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MRes Modelling Biological Complexity: coursework at UCL
Centre for Mathematics and Physics in the Life Sciences and Experimental Biology (CoMPLEX)
http://www.ucl.ac.uk/complex
Mini project 1:
Computational analysis of NIRS and EEG data collected during seizures
Abstract:
Near Infrared Spectroscopy (NIRS) allows noninvasive monitoring of tissue oxygenation and
cerebral haemodynamics. It is particularly well suited to young developmental populations
from birth to toddler years. NIRS can be used to measure
in vivo changes oxygenated haemoglobin (Δ[HbO2]), deoxygenated haemoglobin
(Δ[HHb]), and oxidised cytochrome-c-oxidase (Δ[oxCCO]),
an enzyme in the mitochondria associated with tissue metabolism.
The aims of this report are to explore the data, apply computational methods
to EEG and NIRS measurements in the time and frequency domains to investigate
neurovascular and neurometabolic coupling during seizures, and provide a basis for
hypothesis generation. Preliminary results suggest that NIRS data can
be used for seizure detection and monitoring conditions before and after seizures, and that
NIRS data can confirm the temporal and spatial order in which each seizure spreads.
Mini project 2:
Conjunctive grid cells in the entorhinal cortex respond to location and head direction
Abstract: In contrast to a hippocampal place cell, a grid cell has multiple firing
fields with regular spacing that tessellates the environment with a hexagonal
pattern. Directional grid cells (\conjunctive grid cells") respond selectively
to head direction and location. The results in this report suggest: (1) A
spike rate map’s centre of mass vector (CoM) directionality is correlated with
preferred head direction (HD) when specific thresholds for gridness, CoM
vector magnitude, and HD vector magnitude are applied. However, simply
increasing the gridness threshold does not increase correlation. (2) Global
grid shifts of all fields contribute more to the magnitude of the centre of mass
vector of a spike rate map than local shifts based on a small number of fields
with high spike rates.
Mini project 3:
Neural Networks for Spike Classification
Abstract: Classic spike sorting pipelines cluster spike waveforms into groups that represent
their source neurons, but they suffer from inaccuracy and incomplete automation.
Artificial neural networks (ANNs) are class of machine learning methods that are
remarkably flexible and well suited to learning from large data sets. This report
presents empirical evidence that neural network enhanced pipelines can provide
higher classification accuracy than pipelines that rely exclusively traditional
feature extraction and clustering methods.
SpikeX: spike sorting
Summer Project:
Classification of Post Synaptic Current Events
Abstract: Whole cell recordings from purkinje cells contain a mixture of excitatory
and inhibitory events (EPSCs and IPSCs). The aim of this project was to examine methods
of event detection and classification, i.e. templates versus neural networks.
Results indicated that the neural network based method was easier to apply and more accurate.
Talk 1 slides: project introduction
Talk 2 slides: progress update
Summer project poster: Classification of Post Synaptic Current Events
MRes Transferable Skills at UCL
Machine Learning Task at
Essay: The Methylation Machine Learning Challenge
Data: DNA methylation profiles from 74 subjects; two profiles (visits) per subject.
Each profile is a vector of features (floating point numbers).
For each subject there is 1 positive example (match) and 73 negative examples (mismatches).
Task: Match each patient's visit one profile with his/her visit two profile.
Evaluation: log-loss.
Bioinformatics Database Task
Writeup:
Genes for synaptotagmin, proteins for neurotransmitter vesicle docking and fusion
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Virtual Screening
Using Comparative Genomics and Virtual Screening for Antibiotic Drug Discovery (2010),
paper
supplement
References
>>> project web site <<<
Abstract: Methods from comparative genomics, sequence analysis,
and virtual screening were combined to predict new drug targets and the chemical compounds that bind most strongly
to those targets.
Motivation: The evolution and spread of antibiotic resistant
pathogenic bacteria has been rapid and often lethal, while the pipeline for new antibiotics has
remained virtually bone dry. We face an urgent need for new antibiotics and more cost effective
methods to support drug discovery; greater efficiency may be achieved by prioritizing in vitro
testing.
Results:
This combination of methods provided a cost effective way to predict suitable drug targets,
their active sites, and prioritize chemical compounds for in vitro testing of antimicrobial
properties, especially in the light of domain expertise.
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Publications
Broadband-NIRS System Identifies Epileptic Focus in a Child with Focal Cortical Dysplasia -- A Case Study.,
Metabolites, 2022.
Authors: Katerina Vezyroglou, Peter Hebden, Isabel de Roever, Rachel Thornton, Subhabrata Mitra,
Alan Worley, Mariana Alves, Emma Dean, J. Helen Cross and Ilias Tachtsidis
A new multichannel broadband NIRS system for quantitative monitoring of brain hemodynamics and
metabolism during seizures, Diffuse Optical Spectroscopy and Imaging,
European Conferences on Biomedical Optics (ECBO), June 2019.
Authors:Isabel De Roever, Aikaterini Vezyroglou, Peter Hebden, Gemma Bale,
Helen Cross, Ilias Tachtsidis
Abstract: We present a newly developed multichannel broadband NIRS (or bNIRS) system that
has the capacity to measure changes in light attenuation of 308 NIR wavelengths (610nm to 918nm)
simultaneously over 16 different brain locations.
To achieve this the instrument uses a lens based spectrometer with a
front-illuminated CCD that has a sensor size of 26.8x26mm. This large CCD detector allows the
simultaneous binning of 16 detector fibres. The software uses the UCLn algorithm to quantify the
changes in oxy-, deoxy- haemoglobin concentration (HbO2, HHb) and cytochrome-c-oxidase (oxCCO)
simultaneously over 16 different brain locations with 1 second sampling rate. We demonstrate the use
of the instrument in quantifying brain tissue oxygenation and metabolic activity simultaneously
with electrical changes as measured with EEG in children with seizures.
Distributed Asynchronous Clustering for Self-Organisation of Wireless Sensor
Networks, International Journal of Information Processing (IJIP), March/April 2007.
Authors: Peter Hebden and Adrian Pearce
Abstract: This paper presents a fully distributed asynchronous
clustering protocol for the self-organisation of a wireless sensor network into an infrastructure of
well separated cluster heads that supports in-network processing, routing, and deployment. In this
protocol, nodes volunteer asynchronously for cluster head duty and use a radio beacon to pre-
emptively recruit members. Limited beacon range is used as the primary parameter for self-
organisation. The resulting topology substantially reduces total transmission distance and the
expected energy consumed by radio communication. To further extend network lifetime and capability,
well separated cluster heads may be easily located and replaced by more powerful devices.
Data-Centric Routing using Bloom Filters in Wireless Sensor Networks, Fourth
International Conference on Intelligent Sensing and Information Processing (ICISIP),
Bangalore, India, December 2006.
Authors: Peter Hebden and Adrian Pearce
Abstract: This paper presents a paradigm for reducing communication costs in
wireless sensor networks. The first component is our Distributed Asynchronous Clustering protocol
(DAC), which self-organises the network into an infrastructure that supports in-network processing,
routing, and deployment. The second component, and the focus of this paper, is a data-centric
routing protocol where cluster heads build and maintain sets of Bloom filters to inform routing
decisions and filter out unproductive messages. While other data-centric protocols use a flat
topology and rely to some extent on flooding, our protocol exploits a two tier hierarchy to provide
an adaptable, scalable, and intelligent routing service that is expected to reduce the number of
transmissions and extend network lifetime.