By combining digital holography, multi-photon optics and genetic engineering we developed a method that allows neuroscientists to precisely stimulate individual neurons while recording the activity of hundreds of others.

We implemented fundamental BMI functions by incorporating real-time image processing. This closes the loop between reading activity and deciding what to stimulate, allowing experimenters to automatically perturb circuits based on real-time activity patterns.

We're currently working on a comprehensive guide and trouble-shooting resource for anyone wanting to perform their own all-optical neural circuit interrogations.

By stimulating different numbers of neurons we asked how salient can cortical activity be, and how susceptible to noise is it? We showed that the psychometric function for detection of cortical activity is sensitive, steep and plastic.

By selectively activating specific groups of neurons, that can be close or far apart, similarly tuned or not, we can begin to unravel how brain circuits encode and transform information. We have shown in visual cortex that some neurons can activate other neurons similar to them, but the net influence of a given neuron on the local network is suppression, following a centre surround motif.

Through upgrading the imaging and stimulation optics we opened up much larger volumes of cortex for interrogation, allowing perturbation and observation across millimetres of brain tissue. We investigated how activity propagates across cortical areas, testing both feedback and feedforward pathways between primary and higher visual areas.

Neurons in the deep brain region of the hippocampus (area CA1) are thought to be vital for enabling memory-guided navigation through physical space. We directly test this long-standing hypothesis by using our all-optical method to stimulate specific ensembles of neurons during virtual reality navigation.

Pattern completion and pattern seperation are two algorithms thought to be implemented in the brain (hippocampus). How information undergoes such transformations between downstream (CA3) and upstream (CA1) areas is little understood. We explore this by performing simultaneous 3D imaging of both areas while parametrically manipulating the virtual environment through which subjects navigate.

Comprehensive software to allow non-expert scientists to use holographic stimulation to probe neural circuits. The interface allows the user to select and group neurons by anatomy or function and then produce all required files for the sub-systems including SLM phase masks, microscope galvo and power control, and external triggers. Making 3D all-optical experiments a one-stop process.

Protocols to align two laser sources ensuring micron-level accuracy at the sample plane. Co-registers 3D point clouds in 'SLM space' with 'imaging space' allowing the accurate targeting of individual neurons in a 3D volume. Also equalises laser power distribution ensuring consistent activation.

I'm working with leading microscope companies to disseminate our custom software - easy to use interfaces atop complex calibration and device communication layers - enabling even more scientists to use our multi-laser, multi-photon method to read and write neural activity.

Open-source, low-cost and high-performance software and hardware to enable high-throughput and parallelised psychophysical experiments. A Python GUI customises the configuration of an Arduino microcontroller to synchronise the delivery of visual, auditory and somatosensory stimuli while monitoring participant responses and triggering external devices accordingly.

VR systems to study the neural basis of navigation are typically bulky and cumbersome. We radically miniaturised a low-cost but highly effective solution, freeing applications from spatial constraints, enabling compatibility with a much wider range of imaging systems.

As a proof on concept we developed a wireframe VR application to potentially open up psychological therapy to a wider audience. Tools used: Unity and the Google Cardboard SDK.