Clustering and switching in verbal fluency: a comparison between control and individuals with brain damage

ABSTRACT Purpose The aim of this study is to analyze and compare the performance and strategies used by control subjects and patients with unilateral brain damage on phonemic and semantic Verbal Fluency tasks. Methods The sample consisted of 104 participants divided into four groups (26 with left hemisphere damage and aphasia- LHDa, 28 with left hemisphere damage and no aphasia- LHDna, 25 with right hemisphere damage- RHD and 25 neurologically healthy control subjects). All participants were administered the phonemic (“M” letter-based) and semantic (animals) verbal fluency tasks from the Montreal-Toulouse Language Assessment Battery (MTL-BR). Results Patients in the LHDa group showed the worst performance (fewer words produced, fewer clusters and switches) in both types of fluency task. RHD group showed fewer switching productions when compared with controls and LHDna had fewer words productions than controls in the first 30 seconds block. Conclusion Our findings suggest that the LHDa group obtained lower scores in most measures of SVF and PVF when compared to the other groups.

Investigating Musical Emotions in People with Unilateral Brain Damage

The study under discussion sought to investigate the hemispheric laterality of musical emotions: Is one hemisphere of the brain preferentially involved in recognizing emotions in music? The authors took a neuropsychological approach to answer this question by studying emotional judgments of music in people with brain damage to either hemisphere. Their results indicated that individuals with left hemisphere damage were significantly impaired in recognizing musical emotions as compared to healthy comparison participants. In contrast, individuals with right hemisphere damage were not impaired at identifying emotions in music, but rated the perceived intensity of the emotions lower for sadness and fear (as compared to joy and serenity). Their work suggests that the identification of emotions in music and the perceived intensity of the emotions expressed may rely on different hemispheres of the brain.

Awareness is in the Eye of the Observer: Preserved Third-Person Awareness of Deficit in Anosognosia for Hemiplegia

In recent decades, the research traditions of (first-person) embodied cognition and of (third-person) social cognition have approached the study of self-awareness with relative independence. However, neurological disorders of self-awareness offer a unifying perspective to empirically investigate the contribution of embodiment and social cognition to self-awareness. This study focused on a neuropsychological disorder of bodily self-awareness following right-hemisphere damage, namely anosognosia for hemiplegia (AHP). A previous neuropsychological study has shown AHP patients, relative to neurological controls, to have a specific deficit in third-person, allocentric inferences in a story-based, mentalisation task. However, no study has tested directly whether verbal awareness of motor deficits is influenced by either perspective-taking or centrism, and if these deficits in social cognition are correlated with damage to anatomical areas previously linked to mentalising, including the supramarginal and superior temporal gyri and related limbic white matter connections. Accordingly, two novel experiments were conducted with right-hemisphere stroke patients with (n = 17) and without AHP (n = 17) that targeted either their own (egocentric, experiment 1) or another stooge patient’s (experiment 2) motor abilities from a first-or-third person (allocentric in Experiment 2) perspective. In both experiments, neurological controls showed no significant difference between perspectives, suggesting that perspective-taking deficits are not a general consequence of right-hemisphere damage. More specifically, experiment 1 found AHP patients were more aware of their own motor paralysis when asked from a third compared to a first-person perspective, using both group level and individual level analysis. In experiment 2, AHP patients were less accurate than controls in making allocentric, third-person perspective judgements about the stooge patient, but with only a trend towards significance and with no within-group, difference between perspectives. Deficits in egocentric and allocentric third-person perspective taking were associated with lesions in the middle frontal gyrus, superior temporal and supramarginal gyri, with white matter disconnections more predominate in deficits in allocentricity. This study confirms previous clinical and empirical investigations on the selectivity of first-person motor awareness deficits in anosognosia for hemiplegia and experimentally demonstrates for the first time that verbal egocentric 3PP-taking can positively influence 1PP body awareness.

Storytelling in speakers with and without brain damage: A macrolinguistic approach

Narrative discourse is investigated in clinical and healthy populations. This study explored the discourse strategies used to tell stories, comparing the patterns of people with left- and right-hemisphere brain damage, as well as healthy speakers. We analyzed picture-elicited discourses by four people with aphasia, two people with right hemisphere damage, and four healthy speakers. We examined their microlinguistic properties, as well as macrolinguistic features, such as the discourse production type of utterances and patterns of story component usage. We identified two storytelling strategies used by the speakers: a narrative strategy marked by a prevalence of narrative discourse production type utterances and scarce use of evaluation clauses, and a quasi-narrative strategy with the opposite pattern. These strategies were used by both healthy speakers and participants with brain damage

Explicit Training to Improve Affective Prosody Recognition in Adults with Acute Right Hemisphere Stroke

Difficulty recognizing affective prosody (receptive aprosodia) can occur following right hemisphere damage (RHD). Not all individuals spontaneously recover their ability to recognize affective prosody, warranting behavioral intervention. However, there is a dearth of evidence-based receptive aprosodia treatment research in this clinical population. The purpose of the current study was to investigate an explicit training protocol targeting affective prosody recognition in adults with RHD and receptive aprosodia. Eighteen adults with receptive aprosodia due to acute RHD completed affective prosody recognition before and after a short training session that targeted proposed underlying perceptual and conceptual processes. Behavioral impairment and lesion characteristics were investigated as possible influences on training effectiveness. Affective prosody recognition improved following training, and recognition accuracy was higher for pseudo- vs. real-word sentences. Perceptual deficits were associated with the most posterior infarcts, conceptual deficits were associated with frontal infarcts, and a combination of perceptual-conceptual deficits were related to temporoparietal and subcortical infarcts. Several right hemisphere ventral stream regions and pathways along with frontal and parietal hypoperfusion predicted training effectiveness. Explicit acoustic-prosodic-emotion training improves affective prosody recognition, but it may not be appropriate for everyone. Factors such as linguistic context and lesion location should be considered when planning prosody training.

Pathological Prosody

Prosody in speech arises from fundamental frequency (f0), temporal measures, amplitude, and voice quality. These parameters in various combinations signal linguistic, emotional-attitudinal, and personal identity information. Prosodic processing engages cortical, subcortical, cerebellar, and brainstem systems, and damage to any of these can result in dysprosody. Despite the crucial role played by prosody in communication, little attention has been paid to clinical evaluation and even less to treatment. Numerous research studies of deficient emotional prosodic production and recognition reveal temporal deficits in association with left hemisphere damage and pitch processing failure in right hemisphere damage. Limited attempts at linguistic-prosodic testing suggest that damage to either cerebral hemisphere or to subcortical systems can affect production as well as comprehension. Treatment of linguistic dysprosody has revealed challenges in protocol design and performance evaluation. Prosodic insufficiency, present in cortical, subcortical, and cerebellar disease, has substantial implications for communicative function and deserves to be a strong focus of future research.

Motor Deficits in the Ipsilesional Arm of Severely Paretic Stroke Survivors Correlate With Functional Independence in Left, but Not Right Hemisphere Damage

Chronic stroke survivors with severe contralesional arm paresis face numerous challenges to performing activities of daily living, which largely rely on the use of the less-affected ipsilesional arm. While use of the ipsilesional arm is often encouraged as a compensatory strategy in rehabilitation, substantial evidence indicates that motor control deficits in this arm can be functionally limiting, suggesting a role for remediation of this arm. Previous research has indicated that the nature of ipsilesional motor control deficits vary with hemisphere of damage and with the severity of contralesional paresis. Thus, in order to design rehabilitation that accounts for these deficits in promoting function, it is critical to understand the relative contributions of both ipsilesional and contralesional arm motor deficits to functional independence in stroke survivors with severe contralesional paresis. We now examine motor deficits in each arm of severely paretic chronic stroke survivors with unilateral damage (10 left-, 10 right-hemisphere damaged individuals) to determine whether hemisphere-dependent deficits are correlated with functional independence. Clinical evaluation of contralesional, paretic arm impairment was conducted with the upper extremity portion of the Fugl-Meyer assessment (UEFM). Ipsilesional arm motor performance was evaluated using the Jebsen-Taylor Hand Function Test (JTHFT), grip strength, and ipsilesional high-resolution kinematic analysis during a visually targeted reaching task. Functional independence was measured with the Barthel Index. Functional independence was better correlated with ipsilesional than contralesional arm motor performance in the left hemisphere damage group [JTHFT: [r(10) = −0.73, p = 0.017]; grip strength: [r(10) = 0.64, p = 0.047]], and by contralesional arm impairment in the right hemisphere damage group [UEFM: [r(10) = 0.66, p = 0.040]]. Ipsilesional arm kinematics were correlated with functional independence in the left hemisphere damage group only. Examination of hemisphere-dependent motor correlates of functional independence showed that ipsilesional arm deficits were important in determining functional outcomes in individuals with left hemisphere damage only, suggesting that functional independence in right hemisphere damaged participants was affected by other factors.

The role of the right hemisphere in processing phonetic variability between talkers

Neurobiological models of speech perception posit that both left and right posterior temporal brain regions are involved in the early auditory analysis of speech sounds. However, frank deficits in speech perception are not readily observed in individuals with right hemisphere damage. Instead, damage to the right hemisphere is often associated with impairments in vocal identity processing. Herein lies an apparent paradox: The mapping between acoustics and speech sound categories can vary substantially across talkers, so why might right hemisphere damage selectively impair vocal identity processing without obvious effects on speech perception? In this review, I attempt to clarify the role of the right hemisphere in speech perception through a careful consideration of its role in processing vocal identity. I review evidence showing that right posterior superior temporal, right anterior superior temporal and right inferior / middle frontal regions all play distinct roles in vocal identity processing. In considering the implications of these findings for neurobiological accounts of speech perception, I argue that the recruitment of right posterior superior temporal cortex during speech perception may specifically reflect the process of conditioning phonetic identity on talker information. I suggest that the relative lack of involvement of other right hemisphere regions in speech perception may be because speech perception does not necessarily place a high burden on talker processing systems, and I argue that the extant literature hints at potential subclinical impairments in the speech perception abilities of individuals with right hemisphere damage.