Technical Reports

In this study, the authors direct human iPS and ES cells to adopt cortical progenitor and, subsequently, mature projection neurons with functional synaptic connections. This protocol is able to generate both deep and upper layer neurons in proper temporal order.

This study describes a microinjection technique that allows for the acute manipulation of individual neural stem cells in organotypic slice cultures via direct delivery of biologically active molecules.

The authors describe the design of an optetrode, a device that allows for colocalized multi-tetrode electrophysiological recording and optical stimulation in freely moving mice.

This technical report describes a 360-channel flexible multi-electrode array with high spatial resolution, wide coverage area and minimal damage to the recorded neural tissue. Among other descriptions of multiunit in vivo neuronal recording in cats, the authors also use the electrode array to show spiral-patterned spread of epileptic neural activity in the neocortex.

The authors describe a chemical approach for imaging deep into fixed brain tissue using Scale, a solution that renders biological samples transparent, but preserves fluorescent signals. This technique allows for imaging at unprecedented depth and at subcellular resolution, and makes three-dimensional reconstruction of neural networks possible without serial sectioning.

Two-photon calcium imaging has previously only been useful for imaging ongoing neuronal activity in the superficial cortical layers in vivo. Here the authors describe technology that enables imaging of sensory-evoked neuronal activity in layer 5 of adult mouse somatosensory cortex.

This Technical Report describes an automated algorithm to trace densely labeled neurons and reconstruct their structure, thus providing a new tool in functional connectome analysis.

In this Technical Report, Kleinlogel and colleagues created and characterized a new channelrhodopsin-2 mutant with an enhanced permeability to calcium. Dubbed CatCh (calcium translocating channelrhodopsin), this new variant's enhanced calcium permeability mediates an accelerated response time and voltage response that is ~70-fold more light sensitive than that of wild-type channelrhodopsin-2.

This paper reports an in vivo imaging method that monitors real-time synaptic transmission simultaneously at many release sites with quantal resolution. The authors demonstrate the utility of this technique by using it to study the glutamatergic system of Drosophila larval NMJ.

The authors describe a technique for delivering DNA vectors through a patch-pipette following characterization of the neuron by whole-cell recording. They demonstrate the utility of the approach by mapping the synaptic and anatomical receptive fields of several visual cortical neurons.

Here the authors describe a set of new optogenetic tools for use in primates that are meant to address the unique constraints of working with this species. They characterize opsin expression, the reliability of optogenetic stimulation and its effect on behavior, and methods for determining localization and expression levels prior to the completion of experiments.

Szuts et al. have developed a wireless neural recording system that outperforms existing rodent telemetry systems in either channel count, weight or transmission range. They show that it can be used to record brain signals in animals outdoors and in tunnels.

Dombeck and colleagues describe a method for two-photon calcium imaging using a genetically encoded indicator in the hippocampus of awake, behaving mice. This powerful approach permits the recording of multiple hippocampal place cells' activity with subcellular resolution as the mice run on a track in a virtual reality environment.

This paper reports the development of a K⁺-selective glutamate receptor, HyLighter, that reversibly inhibits neuronal activity in response to light. The low light requirement and bi-stability of HyLighter could be useful for studying neural circuitry.

Dieterich et al. describe a methodology to label all newly synthesized neuronal proteins in situ. This method, which they name FUNCAT, relies on the inclusion of noncanonical amino acids and selective fluorescent labeling via click chemistry. The authors show that this system is amenable to dual pulse-chase experiments and dynamic tracking of newly synthesized proteins.

Understanding the role of astrocytic calcium signals has been hindered by our inability to measure calcium in small volume compartments. Here, the authors develop a technique to do this by modifying the genetically encoded calcium sensor GCaMP2 to ensure greater expression near the membrane.

The authors devised a method for detecting the bioluminescent Ca²⁺ sensor GFP-Aequorin in freely behaving zebrafish larvae. To demonstrate the efficacy of the technique, they targeted the sensor to a genetically specified population of hypothalamic neurons. The resulting neuroluminescence reveals patterns of neuronal activity that are associated with distinct swimming behaviors.

This paper reports the first recording from brain neurons of flying Drosophila. The responses of visual interneurons to moving grate stimuli were substantially modulated by flight, as compared with the resting situation.

Channelrhodopsins such as ChR2 can drive spiking with millisecond precision. However, when ChR2 is highly expressed, a single light pulse can produce extra spikes, and ChR2 does not allow sustained spike trains above about 40 Hz. Rapid ChR2-driven spike trains can also cause plateau potentials. Here, the authors report an engineered opsin gene, ChETA, that overcomes these limitations and allows sustained spike trains up to 200 Hz.

The authors describe cell-based neurotransmitter fluorescent engineered reporters (CNiFERs), a new biosensor for monitoring neurotransmitter receptor activation. CNiFERs are cells engineered to express both a metabotropic receptor that triggers the G_q protein–coupled receptor cascade to increase calcium concentrations and a genetically encoded fluorescent calcium sensor for visualization.