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PubMed2002

Phonology and neuropsychology of the English past tense.

The double dissociation between the regular and irregular past tense in English has been explained in terms of dual and single mechanism accounts. In previous research we have argued that problems with the regular past tense in patients with left inferior frontal damage arise from morpho-phonological parsing difficulties [Trends in Cognitive Science 2 (1998) 428]. This claim has recently been challenged by a single mechanism connectionist account which argues that a general phonological processing deficit causes the poor performance on the regular past tense, with morphological factors playing no explicit role [Proceedings of the National Academy of Sciences 96 (1999) 7592]. We used a speeded judgement task with four patients who have documented difficulties with the regular past tense to contrast the claims made by these different approaches. We compared patients' ability to detect the difference between the past tense and stem of regular (hugged/hug) and irregular (taught/teach) past tense verbs, as well as matched "pseudo" pairs (trade/tray and port/peach). These real word conditions were accompanied by matched sets of non-words (e.g. nugged/nug). Patients' latencies to the regular past tense real word-pairs were consistently slower than in any other condition. To test for a general phonological processing deficit, we conducted several tests of phonological processing ability. The results show that the patients had a range of difficulties in phonological processing, from very mild to severe. This did not correlate with their performance on the speeded judgement task. We interpret this pattern of results as support for a specialised morpho-phonological processing mechanism which can be dissociated from other phonological processes and which is used directly in the processing of the regular past tense in a dual-mechanism system.

Adult↗
PubMed1990

Acquisition and generalization of simple manual sign grammars by aphasic subjects.

The present study investigated the acquisition and generalization of manual sign combinations in four moderately to severely aphasic subjects. Two experiments were conducted: In the first, matrices were employed to train agent-action-object and action-object combinations and monitor generalization. In the second experiment, subjects were trained to combine a different set of single signs into sign combinations (agent-action-object, action-object) that could be used to describe two pictures while generalization was monitored in a third. Results of experiment 1 demonstrated that the two least severely aphasic subjects were able to acquire and generalize all of the sign combinations presented in the training matrices. In the second experiment, although the subjects rapidly acquired single signs and combinations, additional training was required for the subjects to produce the sign combinations to describe the two pictures and no generalization was noted in the third untrained picture. It is concluded that success in manual sign training programs is related to severity of aphasia; that aphasic subjects' propositional use of manual signs rarely follows simple acquisition; and that generalization to untrained stimuli or environments does not occur without additional training.

Aged↗
PubMed1982

The efficacy of functional communication therapy for chronic aphasic patients.

Twelve weeks of therapy emphasizing functional communication content was conducted twice weekly in a group setting for seven chronic aphasic patients whose average post-onset time was 97.9 months. Porch Index of Communicative Abilities (PICA) test scores did not change significantly as a result of this treatment. Communicative Abilities in Daily Living (CADL) test scores, however, revealed statistically significant improvement in post-treatment performances. A final administration of CADL tests six weeks after cessation of functional communication treatment indicated that the positive change in CADL scores had been maintained.

Activities of Daily Living↗
PubMed1987

The aprosodias: further functional-anatomical evidence for the organisation of affective language in the right hemisphere.

Fourteen right-handed patients with right hemispheric strokes were examined for disorders of affective language in order to further define the clinical-anatomical correlates of the aprosodias. A bedside evaluation strategy and CT scan mappings were utilised to make these comparisons. There were six patients with motor aprosodia, one with global aprosodia, two with conduction aprosodia, one with sensory aprosodia, one with transcortical sensory aprosodia, one with pure affective deafness and two with normal examinations of affect. Functional-anatomical correlations were consistent with those predicted previously. Recovery of affective language function in selected cases was characterised by improvements in affective-prosodic repetition and/or evolution into other aprosodic subtypes. Our results lend further support to the hypothesis that the organisation of affective language in the right hemisphere mirrors that of propositional language in the left hemisphere.

Adult↗
PubMed1998

Transcranial magnetic stimulation: language function.

Studies of language using transcranial magnetic stimulation (TMS) have focused both on identification of language areas and on elucidation of function. TMS may result in either inhibition or facilitation of language processes and may operate directly at a presumptive site of language cortex or indirectly through intracortical networks. TMS has been used to create reversible "temporary lesions," similar to those produced by Wada tests and direct cortical electrical stimulation, in cerebral cortical areas subserving language function. Rapid-rate TMS over the left inferior frontal region blocks speech output in most subjects. However, the results are not those predicted from classic models of language organization. Speech arrest is obtained most easily over facial motor cortex, and true aphasia is rare, whereas right hemisphere or bilateral lateralization is unexpectedly prominent. A clinical role for these techniques is not yet fully established. Interfering with language comprehension and verbal memory is currently more difficult than blocking speech output, but numerous TMS studies have demonstrated facilitation of language-related tasks, including oral word association, story recall, digit span, and picture naming. Conversely, speech output also facilitates motor responses to TMS in the dominant hemisphere. Such new and often-unexpected findings may provide important insights into the organization of language.

Cerebral Cortex↗
PubMed2003

The nature of speech production impairments in anterior aphasics: an acoustic analysis of voicing in fricative consonants.

This study investigated the acoustic characteristics of voicing in English fricative consonants produced by anterior aphasics and the effects of phonetic context on these characteristics. Three patients produced voiced and voiceless fricative-vowel syllables in isolation, following a voiced velar stop, and following a voiceless velar stop. Acoustic analyses were conducted of the amplitude and patterning of glottal excitation, as well as fricative noise duration. Results showed that, although the patients are able to coordinate the articulatory gestures for voicing in fricative consonants, they demonstrated abnormal patterns of glottal excitation in the amplitude measures, owing to weaker amplitudes of glottal excitation in voiced fricatives. Context effects failed to emerge because of dysfluent speech. These results suggest that the locus of the speech production deficit of anterior aphasics is not at the higher stages of phoneme selection or planning but rather in articulatory implementation, one related to laryngeal control.

Aged↗
PubMed1989

Reaction time methodology and the aphasic patient: a reply to Hagoort (1988).

P. Hagoort (1988, Brain and Language, 36, 335-348) suggests that the results of an experiment conducted with aphasic patients reported by W. Milberg, S. E. Blumstein, and B. Dworetzky (1987, Brain and Language, 31, 138-150) are "difficult to interpret in terms of a selective access model for normal processing because of a confound caused by the use of repeated lexical decision targets." We argue that the use of repeated lexical decision targets and other methodological compromises are necessary for using the lexical decision reaction time paradigm with aphasic patients. Furthermore, the minor differences between our data and those presented by Hagoort do not undermine our claims concerning semantic processing in different subgroups of aphasics, nor our comparisons of these patients to normal subjects.

Aphasia↗
PubMed1995

Electrophysiological monitoring for selective shunting during carotid endarterectomy.

Selective shunt during carotid endarterectomy is more and more widespread, but it requires a monitoring system able to identify severe brain ischemia correctly. In 255 endarterectomies for severe carotid stenosis, we evaluated cerebral activity by means of sequential use of computerized two-channel electroencephalogram (EEG) and somatosensory evoked potentials (SSEPs). In 1.96% of cases, we observed changes referable to severe cerebral ischemia: in one case, in spite of shunting, EEG asymmetry persisted till the end of the operation, and the patient awoke with irreversible aphasia. In two other cases, a progressive disappearance of the cortical wave (N20) occurred in spite of a normal EEG pattern. None of the unshunted patients had postoperative deficit. Computerized EEG is an easily interpretable method of monitoring and reveals rapidly developing cerebral ischemia, but severe SSEP changes can occur in spite of a normal EEG pattern when cerebral ischemia has a slow onset. Although SSEP monitoring is a slower method of recording, it can give a finer distinction of less severe cerebral ischemia.

Adult↗
PubMed2004

A meta-analytic review of verbal fluency performance following focal cortical lesions.

A meta-analysis of 31 studies with 1,791 participants was conducted to investigate the sensitivity of tests of verbal fluency to the presence of focal cortical lesions. Relative to healthy controls, participants with focal frontal injuries had large and comparable deficits on phonemic (r = .52) and semantic (r = .54) fluency. For frontal but not nonfrontal patients, phonemic fluency deficits qualified as differential deficits when compared with IQ and psychomotor speed; phonemic fluency was also more strongly and more specifically related to the presence of frontal lesions than the Wisconsin Card Sorting Test scores. In contrast, temporal damage was associated with a lesser deficit on phonemic fluency (r = .44) but a larger deficit on semantic fluency (r = .61).

Adult↗
PubMedDate not supplied

[Frequency of neuropsychiatric signs and symptoms in patients with viral encephalitis].

INTRODUCTION: Acute viral encephalitis (AVE) is a frequent condition that usually courses with psychiatric alterations but few systematic studies have been conducted to investigate it. AIMS: To determine the frequency and the progression of the neuropsychiatric symptoms in patients with AVE. PATIENTS AND METHODS: A retrospective study was carried out. AVE was defined as an acute and progressively coursing condition in previously healthy subjects, with clinical signs of diffuse alteration of the central nervous system, abnormal electroencephalogram and/or inflammatory cerebrospinal fluid (CSF). We excluded patients who previously had epilepsy, a positive serodiagnosis for human immunodeficiency virus (HIV), and cases compatible with herpes simplex encephalitis from electroencephalographic or imaging data with focalisation towards temporal, frontal, regions or a positive DNA test for herpes in CSF. Finally, 83 patients were included. The psychiatric signs and symptoms that were produced were recorded during the acute phase and one year after discharge from hospital (sequelae). RESULTS: The psychiatric disorders in the acute phase were psychomotor agitation (67%), drowsiness (55%), disorientation (47%), visual hallucinations (43%) and aggressiveness (34%). One year after hospitalisation, in a sample of 70 patients in a clinical control, we found memory disorders (16%), aggressiveness (9%), aphasia (8%), visual hallucinations (8%), and auditory hallucinations (7%). The mortality rate was 6%. CONCLUSIONS: Neuropsychiatric disorders are very frequent during the acute phase of viral encephalitis, which is relevant for the differential diagnosis in patients who visit emergency departments with behavioural disorders. One year after hospital discharge, the main sequelae are of a neuropsychiatric nature and cognitive impairment is predominant.

Adolescent↗
PubMed1991

Nature of spelling errors in a Thai conduction aphasic.

A Thai conduction aphasic's performance on a written confrontation naming task is reported. Analysis of his spelling errors indicated that errors rarely violated Thai phonotactic constraints; consonant substitutions were phonologically similar to the target stimuli; longer stimuli were more likely to be in error; distribution of errors was the same across consonants, vowels, and tones; and distribution of error types varied between segmentals (consonants, vowels) and suprasegmentals (tones). Error patterns were similar to those observed in oral reading and repetition. The pattern of impaired writing performance is discussed in relation to a functional model of the spelling process, and it is hypothesized to reflect primarily a functional lesion to the phonological buffer.

Agraphia↗
PubMed2000

Sentence repetition test: updated norms and clinical utility.

The Sentence Repetition test (SR) has been used to assess aphasic and other patients in neuropsychological settings. SR has been shown to be reliable and valid, as well as sensitive to patients with brain injury. This study was conducted to update the normative data for the SR. Sensitivity and specificity tests of the SR using the new normative data was also conducted. The findings suggest that SR is sensitive to specific brain dysfunction that affects the ability to repeat sentences as well as attention and concentration. The new normative data show that the ability to repeat sentences is not influenced by age, but education appears to be a significant factor in SR performance. In a clinical group, a reduction of SR performance was related to length of unconsciousness and was more impaired for patients with left-hemisphere injury. Good specificity and sensitivity were found. The findings of this study confirm that with new norms, SR continues to be a useful tool for neuropsychological assessment.

Adolescent↗
PubMed1999

Anatomic asymmetries of the posterior superior temporal lobes: a postmortem study.

OBJECTIVE: To examine for structural asymmetries in the posterior superior temporal lobe at the microscopic level in an effort to explain the gross anatomical and functional asymmetries of this brain region. BACKGROUND: The posterior superior temporal lobe is typically larger on the left and damage to this area frequently results in an aphasia. This has led to the hypothesis that the structural asymmetry determines the functional asymmetry, but no definite confirmation of this hypothesis exists. METHODS: Sixteen men were studied at postmortem. Posterior superior temporal lobe dimensions, gray matter volume, white matter volume, SMI-32 immunopositive neuronal density, and glia cell volume were measured for both the left and right hemispheres. In a subset of eight subjects, myelin sheath and axon diameters were measured with electron microscopy. RESULTS: Posterior superior temporal lobe white matter volume was greater on the left (p = 0.003, t test for dependent samples). This asymmetry did not appear to be the result of an isolated proliferation of glia (p = 0.46, t test for dependent samples), nor the density of cortical to cortical projections neurons in the overlying cortex (p = 0.71, t test for dependent samples). In a subset of eight subjects studied with electron microscopy, axons of the left posterior superior temporal lobe were more thickly myelinated (57 nm [SD = 27] left, 46 nm [SD = 24], p < 0.001, ANOVA). CONCLUSIONS: As axons with thicker myelin sheaths conduct faster and require a greater volume, these results suggest asymmetry of myelination as an explanation for both a left hemisphere dominance for rapid sensory signal processing, leading to a functional asymmetry for language, and a larger left planum temporale.

Axons↗
PubMed1997

Judgments of concept similarity by normal and aphasic subjects: relation to naming and comprehension.

A study was conducted in which aphasic patients, age-matched normals, and normal young adults performed five types of matching judgments for object pictures. These required matching for physical identity, basic object identity, and membership in the same superordinate category. Spoken name-to-picture matching was tested for the last two conditions. An analogous set of conditions was presented for letters. Latency patterns across the conditions showed general slowing for the aphasic patients, but with a differential decrement in the conditions that involved auditory (spoken name) input for the matching task. Results showed that variations in semantic judgment capability among the aphasics did not predict the patients' object naming ability.

Age Factors↗
PubMed2002

Sensitivity to sub-syllabic constituents in brain-damaged patients: evidence from word games.

Two experiments were conducted to examine whether left- (LHD) and right-hemisphere-damaged (RHD) patients exhibit sensitivity to sub-syllabic constituents (i.e., onsets and codas) in the generation of nonwords, using a word games paradigm adapted from. Four groups of individuals (including LHD fluent and nonfluent aphasic patients, RHD patients and normal controls) were trained to add syllables to monosyllabic CVC nonwords either after the initial consonant (Experiment 1) or prior to the final consonant (Experiment 2) to create bisyllabic nonwords. Experimental stimuli consisting of CCVC or CVCC nonwords tested whether participants would preserve or split the onset and coda constituents in producing the novel bisyllabic nonwords. Results revealed that the majority of subjects demonstrated sensitivity to the sub-syllabic constituents, preserving the onsets and codas. The fluent aphasic patients exhibited a greater than normal tendency to split the onset and coda constituents; however, the small number of individuals in that group whose data met inclusion criteria limits the conclusions that may be drawn from these findings. The results are discussed in relation to theories of phonological deficits in aphasia.

Adolescent↗
PubMed1994

Pure alexia: attempted rehabilitation and its implications for interpretation of the deficit.

On the basis of data indicating the failure to encode letters as abstract orthographic identities in a pure alexic patient (D.M.) coupled with hypotheses about the effect of such a failure on word reading, an attempt at changing the nature of letter processing in D.M. was conducted. The training procedures failed to produce any fundamental change in the operations used by D.M. to encode isolated letters or words. However, rapid and massive benefits occurred in the overall speed of reading as a result of the training program. These appear to result from an increased rate of letter identification and the faster integration of individual letters into letter combinations. The observations gathered throughout this rehabilitation attempt provided evidence which constrains the range of possible explanations for the characteristic features of pure alexia. It is proposed that the letter-by-letter reading procedure which is the hallmark of the disorder may follow from an incapacity to directly encode visual letters as abstract orthographic types.

Adult↗
PubMed1989

Phonological transformations in Spanish-speaking aphasics.

Thirty-seven aphasic patients whose native language is Spanish were divided into four groups: (1) Broca's, (2) Wernicke's, (3) Conduction, and (4) Anomia. Phonological errors produced on repetition and object-naming tasks were analyzed in terms of type of transformation and degree of similarity between target and errors in terms of shared distinctive features. Segmental transformations were of the following types: (1) pure substitution, (2) pure addition, (3) deletion, (4) reduplicative addition (doublet creation)--anticipatory (right to left) or preservative (left to right), (5) reduplicative substitution (doublet creation)--anticipatory or perseverative, and (6) mutual exchanges. Pure substitutions were the most prevalent, exchanges, the least. Some error types were found to differentiate significantly between aphasic populations. We suggest that different mechanisms may underlie the same error type for different aphasic populations.

Adult↗
PubMed1984

The effect of sentence boundaries upon aphasic patients' immediate memory for connected speech.

Memory for the terminal portion of connected speech was investigated in Broca's, Wernicke's and Conduction aphasic patients. A multiple choice probe recognition paradigm was employed so that the results would not be contaminated by expressive speech errors. The effects on retention performance of sentence boundaries and the number of words intervening between target word presentation and test were studied. The different aphasic groups showed similar patterns of performance. Sentence boundaries had no effect on retention but more errors were produced with seven than with four words intervening between presentation and test. Errors were classified as semantic, phonemic or unrelated and in all conditions of the experiment semantic confusion errors predominated. It was argued that there was no evidence that the aphasic patients retained the last heard sentence in a superficial form in short-term memory.

Adult↗