Here are the details of some of the current projects we are working on.
Inconsistent language lateralisation: evidence from behaviour and lateralised cerebral blood flow
This research looks into how active the left and right sides of the brain are during language tasks such as speaking or listening to speech. Previous research has shown that for most people, the left side of the brain is more active than the right during language – language is ‘lateralised’ to the left hemisphere. However, we also know that the strength of language lateralisation varies between different language tasks (e.g., speech production or comprehension) and between different people. There is evidence that handedness plays a role: on average, left handers have weaker lateralisation than right handers; and they may show less consistent patterns of lateralisation across different tasks than right handers do.
The reason for these differences between tasks and individuals are not well understood, perhaps because: (1) previous studies have not tested enough people (i.e. they have been statistically underpowered); (2) previous studies have not compared lateralisation for different tasks in the same people; and (3) the tasks used to test lateralisation may have been unreliable. Improving our understanding in this area is important for theoretical reasons, but also for epileptic or brain tumour patients, where surgeons have to decide which ‘eloquent’ areas of the brain can safely be operated on.
Our aim in this study is to test language lateralisation in a large number of left and right handers, using a range of language tasks that have shown good reliability in previous studies. We will test laterality using both online tasks and functional transcranial doppler sonography (fTCD).
This project is headed by Dorothy Bishop, and is a collaboration between COLA teams at Oxford, Bangor, Lancaster, Lincoln and UCL.
Investigating lateralised language networks with functional magnetic resonance imaging (fMRI)
While fTCD is a convenient method for investigating language lateralisation cheaply and easily in large groups of people, it does not tell us which areas of the brain show lateralised activity. For this, we need fMRI.
In a follow up to the project above, we aim to use fMRI to further investigate the networks involved in language, and how they are lateralised. It will also allow us to test how similar laterality measurements are from fTCD versus fMRI.
This project is headed by Dorothy Bishop, and will be a collaboration between COLA teams at Oxford, Bangor, Lancaster, Lincoln and UCL.
Making sense of the handedness data using meta-analysis
The field of handedness is overrun by the amount of published studies.This vast quantity of studies makes it taxing for scientists to distil the knowledge the results carry; even more so when findings are confusing and conflicting. Literature reviews could never hope to handle such an abundance of data. Meta-analysis, by contrast, is a statistical method allowing for the integration and summarizing of the findings from a body of research in a clear, objective way. Meta-analysis further allows for the investigation of the presence of publication bias. Importantly, meta-analysis allows for the assessment of any systematic variation among the results of different studies and, moreover, for the investigation of the sources of any such variance. This is a series of meta-analyses in the field of handedness.
This project is being run by Marietta Papadatou-Pastou (Athens). For further details, see https://osf.io/e5g4k/.
Cerebral Laterality During Writing
The cerebral lateralization of written language has received very limited research attention in comparison to the wealth of studies on the cerebral lateralization of oral language. The neural underpinnings of written language in particular are of great interest, as writing is utilized nearly every day in western societies and it is a skill that demands the contribution of several cognitive and motor functions. This project is a series of studies on the cerebral laterality of written language.
This project is a collaboration between Marietta Papadatou-Pastou (Athens) and Nic Badcock (UWA). For further details, see https://osf.io/7azpu/.