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L J Gonzalez Rothi

Publications and source records attributed to L J Gonzalez Rothi.

18 recordsLinked to original sources
PubMed1998

Functional imaging: heterogeneity in task strategy and functional anatomy and the case for individual analysis.

To learn more about the functional anatomy of language, the authors used [99mTc]HMPAO single photon emission computed tomography (SPECT) functional imaging to study nonword rhyming, lexical-semantics and syntax. The authors did not find any task-related differences in cerebral blood flow using region-by-region analysis of variance. This led them to examine individual subject's task-related patterns of cerebral blood flow. This analysis revealed regions of interest with little or no change but also regions with changes as great as 30%. There was marked subject-to-subject variability in the pattern of blood flow, which precluded statistically significant results using analysis of variance. An alternative analytic strategy based on numbers of subjects exceeding a minimum threshold task-related change in cerebral blood flow was tested and shows promise in identifying commonalities and differences in individual task-related blood flow patterns. The authors conclude that the complex and difficult to interpret pattern of blood flow changes observed in this study reflect in considerable part the combined effects of variability in task strategy, owing in part to insufficiently constrained task performance, and variability in functional anatomy. The authors also tested the differences in results achieved with simple normalization and analysis of covariance approaches and found them to be insignificant.

Adult↗
PubMed1997

Visual-imitative dissociation apraxia.

Liepmann posited that, in right handers, the left parietal lobe contains movement formulas or representations. Therefore, performance failures may be induced by degraded representations, a failure of these representations to influence motor systems or a failure of stimuli to fully access these representations. Imitation may help the performance of subjects with degraded representations. However, patients who have impaired visual access to movement representations may perform more poorly with imitation than to verbal command. Trajectories of repetitive 'slicing' gestures made by a previously reported subject (Raymer et al.) with an infarction in the left visual association cortex (left occipital and inferior temporal lobe) that spared the parietal lobe were contrasted with those of three apraxic subjects with lesions that included the left parietal lobe and four non-brain-damaged control subjects. All subjects were asked to produce the gesture to verbal command and to imitation. Movements of the left hand, wrist, elbow and shoulder were digitized from neighboring views, reconstructed in three dimensions, and analysed graphically and numerically. The apraxic subjects with left parietal damage were unable to maintain the proper linearity and spatiotemporal attributes of their wrist motions and showed interjoint coordination deficits. Their deficits were most pronounced to verbal command, with their movements improving though remaining poorly performed when they imitated. The subject with the left occipital and inferior temporal lesion that spared parietal cortex, however, showed an opposite pattern. This subject exhibited close to normal performance when producing the movement to verbal command, but significant deficits when imitating.

Aged↗
PubMed1997

Why specialty recognition?

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American Speech-Language-Hearing Association↗
PubMed1995

Agrammatic sentence production: the use of a temporal--spatial strategy.

We report the sentence production of a left-handed man with a right-hemisphere infarct. He demonstrated an inability to correctly map grammatical categories (subject, object) onto thematic roles (agent, patient) even for simple active sentences. The patient's performance appears to be the result of selective damage to the functional level (Garrett, 1980) of sentence production. His failure could not be accounted for by theories of agrammatism that implicate memory deficits, phonologic processing impairments, or deficits in processing complex transformations. The patient's performance revealed the consistent application of a temporal-spatial strategy in sentence production, despite adequate lexical-semantic abilities.

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PubMed1995

Asyntactic thematic role assignment: the use of a temporal-spatial strategy.

We report syntactic comprehension performance of a left-handed man with a right-hemisphere infarct. He was unable to accurately map grammatical categories (subject, object) onto thematic roles (agent, patient), despite demonstrating intact conceptual knowledge of these thematic roles. He performed poorly on both active and passive reversible sentences. His asyntactic thematic role assignment cannot be accounted for by a short-term memory impairment or any hypothesis that predicts selective vulnerability to passive sentence constructions. Rather than performing randomly, our patient used a temporal or spatial strategy in assigning thematic roles. Because he also had a production-mapping deficit and used the same temporal-spatial strategy in production tasks, we hypothesize that the mapping of thematic roles onto grammatical categories and vice versa may be a specific aspect of sentence processing that is common to sentential production and comprehension. We also raise the possibility that thematic roles have underlying spatial representations prior to being elaborated by grammar.

Aged↗
PubMed1995

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.

Activities of Daily Living↗
PubMed1995

Joint coordination deficits in limb apraxia.

Competing models of the basis of limb apraxia were tested through analysis of joint coordination deficits in three apraxic subjects with lesions that included the left parietal lobe. Three-dimensional shoulder, elbow, wrist and hand trajectories were recorded for repetitive 'slicing' gestures made in a series of conditions in which contextual cues were introduced in a graded fashion. The apraxic subjects showed marked deficits in joint coordination across context conditions. Even when actually manipulating a tool and object, the apraxic subjects failed to show proper joint synchronization, failed to apportion their relative joint amplitudes properly, and failed to produce the correct phase relationships among pairs of arm angles. Thus, apraxic subjects not only have deficits in the spatial plan for the movement, but they also have deficits in translating those plans into the details of the angular motions at the joints, even when actually manipulating a tool and object. These data support a model of apraxia in which apraxia can result from either the destruction of visuo-kinaesthetic motor representations of learned movement, stored in posterior association cortex, or from a separation of these representations from premotor or motor areas.

Aged↗
PubMed1994

Selective attention and aphasia in adults: preliminary findings.

Thirteen patients with left-hemisphere stroke and history of aphasia and 13 normal controls were administered the covert orientation of visual attention task (COVAT). This task presents targets to the right or left of a central fixation point after a cue (84% of trials) or with no cue (16% of trials). Left-hemisphere damaged patients also received tests of language function at the time of the study. For targets presented 100 msec after cue onset, normal controls demonstrated equivalent responding for targets to the left and to the right of a central fixation point. Patients with left-hemisphere damage showed slower reaction times when responding to targets on the right as opposed to the left side of space when attention was first cued to the opposite side of space (invalid trials) or when attention was focused on a central fixation point (uncued trials), but they did not show slower reaction times on the right side when attention was first cued to the right (valid trials). For left-sided targets, no differences between valid, invalid, and uncued trials existed. Slower responding to right- as opposed to left-sided targets on invalid and uncued trials was correlated with impaired performance on six of seven language measures for patients with left-hemisphere damage. Implications for the relationship between language and selective attention systems in the left hemisphere are discussed.

Adult↗
PubMed1994

Spatial planning deficits in limb apraxia.

Geschwind (1975) proposed a disconnection model in which an apraxic subject is unable to carry out movements to command because the left hemisphere that comprehended the verbal command is disconnected from the right premotor and motor areas which controls the left hand. An alternate model, however, proposes that apraxia results from destruction of spatiotemporal representations of learned movement stored in the left hemisphere (Heilman, 1979). The disconnection hypothesis would predict that apraxic subjects should be able to correctly imitate gestures and correctly use actual tools since these tasks do not require language. The movement representation model predicts that imitation and actual tool use would also be impaired. Motion analyses were performed on the trajectories of repetitive 'slicing' gestures made in a series of conditions in which contextual cues were introduced in a graded fashion. Four cue conditions were presented: no cues (verbal command), object present, tool present and both object and tool present. Positions of the hand, wrist, elbow, and shoulder were digitized from neighbouring views, reconstructed in three dimensions and analysed with respect to specific spatiotemporal features of the trajectories. Three subjects with limb apraxia, who had lesions that included left parietal cortex, and four neurologically intact subjects participated. The apraxic subjects showed disturbances in planning the movement of the hand in space across the cue conditions. For example, they showed deficits in the plane of motion, the shape of the trajectory and in the coupling of hand speed and trajectory shape even when given full contextual cues. These data support the hypothesis that apraxia can result from the destruction of spatiotemporal representations of learned movement, rather than from a disconnection between the receptive language areas in the left hemisphere and the contralateral motor cortices.

Aged↗
PubMed1993

Hemispheric specialization for handwriting in right handers.

Hand preference may be related to either lateralized language, movement representations, or both. Anatomic and behavioral studies have revealed that whereas each hemisphere has motor control of the contralateral distal and proximal limb movements, this same hemisphere's control over the ipsilateral limb is limited to proximal movements. This differential proximal-versus-distal organization may have functional implications such that when right handers write with their left hand they must be use more proximal musculature than when they write with their right hand. If hand preference is related to lateralized movement representations, right handers may also use more proximal than distal movements when drawing with their left than with their right hand. If one uses distal musculature to write or draw, the elbow travels through space less than if one uses proximal musculature. We studied 12 right handers by having them write and draw with their right and left hands and measured the spatial amplitude of their elbow movements. We found that when writing or drawing, right handers moved their left elbow more than their right. These results suggest that it is the lateralized movement representations that may be primarily responsible for writing hand preference.

Adolescent↗
PubMed1989

Predicting the Western Aphasia Battery Aphasia Quotient.

Administration of the Western Aphasia Battery (WAB) yields a total score termed the Aphasia Quotient (AQ), which is said to reflect the severity of the spoken language deficit in aphasia. This score is a weighted composite of performance on 10 separate WAB subtests. Based on data from 100 patients, all 10 subtests were found to correlate highly with each other and with the AQ, but the score from one subtest, Information Content, was the best predictor of the AQ. Time postonset had no influence on the relationships among the subtests or between the 10 subtests and the AQ. These findings are useful in understanding the Western Aphasia Battery and in interpreting the Aphasia Quotient.

Adolescent↗
PubMed1987

Isolated lexical agraphia in a right-handed patient with a posterior lesion of the right cerebral hemisphere.

Lexical agraphia is thought to result from impairment of the lexical spelling system and is characterized by better spelling of nonwords and regularly spelled words than irregularly spelled words. Previous reports have suggested a localization of this syndrome in the region of the left posterior-superior angular gyrus and parietal-occipital lobule, sparing the supramarginal gyrus. We describe a right-handed man who after open-heart surgery displayed lexical agraphia without aphasia, alexia, apraxia, or Gerstmann's syndrome. Computed tomography disclosed a lesion not on the left but on the right in the posterior parietal-occipital region.

Agraphia↗
PubMed1987

Phonological alexia with optic and tactile anomia: a neuropsychological and anatomical study.

We describe a patient with phonological alexia caused by a small hemorrhage in the posterior-inferior portion of the left temporal lobe. The lesion induced a highly selective impairment of phonological reading without concomitant oral language deficits other than anomia for objects presented in the visual and tactile modalities. We propose that an intact dorsal pathway from inferior visual association areas to Wernicke's area via the angular gyrus could mediate reading by the lexical route, while damage to a ventral pathway disrupted the patient's ability to read nonwords. We suggest further that although visually and tactually presented objects could be recognized and both verbally and nonverbally identified, they could not be named because of a disconnection from the area of word representations.

Adult↗
PubMed1987

Apraxia in a patient with atypical cerebral dominance.

Liepmann postulated that the left hemisphere of right-handed persons contains the "movement formulas" that control purposeful skilled movements of the limbs on both sides of the body. Accordingly, in right-handers apraxia should follow damage to the left hemisphere, whereas right hemisphere damage should not lead to apraxia. Although this is generally true, we recently examined a right-handed man who after a right hemispheric stroke became aphasic and apraxic with his nonparalyzed right hand. Our observations suggest that the right hemisphere of this right-handed man made a critical contribution to the planning and execution of skilled movements. This case provides evidence that right-handers should not be considered a homogeneous group in terms of cerebral motor dominance and that contrary to Liepmann's postulate, hemispheric dominance for the control of skilled movements does not entirely determine handedness.

Apraxias↗
PubMed1986

'Inner speech' in conduction aphasia.

It has been suggested by Kurt Goldstein, MD, that conduction aphasia is a disturbance of "inner speech." We tested this hypothesis in five patients who had conduction aphasia with similar speech disturbances. The patients were presented with pictures and were required to perform, without overt vocalization, comparisons of word length and homophonic and rhyming matches. Four patients successfully performed such judgments on words they could not vocalize, but one patient could not. These findings suggest that the hypothesis may have been correct for only a subgroup of conduction aphasics. The findings also provide evidence for heterogeneity within the class of conduction aphasia.

Aged↗