Technical Reports in 2014

In this technical report, Khodagholy and colleagues find that NeuroGrid, a planar, scalable and highly conformable electrode array, allows recordings of local-field potentials and stable single-unit activity from the surface of the rat cortex or hippocampus. The authors also validate NeuroGrid across species by showing that that it can capture LFP-modulated spiking activity intraoperatively in surgical patients, thus demonstrating its utility as tool for fundamental research on the human brain and in the clinic.

Lecoq and colleagues introduce a two-photon microscope with two articulated arms that can image nearly any two brain regions, nearby or distant, simultaneously. They validate this new system by imaging calcium signals in two visual cortical areas in behaving mice, and find evidence suggesting activity fluctuations can propagate between cortical areas

The authors report an optical method involving simultaneous stimulation of single neurons using a red-shifted optogenetic probe and recording of population activity using a green fluorescent calcium sensor. They use this technique to manipulate individual place cells in CA1 during spatial navigation in a virtual reality environment.

In this paper, Atasoy and colleagues use a genetically-encoded synaptic marker for electron microscopy (GESEM) to probe long-range neuronal connectivity at the nanoscale level. The authors fused the horseradish peroxidase to the vesicle-associated membrane protein 2 (VAMP2) to label synaptic vesicles. Focusing on the mouse feeding system, they show that this new tool is suitable for connectomics analyses of genetically defined populations of neurons.

In this Technical Report, Chuong and colleagues introduce Jaws, an archaeon-derived, photoactivatable chloride pump that responds to red light. Owing to its efficiency in absorbing red photons and its large photocurrent, Jaws can be transcranially activated deep in the brain and thus allows noninvasive optogenetic silencing.

This Technical Report describes new methods of transcranial magnetic stimulation (TMS) in non-human primates. By combining single neuron recording with a modified TMS coil with focused stimulation in alert macaques, the authors show that this method can reduce stimulation artifact and allow investigation into the neuronal mechanisms of TMS.

In this technical report, St-Pierre and colleagues introduce a new genetically encoded voltage sensor called Accelerated Sensor of Action Potentials 1 (ASAP1), which consists of a circularly permuted GFP inserted in the extracellular voltage-sensing domain of a phosphatase. ASAP1 surpasses existing sensors in reliably detecting single action potentials and tracking subthreshold potentials and high-frequency spike trains.

In this Technical Report, the authors describe a new technique for the unambiguous lineage tracing of specific Drosophila neuroblasts. This methodology involves the use of lineage-restricted drivers and a modification to GAL4 expression such that it is now permanent and heritable to all descendant cells, directing reporter expression based on neuroblast identity rather than terminal neuronal characteristics.

In this Technical Report, the authors describe a new methodology for rapid and flexible knockdown of specific proteins in vitro and in vivo—without the need for genetic modification of the target—using a small peptide construct that targets the protein of interest and marks it for chaperone-mediated autophagy.

Existing noninvasive neuromodulation methods have poor spatial resolution and may affect neural activity in both the targeted cortical region and unintended surrounding networks. The authors demonstrate that transcranial focused ultrasound, a noninvasive technique with better spatial specificity, can alter neural activity within spatially confined regions of primary somatosensory cortex and enhance somatosensory discrimination.