Spring 2016

6th January: Geoffrey Goodhill (University of Queensland)

SM3, Maths

Axon guidance, neural coding and visual maps: theories and experiments

I will review our recent and current work on the following topics: (i) how growing axons detect and respond to molecular gradients, (ii) decoding of visually-evoked neural activity in the developing visual system, and how spontaneous patterns of activity develop, and (iii) neural plasticity in visual cortex in response to altered visual experience during development. All these projects involve a combination of computational and experimental approaches (including microfluidics, 2-photon calcium imaging and optical imaging of intrinsic signals).

22nd January: Kate Jeffery (University College London) 

C44, Biomedical Sciences

The neural coding of three-dimensional space – properties and constraints

In the past several decades, great strides have been made in our knowledge concerning how neurons encode large-scale (navigable) space. Particularly important has been the discovery of how the metric properties of distance and direction are encoded, and of how the signals are updated following movement. These studies, however, were primarily made in two-dimensional environments. In three dimensions, which is how the natural world is structured, additional encoding complexities arise. This talk will explore the nature of some of these complexities, and review emerging data about how the brain may deal with these.

29th January: Andrew Bagshaw (University of Birmingham)

SM3, Maths

EEG-fMRI integration within an information theoretic framework:

The combined recording of electroencephalography (EEG) and functional MRI (fMRI) is an increasingly common technique for studying brain function, but one of the main outstanding questions regards the optimal way to combine these two very different and very rich data sets. The most common approach is within a general linear model framework, but whether a linearity assumption is valid when combining EEG, fMRI and behavioural data is unclear. An alternative is the use of information theory, and its fundamental quantity of mutual information. Information theory imposes no such linearity constraints, as well as providing a coherent framework to quantify relationships between electrophysiological, haemodynamic and behavioural variables. I will give an overview of the issues underlying EEG-fMRI integration and summarise our work implementing an information theoretic framework to accomplish it.

http://www.birmingham.ac.uk/staff/profiles/psychology/bagshaw-andrew.aspx

5th February, Sabine Hauert

SM3, Maths

From evolving artificial neural networks for robot swarms to engineering nanoparticles for brain tumours 

Swarm strategies inspired from nature (ant colonies and bird flocks) allow large numbers of simple agents to achieve complex tasks. The challenge is to engineer individual behaviours that give rise to desired emergent properties. To this end, we use artificial evolution to automatically design neural network controllers for robot swarms. Demonstrated applications include aerial robotics, or coordination of 1000 coin-sized robots at the Bristol Robotics Laboratory. Work in swarm robotics is also inspiring computational and microfluidic tools to improve the delivery of nanoparticles to brain tumours.

For more information on Dr Hauert’s work please see her website (http://sabinehauert.com/), with particular interests in applying swarm behaviour to nanomedicine.

19th February, Colin Davis

SM3, Maths

Modelling visual word recognition at the computational, algorithmic and implementation levels

26th February, Sarah Hulme

SM3, Maths

NMDAR clustering in layer 4 of developing barrel cortex

One surprising aspect of layer IV local excitatory circuit development in barrel cortex is a dramatic yet transient sensory input-dependent increase in both AMPAR and NMDAR mediated connectivity observed at postnatal day 6. This occurs prior to the emergence of dendritic spines but is hypothesised to be critical for the subsequent rapid and dramatic increase in AMPAR receptor-mediated connectivity observed upon spine emergence at postnatal day 9. A candidate mechanism for this phenomenon is the pattern postsynaptic receptor clustering. This talk will summarise the development of AMPAR/NMDAR connectivity we have characterised as well as discuss in more depth how we have approached characterising NMDAR clustering using multiphoton glutamate uncaging along developing dendrites, the challenges associated with this and the results thus far.

4th March, Pedro Martinez (Imperial College London)

SM3, Maths

Modelling cortical oscillations with BrainStudio

Cortical oscillations are an ubiquitous topic in Neuroscience research, playing a major role in the functioning of the mammalian brain. Oscillatory phenomena are often featured in the models we use to replicate experimental findings, and they have proven to be fruitful, but writing and testing these models is usually cumbersome for scientists without a strong background in programming. In this talk we will discuss the origin and relevance of cortical oscillations, and point out their role in resting state dynamics, epileptic seizures and in particular action selection in the basal ganglia. All examples will be implemented in two software packages, BrainStudio and JIDT. BrainStudio is a new software package for the design and real-time simulation of large-scale neural systems. We will highlight the features of BrainStudio as an effective, user-friendly simulation tool. JIDT is a toolbox for the calculation of information-theoretic measures of interest to Neuroscience, such as transfer entropy and mutual information. Combining both tools we can easily set up neural systems and analyse their dynamical and functional properties. This talk contains a total of zero equations, and the constant thrill of live (computational) experimentation. (Work in collaboration with Zafeirios Fountas and Dave Bhowmik.)

11th March, Claire Booth

SM3, Maths

Alterations to intrinsic, synaptic and network properties in the hippocampal formation in a neurodegenerative mouse model of tauopathy

The formation and deposition of tau protein aggregates is proposed to contribute to cognitive impairments in dementia by disrupting neuronal function in brain regions including the hippocampal formation. The rTg4510 transgenic mouse model overexpresses a mutant form of human tau protein and develops hyperphosphorylated tau, neurofibrillary tangles, neurodegeneration, and associated cognitive impairments in an age-dependent manner. We used a battery of in vivo and in vitro electrophysiological recordings in 7-8 month old rTg4510 mice to investigate the effects of tau pathology on neuronal function in hippocampal area CA1 and layer II medial entorhinal cortex (mEC).

CA1: In vitro recordings revealed shifted theta-frequency resonance properties of CA1 pyramidal neurons, deficits in synaptic transmission at Schaffer collateral synapses, and blunted plasticity and imbalanced inhibition at temporoammonic synapses. These changes were associated with aberrant CA1 network oscillations, pyramidal neuron bursting, and spatial information coding in vivo. Our findings relate tauopathy-associated changes in cellular neurophysiology to altered behavior-dependent network function.

mEC: In the mEC, the responsiveness of individual neurons to electrical and environmental stimuli varies along the dorsal–ventral axis in a manner that suggests this topographical organization plays a key role in neural encoding of geometric space. Our recordings revealed that dorsal aspects of the mEC were preferentially affected in rTg4510 mice, with alterations in certain intrinsic properties, gamma frequency oscillations in vitro and theta-gamma cross-frequency coupling in freely moving animals. Ventral regions were unaffected, resulting in flattened dorsal-ventral gradients of these properties in rTg4510 mice. We propose that the selective disruption to dorsal mEC, and the resultant flattening of certain dorsal-ventral gradients, may contribute to disturbances in spatial information processing observed in this model of dementia.

18th March, Nina Kazanina 

SM3, Maths

The role of oscillatory brain activity in tracking speech

22nd April, Romain Veltz (INRIA)

SM3, Maths