Bruce E. Murdoch

Language disorders in dementia of the Alzheimer type

The language profile of a group of 18 Alzheimer patients is documented and their performance on a standard aphasia test battery compared to a group of institutionalized, nonneurologically impaired control subjects matched for age, sex, and educational level. The Alzheimer patients scored significantly lower than the controls in the areas of verbal expression, auditory comprehension, repetition, reading, and writing. Articulation abilities were the same in each group. A language deficit was evident in all Alzheimer patients. The language disorder exhibited resembled a transcortical sensory aphasia. Syntax and phonology remained relatively intact but semantic abilities were impaired. The results support the inclusion of a language deficit as a diagnostic criterion of Alzheimers disease.

Consensus Paper: Language and the Cerebellum: an Ongoing Enigma

In less than three decades, the concept “cerebellar neurocognition” has evolved from a mere afterthought to an entirely new and multifaceted area of neuroscientific research. A close interplay between three main strands of contemporary neuroscience induced a substantial modification of the traditional view of the cerebellum as a mere coordinator of autonomic and somatic motor functions. Indeed, the wealth of current evidence derived from detailed neuroanatomical investigations, functional neuroimaging studies with healthy subjects and patients and in-depth neuropsychological assessment of patients with cerebellar disorders shows that the cerebellum has a cardinal role to play in affective regulation, cognitive processing, and linguistic function. Although considerable progress has been made in models of cerebellar function, controversy remains regarding the exact role of the “linguistic cerebellum” in a broad variety of nonmotor language processes. This consensus paper brings together a range of different viewpoints and opinions regarding the contribution of the cerebellum to language function. Recent developments and insights in the nonmotor modulatory role of the cerebellum in language and some related disorders will be discussed. The role of the cerebellum in speech and language perception, in motor speech planning including apraxia of speech, in verbal working memory, in phonological and semantic verbal fluency, in syntax processing, in the dynamics of language production, in reading and in writing will be addressed. In addition, the functional topography of the linguistic cerebellum and the contribution of the deep nuclei to linguistic function will be briefly discussed. As such, a framework for debate and discussion will be offered in this consensus paper.

The cerebellum and language: Historical perspective and review

Investigation of a possible role for the cerebellum in the mediation of cognitive processes, including language, has historically been overshadowed by research interest in cerebellar coordination of motor control. Over the past two decades, however, the question of a possible participation of the cerebellum in language processing itself has come to the forefront. In particular recent advances in our understanding of the neuroanatomy of the cerebellum combined with evidence from functional neuroimaging, neurophysiological and neuropsychological research, have extended our view of the cerebellum from that of a simple coordinator of autonomic and somatic motor function. Rather it is now more widely accepted that the cerebellum, and in particular the right cerebellar hemisphere, participates in modulation of cognitive functioning, especially to those parts of the brain to which it is reciprocally connected. The present paper reviews the neuroanatomical, clinical and functional neuroimaging evidence suggestive of a role for the cerebellum in language processing. The possible neuropathophysiological substrates of language impairment associated with cerebellar pathology are discussed and the nature of the linguistic deficits associated with disease or damage to the cerebellum described.

Improved language performance subsequent to low-frequency rTMS in patients with chronic non-fluent aphasia post-stroke

Background:  Low‐frequency repetitive transcranial magnetic stimulation (rTMS) has emerged as a potential tool for neurorehabilitation and remediation of language in chronic non‐fluent aphasia post‐stroke. Inhibitory (1 Hz) rTMS has been applied to homologous language sites to facilitate behavioural language changes. Improvements in picture‐naming performance and speech output over time have been reported.

Acoustic signature of the normal swallow: characterization by age, gender, and bolus volume.

Despite growing clinical use, cervical auscultation suffers from a lack of research-based data. One of the strongest criticisms of cervical auscultation is that there has been little research to demonstrate how dysphagic swallowing sounds are different from normal swallowing sounds. In order to answer this question, however, one first needs to document the acoustic characteristics of “normal,” nondysphagic swallowing sounds. This article provides the first normative database of normal swallowing sounds for the adult population. The current investigation documents the acoustic characteristics of normal swallowing sounds for individuals from 18 to more than 60 years of age over a range of thin liquid volumes. Previous research has shown the normal swallow to be a dynamic event. The normal swallow is sensitive to aging of the oropharyngeal system, and also to the volume of bolus swallowed. The current investigation found that the acoustic signals generated during swallowing were sensitive to an individuals age and to the volume of the bolus swallowed. There were also some gender-specific differences in the acoustic profile of the swallowing sound. It is anticipated that the results will provide a catalyst for further research into cervical auscultation.

How Thick Is Thick? Multicenter Study of the Rheological and Material Property Characteristics of Mealtime Fluids and Videofluoroscopy Fluids

Abstract Objective rheological assessment of fluids given to dysphagic patients at mealtime and during videofluoroscopy was carried out using a multicenter format. Thin, quarter-thick, half-thick and full-thick fluids were examined for the degree of correlation between mealtime fluids and their allegedly matched videofluoroscopy counterparts. The study was carried out to determine whether perceived subjective differences between mealtime fluids and videofluoroscopy fluids could be quantified using the rheological parameters of viscosity, density, and yield stress. The results showed poor correlation between mealtime fluids and videofluoroscopy fluids over all parameters. In general, the videofluoroscopy fluids were more viscous, more dense, and showed higher yield stress values than their mealtime counterparts. Given these results, it is reasonable to assume that the fluids used during videofluoroscopy do not provide an accurate indication of swallowing ability at mealtime. Therefore, it is suggested that clinicians use objective methods to rheologically match videofluoroscopy fluids to mealtime fluids.

Language impairment in Parkinson's disease

Abstract Increasingly, researchers and clinicians are beginning to unveil both cognitive and linguistic impairments in Parkinsons disease (PD), a condition characterized in the past primarily by impairment of the motoric aspects of ambulation and speech. This study describes subtle language impairment in 20 subjects with PD on a battery of measures selected to be sensitive to frontal lobe language function. Comparative performances of the PD subjects with an age, gender, and education-matched control group revealed significant performance level differences across several language variables. The PD subject group as a whole, presented with impaired naming and definitional abilities, and difficulties in interpreting ambiguity and figurative language. When the PD subjects were divided on the basis of their score on a cognitive rating scale, PD subjects with below normal cognitive status presented with deficits in naming, definition, and multi-definition abilities, as well as problems in interpreting ambiguit...

Detection of Swallowing Sounds: Methodology Revisited

Cervical auscultation is in the process of gaining clinical credibility. In order for it to be accepted by the clinical community, the procedure and equipment used must first be standardized. Takahashi et al. [Dysphagia 9:54-62, 1994] attempted to provide benchmark methodology for administering cervical auscultation. They provided information about the acoustic detector unit best suited to picking up swallowing sounds and the best cervical site to place it. The current investigation provides contrasting results to Takahashi et al. with respect to the best type of acoustic detector unit to use for detecting swallowing sounds. Our study advocates an electret microphone as opposed to an accelerometer for recording swallowing sounds. However, we agree on the optimal placement site. We conclude that cervical auscultation is within reach of the average dysphagia clinic.

The physiologic cause of swallowing sounds: Answers from heart sounds and vocal tract acoustics

Abstract. A hypothetical discussion of the cause of swallowing sounds is presented. It is suggested that the pharynx contains a number of valves and pumps that produce reverberations within the pharynx to generate swallowing sounds. As heart sounds are propagated via vibration of muscles and valves, it is further suggested that an analogy exists between the generation of heart sounds and swallowing sounds. This new theory is known as the cardiac analogy hypothesis. The inability of the current literature to explain the cause of swallowing sounds is seen to limit the diagnostic potential of cervical auscultation for dysphagia assessment. Future investigators are encouraged to prove or disprove the cardiac analogy hypothesis.

Automatic auditory processing of English words as indexed by the mismatch negativity, using a multiple deviant paradigm

Objective: The aim of this study was to investigate mismatch negativity (MMN) responses to a variety of speech stimuli (/de:/, /ge:/, /deI/ “day”, and /geI/ “gay”) in a multiple deviant paradigm. It was hypothesized that all speech stimulus contrasts in the multiple deviant paradigm, including the fine acoustic speech contrast [d/g], would elicit robust MMN responses and that consonant vowel (CV) real word deviants (e.g., “day” and “gay”) would elicit larger MMN responses than CV nonword deviants (e.g., “de” and “ge”) within and across experimental contrasts. Design: Ten healthy, right-handed, native English–speaking adults (23.4 ± 2.27 yr) with normal hearing were presented with 12 blocks of stimuli, using a multiple deviant oddball paradigm. Each of the four speech stimuli were presented as standards (p = 0.7) in three blocks, with the remaining stimuli acting as deviants (p = 0.1 each). Subjects were also presented with the same stimuli in a behavioral discrimination task. Results: MMN responses to the fine acoustic speech contrast [d/g] (e.g., “de” versus “ge”, “day” versus “gay”) did not reach significance. However, a significant and larger MMN response was obtained at an earlier latency to the real word deviants among nonword standards with the same initial consonant (i.e., de→day, ge→gay) when compared with the responses to nonword deviants among word standards (day→de, gay→ge). Conclusions: The results showed that MMN responses could be elicited by speech stimuli with large, single acoustic deviances, within a multiple deviant paradigm design. This result has positive clinical implications for the testing of subjects who may only tolerate short testing sessions (e.g., pathological populations) in that responses to a wider range of speech stimuli may be recorded without necessarily having to increase session length. The results also demonstrated that MMN responses were elicited by large, single acoustic deviances but not fine acoustic deviances within the speech stimuli. The poor results for the fine acoustic deviances support previous studies that have used single contrast paradigms and found that when carefully controlled methodological designs and strict methods of analysis are applied, robust responses to fine-grained CV syllable contrasts may be difficult to obtain. The enhanced MMN observed in response to the real word deviants among nonword standards may provide further evidence for the presence of long-term neural traces for words in the brain, however possible contextual effects limit the interpretation of these data. Further research is needed to investigate the ability of the MMN response to accurately reflect speech sounds with fine acoustic contrasts, as well as the ability of the MMN to reflect neural traces for words in the brain, before it can be reliably used as a clinical tool in the investigation of spoken word processing in pathological populations.