My main research interests is in understanding how large scale neural networks in the brain support cognitive function and how breakdown in such networks lead to cognitive impairment. I have been examining these issues by investigating the visual system and memory in healthy subjects and in cognitively impaired groups such as Alzheimer’s disease patients. My group is investigating these issues with functional magnetic resonance imaging (fMRI), structural magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI).
In our research programme we have investigated how individual differences interact with the emotional content of images and how the activation levels in the brain vary as a function of individual differences. We have found that individuals high in neuroticism demonstrated reduced sustained activation in the orbitofrontal cortex (OFC) and attenuated valence processing in the right temporal lobe while viewing emotional images, but an increased activation response to emotional arousal in the right medial prefrontal cortex (mPFC). In addition, we examined the influence of normal ageing on the neural subtrates of emotional perception, and found that in accordance with previous studies we found that the older group showed greater activation in response to positive valence, in the left amygdala, left middle temporal gyrus and right lingual gyrus. In contrast however, the older group showed reduced reactivity to emotional arousal, in occipital and temporal visual cortices bilaterally, the left inferior parietal cortex, and the supplementary motor area bilaterally. This study represented the first of its kind to clearly dissociate how ageing affects the neural correlates of emotional arousal and valence.
Dr Bokde's group also investigated the changes in white matter integrity using diffusion imaging of Alzheimer's disease patients and in Mild Cognitive Impaired (MCI) subjects (high risk group for Alzheimer's disease). Analysis of differences between the Alzheimer's disease versus non-amnestic MCI, and Alzheimer's Disease versus amnestic MCI contrasts, highlighted regions that are increasingly compromised in more severe disease stages. Microstructural damage independent of gross tissue loss was widespread in later disease stages. The findings suggested that white matter damage begins in the core memory network of the temporal lobe, cingulum and prefrontal regions, and spreads beyond these regions in later stages.
Dr Bokde's group is member of two large European neuroimaging consortia investigating Alzheimer's disease (European DTI Study on Dementia) and study of high risk behaviours and mental disorders (IMAGEN).
Visualisation of large scale white matter tracts in the brain.
Activation pattern in young healthy subjects leading to successful remembering of images
For further information on Dr Arun Bokde please view his CV profile
The discipline web site is at https://www.tcd.ie/medicine/psychiatry/research/projects/cognitive-systems-group.php