Future directions for examining semantic memory in schizophrenia spectrum disorders

from Clinical EEG and Neuroscience

Language abnormalities in schizophrenia are regarded as a hallmark of the disease. Clinical investigations provided accurate descriptions of the different manifestations of abnormal language use, and behavioral studies suggested several mechanisms that might contribute to these abnormalities. This review focuses on semantic memory dysfunction and, primarily, on functional methodologies such as ERP and fMRI that provide more direct measures of abnormal neural mechanisms related to language use in schizophrenia. In addition, the review points to future directions of study of the areas that received little attention thus far and whose investigation might contribute to a more detailed understanding of semantic memory dysfunction in schizophrenia.

Hallucinations, thought disorders, and the language domain in schizophrenia

from Clinical EEG and Neuroscience

Auditory hallucinations and formal thought disorders are major diagnostic features of schizophrenia. From a neurobiological point of view, they are of particular interest since both can be attributed to the language domain of human communication. In the last decade, brain imaging studies have contributed to the understanding of the functional dynamics underlying these phenomena. In particular, auditory hallucinations were found to involve the regions generating inner speech as well as the primary acoustical cortex and the intrahemispheric fiber bundles connecting the left frontal with the temporal lobe. In patients with formal thought disorders, on the other hand, the left temporal language area showed structural deficits and functional abnormalities, i.e., reduced reactivity to stimulation and increased activity at rest; left frontal language regions were also hyperactive at rest but showed no structural deficits. The available evidence indicates a dynamic imbalance of the language system, triggered by subtle structural changes, as the possible common neurobiological basis of hallucinations and formal thought disorders.

Semantic activation and verbal working memory maintenance in schizophrenic thought disorder: insights from electrophysiology and lexical ambiguity

from Clinical EEG and Neuroscience

We have examined language processing using ambiguous words (homographs like panel or toast) and rapid or slow presentation rates while recording event-related brain potentials (ERPs). Homographs allow for tracking the train of thought at points of lexical ambiguity and detecting modulation of associative threads by previous context. Rapid presentation rates stress automatic semantic activation, and slow rates stress controlled verbal working memory contextual modulation. In conjunction with reaction times and performance, ERPs allow for objective measurement of activity related to language processing from word presentation through overt behavioral response. Smaller N400 to related and unrelated items at short stimulus onset asynchronies (SOAs), the presence of a semantic bias, and large N400 to related and unrelated items at long SOAs are present in schizophrenia. We describe a model of initial semantic memory hyper-priming and subsequent decay of information in verbal working memory stores, the activation-maintenance model of schizophrenic thought disorder hypothesized to underlie the thought disorder in schizophrenia.

Moms have few interactions with their infants during TV time

from EurekAlert.org

Infants who are exposed to television and video in low socio-economic households tend to have limited verbal interactions with their mothers, according to a new study led by Alan L. Mendelsohn, MD, Assistant Professor of Pediatrics and Director of Clinical Research for the divisions of General and Developmental-Behavioral Pediatrics in the Department of Pediatrics at NYU School of Medicine.

Timing of Palatal Surgery and Speech Outcome

from the Cleft Palate-Craniofacial Journal

examine the impact of age and lexical status at the time of primary palatal surgery on speech outcome of preschoolers with cleft palate.

Participants: Forty children (33 to 42 months) with nonsyndromic cleft palate participated in the study. Twenty children (Group 1) were less lexically advanced and younger (mean age = 11 months) and 20 children (Group 2) were more lexically advanced and older (mean age = 15 months) when palatal surgery was performed.

Main Outcome Measures: Samples of the children’s spontaneous speech were compared on 11 speech production measures (e.g., size of consonant inventory, total consonants correct, % correct for manner of articulation categories, compensatory articulation usage, etc.). Next, listeners rated a 30-second sample of each child’s connected speech for articulation proficiency and hypernasality, separately, using direct magnitude estimation (DME).

Results: Group differences were noted for 4 of the 11 speech production measures. Children in Group 1 exhibited larger consonant inventories (and true consonant inventories) and more accurate production of nasals and liquids compared to children in Group 2. On the DME task, significant group differences were found for ratings of articulation proficiency and hypernasality. Children in Group 1 exhibited better articulation and less hypernasality than children in Group 2.

Conclusions: The findings suggested that children who were less lexically advanced and younger at the time of palatal surgery exhibited better articulation and resonance outcomes at 3 years of age.

Ethical and social implications of genetic testing for communication disorders

from the Journal of Communication Disorders

Advances in genetics and genomics have quickly led to clinical applications to human health which have far-reaching consequences at the individual and societal levels. These new technologies have allowed a better understanding of the genetic factors involved in a wide range of disorders. During the past decade, incredible progress has been made in the identification of genes involved in the normal process of hearing. The resulting clinical applications have presented consumers with new information and choices. Many of the same gene identification techniques are increasingly being applied to the investigation of complex disorders of speech and language. In parallel with gene identification, studies of the legal, ethical and psychosocial impacts of the clinical application of these advances and their influence on specific behaviors of individuals with communication disorders are paramount, but often lag behind. These studies will help to ensure that new technologies are introduced into clinical practice in a responsible manner.

Differences in Noun and Verb Processing in Lexical Decision Cannot be Attributed to Word Form and Morphological Complexity Alone

from the Journal of Psycholinguistic Research

Abstract It has been suggested that the effect of word category in noun and verb processing reflects typical word class properties, which can be characterized in terms of semantic as well as syntactic and morphological features. The present study is aimed at differentiating and discussing the relative contribution of these aspects with a main focus on syntactic and morphological processing. Experiment 1 established a processing advantage for nouns in German visual lexical decision, using nouns denoting biological and man-made objects as compared to transitive and intransitive verbs. Experiment 2 showed that the noun advantage persisted even when the morphological differences between word categories were reduced by using identical suffixes in nouns and verbs. Overall results suggest that the processing differences cannot be reduced to variables such as frequency, word form, or morphological complexity. Reaction time differences between transitive and intransitive verbs strengthen the role of syntactic information. In line with previous accounts the observed effects are discussed in terms of a category-specific combination of linguistic parameters.

Early intervention in phonological awareness seems to improve phonological working memory in young children with specific language impairment

from Evidence-Based Communication Assessment and Intervention

No abstract available.

Study Suggests Vocabulary Evolved To Fit In The Brain

from Medical News Today.com

Changizi’s research, which was published online this week and will appear in the June print edition of the Journal of Cognitive Systems Research, indicates that the dictionaries we use every day utilize approximately the optimal number of hierarchical levels – and provide a visual roadmap of how the lexicon itself has culturally evolved over tens of thousands of years to help lower the overall “brain space” required to encode it, according to Changizi.

Deep dysphasia as a phonetic input deficit: Evidence from a single case

from Aphasiology

Background: The syndrome of deep dysphasia is characterised by an inability to repeat pseudowords and the production of semantic errors in word repetition. Several single case studies revealed that phonological decoding might be outstandingly impaired. Recovery of deep dysphasia has only been illustrated in detail for patient NC (Martin & Saffran, 1992). Dell, Schwartz, Martin, Saffran, and Gagnon (1997) tried to simulate NC’s repetition performance in their connectionist lexical activation model, but it did not fit his error pattern as it assumes perfect recognition of auditory input.

Aims: In this new single case study on recovery of deep dysphasia, we intended to collect further evidence for the assumption that impaired input processing is the crucial cause of the impairment. Moreover, we aimed to explain impairment and psycholinguistic parameter effects in the connectionist semantic-phonological model (Foygel & Dell, 2000) by adding a phonetic input level.

Methods & Procedures: JR’s performance was repeatedly assessed in the course of recovery. Errors in naming and repetition were classified according to the taxonomy of Dell et al. (1997). JR’s error patterns were simulated in the semantic-phonological model to determine the naming disorder and to predict word repetition. In addition, we established an error modality analysis to disentangle input and output impairments in repetition. Thus, the source of each error could be subclassified as belonging to either expressive or receptive components of repetition.

Outcomes & Results: Initially there was a sharp contrast between severely impaired word and pseudoword repetition and almost unimpaired reading aloud. During recovery, performance in naming and word repetition improved a great deal, while repetition of pseudowords remained impossible. The evolvement of real word repetition was characterised by psycholinguistic parameter effects at different points in time: concreteness before length, before frequency. The connectionist model over-predicted correct responses in word repetition as for NC. There were only few expressive repetition errors; regarding receptive errors, nonwords and null responses decreased significantly while formal errors became the dominant error type in the course of recovery.

Conclusions: The development of psycholinguistic parameter effects, dissociations in performance, the computer simulations, and results from error modality analysis as well as changes of error pattern are ample evidence for the primary decoding disorder in JR. We argue that deep dysphasia can be explained by an impairment of phonetic-phonological connections in an extended version of the connectionist one-route model of repetition with four rather than three levels of auditory word processing. The improved real word repetition despite persisting failure on pseudowords is accounted for by an increase of both phonetic-phonological and lexical-phonological connection weights.

Specific language impairment in childhood is associated with impaired mental and social well-being in adulthood

from Logopedics Phoniatrics Vocology

To study the possible influence of childhood language impairment on adult life and well-being, 35 persons with a mean age of 34 years filled out two questionnaires. Compared with the general population, subjects more often lived with parents, and were pensioned. Only a few reported having literacy problems, but over 40% had difficulty in finding words and remembering instructions. Childhood performance IQ was associated with education and word-finding difficulties, and verbal IQ with difficulties in remembering instructions. Health-related quality of life was related to literacy skills, finding words, and remembering instructions. In conclusion, adults with childhood language impairment differ markedly from the general population. Problems in expressing themselves and receiving information affect their well-being the most. Childhood performance seems to have some prognostic value for language-based problems in adulthood.

Hearing status among commercial pilots in a Swedish airline company

from the International Journal of Audiology

The aim was to study hearing impairment in commercial pilots. A total of 634 male and 30 female pilots (n=664) in a Swedish airline company underwent repeated audiological tests during the period 1974-2005. The last test was used to study hearing impairment. The mean values for the hearing test at 3, 4, and 6 kHz were used for the ear with worse hearing impairment. Data was compared with a general adult Swedish population (n=603) not occupationally exposed to noise. Equivalent noise levels gate to gate (Leq) were measured in the cockpit of different aircraft. Leq was 75-81 dB (A), peak exposures were 105 dB (A) from the cabin call signal. Median values were similar as in the reference group at all ages. There was no association between years of employment, tobacco smoking, and hearing impairment, when adjusted for age and gender by multiple logistic regressions analysis. In conclusion, pilots are exposed to equivalent noise levels below the current Swedish occupational standard of 85 dB (A), with short peak exposures above the standard, and have normal age-matched hearing thresholds.

Reacquisition of semantic knowledge by errorless learning in a patient with a semantic deficit and anterograde amnesia

from Aphasiology

Background: So far 11 therapy studies have been reported which aimed to re-teach semantic knowledge in brain-damaged patients presenting with a semantic deficit consecutive to stroke, herpes encephalitis, or semantic dementia. All these semantic therapy studies but one recorded a significant improvement in the patients’ performance on tasks requiring semantic processing. The exception to this pattern was the semantic therapy study by Sartori, Miozzo, and Job (1994), which yielded negative results. Because the study concerned two patients with anterograde amnesia associated with the semantic deficit, Sartori et al. concluded that reacquiring semantic knowledge was not possible when such association of deficits was present.

Aims: Sartori et al.’s study, like all the other semantic therapy studies, applied an errorful learning procedure during the therapy. However, the question can be raised of whether such procedure is appropriate when amnesia is associated with the semantic deficit. Because error elimination is likely a function of explicit memory, which is impaired in amnesic patients, wrong stimulus-response associations would be repeatedly retrieved and strengthened in (spared) implicit memory, thus preventing the patient from learning novel semantic knowledge. In the present single-case study we addressed this issue by using an errorless learning procedure during semantic therapy in a post-encephalitis patient (DL) who suffered both a semantic deficit and anterograde amnesia.

Methods & Procedures: The therapy aimed at re-teaching semantic attributes of 16 items. The design included, further to these 16 target items, 16 contrast and 16 control items, which were semantic coordinates of the target items. Both shared (category) and distinctive (non-category) attributes were included in the learning set. Learning was based on an attribute classification task in which the properties of the target items had to be contrasted with those of coordinate items, within a paradigm that greatly reduced the chance of making errors. A pre- and post-therapy picture naming and an attribute verification task allowed us to assess the therapy effects at the end of therapy and 1 year later.

Outcomes & Results: Significant therapy effects were observed in the attribute verification task and were still present 1 year afterwards. Thus, the patient’s performance significantly improved for the category (i.e., shared) attributes of the target, contrast, and control items, and for the non-category (i.e., distinctive) attributes of the target items.

Conclusions: This finding showed that, contrary to Sartori et al.’s claim, re-acquiring semantic knowledge was possible in a patient with anterograde amnesia associated with her semantic deficit.

The choice of distracting task can affect the quality of auditory evoked potentials recorded for clinical assessment

from the International Journal of Audiology

Auditory evoked potential (AEP) recordings often require subjects to ignore the stimuli and stay awake. In the present experiment, early (ABR), middle (MLR), and late latency (LLR) AEPs were recorded to compare the effect of five different distracting tasks: (1) doing nothing eyes open, (2) reading, (3) watching a movie, (4) solving a three-digit sum, and (5) doing nothing eyes closed (or counting the stimuli for LLR). Results showed that neither the amplitudes nor the latencies of the ABR, MLR, or LLR were affected by task. However, the amount of pre-stimulus activity (noise) or amplitude rejection was significantly and differently affected by the distracting task. For the ABR, the math task was the noisiest but, for the MLR, the amount of noise was greater when watching a movie. As for the LLR, reading and watching a movie yielded the lowest percentage of rejected traces. In conclusion, the choice of distracting task depends on the AEP being measured and should be chosen to improve the quality of the AEP traces and thus reduce recording time.

The role of semantic knowledge in relearning spellings: Evidence from deep dysgraphia

from Aphasiology

Background: Remediation techniques for dysgraphia have focused on targeting different components of the theoretical models for spelling. Studies have revealed that targeting lexically oriented strategies can prove beneficial for patients with deep dysgraphia. Studies on short-term memory have also demonstrated a role of semantic knowledge in short-term retention

Aims: Two variants of lexically oriented strategies were applied to remediate a deep dysgraphic patient, PH, and the role of imagery in supporting the learning was examined.

Methods & Procedures: Retraining was explored using a visual-kinaesthetic learning technique, contrasting performance with high- and low-imagery words.

Outcomes & Results: Positive effects of learning were demonstrated. There was effective initial learning of blocks of both high-imagery and low-imagery target words, but high-imagery words had a clear advantage in terms of longer-term maintenance.

Conclusions: The data demonstrate that semantic knowledge may play a role in strengthening graphemic representations of words, helping in the maintenance of the orthography of target words over time.