Lexical-semantic deficits following right hemisphere damage: evidence from verbal fluency tasks

The Emotional Verbal Fluency Task: A Close Examination of Verbal Productivity and Lexical-Semantic Properties

Purpose Emotional verbal fluency (Emo-VF) has the potential to expand neuropsychological assessment by providing information about affective memory retrieval. The usability of Emo-VF is limited, however, by significant variations in task administration and the lack of information about Emo-VF responses. This study investigated verbal productivity and the lexical-semantic properties of responses on positive and negative Emo-VF tasks. Comparing Emo-VF to non-Emo-VF tasks used regularly in neuropsychological assessment provided additional information about the basic characteristics of Emo-VF tasks. Method Twenty-five adult native speakers provided verbal responses to three Emo-VF ("happy," "sad," "negative emotions") and two non-Emo-VF categories ("animals," "things people do"). Verbal productivity was measured at the word and syllable levels. Multiple large-scale data corpora were used to estimate the lexical-semantic properties of the verbal responses. Results There was a robust positivity bias in verbal productivity within Emo-VF tasks. Emo-VF tasks tended to elicit longer words than "animals" and "things people do," which might impact the results of verbal productivity analyses, especially in comparisons with "things people do." Within Emo-VF tasks, negative Emo-VF elicited words from a wider range of valence than positive Emo-VF tasks. Similarities (e.g., word length and complexity) and differences (e.g., concreteness, age of acquisition) were found between positive and negative Emo-VF tasks. Conclusions The study provided information about the basic characteristics of Emo-VF tasks, which included evidence for a robust positivity bias, suggestions for analyses of verbal productivity (e.g., consideration of word length), and lexical-semantic properties associated with positive and negative Emo-VF tasks using corpora data.

Observational assessment of communication disorders in vascular dementia patients with right hemisphere damage

AIM

After stroke, communication disability often occurs, with left side brain-damaged (LBD) patients having aphasia and right side brain-damaged (RBD) patients having deficits in conversation, despite their apparent lack of any language disability. Herein, we developed an original scale, the Daily Communication Assessment Scale (DCAS) and compared the scores from the RBD and left side brain-damaged patients with their matched Mini-Mental State Examination (MMSE) scores.

METHODS

This cross-sectional survey involved three pairs of MMSE-matched patients (n = 6) with vascular dementia who met the following criteria: a history of stroke, unilateral localized basal ganglia legion (as shown by magnetic resonance imaging/computed tomography images), MMSE scores ≥9, and ability to engage in minimal conversation. Patients' MMSE scores were 11, 12, 15, 16, and 19. We interviewed patients' primary staff regarding their abilities to communicate over the previous 4 weeks in order to evaluate them using the DCAS.

RESULTS

In each MMSE-matched pair, the RBD patient had a lower Deviation score on the DCAS, and in two pairs, the left side brain-damaged patient had a lower score for Coarse speech.

CONCLUSION

We believe that communication disorder in the RBD patients may be evaluated with the DCAS. We plan to standardize the DCAS and apply it for use in rehabilitation in the future.

Impairment in Cognitive and Affective Empathy in Patients with Brain Lesions: Anatomical and Cognitive Correlates

The present study was designed to examine the degree of impairment in cognitive and affective empathy among patients with focal brain lesions, and the contribution of specific cognitive abilities (such as cognitive flexibility and processing of emotional information), to empathy. The cognitive and affective empathic response of patients with localized prefrontal lesions (n=36) was compared to responses of patients with parietal lesions (n=15) and healthy control subjects (n=19). Results indicate that patients with prefrontal lesions (especially those with lesions involving the orbitoprefrontal and medial regions) were significantly impaired in both cognitive and affective empathy as compared to parietal patients and healthy controls. When the damage was restricted to the prefrontal cortex, either left- or right-hemisphere lesions resulted in impaired empathy. However, when the lesion involved the right hemisphere, patients with parietal lesions were also impaired. The pattern of relationships between cognitive performance and empathy suggested dissociation between the cognitive correlates of affective and cognitive empathy.

Exploring cerebral asymmetries for the verb generation task

This study investigated potential right hemisphere involvement in the verb generation task. Six divided visual field experiments explored cerebral asymmetries for word retrieval in the verb generation task as well as in rhyme generation and immediate and delayed word pronunciation. The typical right visual field/left hemisphere (RVF/LH) advantage was observed for pronunciation and rhyme generation. For verb generation, the RVF/LH advantage was obtained only when stimulus items had a single prepotent response and not when there were multiple response alternatives. A semantic priming experiment suggested that activation for less common, related verbs was maintained for a longer time course within the right than within the left hemisphere. The authors suggest that the right hemisphere may play a role in continued activation of semantically related response alternatives in word generation and discuss methodological implications of their findings.

Affecting factors in second language learning

The present study investigated the influence of sex, handedness, level in second language (L2) and Faculty choice on the performance of phonological, syntactical and semantic tasks in L2. Level in L2 and sex were the most affecting factors. Subjects who achieved higher scores on L2 tasks had strong second language aptitude skills since they were those who had obtained a professional degree in the second language. Females performed better than males in syntax and semantics which is explained by the general female superiority on verbal tasks based on differences in hemispheric specialization for language functions between the sexes. Handedness and Faculty choice on the part of the participants had an impact on our results but only when combined with other factors.

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).

Levels of processing with free and cued recall and unilateral temporal lobe epilepsy

This study investigates the role of the temporal lobes in levels-of-processing tasks (phonetic and semantic encoding) according to the nature of recall tasks (free and cued recall). These tasks were administered to 48 patients with unilateral temporal epilepsy (right "RTLE"=24; left "LTLE"=24) and a normal group (n=24). The results indicated that LTLE patients were impaired for semantic processing (free and cued recall) and for phonetic processing (free and cued recall), while for RTLE patients deficits appeared in free recall with semantic processing. It is suggested that the left temporal lobe is involved in all aspects of verbal memory, and that the right temporal lobe is specialized in semantic processing. Moreover, our data seem to indicate that RTLE patients present a retrieval processing impairment (semantic condition), whereas the LTLE group is characterized by encoding difficulties in the phonetic and semantic condition.

Exploration of hemispheric specialization and lexico-semantic processing in unilateral temporal lobe epilepsy with verbal fluency tasks

Verbal production has been shown to rely on both hemispheres differentially. To determine how lateralized brain lesions affect the generation of isolated words, we evaluated three subject groups: normal controls (n=22), and patients with right (n=23), and left (n=22) non-operated temporal lobe epilepsy (TLE) using three verbal fluency tasks (letter, phonetic, semantic). LTLE patients produced fewer words than controls in the phonetic, letter, semantic conditions, whereas RTLE patients were only impaired in the semantic task. Hence, there would be a hemispheric specialization in language where phonetic processing involves mostly the left temporal lobe and semantic aspects of production involve both temporal lobes. And, in order to study disruption of semantic lexicon involved in supermarket fluency (to name things which can be bought in a supermarket), specific indicators Tröster et al., (1998) [Tröster AI, Fields JA, Testa JA, Paul RH, Blanco CR, Hames KA, Salmon DP, Beatty WW. Cortical and subcortical influences on clustering and switching in the performance of verbal fluency Tasks, Neuropsychologia 1998;36:295-304.] were exploited. Our results indicated that TLE groups made fewer category shifts than controls. Also, RTLE patients used labels more frequently and produced fewer exemplars. Results show the specificity of processing according to cue, and suggest that the semantic fluency deficits due to TLE be primarily due to an alteration of the mental lexicon.

The effects of varying attentional demands on the word retrieval skills of adults with aphasia, right hemisphere brain damage, or no brain damage

Adults with mild aphasia, right hemisphere brain damage (RBD), or no brain damage (NBD) provided one-word phrase completions under isolation, focused attention, and divided attention conditions and in response to relatively constrained or unconstrained phrase stems. Despite comparable word retrieval accuracy among groups during the isolation condition, aphasic and RBD groups performed less accurately than the NBD group during focused and divided attention conditions. Across conditions, there were no significant differences between aphasic and RBD groups. Only aphasic subjects demonstrated a significant effect of phrase type, responding more accurately when completing constrained versus unconstrained stimuli. For aphasic and RBD groups, error type analysis indicated that semantic and phonological aspects of word retrieval were influenced by increased attentional demands. These findings suggest that for adults with aphasia or RBD, there is a negative relation between attention impairments and word retrieval abilities.

Hemispheric asymmetries in category-specific word retrieval

We examined whether 53 adult non-aphasic patients with either left (22) or right temporal lobe lesions (31) demonstrate dissociable patterns of hemispheric asymmetries in category-specific word fluency tasks. The patients were asked to articulate as many appropriate words as possible within 60 or 90 s in response to six target categories. There was no effect of patient groups on the overall fluency. However, patients with a left-sided temporal lobe lesion were impaired retrieving words to 'initial letters' and to the category 'animals'. Right temporal lobe patients were impaired retrieving 'tools' and words referring to specific visual attributes. There were no fluency differences for 'food-supermarket goods' and 'flat interior'. We conclude that temporal lobe damage can result in category-specific impairments in word retrieval depending on the affected hemisphere.

Word fluency after a right-hemisphere lesion

Joanette and Goulet (Neuropsychologia, 1986, 24, 875-879) reported that right-handed patients suffering from a right-hemisphere stroke were impaired on semantic but not on orthographic criteria when they were submitted to a word fluency task. The interpretation of this dissociation was that the right hemisphere would subtend a particular contribution to the semantic component of word processing in right handers. The goal of the research reported here was to challenge this dissociation. In contrast with the first study, the production criteria were presented randomly and their level of productivity was a controlled factor. The semantic-orthographic dissociation was not replicated under these conditions.