Beyond verbal fluency: Investigating the long-term effects of bilateral subthalamic (STN) deep brain stimulation (DBS) on language in two cases

Cognitive functioning has been described as largely impervious to chronic STN-DBS administered over 12-month periods. In relation to the domain of language, however, the effects of STN-DBS are yet to be thoroughly delineated. Verbal fluency tasks represent an almost exclusively applied index of linguistic proficiency relative to neuropsychological research within this population. Comprehensive investigations of the impact of STN-DBS on language function, however, have never been undertaken. The more precise elucidation of the role of the STN in the mediation of language processes, by way of assessments which probe language comprehension and production mechanisms, served as the primary focus of this research. Longitudinal analysis also afforded consideration of the way in which cognitive-linguistic circuits respond to STN-DBS over time. Bilateral STN-DBS primarily effected clinically reliable fluctuations (i.e., both improvements and declines) in performance in both subjects on tasks demanding cognitive-linguistic flexibility in the formulation and comprehension of complex language. Of particular note, both subjects demonstrated a cumulative increase in the proportion of reliable post-operative improvements achieved over time. The findings of this research lend support to models of subcortical participation in language which endorse a role for the STN, and suggest that bilateral STN-DBS may serve to enhance the proficiency of basal ganglia-thalamocortical linguistic circuits over time.

Self-paced reading and sentence comprehension in Parkinson's disease

Parkinson's disease (PD) is associated with disturbances in sentence processing, particularly for noncanonical sentences. The present study aimed to analyse sentence processing in PD patients and healthy control participants, using a word-by-word self-paced reading task and an auditory comprehension task. Both tasks consisted of subject relative (SR) and object relative (OR) sentences, with comprehension accuracy measured for each sentence type. For the self-paced reading task, reading times (RTs) were also recorded for the non-critical and critical processing regions of each sentence. Analysis of RTs using mixed linear model statistics revealed a delayed sensitivity to the critical processing region of OR sentences in the PD group. In addition, only the PD group demonstrated significantly poorer comprehension of OR sentences compared to SR sentences during an auditory comprehension task. These results may be consistent with slower lexical retrieval in PD, and its influence on the processing of noncanonical sentences. (c) 2005 Elsevier Ltd. All rights reserved.

Apnea diving: Long-term neurocognitive sequelae of repeated hypoxemia

This article examines the neurocognitive sequelae of repeated exposure to hypoxemia in apnea (breath-hold) divers. A brief review of the literature on the physiological and neurological adaptations involved in the human diving reflex is presented. The results from a neuropsychological investigation of N = 21 elite apnea divers are evaluated. Standard neuropsychological tests, with known sensitivity to mild brain insults, included speed of visuo-motor responding, speed of language comprehension, response inhibition, and visual and verbal attention and recall tasks. Results indicated that the breath-hold divers performed tasks within the average range compared to norms on all tests, suggesting that 1-20 years of repeated exposure to hypoxemia including multiple adverse neurological events did not impact on performance on standard neuropsychological tasks. The results are discussed in relation to implications for clinical conditions such as sleep apnea, respiratory disorders, altitude sickness, and recreational apnea activities.

Reappraising contemporary theories of subcortical participation in language: Proposing an interhemispheric regulatory function for the subthalamic nucleus (STN) in the mediation of high-level linguistic processes

Apropos the basal ganglia, the dominant striatum and globus pallidus internus (GPi) have been hypothesised to represent integral components of subcortical language circuitry. Working subcortical language theories, however, have failed thus far to consider a role for the STN in the mediation of linguistic processes, a structure recently defined as the driving force of basal ganglia output. The aim of this research was to investigate the impact of surgically induced functional inhibition of the STN upon linguistic abilities, within the context of established models of basal ganglia participation in language. Two males with surgically induced 'lesions' of the dominant and non-dominant dorsolateral STN, aimed at relieving Parkinsonian motor symptoms, served as experimental subjects. General and high-level language profiles were compiled for each subject up to 1 month prior to and 3 months following neurosurgery, within the drug-on state (i.e., when optimally medicated). Comparable post-operative alterations in linguistic performance were observed subsequent to surgically induced functional inhibition of the left and right STN. More specifically, higher proportions of reliable decline as opposed to improvement in post-operative performance were demonstrated by both subjects on complex language tasks, hypothesised to entail the interplay of cognitive-linguistic processes. The outcomes of the current research challenge unilateralised models of functional basal ganglia organisation with the proposal of a potential interhemispheric regulatory function for the STN in the mediation of high-level linguistic processes.

Language outcomes subsequent to treatment of brainstem tumour in childhood

While the occurrence and management of brainstem tumours in children would not traditionally indicate potential direct structural impact on classical language centres, recent theories have implicated some involvement of the brainstem in a functional language and cognitive neural loop between the cerebellum and the cerebral hemispheres. Thus, the present paper explored the impact of treatment for brainstem tumour on the general and high-level language abilities of six children treated for brainstem tumour, in addition to phonological awareness skills. Group analysis revealed that children treated for brainstem tumour demonstrated intact language and phonological awareness abilities in comparison to an age- and gender-matched control group. Individual analysis revealed only one of six children treated for brainstem tumour revealed evidence of language disturbances, with an additional child demonstrating an isolated mildly reduced score on one phonological awareness task. Language deficits identified in a child treated with a combination of both radiotherapy and chemotherapy were noted in the high-level language area of lexical generation. Findings highlighted that no overt language disturbances were evident in children treated for brainstem tumour. However, further analysis into higher-level language skills in the present study indicated that both general and high-level language abilities require long-term monitoring in this population.

The commentariat and discourse failure: language and atrocity in Cool Britannia

Recent terrorist events in the UK, such as the security alerts at British airports in August 2006 and the London bombings of July 2005 gained extensive media and academic analysis. This study contends, however, that much of the commentary demonstrated a wide degree of failure among government agencies, academic and analytic experts and the wider media, about the nature of the threat and continues to distort comprehension of the extant danger. The principal failure, this argument maintains, was, and continues to be, one of an asymmetry of comprehension that mistakes the still relatively limited means of violent jihadist radicals with limited political ends. The misapprehension often stems from the language that surrounds the idea of 'terrorism', which increasingly restricts debate to an intellectually redundant search for the 'root causes' that give rise to the politics of complacency. In recent times this outlook has consistently underestimated the level of the threat to the security of the UK. This article argues that a more realistic appreciation of the current security condition requires abandoning the prevailing view that the domestic threat is best prosecuted as a criminal conspiracy. It demands instead a total strategy to deal with a totalizing threat. The empirical evidence demonstrates the existence of a physical threat, not merely the political fear of threat. The implementation of a coherent set of social policies for confronting the threat at home recognizes that securing state borders and maintaining internal stability are the first tasks of government. Fundamentally, this requires a return to an understanding of the Hobbesian conditions for sovereignty, which, despite the delusions of post-Cold War cosmopolitan multiculturalism, never went away.

Successes and failures in assessing acquired language disorders using an Internet-based telerehabilitation system

We have used a telerehabilitation system (eREHAB) to remotely assess acquired language disorders via the Internet. The system was used to establish a 128 kbit/s videoconference between two sites and allowed a remote language assessment to be conducted using the standardized Boston Diagnostic Aphasia Examination (BDAE). The system had the capacity to display text and images, and could play pre-recorded instructions to the participant via various built-in tools. A touch screen allowed tasks involving picture identification to be completed easily. Eighteen participants with a diagnosis of an acquired language disorder were simultaneously assessed using the eREHAB system, and in the traditional face-to-face manner by two speech pathologists. There was very high agreement between the two assessors, with weighted kappa scores of 0.8–1.0 for 88% of the sub-tests of the BDAE. There was also high agreement (80–100%) and high kappa scores (0.67–0.90) between assessors on the six rating scales relating to language characteristics. The agreement between the two assessors for the diagnosis of the type of aphasia was 83%. Limitations of the system related mainly to problems inherent in IP videoconferencing. The inability to maintain the preferred speed of 128 kbit/s for the duration of the videoconference and the resultant increase in video and audio breakup and latency affected the clinician’s ability to administer the BDAE with the same ease and accuracy as in face-to-face administration. These difficulties were exacerbated when participants presented with a moderate to severe language disorder, auditory comprehension deficits or significant hearing loss. Despite these limitations, a valid assessment of language disorder was found to be feasible via this telerehabilitation application.

Progressive loss of expressive language in a journalist: What news for dementia?

A 77-year-old man with 8 year progressive language deterioration in the face of grossly intact memory was followed. No acute or chronic physiological or psychological event was associated with symptom onset. CT revealed small left basal ganglia infarct. Mild atrophy, no lacunar infarcts, mild diffuse periventricular changes registered on MRI. Gait normal but slow. Speech hesitant and sparse. Affect euthymic; neurobehavioral disturbance absent. MMSE 26/30; clock incorrect, concrete. Neuropsychological testing revealed simple attention intact; complex attention, processing speed impaired. Visuospatial copying and delayed recall of copy average with some perseveration. Apraxia absent. Recall mildly impaired. Mild deficits in planning, organization apparent. Patient severely aphasic, dysarthric without paraphasias. Repetition of automatic speech, recitation moderately impaired; prosody intact. Understanding of written language, nonverbal communication abilities, intact. Frontal release signs developed over last 12 months. Repeated cognitive testing revealed mild deterioration across all domains with significant further decrease in expressive, receptive language. Neurobehavioral changes remain absent to date; he remains interested, engaged and independent in basic ADLs. Speech completely deteriorated; gait and movements appreciably slowed. Although signs of frontal/executive dysfunction present, lack of behavioral abnormalities, psychiatric disturbance, personality change argue against focal or progressive frontal impairment or dementia. Relative intactness of memory and comprehension argue against Alzheimer’s disease. Lack of findings on neuroimaging argue against CVA or tumor. It is possible that the small basal ganglia infarct has resulted in a mild lateral prefrontal syndrome. However, the absence of depression as well as the relatively circumscribed language problem suggests otherwise. The progressive, severe nature of language impairments, with relatively minor impairments in attention and memory, argues for a possible diagnosis of primary progressive aphasia.