Silicon Neural Probe Optogenetics

Photoelectric artifact-free electrophysiology combined with optogenetics in acute and freely-behaving animals

Enjoy artifact-free data with our silicon neural probes during optogenetic stimulation - a major breakthrough in enabling the bringing together of electrophysiology with optogenetics.

Optogenetics-safe silicon neural probes - monitor during manipulation

Our innovative silicon neural probes are the only probes on the market that are optimized for use in optogenetic experiments due their built-in minimal sensitivity to photoelectric artifacts. 

Not only that, our chronic nano-Drives offer convenient and spatially-defined alignment between your silicon neural probes and a fiber optic cannula, enabling both devices to be physically-movable in freely-behaving animals.

Minimal optogenetic photoelectric artifact sensitivity for optimized silicon neural probe electrophysiology

Data recorded from the posterior striatum in the awake head-fixed mouse using an Ai32 mouse line crossed to the Adora2A Cre line; a marker of indirect pathway medium spiny neurons (MSNs) which in turn express ChR2 - note photo-evoked spikes with ~8 ms onset latency. Recorded with a P-series probe closely apposed to 125 core fibre optic cannula. [Data courtesy of Max Liu and Anatol Kreitzer, University of California, San Francisco, USA.]

•See also: Kravitz, A. V., Owen, S. F., & Kreitzer, A. C. (2013). Optogenetic identification of striatal projection neuron subtypes during in vivo recordings. Brain Research, 1511, 21–32.

Combining in vivo optogenetics with electrophysiology is an important and versatile integration with broad relevance since it opens up the possibility to monitor single unit and local network activity during manipulation. This combined approach can be used for photo-identification of single units being recorded, interrogation of the contribution of defined inputs from one region to another to the circuit-level encoding of a stimulus or behavior and moreover for the establishment of closed-loop optogenetic manipulation based on fast-readout of network state / activity.

Photoelectric artifact free data - why it matters...

A common problem when combining electrophysiology and optogenetics is that ideally you want your specific target neurons to respond to light but so too will your electrodes since when light strikes a metal electrode it commonly causes a photoelectric artifact due to the Becquerel effect. These artifacts may be large amplitude and long-lasting, resulting in potential data loss and / or contamination of your signal with artifacts that may mimic spikes so single unit recordings during optogenetic stimulation have proved tricky so far....examples of this in the literature can be found in Cardin et al., 2010 and Park et al., 2014; Fig. 4). Our probes are purpose-engineered to be minimally-responsive to light, enabling artifact free recording of single unit activity during optogenetic stimulation...

Optogenetic photoelectric artifact on Neuronexus probe versus Cambridge Neurotech silicon neural probe

(A) shows a typical photoelectric artifact on a Neuronexus probe evoked by a modest light stimulus delivered to TH::Cre rat VTA neurons expressing ChR2Y - spikes indicated by blue arrows. The artifact is ~25x larger amplitude than the spikes and results in data loss during a period when short latency photo-evoked spikes are most likely to occur. [Data courtesy of Paul Anderson and Mike Cohen, Radboud University, Netherlands] (B) shows evoked photo-evoked activity in the mouse brainstem in a freely-behaving transgenic mouse expressing vGlut2::Cre with ReachR opsin - short-latency evoked spikes are visible in the absence of a photo-electric artifact. [Data courtesy of Ludwig Ruder, Eduardo Arteaga and Silvia Arber, University of Basel, Switzerland]

Simple and convenient co-alignment of fiber optics with silicon neural probes

Our chronic nano-Drives are designed to precisely co-align fiber cannulas alongside our silicon neural probes with spatially defined separation (300 or 650 microns between the fiber and probe) so as to minimize local tissue damage arising from the fiber, whilst maintaining proximity to the neurons being recorded to spill sufficient light power to drive the expressed target opsin. Our solution to the problem of uniting silicon neural probe microelectrodes with fiber optics allows both devices to be moved through the brain together in a freely-behaving animal.

Implantable chronic microdrives offering small footprint, lightweight multi-functional implants

The uniquely small footprint of the nano-Drives facilitates implants targeting multiple brain regions, such as in the example shown above where orbitofrontal cortex in the right hemisphere and medial prefrontal cortex in the left hemisphere were implanted each with a 32 channel silicon neural probe. Note the small overall size of the implant; a benefit for your animals and their behavior. Click here to see real-time data from this animal.

Optrode assembly in action

A four-shank 64 channel probe with co-aligned fiber cannula smoothly penetrating the cortex [Courtesy of Maxym Myroshnychenko, Lab of Christopher Lapish, Indiana University - Purdue University Indianapolis, USA.]

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