spontaneous reorganization of language production functions to the right hemisphere. Implications regarding the theoretical framework for the intention treatment are discussed.

A pilot study of use-dependent learning in the context of Constraint Induced Language Therapy

This investigation reports the results of a pilot study concerning the application of principles of use-dependent learning developed in the motor rehabilitation literature as Constraint Induced Therapy to language rehabilitation in a group of individuals with chronic aphasia. We compared treatment that required forced use of the language modality, Constraint Induced Language Therapy, (CILT) to treatment allowing all modes of communication. Both treatments were administrated intensively in a massed practice paradigm, using the same therapeutic stimuli and tasks. Results suggest that whereas both interventions yielded positive outcomes, CILT participants showed more consistent improvement on standard aphasia measures and clinician judgments of narrative discourse. These findings suggest that CILT intervention may be a viable approach to aphasia rehabilitation.

Repetitive transcranial magnetic stimulation as an adjunct to constraint-induced therapy: an exploratory randomized controlled trial.

Malcolm MP, Triggs WJ, Light KE, Gonzalez Rothi LJ, Wu S, Reid K, Nadeau SE: Repetitive transcranial magnetic stimulation as an adjunct to constraint-induced therapy: an exploratory randomized controlled trial. Am J Phys Med Rehabil 2007;86:707–715. Objective:To test the potential adjuvant effect of repetitive transcranial magnetic stimulation (rTMS) on motor learning in a group of stroke survivors undergoing constraint-induced therapy (CIT) for upper-limb hemiparesis. Design:This was a prospective randomized, double-blind, sham-controlled, parallel group study. Nineteen individuals, one or more years poststroke, were randomized to either a rTMS + CIT (n = 9) or a sham rTMS + CIT (n = 10) group and participated in the 2-wk intervention. Results:Regardless of group assignment, participants demonstrated significant gains on the primary outcome measures: the Wolf Motor Function Test (WMFT) and the Motor Activity Log (MAL)–Amount of Use, and on secondary outcome measures including the Box and Block Test (BBT) and the MAL–How Well. Participants receiving rTMS failed to show differential improvement on either primary outcome measure. Conclusions:Although this study provided further evidence that even relatively brief sessions of CIT can have a substantial effect, it provided no support for adjuvant use of rTMS.

Age-related changes in word retrieval: Role of bilateral frontal and subcortical networks

Healthy older adults frequently report word-finding difficulties, yet the underlying cause of these problems is not well understood. This study examined whether age-related changes in word retrieval are related to changes in areas of the frontal lobes thought to subserve word retrieval or changes in areas of the inferior temporal lobes thought to be involved in semantic knowledge. Twenty younger and 20 older healthy adults named aloud photographs during event-related fMRI. Results showed that in the face of equivalent naming accuracy, older adults activated a larger frontal network than younger adults during word retrieval, but there were no activity differences between groups in the fusiform gyrus, suggesting that the substrates for word retrieval but not for semantic knowledge change with aging. Additionally, correlations between BOLD response and naming accuracy and response latency were found in several frontal and subcortical regions in older adults. Findings are discussed in the context of possible compensatory mechanisms invoked to maintain performance in healthy aging, and suggest that increased involvement of the right hemisphere is not universally beneficial to performance.

Conceptual apraxia from lateralized lesions

Models of praxis have posited two major components, production and conceptual. Conceptual praxis disorders may occur in two domains: associative knowledge (tool-action associations such as hammer pound; tool-object associations such as hammer nail) and mechanical knowledge such as knowing the advantage that tools afford. Patients with Alzheimers disease not only have conceptual apraxia (CA) but can dissociate CA from language deficits and from praxis production deficits (ideomotor apraxia). These findings suggests that knowledge about tools (action semantics) is independent of verbal semantics as well as movement representations. To learn if conceptual praxis knowledge is stored in one hemisphere (right or left) and if associative and mechanical conceptual praxis knowledge can be dissociated, we studied 29 right-handed subjects with unilateral strokes. Ten had left-hemisphere damage with no ideomotor apraxia. Eleven had left-hemisphere damage with ideomotor apraxia. There were eight right-hemisphere-damaged controls and 10 normal controls. These subjects were given tests for conceptual apraxia. There was a significant difference between groups, the left-hemisphere group with ideomotor apraxia being most impaired on both the associative and mechanical CA tests. There was a trend for associative and mechanical knowledge to be dissociated. Although conceptual praxis representations are stored in the left hemisphere, analysis of lesion sites did not reveal where in the left hemisphere they may be stored.

Cognitive neuropsychological analysis and neuroanatomic correlates in a case of acute anomia

We describe an analysis of lexical processing performed in a patient with the acute onset of an isolated anomia. Based on a model of lexical processing, we evaluated hypotheses as to the source of the naming deficit. We observed impairments in oral and written picture naming and oral naming to definition with relatively intact semantic processing across input modalities, suggesting that output from the semantic system was impaired. In contrast to previous reports, we propose that this pattern represents an impairment that arises late in semantic processing prior to accessing mode-specific verbal and graphemic output lexicons. These deficits were associated with a lesion in the posterior portion of the middle temporal gyrus or area 37, an area of supramodal association cortex that is uniquely suited as a substrate for the multimodal deficit in naming.

Ecological implications of limb apraxia: evidence from mealtime behavior.

Humans learn skilled acts in order to effectively interact with their environment. A loss of the ability to perform skilled acts is termed apraxia. Apraxia has been thought to be of theoretical interest, but the ecological implications of apraxia are controversial and have not been fully studied. We examined ten patients with unilateral left hemisphere cerebral infarctions (eight of whom were apraxic) and compared their mealtime eating behavior to a group of neurologically normal, age-matched controls. The stroke patients were less efficient in completing the meal. They made more action errors and were less organized in the sequencing of mealtime activities. Because the patients made more errors while using tools than when performing nontool actions, their deficit could not be accounted for by an elemental motor deficit. A positive relationship was found between mealtime action errors and the severity of apraxia. These findings suggest that limb apraxia may adversely influence activities of daily living.

Effects of gesture+verbal treatment for noun and verb retrieval in aphasia

Links between verbs and gesture knowledge suggest that verb retrieval may be particularly amenable to gesture+verbal training (GVT) in aphasia compared to noun retrieval. This study examines effects of GVT for noun and verb retrieval in nine individuals with aphasia subsequent to left hemisphere stroke. Participants presented an array of noun and verb retrieval deficits, including impairments of semantic and/or phonologic processing. In a single-participant experimental design, we investigated effects of GVT for noun and verb retrieval in two counterbalanced treatment phases. Effects were evaluated in spoken naming and gesture production to pictured objects and actions. Spoken naming improvements associated with large effect sizes were noted for trained nouns (5/9) and verbs (5/9); no improvements were evident for untrained words. Gesture production improved for trained nouns (8/9) and verbs (6/9), and for untrained nouns (2/9) and verbs (2/9). No significant differences were evident between nouns and verbs in spoken naming or gesture production. Improvements were evident across individuals with varied sources of word retrieval impairments. GVT has the potential to improve communication by increasing spoken word retrieval of trained nouns and verbs and by promoting use of gesture as a means to communicate when word retrieval fails.