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Mapping Inhibitory Neuronal Circuits by Laser Scanning Photostimulation
Published on: October 6, 2011
Mapping inhibitory neuronal circuits by laser scanning photostimulation.
Taruna Ikrar1, Nicholas D Olivas, Yulin Shi
1Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, USA.
Journal of Visualized Experiments : Jove
|October 19, 2011
Summary
Laser scanning photostimulation (LSPS) precisely maps local circuit connections to specific inhibitory neurons in the cortex. This technique reveals detailed synaptic input maps, advancing our understanding of cortical circuit organization.
Area of Science:
- Neuroscience
- Computational Neuroscience
- Systems Neuroscience
Background:
- Inhibitory neurons are vital for cortical function, comprising ~20% of cortical neurons and existing in diverse subtypes.
- While intrinsic properties of inhibitory neurons are known, their local circuit connections remain less understood.
- Understanding synaptic input is crucial as it shapes individual neuron function within cortical circuits.
Purpose of the Study:
- To introduce and detail the technique of laser scanning photostimulation (LSPS) combined with whole-cell patch clamping for mapping local inhibitory circuits.
- To demonstrate the application of LSPS for detailed functional analysis of synaptic inputs onto specific inhibitory neuron types.
- To provide a powerful tool for neuroscientists to investigate the functional organization of local cortical circuits.
Main Methods:
- Utilized laser scanning photostimulation (LSPS) with caged glutamate uncaging for precise, spatially restricted neuronal activation.
- Employed whole-cell patch clamp recordings to detect photostimulation-evoked synaptic responses.
- Used transgenic mice expressing green fluorescent proteins (GFP) for targeted recording and unambiguous identification of specific inhibitory neuron subtypes.
- Scanned laser beam across hundreds of potential presynaptic sites to generate comprehensive input maps.
Main Results:
- LSPS allows for extensive mapping and quantitative analysis of local functional inputs to individually recorded neurons.
- The technique achieves sub-laminar mapping resolution by selectively activating neurons perisomatically.
- Detailed maps of excitatory and inhibitory synaptic inputs onto specific inhibitory neuron types were successfully generated in mouse primary somatosensory cortex.
Conclusions:
- LSPS combined with whole-cell patch clamping is a powerful and efficient technique for mapping local inhibitory circuits.
- This method enables detailed construction of synaptic input maps onto specific inhibitory neuron types.
- The technique provides neuroscientists with a valuable tool for elucidating the functional organization of local cortical networks.
