The influence of acquired dysarthria on conversational turn-taking

To investigate the influence of acquired dysarthria on conversational turn-taking, contributions from five stroke and 19 non-brain damaged (NBD) elderly subjects were analysed. It was hypothesized that the dysarthric (DYS) group would be less active participants. In subject-researcher conversations the DYS subjects contributed a lower percentage of the total conversational parameter turns than did the control subjects. Number of turns did not differ in the groups, but for the DYS group fewer of these were major turns and their length was shorter. This less active participation was consistent with subjects' perceptions of post stroke change to interaction style. Intelligibility may influence conversational contribution: the pattern of the more intelligible speakers more closely approached that of the NBD group. DYS subjects also paused more than NBD before turns. Dysarthria assessment should include appropriate evaluation of conversation, to guide management decisions. Future research should involve larger subject groups. Analysis should encompass further aspects of the conversational process, such as topic, repair and non-verbal responses, with attention to both participants, and preferably with familiar conversational partners.     

Perceptuo-acoustic assessment of prosodic impairment in dysarthria

Dysprosody was studied in four groups of male subjects: subjects with amyotrophic lateral sclerosis (ALS) and mild intelligibility impairment, subjects with ALS and a more severe intelligibility loss, subjects with cerebellar disease, and neurologically normal controls. Dysprosody was assessed with perceptual ratings and acoustic measures pertaining to the regulation of duration, ?₀, and intensity within tone units of conversational samples. Intelligibility reduction and prosodic disturbance were not necessarily equally impaired in all subjects, and it is concluded that these are complementary indices of severity of dysarthria. Compared to the neurologically normal control group, the clinical groups tended to decrease the overall duration of tone units, produce fewer words in a tone unit, and use smaller variations in ?₀. Recommendations are offered for the assessement of     

Perceptual characteristics of Cantonese hypokinetic dysarthria

The aims of this study were to provide a perceptual speech ‘profile’ for Cantonese speakers with hypokinetic dysarthria, to examine the reliability of non‐expert listeners in perceptual judgements of dysarthric speech, and to investigate cross‐language differences in profiles of hypokinetic dysarthria. Participants included 19 speakers with Parkinson's disease and 10 speech‐language pathologists who served as listeners. Listeners rated 21 speech dimensions, using seven‐point interval scales. Mean intralistener agreement was 94.52% and mean interlistener reliability was 0.88 (Cronbach's alpha). Mean scale values (MSV) for each dimension ranged from 3.37 to 1.36. The perceptual profile of Cantonese hypokinetic dysarthria was largely similar to profiles for English and Japanese speakers; notable differences are discussed. Possible reasons for the relatively high reliability obtained are presented.     

Lognormal distribution of pause length in ataxic dysarthria

Previous investigations indicated that pauses in ataxic dysarthric speech are abnormal, but little is known about the nature of their variation or whether it can be characterized by a common distribution. The following types of pauses were measured in spontaneous monologues of 16 speakers with ataxic dysarthria: pauses that contained evidence of respiration, pauses that occurred between words, between phonemes, within phonemes, and those associated with stop consonants. Results showed that the duration of pauses not associated with stop consonants can be modeled with two distinct lognormal distributions. The lognormal distribution predicted duration across pause types within 1.67% standard error, with the exception of pauses that occurred within phonemes. Distributional parameters pointed to some fundamental similarities between pauses that occur within words. The robustness of the lognormal distribution across pause types strongly supports this distribution as a viable and useful method of analysis. We hope this work will encourage others to consider the lognormal distribution.     

Intelligibility in dysarthria: Effects of listener familiarity and speaking condition

This study examined the effects of familiarization and speaking condition on sentence intelligibility for a speaker with dysarthria secondary to a traumatic brain injury (TBI). Familiarization procedures included hearing the speaker read a paragraph or a word list comprised of a random ordering of the words in the paragraph. Such an approach allowed for statements concerning the benefit of prior exposure to a sentence‐level prosody and word level articulatory‐acoustic patterns versus only word‐level articulatory‐acoustic patterns. Following word list, paragraph, or no familiarization, listeners orthographically transcribed sentences in either a habitual, slow, fast, or loud condition. Listeners receiving either word list or paragraph familiarization accurately transcribed a higher percentage of words in sentences than listeners receiving no familiarization. Intelligibility scores did not differ for word list or paragraph familiarization, however. Listeners also were more accurate transcribing sentences produced in the loud condition compared to habitual and fast conditions. Clinical implications are discussed.     

Perceptual and acoustic analysis of lexical stress in Greek speakers with dysarthria

The study reported in this paper investigated the abilities of Greek speakers with dysarthria to signal lexical stress at the single word level. Three speakers with dysarthria and two unimpaired control participants were recorded completing a repetition task of a list of words consisting of minimal pairs of Greek disyllabic words contrasted by lexical stress location only. Fourteen listeners were asked to determine the attempted stress location for each word pair. Acoustic analyses of duration and intensity ratios, both within and across words, were undertaken to identify possible acoustic correlates of the listeners’ judgments concerning stress location. Acoustic and perceptual data indicate that while each participant with dysarthria in this study had some difficulty in signaling stress unambiguously, the pattern of difficulty was different for each speaker. Further, it was found that the relationship between the listeners’ judgments of stress location and the acoustic data was not conclusive.     

Voicing status of word final plosives in Friedreich's Ataxia dysarthria

In a previous study, the authors identified final plosive voicing contrast as the highest single error source in dysarthria associated with Friedreich's Ataxia in a group of Irish English‐speaking participants. This study aimed to determine the acoustic features underlying misperceptions of voicing status and implications for clinical management. Words with final plosives were extracted from recordings of ten speakers with Friedreich's Ataxia. Various measures of the syllable rhyme were compared with intelligibility scores. Vowel duration, voicing in the closure, F1 frequency at mid‐vowel and a drop in F1 at vowel termination accounted for 58% of the variance in the relevant intelligibility scores, with vowel duration being most heavily implicated. While inappropriate vowel duration is the factor most likely to lead to misperceptions of final plosive voicing status, other factors may overcome its effect. Therapeutic intervention with this population should be based on a comparison of intelligibility assessment with acoustic measurement.     

急性缺血性脑卒中构音障碍及磁共振弥散加权影像特点研究

目的通过分析急性缺血性脑卒中构音障碍的临床及磁共振弥散加权影像特点,探讨构音障碍与脑梗死损害部位关系。方法总结155例早期表现构音障碍的急性缺血性脑梗死患者的临床表现,同时进行磁共振T1加权、T2加权、FLAIR及弥散加权成像检查(diffusion-weighted imaging,DWI),分析构音障碍患者临床与DWI显示梗死灶部位关系。结果155例急性缺血性脑梗死患者中,8例表现为单纯构音障碍(5.2%),141例伴有肢体偏瘫(91%),123例伴有椎体束征(79.4%)。DWI显示梗死病灶主要位于幕上96例(61.9%),病变灶位于左侧。28例患者的DWI显示为腔隙性梗死,其中20例(71%)临床表现为典型的伴构音障碍的腔隙性梗死综合征。结论急性脑梗死引起构音障碍多伴随其它神经功能障碍。梗死病灶多沿皮质延髓束分布,以幕上梗死多见,病灶多位于左半侧,可能与左侧半球对言语功能控制占优势有关。     

The cerebellum and neural networks for rhythmic sensorimotor synchronization in the human brain

Sensorimotor synchronization (SMS) is the rhythmic synchronization between a timed sensory stimulus and a motor response. This rather simple function requires complex cerebral processing whose basic mechanisms are far from clear. The importance of SMS is related to its hypothesized relevance in motor recovery following brain lesions. This is witnessed by the large number of studies in different disciplines addressing this issue. In the present review we will focus on the role of the cerebellum by referring to the general modeling of SMS functioning. Although at present no consensus exists on cerebellar timekeeping function it is generally accepted that cerebellar input and output flow process time information. Reviewed data are considered within the framework of the ‘sensory coordination’ hypothesis of cerebellar functioning. The idea that timing might be within the parameters that are under cerebellar control to optimize cerebral cortical functioning is advanced.     

The production effect in adults with dysarthria: improving long-term verbal memory by vocal production

People show better memory for words read aloud relative to words read silently, the Production Effect (PE). Vocalisation at study makes the produced (aloud) words more distinct than the non-produced (silent) words, hence more memorable. Such encoding distinctiveness is related to the additional processing of aloud words that is later used during retrieval. This study investigated the PE in dysarthric adults, characterised by speech production difficulties. Their memory performance (recognition) was compared to a group of healthy adults. Results showed a PE for both groups. The production benefit was significantly larger for the dysarthric adults, despite their overall memory performance being reduced relative to controls. The results demonstrate long-term verbal memory deficits in dysarthria, and suggest that vocalisation (although impaired) may assist in remembering. Hence, vocalisation may be used in intervention contexts with this population, to compensate for memory decrease.     

Clinical manifestation of focal cerebellar disease as related to the organization of neural pathways

Neural pathways connect different parts of the cerebellum to different parts of the central nervous system. The cerebellum may be divided anatomically and functionally into three major regions. The cerebellar hemispheres and a small part of the posterior lobe vermis form the pontocerebellum, which receives inputs from the cerebral cortex via the pontine nuclei. The anterior lobe and most of the posterior lobe vermis make up the spinocerebellum, which receives afferents from the spinal cord. The nodulus and flocculus are connected with the vestibular nuclei and constitute the vestibulocerebellum. Most cases of cerebellar disease affect more than one region and different pathways. Hence, they cause generalized cerebellar symptoms dominated by impaired motor control and balance. Focal syndromes after restricted cerebellar lesions are rare. Isolated spinocerebellar affection may give gait ataxia. Vestibulocerebellar disease causes equilibrium disturbances with truncal ataxia and nystagmus. Pontocerebellar lesions typically give ipsilateral limb ataxia, but also dysartria and oculomotor dysfunction if vermal parts are involved. The clinical picture is in most cases of cerebellar disease dominated by motor disturbances, but the cerebellum also participates in the modulation of autonomic and affective responses and in cognitive functions. The cerebrocerebellar and hypothalamocerebellar circuits may be important for these tasks.     

Differential Effects of Cerebellar Degeneration on Feedforward versus Feedback Control across Speech and Reaching Movements

Errors that result from a mismatch between predicted movement outcomes and sensory afference are used to correct ongoing movements through feedback control and to adapt feedforward control of future movements. The cerebellum has been identified as a critical part of the neural circuit underlying implicit adaptation across a wide variety of movements (reaching, gait, eye movements, and speech). The contribution of this structure to feedback control is less well understood. Although it has recently been shown in the speech domain that individuals with cerebellar degeneration produce larger online corrections for sensory perturbations than control participants, similar behavior has not been observed in other motor domains. Currently, comparisons across domains are limited by different population samples and potential ceiling effects in existing tasks. To assess the relationship between changes in feedforward and feedback control associated with cerebellar degeneration across motor domains, we evaluated adaptive (feedforward) and compensatory (feedback) responses to sensory perturbations in reaching and speech production in human participants of both sexes with cerebellar degeneration and neurobiologically healthy controls. As expected, the cerebellar group demonstrated impaired adaptation in both reaching and speech. In contrast, the groups did not differ in their compensatory response in either domain. Moreover, compensatory and adaptive responses in the cerebellar group were not correlated within or across motor domains. These results point to a general impairment in feedforward control with spared feedback control in cerebellar degeneration. However, the magnitude of feedforward impairments and potential changes in feedback-based control manifest in a domain-specific manner across individuals.SIGNIFICANCE STATEMENT The cerebellum contributes to feedforward updating of movement in response to sensory errors, but its role in feedback control is less understood. Here, we tested individuals with cerebellar degeneration (CD), using sensory perturbations to assess adaptation of feedforward control and feedback gains during reaching and speech production tasks. The results confirmed that CD leads to reduced adaption in both domains. However, feedback gains were unaffected by CD in either domain. Interestingly, measures of feedforward and feedback control were not correlated across individuals within or across motor domains. Together, these results indicate a general impairment in feedforward control with spared feedback control in CD. However, the magnitude of feedforward impairments manifests in a domain-specific manner across individuals.     

Prediction of human actions: Expertise and task‐related effects on neural activation of the action observation network

The action observation network (AON) is supposed to play a crucial role when athletes anticipate the effect of others' actions in sports such as tennis. We used functional magnetic resonance imaging to explore whether motor expertise leads to a differential activation pattern within the AON during effect anticipation and whether spatial and motor anticipation tasks are associated with a differential activation pattern within the AON depending on participant expertise level. Expert (N = 16) and novice (N = 16) tennis players observed video clips depicting forehand strokes with the instruction to either indicate the predicted direction of ball flight (spatial anticipation) or to decide on an appropriate response to the observed action (motor anticipation). The experts performed better than novices on both tennis anticipation tasks, with the experts showing stronger neural activation in areas of the AON, namely, the superior parietal lobe, the intraparietal sulcus, the inferior frontal gyrus, and the cerebellum. When novices were contrasted with experts, motor anticipation resulted in stronger activation of the ventral premotor cortex, the supplementary motor area, and the superior parietal lobe than spatial anticipation task did. In experts, the comparison of motor and spatial anticipation revealed no increased activation. We suggest that the stronger activation of areas in the AON during the anticipation of action effects in experts reflects their use of the more fine‐tuned motor representations they have acquired and improved during years of training. Furthermore, results suggest that the neural processing of different anticipation tasks depends on the expertise level. Hum Brain Mapp 35:4016–4034, 2014. © 2014 Wiley Periodicals, Inc .     

The neural basis of video gaming

Video game playing is a frequent recreational activity. Previous studies have reported an involvement of dopamine-related ventral striatum. However, structural brain correlates of video game playing have not been investigated. On magnetic resonance imaging scans of 154 14-year-olds, we computed voxel-based morphometry to explore differences between frequent and infrequent video game players. Moreover, we assessed the Monetary Incentive Delay (MID) task during functional magnetic resonance imaging and the Cambridge Gambling Task (CGT). We found higher left striatal grey matter volume when comparing frequent against infrequent video game players that was negatively correlated with deliberation time in CGT. Within the same region, we found an activity difference in MID task: frequent compared with infrequent video game players showed enhanced activity during feedback of loss compared with no loss. This activity was likewise negatively correlated with deliberation time. The association of video game playing with higher left ventral striatum volume could reflect altered reward processing and represent adaptive neural plasticity.     

The neural basis of mental imagery

Visual mental imagery, or 'seeing with the mind's eye', has been the subject of considerable controversy in cognitive science. At issue is whether images are fundamentally different from verbal thoughts, whether they share underlying mechanisms with visual perception, and whether information in images is represented in a spatial (i.e. map-like) format. Research on the neural systems underlying imagery brings a new source of evidence to bear on these cognitive science controversies, as well as on the cerebral localization of imagery processes. Emerging from this work is the view that mental imagery involves the efferent activation of visual areas in prestriate occipital cortex, parietal and temporal cortex, and that these areas represent the same kinds of specialized visual information in imagery as they do in perception. In addition, different components of imagery processing appear to be differentially lateralized, with the generation of mental images from memory depending primarily upon structures in the posterior left hemisphere, and the rotation of mental images depending primarily upon structures in the posterior right hemisphere.     

The neural basis of romantic love

The neural correlates of many emotional states have been studied, most recently through the technique of fMRI. However, nothing is known about the neural substrates involved in evoking one of the most overwhelming of all affective states, that of romantic love, about which we report here. The activity in the brains of 17 subjects who were deeply in love was scanned using fMRI, while they viewed pictures of their partners, and compared with the activity produced by viewing pictures of three friends of similar age, sex and duration of friendship as their partners. The activity was restricted to foci in the medial insula and the anterior cingulate cortex and, subcortically, in the caudate nucleus and the putamen, all bilaterally. Deactivations were observed in the posterior cingulate gyrus and in the amygdala and were right-lateralized in the prefrontal, parietal and middle temporal cortices. The combination of these sites differs from those in previous studies of emotion, suggesting that a unique network of areas is responsible for evoking this affective state. This leads us to postulate that the principle of functional specialization in the cortex applies to affective states as well.     

The neural basis of scene preferences

What is the neural correlate of preference that governs our spontaneous selection of visual information? With a rapid, event-related functional magnetic resonance imaging design, we showed that the viewing of highly preferred compared to less preferred scenes (as assessed by participant ratings) was associated with greater blood-oxygen level dependent responses in the right parahippocampal cortex but not in the lateral occipital complex, ruling out feed forward and attentional effects. Highly preferred images also produced greater activation in the ventral striatum, suggesting that perceptual preference might engage the conventional reward system. These results are consistent with the hypothesis that high activity in the parahippocampal cortex, an area with a high density of cortical mu-opioid receptors, may be experienced as cognitively pleasurable.     

The neural basis for mental state attribution: A voxel‐based lesion mapping study

The ability to infer other persons' mental states, “Theory of Mind” (ToM), is a key function of social cognition and is needed when interpreting the intention of others. ToM is associated with a network of functionally related regions, with reportedly key prominent hubs located in the dorsolateral prefrontal cortex (dlPFC) and the temporoparietal junction (TPJ). The involvement of (mainly the right) TPJ in ToM is based primarily on functional imaging studies that provide correlational evidence for brain‐behavior associations. In this lesion study, we test whether certain brain areas are necessary for intact ToM performance. We investigated individuals with penetrating traumatic brain injury (n = 170) and healthy matched controls (n = 30) using voxel‐based lesion‐symptom mapping (VLSM) and by measuring the impact of a given lesion on white matter disconnections. ToM performance was compared between five patient groups based on lesion location: right TPJ, left TPJ, right dlPFC, left dlPFC, and other lesion, as well as healthy controls. The only group to present with lower ToM abilities was the one with lesions in the right dlPFC. Similarly, VLSM analysis revealed a main cluster in the right frontal middle gyrus and a secondary cluster in the left inferior parietal gyrus. Last, we found that disconnection of the left inferior longitudinal fasciculus and right superior longitudinal fasciculus were associated with poor ToM performance. This study highlights the importance of lesion studies in complementing functional neuroimaging findings and supports the assertion that the right dlPFC is a key region mediating mental state attribution.