Articles

Schroedinger's importer

27th August, 2018

A Python package I'm working on combines several submodules with mixed licensing — some will be open source and redistributed, others will be proprietary and in-house only. I wanted to ease importing of the package by automatically detecting which submodules are present, and dynamically importing only those.

Visualised behaviour of dynamic neural networks

27th July, 2017
Behaviour of a random two-neuron dynamic neural network.

The dynamics of simple nonlinear systems can be dramatically beautiful. I visualised a large number of randomly-generated systems as an exploration.

Stochastic descent optimisation in Matlab


Using the Adam optimiser

21st February, 2017

Seeking a minimum

Seeking a minimum

Image credit: CPGXK

Stochastic gradient descent is a powerful tool for optimisation, which relies on estimation of gradients over small, randomly-selected batches of data. This approach is efficient (since gradients only need to be evaluated over few data points at a time) and uses the noise inherent in the stochastic gradient estimates to help get around local minima. This is a Matlab implementation of a recent powerful SGD algorithm.

Putting vision into context


And adding context to vision

21st December, 2015
This optical illusion shows how strongly the context of a visual scene influences what we see, and how that context can sometimes mislead us. The three people in the picture are exactly the same size. However, because our brain judges the size of an object based on its perceived distance, the person at the back seems to be further away and therefore appears larger.

Our brain does not faithfully interpret visual information, but instead uses a complex mixture of prior experience and context to shape our perception of the world. We described a pathway in the brain for this contextual information, from the mouse thalamus to visual cortex.

Thalamus conveys diverse contextual information to layer 1 of visual cortex


Poster at SfN 2015

17th October, 2015

Sensory perception depends on context. Many models emphasise cortical feedback as the source of contextual modulation. However, higher-order thalamic nuclei, such as the pulvinar, interconnect with many cortical and subcortical areas, suggesting a role for the thalamus in providing sensory and behavioral context — yet the nature of the signals conveyed to cortex by higher-order thalamus remains poorly understood.