Blog Archives

Functional magnetic resonance imaging exploration of combined hand and speech movements in Parkinson’s disease

Among the repertoire of motor functions, although hand movement and speech production tasks have been investigated widely by functional neuroimaging, paradigms combining both movements have been studied less so. Such paradigms are of particular interest in Parkinson’s disease, in which patients have specific difficulties performing two movements simultaneously. In 9 unmedicated patients with Parkinson’s disease and 15 healthy control subjects, externally cued tasks (i.e., hand movement, speech production, and combined hand movement and speech production) were performed twice in a random order and functional magnetic resonance imaging detected cerebral activations, compared to the rest. F-statistics tested within-group (significant activations at P values < 0.05, familywise error corrected), between-group, and between-task comparisons (regional activations significant at P values 10 voxels). For control subjects, the combined task activations comprised the sum of those obtained during hand movement and speech production performed separately, reflecting the neural correlates of performing movements sharing similar programming modalities. In patients with Parkinson’s disease, only activations underlying hand movement were observed during the combined task. We interpreted this phenomenon as patients’ potential inability to recruit facilitatory activations while performing two movements simultaneously. This lost capacity could be related to a functional prioritization of one movement (i.e., hand movement), in comparison with the other (i.e., speech production). Our observation could also reflect the inability of patients with Parkinson’s disease to intrinsically engage the motor coordination necessary to perform a combined task. © 2011 Movement Disorder Society

from Movement Disorders

Advertisements

Functional activation for imitation of seen and heard speech

This study examined fMRI activation when perceivers either passively observed or observed and imitated matched or mismatched audiovisual (“McGurk”) speech stimuli. Greater activation was observed in the inferior frontal gyrus (IFG) overall for imitation than for perception of audiovisual speech and for imitation of the McGurk-type mismatched stimuli than matched audiovisual stimuli. This unique activation in the IFG during imitation of incongruent audiovisual speech may reflect activation associated with direct matching of incongruent auditory and visual stimuli or conflict between category responses. This study provides novel data about the underlying neurobiology of imitation and integration of AV speech.

from the Journal of Neurolinguistics

Interaction and representational integration: Evidence from speech errors

We examine the mechanisms that support interaction between lexical, phonological and phonetic processes during language production. Studies of the phonetics of speech errors have provided evidence that partially activated lexical and phonological representations influence phonetic processing. We examine how these interactive effects are modulated by lexical frequency. Previous research has demonstrated that during lexical access, the processing of high frequency words is facilitated; in contrast, during phonetic encoding, the properties of low frequency words are enhanced. These contrasting effects provide the opportunity to distinguish two theoretical perspectives on how interaction between processing levels can be increased. A theory in which cascading activation is used to increase interaction predicts that the facilitation of high frequency words will enhance their influence on the phonetic properties of speech errors. Alternatively, if interaction is increased by integrating levels of representation, the phonetics of speech errors will reflect the retrieval of enhanced phonetic properties for low frequency words. Utilizing a novel statistical analysis method, we show that in experimentally induced speech errors low lexical frequency targets and outcomes exhibit enhanced phonetic processing. We sketch an interactive model of lexical, phonological and phonetic processing that accounts for the conflicting effects of lexical frequency on lexical access and phonetic processing.

from Cognition

Linguistic Complexity, Speech Production, and Comprehension in Parkinson’s Disease: Behavioral and Physiological Indices

Conclusions: These findings provide a novel window into the speech deficits associated with PD by examining performance on longer, sentence-level utterances in contrast to earlier investigations of single-word or nonword productions. Speech motor control processes and language comprehension were adversely affected in the majority of our participants with mild to moderate PD compared to the control group. Finally, increased syntactic complexity and sentence length affected both the healthy aging and PD groups’ speech production performance at the behavioral and kinematic levels.

from the Journal of Speech, Language, and Hearing Research

Neural correlates of phonological processing in speech sound disorder: A functional magnetic resonance imaging study

Speech sound disorders (SSD) are the largest group of communication disorders observed in children. One explanation for these disorders is that children with SSD fail to form stable phonological representations when acquiring the speech sound system of their language due to poor phonological memory (PM). The goal of this study was to examine PM in individuals with histories of SSD employing functional MR imaging (fMRI). Participants were six right-handed adolescents with a history of early childhood SSD and seven right-handed matched controls with no history of speech and language disorders. We performed an fMRI study using an overt non-word repetition (NWR). Right lateralized hypoactivation in the inferior frontal gyrus and middle temporal gyrus was observed. The former suggests a deficit in the phonological processing loop supporting PM, while the later may indicate a deficit in speech perception. Both are cognitive processes involved in speech production. Bilateral hyperactivation observed in the pre and supplementary motor cortex, inferior parietal, supramarginal gyrus and cerebellum raised the possibility of compensatory increases in cognitive effort or reliance on the other components of the articulatory rehearsal network and phonologic store. These findings may be interpreted to support the hypothesis that individuals with SSD may have a deficit in PM and to suggest the involvement of compensatory mechanisms to counteract dysfunction of the normal network.

from Brain and Language

“W” is for bath: Can associative errors be cued?

Semantic aphasia (SA) refers to a condition in which the control processes associated with the use of semantic information become compromised. This condition compromises patients’ abilities to accurately name pictures, and they produce semantic errors in the form of co-ordinate items, such as “shower” for BATH. Previous research has demonstrated that these patients are sensitive to phonemic cues during picture naming, whether they promote the correct response (e.g., /b/) or the incorrect semantically related response (e.g., /sh/). A similar pattern is observed in normal participants when asked to perform tempo picture naming, in which the timing constraints undermine semantic control processes. SA patients are also known to produce associative errors in picture naming, such as “water” for BATH. In this study, we extended previous work on phonemic cueing in SA patients and in normal participants in two ways: firstly, by using associative miscues to promote associative errors (e.g., /w/), and secondly, to confirm miscueing effects still hold when assessed relative to a neutral condition of an unrelated phoneme rather a simple beep. The results revealed that associative miscues are effective in reducing accuracy and promoting semantic errors in SA patients. Correlations between associative cueing effects and executive tests showed that the impact of associative miscues was more pronounced in those with greater semantic control impairment. Associative miscueing was also seen for normal participants during tempo picture naming, including a latency cost. Both the associative and also the co-ordinate miscueing effects were still apparent when the neutral condition consisted of an unrelated phoneme. The implications of these results for models of speech production and semantic representation are outlined.

from the Journal of Neurolinguistics

Conduction aphasia, sensory-motor integration, and phonological short-term memory – An aggregate analysis of lesion and fMRI data

Conduction aphasia is a language disorder characterized by frequent speech errors, impaired verbatim repetition, a deficit in phonological short-term memory, and naming difficulties in the presence of otherwise fluent and grammatical speech output. While traditional models of conduction aphasia have typically implicated white matter pathways, recent advances in lesions reconstruction methodology applied to groups of patients have implicated left temporoparietal zones. Parallel work using functional magnetic resonance imaging (fMRI) has pinpointed a region in the posterior most portion of the left planum temporale, area Spt, which is critical for phonological working memory. Here we show that the region of maximal lesion overlap in a sample of 14 patients with conduction aphasia perfectly circumscribes area Spt, as defined in an aggregate fMRI analysis of 105 subjects performing a phonological working memory task. We provide a review of the evidence supporting the idea that Spt is an interface site for the integration of sensory and vocal tract-related motor representations of complex sound sequences, such as speech and music and show how the symptoms of conduction aphasia can be explained by damage to this system.

from Brain and Language

Tracking Talking: Dual Task Costs of Planning and Producing Speech for Young versus Older Adults

A digital pursuit rotor was used to monitor speech planning and production costs by time-locking tracking performance to the auditory wave form produced as young and older adults were describing someone they admire. The speech sample and time-locked tracking record were segmented at utterance boundaries and multilevel modeling was used to determine how utterance-level predictors such as utterance duration or sentence grammatical complexity and person-level predictors such as speaker age or working memory capacity predicted tracking performance. Three models evaluated the costs of speech planning, the costs of speech production, and the costs of speech output monitoring. The results suggest that planning and producing propositionally dense utterances is more costly for older adults and that older adults experience increased costs as a result of having produced a long, informative, or rapid utterance.

from Aging, Neuropsychology, and Cognition

Tracking Talking: Dual Task Costs of Planning and Producing Speech for Young versus Older Adults

A digital pursuit rotor was used to monitor speech planning and production costs by time-locking tracking performance to the auditory wave form produced as young and older adults were describing someone they admire. The speech sample and time-locked tracking record were segmented at utterance boundaries and multilevel modeling was used to determine how utterance-level predictors such as utterance duration or sentence grammatical complexity and person-level predictors such as speaker age or working memory capacity predicted tracking performance. Three models evaluated the costs of speech planning, the costs of speech production, and the costs of speech output monitoring. The results suggest that planning and producing propositionally dense utterances is more costly for older adults and that older adults experience increased costs as a result of having produced a long, informative, or rapid utterance.

from Aging, Neuropsychology, and Cognition

Intention in articulation: Articulatory timing in alternating consonant sequences and its implications for models of speech production

Several studies have reported that during the production of phrases with alternating consonants (e.g., top cop), the constriction gestures for these consonants can come to be produced in the same prevocalic position. Since these coproductions occur in contexts that also elicit segmental substitution errors, the question arises whether they may result from monitoring and repair, or whether they arise from the architecture of the phonological and phonetic planning process. This paper examines the articulatory timing of the coproduced gestures in order to shed light on the underlying process that gives rise to them. Results show that overall at movement onset the gestures are mostly synchronous, but it is the intended consonant that is released last. Overall the data support the view that the activation of two gestures is inherent to the speech production process itself rather than being due to a monitoring process. We argue that the interactions between planning and articulatory dynamics apparent in our data require a more comprehensive approach to speech production than is provided by current models.

from Language and Cognitive Processes

Simulating children’s retrieval errors in picture-naming: A test of Foygel and Dell’s (2000) semantic/phonological model of speech production

This study investigated whether Foygel and Dell’s (2000) interactive two-step model of speech production could simulate the number and type of errors made in picture-naming by 68 children of elementary-school age. Results showed that the model provided a satisfactory simulation of the mean error profile of children aged five, six, seven, eight and eleven years-old. Consistent with previous research, children made a relatively large number of semantic errors when naming pictures. This was particularly noticeable for several of the younger children who made more semantic errors than the model would predict. This discrepancy between the data and the model seemed to occur because some semantic errors made by the younger children reflected a lack of semantic knowledge about the target word rather than retrieval failures. When the simulation was confined to 25 highly familiar picture names, the Foygel and Dell (2000) model provided a good fit to the observed data from children of all ages. Our findings suggest that the differences between the speech production systems used by children and adults are quantitative rather than qualitative. Connections between semantic and lexical representations and between lexical and phonological representations appear to increase in strength linearly as children get older.

from the Journal of Memory and Language

Intelligibility of hearing impaired children as judged by their parents: A comparison between children using cochlear implants and children using hearing aids

Conclusion
The intelligibility of the prelingually deaf CI children is very close to the intelligibility of NH children, while the HA children still show a decreased mean intelligibility.

from the International Journal of Pediatric Otorhinolaryngology

Phonological advance planning in sentence production

Our study addresses the scope of phonological advance planning during sentence production using a novel experimental procedure. The production of German sentences in various syntactic formats (SVO, SOV, and VSO) was cued by presenting pictures of the agents of previously memorized agent–action–patient scenes. To tap the phonological activation of the agent (encoded as sentence subject) and the patient (encoded as sentence object), auditory distractor words, which were either phonologically related to the subject, or to the object, or were unrelated to both, were used. Compared with the unrelated control condition, distractors related to the subject in the utterance-initial phrase facilitated the response, while distractors related to the subject or to the object appearing in a non-initial phrase interfered with the response. Because some automatic phonological activation resulting from the perceptual processing of the visual stimulus cannot be responsible for the object-related interference effects, our results suggest that phonological advance planning exceeds a single syntactic phrase and may even span a whole simple sentence. The data are discussed in the context of current models of phonological encoding.

from the Journal of Memory and Language

Connected speech production in three variants of primary progressive aphasia

Primary progressive aphasia is a clinical syndrome defined by progressive deficits isolated to speech and/or language, and can be classified into non-fluent, semantic and logopenic variants based on motor speech, linguistic and cognitive features. The connected speech of patients with primary progressive aphasia has often been dichotomized simply as ‘fluent’ or ‘non-fluent’, however fluency is a multidimensional construct that encompasses features such as speech rate, phrase length, articulatory agility and syntactic structure, which are not always impacted in parallel. In this study, our first objective was to improve the characterization of connected speech production in each variant of primary progressive aphasia, by quantifying speech output along a number of motor speech and linguistic dimensions simultaneously. Secondly, we aimed to determine the neuroanatomical correlates of changes along these different dimensions.

from Brain

A case of foreign accent syndrome: Acoustic analyses and an empirical test of accent perception

Foreign Accent Syndrome (FAS) is a rare acquired syndrome following stroke, manifesting as a perceived change in the speaker’s accent. We present acoustic-phonetic analyses of the speech of a patient, RD, with FAS presenting as an apparent accent shift from Southern Ontarian to Atlantic Canadian who was first described in Naidoo, Warriner, Oczkowski, Sévigny, and Humphreys (2008). As well as more fully documenting this case, this paper also seeks to examine whether the accompanying articulatory deficits constitute a mild form of some other motor speech disorder such as apraxia of speech (AOS) or dysarthria. Acoustic-phonetic analyses showed increased vowel formant variability, overlap of voice onset times for phonemically contrastive stops, inconsistent consonant distortions, and global prosodic attenuation. These, combined with the patient’s fluent speech, can account for the perception of a foreign accent as opposed to disordered speech. The observed inconsistency of consonant distortions coupled with other articulatory deficits suggest that at least in this case, FAS can be considered to be a mild form of AOS.

from the Journal of Neurolinguistics