20th May, Henry Darch
D3, Biomedical Sciences
Problem solving session
Summary of the problem: “I have simultaneously recorded 51 channels of continuous extracellular neural activity (LFP) during a reach-retrieve behaviour. Unfortunately, I have an artefact present as the animal’s paw is entering the tube. The artefact is present in a large proportion of recorded reaches, and so is reducing my ‘trial n’. I wish to explore possible methods of detecting and removing these artefacts, without simply excluding the affected trials, and recovering as much neural signal as possible.”
26th May, Michael Knight
D3, Biomedical Sciences
Many changes occur in the brain during the hyperacute phase of ischaemic stroke. Certain physiological and chemical changes manifest themselves as changes in quantities measurable by magnetic resonance imaging (MRI), from which one might hope to infer details of the stroke event, in particular its time of onset, for this determines choice of treatment and is often unknown by the patient. We have developed a simplified model for the hyperacute phase of ischaemic stroke, intended to calculate the spatiotemporal changes in the apparent diffusion coefficient (ADC) for water, and the coherence lifetime (lifetime of MRI signal). These are easily measured by MRI. These have distinct kinetics, the ADC dropping quickly after onset and defining the infarct, the T2 dropping quickly then gradually increasing. I will present our model and how we might in future use it to guide treatment choices in stroke.
3rd June, Nathan Lepora
D3, Biomedical Sciences
A biomimetic brain for active touch
10th June, Chayanin Tangwiriyasakul (UCL)
SM3, Maths
Network decomposition in patients with IGE – an EEG-fMRI study
Many recent studies suggest that generalized seizures arise from abnormality in whole brain networks. Most evidence shows abnormalities in static networks (e.g. reduced default mode network connectivity). We investigated dynamic changes in the level of synchrony during generalized spike and wave discharge (GSW) period using simultaneous EEG-fMRI recordings. The results from this study suggest two possible causes of SWD generation: (1) transition between two states, which may cause instability in brain networks or (2) over synchronization of the brain networks.
http://epilepsy-london.org/doctor/chayanin-tangwiriyasakul/
17th June, Eder Zavala (Exeter)
F40, Biomedical Sciences
Modelling the Intra–Adrenal Regulatory Network Underlying Glucocorticoid Secretion During Stress
The stress response is mediated by glucocorticoid hormones (CORT) secreted by the adrenal glands upon stimulation by adrenocorticotropic hormone (ACTH) from the pituitary. These hormones exhibit a complex pattern of highly correlated ultradian oscillations that becomes altered during inflammation and disease. In particular, the role of intra-adrenal control mechanisms on the dynamic dissociation of these hormones during stress is poorly understood. Here, we develop a mathematical model of the intra-adrenal regulatory network controlling the synthesis of CORT, accounting for both genomic and non-genomic processes occurring at different time scales within the network. We test the model through computer simulations of ACTH perturbations, and successfully predict responses to acute stressors, as judged from experiments in rats injected with high doses of ACTH and a bacterial toxin (LPS) that triggers an inflammatory response. Our results show that post-transcriptional and post-translational regulatory mechanisms are key for a rapid response to stress, and suggest the presence of novel regulatory mechanisms that can be tested experimentally. Moreover, our model provides insight into the regulatory roles of some steroidogenic genes during normal and diseased states.
1st July, Stafford Lightman
SM3, Maths