Neural signatures of semantic and phonemic fluency in young and old adults

As we age, our ability to select and to produce words changes, yet we know little about the underlying neural substrate of word-finding difficulties in old adults. This study was designed to elucidate changes in specific frontally mediated retrieval processes involved in word-finding difficulties associated with advanced age. We implemented two overt verbal (semantic and phonemic) fluency tasks during fMRI and compared brain activity patterns of old and young adults. Performance during the phonemic task was comparable for both age groups and mirrored by strongly left-lateralized (frontal) activity patterns. On the other hand, a significant drop of performance during the semantic task in the older group was accompanied by additional right (inferior and middle) frontal activity, which was negatively correlated with performance. Moreover, the younger group recruited different subportions of the left inferior frontal gyrus for both fluency tasks, whereas the older participants failed to show this distinction. Thus, functional integrity and efficient recruitment of left frontal language areas seems to be critical for successful word retrieval in old age.

Predicting aspiration in patients with ischemic stroke: comparison of clinical signs and aerodynamic measures of voluntary cough

BACKGROUND

Clinical signs often fail to identify stroke patients who are at increased risk of aspiration. We hypothesized that objective measure of voluntary cough would improve the accuracy of the clinical evaluation of swallow to predict those patients who are at risk.

METHODS

A comprehensive diagnostic evaluation was completed for 96 consecutive stroke patients that included cognitive testing, a bedside clinical swallow examination, aerodynamic and sound pressure level measures of voluntary cough, and "gold standard" instrumental swallowing studies (ie, videofluoroscopic evaluation of swallow [VSE] or fiberoptic endoscopic evaluation of swallow [FEES]). Stroke severity was assessed retrospectively using the Canadian neurologic scale.

RESULTS

Based on the findings of VSE/FEES, 33 patients (34%) were at high risk of aspiration and (66%) were nonaspirators. Clinical signs (eg, absent swallow, difficulty handling secretions, or reflexive cough after water bolus) had an overall accuracy of 74% with a sensitivity of 58% and a specificity of 83% for the detection of aspiration. Three objective measures of voluntary cough (expulsive phase rise time, volume acceleration, and expulsive phase peak flow) were each associated with an aspiration risk category (areas under the curves were 0.93, 0.92, and 0.86, respectively). Expulsive phase rise time > 55 m/s, volume acceleration < 50 L/s/s, and expulsive phase peak flow < 2.9 L/s had sensitivities of 91%, 91%, and 82%, respectively; and specificities of 81%, 92%, and 83%, respectively for the identification of aspirators.

CONCLUSION

Objective measures of voluntary cough can identify stroke patients who are at risk for aspiration and may be useful as an adjunct to the standard bedside clinical assessment.

Active treatments for aprosodia secondary to right hemisphere stroke

This study investigates the effects of two mechanism-based treatments for expressive aprosodia. Three participants, two women and one man, had a right hemisphere cerebral infarction resulting in affective aprosodia with greater expressive than receptive deficits. Trained raters determined presence of aprosodia by judging participants' performance on two emotional communication batteries. A single-subject design with replication across three participants was employed. Sentence production with the use of treated and nontreated emotions was measured during baseline and treatment phases. Sentences were scored for accuracy by a trained rater blind to time of testing and analyzed visually and statistically. Effect sizes calculated on the resulting data for each participant and treatment confirmed modest to substantial treatment effects for both treatments in all three participants. Because of a relative paucity of treatment studies investigating expressive aprosodia, these data are among the first to suggest that aprosodia may be amenable to behavioral treatments.

Novel treatments for expressive aprosodia: a phase I investigation of cognitive linguistic and imitative interventions

This study investigated two mechanism-based treatments for expressive aprosodia, a disturbance in emotional prosody thought to be governed by the right hemisphere. The 3 participants all suffered right CVA's resulting in expressive aprosodia. Presence of expressive aprosodia was determined by performance on two batteries of emotional communication. A single subject ABAC design was employed in which two treatments, one imitative and one cognitive linguistic, were assigned in random order. All participants in this study were randomly assigned to begin with the cognitive linguistic treatment. Probes of treated and untreated emotions were completed during baseline and therapy phases. Probe items were judged by a reliable, trained rater blind to time of testing. Visual and statistical analyses were completed. These analyses confirmed that both treatments were active. For example, effect size calculations confirmed modest to substantial treatment effects for both treatments in all 3 patients. Replication to increase confidence about treatment effect and enhance understanding of the neuromechanisms underlying aprosodia is underway.

Processing words with emotional connotation: an FMRI study of time course and laterality in rostral frontal and retrosplenial cortices

Responses of rostral frontal and retrosplenial cortices to the emotional significance of words were measured using functional magnetic resonance imaging (fMRI). Twenty-six strongly right-handed participants engaged in a language task that alternated between silent word generation to categories with positive, negative, or neutral emotional connotation and a baseline task of silent repetition of emotionally neutral words. Activation uniquely associated with word generation to categories with positive or negative versus neutral emotional connotation occurred bilaterally in rostral frontal and retrosplenial cortices. Furthermore, the time courses of activity in these areas differed, indicating that they subserve different functions in processing the emotional connotation of words. Namely, the retrosplenial cortex appears to be involved in evaluating the emotional salience of information from external sources, whereas the rostral frontal cortex also plays a role in internal generation of words with emotional connotation. In both areas, activity associated with positive or negative emotional connotation was more extensive in the left hemisphere than the right, regardless of valence, presumably due to the language demands of word generation. The present findings localize specific areas in the brain that are involved in processing emotional meaning of words within the brain's distributed semantic system. In addition, time course analysis reveals diverging mechanisms in anterior and posterior cortical areas during processing of words with emotional significance.

Functional Outcome Questionnaire for Aphasia: overview and preliminary psychometric evaluation

OBJECTIVE

To perform a preliminary evaluation of a questionnaire designed to assess functional outcomes of treatment for aphasia.

METHODS

The Functional Outcome Questionnaire for Aphasia (FOQ-A) is an inventory consisting of 32 caregiver-completed items rating the person with stroke's ability to perform various communication behaviors on a 5-point scale. The total score for the FOQ-A is reported as a mean of all completed items. The FOQ-A was administered by research assistants to caregivers of patients with left hemisphere stroke (n = 18).

RESULTS

The FOQ-A showed acceptable initial reliability and validity properties. As predicted, the FOQ-A displayed high positive correlations with standardized functional communication measures. The FOQ-A also showed only weak associations with other measures (health-related quality of life, caregiver strain).

CONCLUSIONS

Overall results of our preliminary psychometric examination of the FOQ-A were promising. The findings suggested that the FOQ-A may be a sensitive measure of functional communication abilities and does not appear to be biased heavily by caregiver strain. Plans for further evaluation of the FOQ-A are discussed.

Apraxia and the supplementary motor area

Anatomical, electrophysiological, and cerebral blood flow studies suggest that the supplementary motor area (SMA) may be important for programming certain skilled motor acts of the limbs. However, to our knowledge, abnormalities of complex distal motor behavior following SMA lesions have not been reported. We have studied two patients with left mesial hemisphere infarctions that included the SMA. These patients had bilateral ideomotor apraxia for transitive limb movements without buccofacial apraxia. The observations suggest that the types of skilled motor acts programmed by the left SMA are learned transitive limb movements.