The brain, verbs, and the past: Neurolinguistic studies on time reference

De zin ‘de man fietste’ is moeilijker dan ‘de man fietst’ voor mensen met een agrammatische afasie. Agrammatische afasie is een grammaticale stoornis als gevolg van hersenletsel, bijvoorbeeld een beroerte. In het Nederlands/Engels kun je op paradoxale wijze ook naar het verleden verwijzen met een werkwoordsvorm in (voltooid) tegenwoordige tijd, bijvoorbeeld ‘heeft gefietst’. Laura Bos toont aan dat het niet zozeer de verleden werkwoordstijd is die moeilijk is voor mensen met afasie, maar het verwijzen naar het verleden, ongeacht de werkwoordstijd: voor Nederlandse mensen met afasie was het moeilijker om zinnen af te maken met de onvoltooid verleden tijd of voltooid tegenwoordige tijd dan met de onvoltooid tegenwoordige tijd. Volgens Bastiaanse en collega’s (2011) komt dit doordat er voor verwijzing naar het verleden naar een gebeurtenis vóór het moment van spreken verwezen wordt. Die gebeurtenis moet daarom uit de context (ofwel ‘discourse’) worden opgeroepen. Dit oproepen kost extra hersencapaciteit. Deze ‘discourse’-verklaring wordt ondersteund door een andere studie uit dit promotieonderzoek: bij Russische mensen met afasie trad een simultane stoornis op in het begrip van ‘discourse’-processen, waaronder tijdsverwijzing. Ook gezonde mensen maakten dit ‘discourse’-gerelateerde onderscheid in tijdsverwijzing, zo blijkt een derde studie met hersenactiviteitmetingen door middel van elektro-encefalografie. In een vierde studie heeft Laura Bos oogbewegingen bestudeerd. Hieruit bleek dat Duitse agrammatisch-afatische proefpersonen een werkwoordsvorm die naar de toekomst verwijst even snel verwerkten als gezonde proefpersonen, maar een werkwoordsvorm die naar het verleden verwijst minder snel. Deze resultaten vormen een klein puzzelstuk in de grote puzzel van taalverwerking

Aphasia after Stroke: the SPEAK Study

Aphasia is a disorder of the production and comprehension of written and spoken language as a result of acquired brain damage. This damage is located in the dominant hemisphere, which is the left hemisphere for nearly all the right-handers and for about 70% of the left-handers. The evolvement of aphasia is usually rapid if caused by a head injury or stroke, but can also evolve slowly as a consequence of a brain tumor, infection, or dementia. The most common cause of aphasia is a stroke. The number of people living with aphasia in the Netherlands is approximately 30,000. Every year, about 9,600 new cases of aphasia after stroke occur. The first and main question of patients and their family in the acute stage of stroke is whether the symptoms will decrease, and the patient will ever be able to speak and comprehend as before the stroke again. The severity of aphasia after stroke ranges from having difficulties with infrequent words, complex sentences and texts, to being completely unable to speak, comprehend, read, or write. The impact on one’s ability to communicate is devastating, not only for the patients with aphasia but also for their family and friends. Patients with aphasia are no longer sufficiently capable of expressing and clarifying their thoughts, wishes, and needs, which puts an aphasic patient at a higher risk for depression. Ninety percent of persons with aphasia feel socially isolated. Stroke patients with aphasia also have a higher mortality rate and a worse rehabilitation outcome than stroke patients without aphasia. In this thesis, I address the natural course and prognosis of aphasia after stroke in a large Dutch multicenter prospective study, the Sequential Prognostic Evaluation of Aphasia after stroKe study, known as the SPEAK study

Factors influencing the accessibility of Yam planting materials in the Techiman District of Ghana

Yam is a major economic crop that plays a significant role in food security and poverty alleviation in Ghana. Despite this role of yam in Ghana, farmers have incessant difficulty in accessing adequate planting materials for cultivation. In order to understand this problem, this research was conducted to determine the various factors that can influence the accessibility of yam planting materials to farmers in the Techiman District of the Brong Ahafo Region of Ghana. Quantitative and qualitative research techniques including semi-structured interviews and observations were employed for this study. The research identified six main factors as critical to accessing yam planting materials in the study area. These included the cultivar of yam that farmers want to grow, access to capital to purchase planting materials, and availability and cost of transportation to convey planting materials to store at farmer homes. The others were pests and diseases infestation of planting materials in storage, farmers’ membership in co-operatives that assist members with acquisition of credit and/or planting materials, and the adoption of minisett and microsett techniques by farmers.KEY DESCRIPTORS: Yam, Planting Materials, Seed Yam, Accessibility, Minisett and Microset

Word finding deficitsin aphasia: diagnosis and treatment. Rotterdam Aphasia Therapy Study-2

Aphasia Imagine finding yourself all of a sudden alone in a Chinese city and not speaking or understanding Chinese. How do you ask for the way or read the signs, buy food and other necessities, watch tv or listen to the news, let alone have a social conversation with someone? This thought experiment might shed some light on how it must be for people to have a stroke and suddenly have lost the ability to communicate. The term aphasia is used to describe an acquired loss or impairment of the language system following brain damage. Damage to the brain can be caused by trauma, a tumor, infection or neurodegenerative disease such as Alzheimer’s disease. But the most frequent cause of aphasia is a stroke, mainly to the left hemisphere, where the language function of the brain is located in nearly all right-handed people and half of the left handers. In the Netherlands, approximately 40,000 people per year experience a stroke.1 About one-third of these patients develop aphasia, with higher frequencies in the early stages after stroke onset. It is estimated that there are about 30,000 people with aphasia in the Netherlands (www.afasie.nl). The severity of aphasia varies from occasional word-finding di≤culties to having no means of communication at all. Individual aphasia profiles also vary regarding the degree of involvement of the modalities of language processing: speaking, comprehension of speech, writing and reading. A central problem for nearly all aphasic people is word finding, which requires intact semantic and phonological processing. During the first year following the stroke event, aphasia tends to improve.2 A recent study found that 74% of patients presenting with aphasia in the hyperacute stage have completely recovered after six months and that aphasia improved in 86% of the patients.3 Most of the recovery occurs in the first three months after which the speed of spontaneous recovery slows, and little additional recovery can be expected after 12 months. Spontaneous recovery of cognitive functions is considered to be associated with the reduction of edema and the reperfusion of previously hypoxic tissue in the perilesional area.4 Neuroplasticity might also underlie some degree of functional recovery after stroke and has been shown to occur in perilesional areas and in areas distant from the lesion in both the acute and chronic phase.5 The most powerful

Quantitative analysis of language production in Parkinson's disease using a cued sentence generation task

The present study examined language production skills in Parkinson's disease (PD) patients. A unique cued sentence generation task was created in order to reduce demands on memory and attention. Differences in sentence production abilities according to disease severity and cognitive impairments were assessed. Language samples were obtained from 20 PD patients and 20 healthy control participants matched for age, sex and educational level. In addition, a cognitive test for verbal memory and resistance to cognitive interference was administered. Statistical comparisons revealed significant language changes in an advanced stage of the disease. Advanced PD patients showed a reduction in lexical diversity in notional verbs, which was absent in nouns. Cognitive dysfunctions such as impaired verbal memory are suggested to contribute to the typical noun/verb dissociation in PD patients. In addition, advanced PD patients produced more semantic perseverations, which may be related to set-switching problems. In conclusion, whether language disturbances in PD are the result of non-linguistic cognitive dysfunctions or reflect pure language deficits exacerbated by cognitive impairments, remains a matter of debate. However, the negative impact of cognitive dysfunctions may be important