Language Processing Deficits Research Articles

Lexical acquisition in progressive aphasia and frontotemporal dementia

We investigated the characteristics of language difficulty in frontotemporal dementia (FTD) by exposing these patients to a new verb in a naturalistic manner and then assessing acquisition of the grammatical, semantic, and thematic matrix information associated with the new word. We found that FTD patients have difficulty relative to healthy seniors in their acquisition of the new verb, but that progressive nonfluent aphasia (PNFA), semantic dementia (SD), and social/dysexecutive variant (SOC/EXEC) subgroups of FTD demonstrate relatively distinct impairment profiles. Specifically, PNFA patients showed relative difficulty assigning the new verb to its correct grammatical form class, reflecting compromised processing of the associated grammatical information. SD patients were impaired at associating the new word with its pictorial representation, suggesting impaired processing of the new verb's semantic attributes. SOC/EXEC patients showed their greatest difficulty judging violations of the new word's associated thematic roles, implying that limited executive resources underlie in part the difficulty in integrating grammatical and semantic information into a coherent thematic matrix. Similar impairment profiles were seen during a follow-up session one week after the initial evaluation. These deficits in lexical acquisition reflect the breakdown of a language-processing system that consists of highly interactive but partially dissociable grammatical, semantic, and resource-based components, leading to relatively distinct language-processing deficits in each subgroup of patients with FTD.

Cortical intercorrelations of frontal area volumes in schizophrenia

Background: Abnormal regional volume intercorrelations between selected cortical areas in schizophrenia patients were previously reported in several MRI studies. Methods: A detailed analysis of frontal gray and white matter volume correlations with Brodmann's area volumes in the rest of the cortex was undertaken in normal subjects ( n = 42) and patients with schizophrenia ( n = 106), divided into good-outcome ( n = 52) and poor-outcome (Kraepelinian; n = 54) subtypes. Results: Frontal gray matter volumes were correlated with temporal lobe volumes in schizophrenics but not in normal subjects. Some frontal–parietal and frontal–occipital correlations showed a similar pattern. In comparison to normal subjects, schizophrenia patients showed weaker or absent intercorrelations intrafrontally, specifically between left motor–premotor and eye-movement areas (4, 6, 8) and dorsolateral area 44, as well as between left areas 9 and 46 vs. area 24 (cingulate gyrus). Poor outcome among patients with schizophrenia was associated with weaker correlations between left frontal area 9 and both medial and lateral temporal cortices, as compared to normal subjects or good-outcome patients. Conclusions: There appears to be a structural component in the task or symptom-related dysfunctional interactions between the frontal and more posterior cortical regions with preferential pathological involvement of frontotemporal and more limited involvement of frontoparietal and fronto-occipital systems in schizophrenia. Impaired regional associations within the frontal lobe, between left motor–premotor and Broca's areas, may play a role in language processing deficits in schizophrenia, while frontocingulate disconnection may result in working memory disturbances. Poor outcome may be associated with more widespread disconnections between prefrontal vs. cingulate and temporal regions in the left hemisphere, consistent with a disruption along the course of the left cingulum or uncinate bundles.

Information Transmission Defect Identified and Localized in Language Learning Impaired Children by Means of Electrophysiology

Children with language processing deficits have various learning impairments and poor scholastic performance. In 3-10% of all children a specific language processing deficit can be identified by the Sound Connecting Sub-Test of the Illinois Test of Psycholinguistic-Abilities (SC-ITPA). These children among which we drew our index group (AS-Group) suffer from the disability to recognize isolated sounds as parts of words. Following linguistic terminology this is known as an auditory sequential sound processing deficit (ASSPD) Eighteen children (AS-Group) and 21 controls (C-Group) were subjected to mapped P300 evoked potential analyses of cortical response to acoustic stimulation in the oddball paradigm. The data presented here show that there exists significant relation between the P300 amplitude reduction and ASSPD. The P300 amplitude decrease measured in the AS-Group is due to a reduced information transmission in accordance with Johnson's Triarchic Model of the P300 Amplitude. The cerebral structures involved in poor language processing are localized at the left temporo-parietal cortex. This supports the hypothesis that the underlying neuronal defect of ASSPD is localized in the language center and not in the auditory pathway. The P300 amplitude may serve as electrophysiological tool to identify ASSPD and to quantify the degree of improvement in the course of specific therapy.

Direct speech and language therapy for children with cerebral palsy: findings from a systematic review.

Children with cerebral palsy (CP) often have speech, language, and/or communication disorders and are referred to speech and language therapy (SLT). They may also be referred to SLT services for dysphagia: treatment of which is beyond the scope of this review. Although the exact prevalence of the communication disorders associated with CP is not known, it has been estimated that approximately 20% of children with a diagnosis of CP have severe communication impairment and are classified as non-verbal. Many more will have less severe speech and communication disorders as a consequence of their motor impairment, or disorders arising from speech, language, and cognitive processing deficits associated with CP.

Disentangling the Web: Neologistic Perseverative Errors in Jargon Aphasia

This article explores the relationship between the neologisms and perseverative errors produced by KVH, a man with severe neologistic jargon aphasia. Detailed examination of KVH's level of language processing breakdown revealed mild difficulties with phonological encoding and severe difficulties accessing the lexical form of the word. Many of KVH's neologisms contained phonemes perseverated from previous neologisms, suggesting an integral relationship between the production of neologisms and the perseveration of phonemes. Furthermore, KVH's patterns of whole word (total) and phonological (blended) perseverations reflected his proposed underlying language processing deficits, consistent with recent literature on perseveration (e.g., Cohen and Dehaene, 1998). However, the simple binary distinction of total and blended perseveration is proposed to be somewhat limited for understanding the underlying nature of KVH's complex neologistic errors. Possible explanations regarding the mechanisms underlying the production of KVH's neologistic and perseverative errors also are discussed.

Investigating the neurobiological basis of cognitive rehabilitation therapy with fMRI

The neurobiological changes occurring during cognitive rehabilitation therapy (CRT) have yet to be systematically studied. In the present study, functional magnetic resonance imaging (fMRI) was used to demonstrate brain plasticity in response to CRT (n = 5) following mild traumatic brain injury. Neuropsychological tests and two fMRI activation tasks, a visually guided saccades and a reading comprehension task, were employed pre- and post-CRT. CRT was used to systematically address the identified deficits in visual scanning and language processing. As hypothesized, changes in the pattern and extent of activation within expected neuroanatomical areas occurred post-CRT. Changes in fMRI activation are discussed for each subject and related to changes on neuropsychological measures. This study demonstrates how fMRI can illustrate the neurobiological mechanisms of recovery in individual subjects. The variability in subject responses to CRT supports the notion of tailoring rehabilitation strategies to each subject in order to optimize recovery following brain injury.

Visual and language processing deficits in compensated and uncompensated college students with dyslexia.

In seven experiments, we investigated whether compensated and uncompensated adults with dyslexia show different patterns of deficits in magnocellular visual processing and in language processing tasks. In four visual tasks, we failed to find evidence of magnocellular deficits in either group. However, both groups of adults with dyslexia showed deficits in component language skills, and the degree of reading impairment predicted the nature and extent of these deficits. Uncompensated readers showed deficits in orthographic and especially phonological coding and awareness and were slower on rapid naming. Compensated readers showed word and nonword performance below controls but better than the uncompensated readers. The compensated group was not significantly less accurate than controls on phonological awareness, nor significantly worse overall on rapid naming.

Atypical cerebral laterality in adults with persistent developmental stuttering.

Two of the most consistent anatomic asymmetries found in the human brain are a larger right than left prefrontal and left than right occipital lobe. Reduced or reversed asymmetries of these regions are considered markers of atypical cerebral laterality, and atypical cerebral laterality has been proposed to increase neural risk for developmental stuttering. S: To learn if atypical prefrontal and occipital lobe asymmetries are more common in adults who stutter vs fluent control subjects and to determine whether lobar size or asymmetry patterns are associated with stuttering severity or language abilities. Adults with persistent developmental stuttering (n = 16) and matched control subjects (n = 16) had language and stuttering assessments. Subjects were also studied with volumetric MRI scans. Total hemisphere, prefrontal, and occipital lobe regions were measured, and volumes were calculated proportionally to hemisphere volume. Hemisphere and total brain volumes did not differ between the groups. Control subjects had the expected larger right than left prefrontal and larger left than right occipital lobe volume. In contrast, the adults who stutter did not have these asymmetries. Stuttering severity was not associated with specific anatomic configurations, whereas language-processing deficits in adults who stutter were associated with prefrontal and occipital volume reduction. Developmental stuttering is associated with atypical prefrontal and occipital lobe asymmetries. In addition, deficits in language processing were associated with some anatomic measures in the adults who stutter.

The processing of pseudohomophones by adults with a history of developmental language disabilities

Psuedohomophones are nonwords that sound like real words (e.g., BRANE). These items were used to gauge phonological access in adults who have experienced developmental language processing deficits (DLD). The standard effect for these items in lexical decision is an increase in response times over nonpseudohomophone nonwords. This disadvantage reflects phonological processing. In our first experiment the DLD group did not produce this pseudohomophone effect whereas in a second experiment they showed semantic priming effects when pseudohomophones were used as primes in lexical decision. The results therefore indicate that phonological processing of nonwords by adults with DLD can be uncovered under certain carefully controlled experimental conditions.

Neural deficits in children with dyslexia ameliorated by behavioral remediation: evidence from functional MRI.

Developmental dyslexia, characterized by unexplained difficulty in reading, is associated with behavioral deficits in phonological processing. Functional neuroimaging studies have shown a deficit in the neural mechanisms underlying phonological processing in children and adults with dyslexia. The present study examined whether behavioral remediation ameliorates these dysfunctional neural mechanisms in children with dyslexia. Functional MRI was performed on 20 children with dyslexia (8-12 years old) during phonological processing before and after a remediation program focused on auditory processing and oral language training. Behaviorally, training improved oral language and reading performance. Physiologically, children with dyslexia showed increased activity in multiple brain areas. Increases occurred in left temporo-parietal cortex and left inferior frontal gyrus, bringing brain activation in these regions closer to that seen in normal-reading children. Increased activity was observed also in right-hemisphere frontal and temporal regions and in the anterior cingulate gyrus. Children with dyslexia showed a correlation between the magnitude of increased activation in left temporo-parietal cortex and improvement in oral language ability. These results suggest that a partial remediation of language-processing deficits, resulting in improved reading, ameliorates disrupted function in brain regions associated with phonological processing and produces additional compensatory activation in other brain regions.

Affective language and humor appreciation after right hemisphere brain damage.

Many adults with right hemisphere brain damage exhibit difficulties in the comprehension and expression of emotional language and humor. Affective comprehension deficits range in severity and can be modulated by task and response demands as well as by the strength of emotional content. Expressive emotional language deficits, as characterized by reduced emotional intensity, are more pervasive than comprehension deficits. Deficits in humor appreciation generally affect the ability to integrate an incongruous element (e.g., a punch line) with the preceding context. Several co-occurring disorders (e.g., depression, cognitive and visuoperceptual deficits, and reduced auditory comprehension) may exacerbate problems with affective language and humor. Although some formal measures evaluate humor appreciation, none specifically addresses emotional language. While no hard data exist regarding efficacy of treatment for deficits in affective language or humor processing, several suggestions for such treatment are provided.

Language-Related Symptoms in Persons with Schizophrenia and How Deaf Persons May Manifest These Symptoms

Disturbances in language have long been viewed as a principal identifying characteristic of schizophrenia. The language-processing deficits of persons with schizophrenia are manifested in a variety of ways. Historically, analyses of schizophrenic patients� language disorders have focused almost entirely on speech. Deaf persons, however, constitute a portion of the population that is diagnosed as schizophrenic, and sign languages are often their principal means of communication. In recent years, preliminary observations have been reported that indicate that there are a number of similarities between the linguistic deficits of signing Deaf persons with schizophrenia and those evident in the speech of hearing schizophrenic patients. Systematic investigations of schizophrenic Deaf persons� signing need to be conducted both to improve treatment programs for Deaf patients and to increase our understanding of the language aspects of schizophrenia.

Cognitive impairments in patients with schizophrenia displaying preserved and compromised intellect.

Although intellectual and neurocognitive deficits accompany schizophrenia, there are inconsistencies in the literature concerning issues of intellectual decline, premorbid deficits, a modal deficit pattern, and preserved abilities. A battery of neuropsychological tests was administered once to 117 consecutively admitted patients with chronic schizophrenia and a group of 27 healthy control subjects to examine patterns of premorbid and current intellect (measured by means of reading scores and IQ, respectively) and the attendant cognitive profiles in schizophrenia using classification methods based on clinically derived (IQ levels) and atheoretical (cluster) techniques. Sixty patients (51%) with schizophrenia who displayed a general intellectual decline of 10 points or greater from estimated premorbid levels also exhibited deficits of executive function, memory, and attention. Twenty-eight patients (23%) with consistently low estimated premorbid intellect and current intellectual levels who displayed no evidence of IQ decline exhibited language and visual processing deficits in addition to deficits present in the intellectually declining group. The remaining 29 patients (25%) who displayed average estimated premorbid intellectual levels did not show IQ decline and exhibited a cognitive profile similar to normal, with the exception of executive function and attention impairment. Atheoretical analyses support the findings from clinically derived subgroups. These results suggest that IQ decline, although modal in schizophrenia, is not universally characteristic and that executive function and attention deficits may be core features of schizophrenia, independent of IQ variations.

Spoken Language Correlates of Reading Impairments Acquired in Childhood

This study reports the reading difficulties of five children following unilateral left hemisphere stroke sustained either before or during the early stages of literacy acquisition. Although each of the children experienced a period of disturbed language processing in the initial stages postonset, at the time of testing none of the children were considered to be clinically aphasic. Yet, on a standardized test of oral reading each of the children achieved a reading age that lagged behind chronological age and marked reading impairments were disclosed in four of the five children. A set of standardized and nonstandardized tests, aimed at measuring aspects of cognitive and spoken language processing that are considered to be important for normal reading acquisition, was administered. Where nonstandardized tests were used, performance of each of the stroke children was compared to that of groups of normally developing control children, closely matched for chronological age. A range of residual deficits in cognitive and spoken language processing was disclosed among the five brain-damaged children that appeared to be associated with their reading impairments. Two children had expectedly poor reading due to a selective impairment in verbal IQ; a specific phonological reading disorder was revealed in two children, each of which had a residual impairment to phonological awareness; and delayed reading acquisition was observed in one child with a general language deficit. It is suggested that when a child suffers damage to the left hemisphere in the early stages of reading acquisition, difficulties with learning to read are likely to ensue and may arise as a consequence of an underlying cognitive or linguistic deficit.

The Role of the Human Thalamus in Language and Memory: Evidence from Electrophysiological Studies

The data reviewed here indicate that electrical stimulation of the dominant ventrolateral thalamus can produce deficits in language processing that are not seen after similar stimulation of the nondominant ventrolateral thalamus. The nature of the language deficit produced varies, depending upon the rostrocaudal location of the stimulation site. Stimulation of the anterior left ventrolateral thalamus in right-handed patients resulted in production of a repeated erroneous word, stimulation of the medial ventrolateral thalamus evoked perseveration, and stimulation of the posterior ventrolateral thalmus and anterior pulvinar resulted in misnaming and omissions. Additional studies have examined the effect of electrical thalamic stimulation on verbal and nonverbal short-term memory. Left (but not right) ventrolateral thalamic stimulation during verbal memory input greatly decreased subsequent recall errors, while stimulation during verbal memory retrieval increased recall errors. This finding contrasted with those obtained from studies on nonverbal memory, in which right ventrolateral stimulation during memory input decreased recall errors, while left thalamic stimulation at the same stage increased recall errors. Left pulvinar stimulation disrupted verbal memory processing, while right pulvinar stimulation disrupted nonverbal memory processing. Limited evidence suggests that the effects of thalamic electrical stimulation on verbal memory may persist for several days after the stimulation has ended. The lateralization of thalamic functions also affects the motoric aspects of speech production. Left (but not right) ventrolateral thalmic stimulation disrupted speech articulation and increased the expiratory phase of respiration. The fact that these motor effects were evoked from the same general area of the thalamus that produced the language deficits discussed above raises the possibility that the thalamus is involved in coordinating the cognitive and motoric aspects of language production. A model of thalamic function is discussed in which defined regions of the thalamus operate as a “specific alerting response,” increasing the input to memory of category-specific material while simultaneously inhibiting retrieval from memory.

Cognitive and Emotional Sequelae of Cerebellar Infarct: A Case Report

The cerebellum has long been the subject of scientific investigation, but its role in nonmotor functions has only recently begun to receive serious consideration. Despite the growing literature linking the cerebellum to nonmotor/cognitive functions in humans, some controversy remains concerning the cerebellum’s role in these processes. We present a patient who developed both specific language processing and verbal memory deficits and emotional changes in the context of normal intelligence following a bilateral cerebellar ischemic stroke. Despite having multiple localized cerebellar lesions, this patient had no significant motor problems, nor was there radiological evidence of focal forebrain lesions to which the cognitive and emotional effects might be attributed. The role of the cerebellum in cognition and the relevance of cerebellum-associated cognitive/emotional dysfunction to the practicing clinician are discussed.

A Neural Network Model of Semantic Processing Errors in Parkinson‘s Disease

Recent research has indicated that degradation of dopaminergic pathways in the mesolimbic forebrain and neocortex are related to the language processing deficits observed in Parkinson‘s disease (PD) patients, with experimental investigations indicating that the semantic system suffers the greatest impairment. PD patients make slower responses and more errors in semantic judgement tasks compared to controls, even though nonsemantic performance on word-search tasks is unimpaired. These findings are used in this study to predict the performance of the semantic system of the dual-route model of skilled reading (DRC), where the connection strengths between word and word sense levels in the system are systematically manipulated to produce PD-like reductions in dopamine transmission. Low excitation between layers is predicted to produce PD errors in semantic judgements of polysemous words which have a low sense-frequency delta (s.f.d.), that is, a small difference in sense frequency between at least two word senses. Judgements made on high s.f.d words resulted in 100% correct responses over all excitation values, with a stable solution reached at 39–48 epochs. However, for low s.f.d words, incorrect responses were made for low to medium levels of excitation (30–50% errors), only providing the correct solution for medium to high levels of excitation. An interaction was also observed for low s.f.d words between high lateral inhibition in the word sense level, and low-medium excitation, to produce the results most characteristic of PD semantic errors. The results of this study confirm that competitive and inhibitory mechanisms related to dopaminergic gain are responsible for impaired PD performance on semantic processing tasks.

Attention Deficit/Hyperactivity Disorders

Attention Deficit/Hyperactivity Disorders

Anomalous cerebral asymmetry and language processing in schizophrenia.

Reversal or reduction of normal structural cerebral asymmetries may be related to the pathogenesis of schizophrenia, but this relationship remains controversial. We review the literature and describe a further study designed to detect whether anomalous asymmetries are present early in the illness (at the first episode), whether they predict deficits in language processing, and whether they may be related to a genetic predisposition for schizophrenia. Asymmetries of brain widths and segments of the sylvian fissure were assessed in a magnetic resonance imaging study of 87 patients with a first episode of schizophrenia and 52 normal controls. These asymmetries were correlated with specific measures of language processing, memory, and hand skill. An independent group of 14 pairs of siblings with schizophrenia were also evaluated for evidence of heritability to cerebral asymmetries. Width asymmetries were reduced in patients compared with controls in the posterior (p = 0.02) and occipital (p = 0.05) regions. Brain horizontal length, on the other hand, was significantly more asymmetrical in patients (left > right; p = 0.04). For sylvian fissure measurements, asymmetries in controls (left > right) were greatest for the horizontal component; this asymmetry tended to detect differences in patients by comparison with controls (p < 0.06). In a range of tests of language and memory, few significant correlations between performance and cerebral asymmetries were detected either in patients or controls, although patients consistently scored poorer than controls in the majority of tests. In 14 pairs of psychotic siblings, within-pair correlations for the horizontal sylvian fissure asymmetry were significantly greater than between-pair correlations. These findings are consistent with the early presence (possibly genetic) of anomalous cerebral asymmetry. However, the functional correlates of reduced asymmetry remain obscure.

Brain potentials reveal deficits of language processing after closed head injury.

To delineate deficits in language processing after closed head injury with use of behavioral measures and event-related brain potentials. Case-control design. All subjects participated in three verbal event-related brain potential experiments, and the resulting measures were compared both within and between groups. PATIENTS/CONTROLS: Eleven patients at least 2 years after severe closed head injury (Glasgow Coma Scale score < 8 at admission and duration of posttraumatic amnesia > 48 hours) were compared with a control group matched for age and educational level. None. Reaction times and percentage correct as behavioral measures in the three experiments (sentence verification, semantic and repetition priming with lexical decision task, and continuous word recognition). Event-related brain potentials were quantified by area measures in successive time windows for the different experimental conditions and for different experiments. The reaction times of the patient group were significantly longer than those of the controls (P < .005). Similarly, the patients' accuracy was significantly worse in all experiments (P < .03). The event-related brain potentials of the controls showed a clear and significant reduction of a negative component (N400) to terminal words of true sentences (sentence verification experiment), semantically primed words and repeated words (lexical decision experiment), and recognized words (continuous word recognition). For the patients, a clear N400 effect was seen only in the sentence verification task (delayed by about 100 milliseconds), while only later event-related brain potential modulations were seen in the other tasks. Language functions are disturbed after closed head injury. The electrophysiologic data suggest difficulties in the integration of incoming linguistic stimuli with the previous context as a possible underlying cause.