Margaret L. Greenwald

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.

Language laterality determined by MEG mapping with MR-FOCUSS

Magnetoencephalography recordings were made on 27 patients with localization related epilepsy during two different language tasks involving semantic and phonological processing (verb generation and picture naming). These patients underwent the semi-invasive intracarotid amobarbital procedure (IAP), also referred to as the Wada test, to determine the language-dominant hemisphere. Magnetoencephalography (MEG) data were analyzed by MR-FOCUSS, a current density imaging technique. A laterality index (LI) was calculated from this solution to determine which hemisphere had more neural activation during these language tasks. The LIs for three separate latencies, within each language task, were calculated to determine the latency that correlated best with each patients IAP result. The LI for all language processing was calculated for the interval 150-550 ms, the second LI was calculated for the interval 230-290 ms (Wernickes activation), and the third LI was calculated for the interval 396-460 ms (Brocas activation). In 23 of 24 epilepsy patients with a successful IAP, the LIs for Brocas activation, during the picture naming task, were in agreement with the results of the IAP (96% agreement). One of three patients who had an undetermined or bilateral IAP had an LI calculated for Brocas activation (396-460 ms) that agreed with intracranial mapping and clinical testing. These results indicate an 89% agreement rate (24 of 27) for magnetoencephalographic LI determination of the hemisphere of language dominance.

Contrasting treatments for severe impairments of picture naming

Abstract Little is known about the treatment of object naming impairments in patients with multiple loci of deficit in the cognitive processes underlying picture naming. We evaluated the outcome of naming treatment in two such patients. We developed two treatments on the basis of a cognitive neuropsychological assessment of naming and contrasted their effectiveness with that of simple verbal rehearsal. In Treatment Programme 1, we targeted presumed impairment at the level of lexical retrieval by attempting to train subjects to use a phonological cueing hierarchy during a name to auditory definition task. In Treatment Programme 2, we targeted presumed impairment of visual-semantic processing by attempting to train subjects to use a visual-semantic cueing hierarchy during an oral picture naming task. Treatment Programme 3 was designed to determine if improvement in oral naming could result from simple rehearsal. All three treatment programmes improved naming abilities of the two subjects to some degree, par...

Cognitive treatments of sentence processing disorders: What have we learned?

Several cognitive neuropsychological studies describing treatments of sentence processing disorders have been reported in recent years. We review the outcome of 10 studies that describe treatment outcomes for 17 aphasic patients. Although the studies used different approaches to intervention, they shared the goal of improving reversible sentence comprehension, and they targeted a hypothesised deficit of “thematic mapping”. Several trends in treatment outcomes were observed. In most cases, there was strong evidence that the treatments induced a change in the pattern of sentence processing. Moreover, the outcomes indicated that impaired reversible sentence comprehension can arise from a range of impairments, only some of which directly implicate structural and/or lexical deficits assumed to be the source of poor thematic mapping abilities. Patterns of post-therapy generalisation within and across processing modalities appeared to be related, among other things, to the therapy approach and to the selection of treatment materials. These findings are discussed with regard to the theoretical implications of sentence processing treatment data.

Magnetoencephalographic localization of the basal temporal language area.

Magnetoencephalography (MEG) recordings were made on 25 native English-speaking patients with localization-related epilepsy during a semantic language task (verb generation). Eighteen right-handed subjects with normal reading ability had MEG scans performed during the same language task. MEG data was analyzed by MR-FOCUSS, a current density imaging technique. Detectable MEG signals arising from activation in the left fusiform gyrus, also known as the basal temporal language area (BTLA), occurred at 167 +/- 18 ms (n = 43) in all subjects. The BTLA has been associated with a variety of language production and comprehension tasks involving processing of semantic, orthographic, and phonologic information. MEG may become an important tool in efforts to further define the linguistic operations of specific regions within this language area.

Lexical access via letter naming in a profoundly alexic and anomic patient: a treatment study.

We report the results of a letter naming treatment designed to facilitate letter-by-letter reading in an aphasic patient with no reading ability. Patient M.R.s anomia for written letters reflected two loci of impairment within visual naming: impaired letter activation from print (a deficit commonly seen in pure alexic patients who read letter by letter) and impaired access to phonology via semantics (documented in a severe multimodality anomia). Remarkably, M.R. retained an excellent ability to pronounce orally spelled words, demonstrating that abstract letter identities could be activated normally via spoken letter names, and also that lexical phonological representations were intact when accessed via spoken letter names. M.R.s training in oral naming of written letters resulted in significant improvement in her oral naming of trained letters. Importantly, as M.R.s letter naming improved, she became able to employ letter-by-letter reading as a compensatory strategy for oral word reading. M.R.s success in letter naming and letter-by-letter reading suggests that other patients with a similar pattern of spared and impaired cognitive abilities may benefit from a similar treatment. Moreover, this study highlights the value of testing the pronunciation of orally spelled words in localizing the source of prelexical reading impairment and in predicting the functional outcome of treatment for impaired letter activation in reading.

“Blocking” Lexical Competitors in Severe Global Agraphia: A Treatment of Reading and Spelling

Severe global agraphia in Patient MM is analyzed via anagram spelling. Errors in word spelling reflect conflict among lexical competitors and “blocking” of semantic errors by sublexical and lexical cues. Lexical graphemic competition predominates in the context of MM’s nearly absent sublexical transcoding of phonemes into graphemes. His orthographic lexicon is severely impaired, resulting in poor activation of lexemes and impaired activation and inhibition of the grapheme level in spelling. In MM’s multiple revisions of spelling errors, graphemes from more than one lexical competitor persist in an active state simultaneously. Experimental treatment addressed MM’s impaired sublexical reading and spelling, and facilitated sentence spelling through functional computer tasks. Spelling treatment resulted in evolution of MM’s global agraphia to surface agraphia. MM’s spelling performance supports the claim that lexical and sublexical processes interact during normal spelling, and shows that severe global agraphia is amenable to treatment.

Teaching Research Methods in Communication Disorders A Problem-Based Learning Approach

A critical professional issue in speech—language pathology and audiology is the current shortage of researchers. In this context, the most effective methods for training graduate students in research must be identified and implemented. This article describes a problem-based approach to teaching research methods. In this approach, the instructor poses complex clinical problems and students work cooperatively to define relevant questions, evaluate resources, and find solutions. Students develop understanding of experimental designs through problem solving and descriptions of their clinical research designs in group discussions or class debates. Through research training based on clinical problems, students learn to integrate clinical questions with research questions and to link the dual professional roles of clinician and researcher.

The role of cognitive models in language rehabilitation

Recently, researchers have advocated the use of cognitive neuropsychological models as an infrastructure for efforts in language rehabilitation. In this approach, clinicians characterize language impairments in individual patients with respect to cognitive models of lexical and sentence processing. This approach contrasts with many earlier efforts in which evaluation and treatment focused on the presence or absence of aphasia viewed as a general language impairment, or on syndromes of aphasia. We consider the structure that cognitive neuropsychological models may provide in different portions of the rehabilitation process and find that this approach, when applied with methodological rigor, has practical implications for practice in aphasia assessment and treatment. In turn, some hope that data derived from clinical applications with this approach may support the modification of cognitive neuropsychological models.