Fellow, Group Leader (Neuro-photonics Group)
ANU College of Health and Medicine
Australian National University Canberra, AU
Using Complex Light Patterns To Understand Brain Circuits
We aim to understand how information is processed in cortical circuits of the mammalian brain. To achieve this, we use complex light patterns to stimulate and record the activity of single cortical neurons in a rat brain slice. We use holographic projection of an ultrafast laser to produce multiple foci, where each focus emulates a synaptic input or an optical recording probe. To emulate synaptic inputs, multiple foci are directed onto spines of a neuron and gated illumination enables localized two-photon (2P) photolysis of caged neurotransmitters. Patterned spatio-temporal release of neurotransmitters onto multiple spines allows us to study the input-output characteristics of single neurons in the cortex. As an optical recording probe, each focus excites neuronal activity reporters via 2P multi-foci excitation. The fluorescence emanating from all foci are simultaneously recorded using an electron-multiplying charge-coupled device (EMCCD) camera thereby enabling simultaneous multi-channel recording of the neuronal activity from multiple sites. We report recording of neuronal activity from two types of reporters: (1) calcium indicator, Cal520; and (2) voltage indicator, JPW1114. We optically recorded the activity evoked by the neuron following injection of current onto the soma. Using this technique, we have uniquely identified a crucial function of a specific set of dendrites for learning and memory. Moreover, we can disable such function by prunning the specific dendrite via highly targetted femtosecond laser dendrotomy. Using complex light patterns to understand the input-output transfer function of single neurons enables bottom-up approach to understand information processing in the brain.
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Hosted by Dr. Daryl C Preece