@article {48803, title = {Q\&A: The brain under a mesoscope: the forest and the trees.}, journal = {BMC Biology}, volume = {15}, year = {2017}, month = {2017 Sep 14}, pages = {82}, abstract = {

Neurons relevant to a particular behavior are often widely dispersed across the brain. To record activity in groups of individual neurons that might be distributed across large distances, neuroscientists and optical engineers have been developing a new type of microscope called a mesoscope. Mesoscopes have high spatial resolution and a large field of view. This Q\&A will discuss this exciting new technology, highlighting a particular instrument, the two-photon random access mesoscope (2pRAM).

}, issn = {1741-7007}, doi = {10.1186/s12915-017-0426-y}, author = {Sofroniew, Nicholas James} } @article {47551, title = {A large field of view two-photon mesoscope with subcellular resolution for in vivo imaging.}, journal = {eLife}, volume = {5}, year = {2016}, month = {2016 Jun 14}, pages = {e14472}, abstract = {

Imaging is used to map activity across populations of neurons. Microscopes with cellular resolution have small (\<1 millimeter) fields of view and cannot simultaneously image activity distributed across multiple brain areas. Typical large field of view microscopes do not resolve single cells, especially in the axial dimension. We developed a 2-photon random access mesoscope (2p-RAM) that allows high-resolution imaging anywhere within a volume spanning multiple brain areas (∅ 5 mm x 1 mm cylinder). 2p-RAM resolution is near diffraction limited (lateral, 0.66 μm, axial 4.09 μm at the center; excitation wavelength = 970 nm; numerical aperture = 0.6) over a large range of excitation wavelengths. A fast three-dimensional scanning system allows efficient sampling of neural activity in arbitrary regions of interest across the entire imaging volume. We illustrate the use of the 2p-RAM by imaging neural activity in multiple, non-contiguous brain areas in transgenic mice expressing protein calcium sensors.

}, issn = {2050-084X}, doi = {10.7554/eLife.14472}, author = {Sofroniew, Nicholas James and Flickinger, Daniel and King, Jonathon and Svoboda, Karel} } @article {47354, title = {Neural coding in barrel cortex during whisker-guided locomotion.}, journal = {eLife}, volume = {4}, year = {2015}, month = {2015 Dec 23}, abstract = {

Animals seek out relevant information by moving through a dynamic world, but sensory systems are usually studied under highly constrained and passive conditions that may not probe important dimensions of the neural code. Here, we explored neural coding in the barrel cortex of head-fixed mice that tracked walls with their whiskers in tactile virtual reality. Optogenetic manipulations revealed that barrel cortex plays a role in wall-tracking. Closed-loop optogenetic control of layer 4 neurons can substitute for whisker-object contact to guide behavior resembling wall tracking. We measured neural activity using two-photon calcium imaging and extracellular recordings. Neurons were tuned to the distance between the animal snout and the contralateral wall, with monotonic, unimodal, and multimodal tuning curves. This rich representation of object location in the barrel cortex could not be predicted based on simple stimulus-response relationships involving individual whiskers and likely emerges within cortical circuits.

}, issn = {2050-084X}, doi = {10.7554/eLife.12559}, author = {Sofroniew, Nicholas James and Vlasov, Yurii A and Andrew Hires, Samuel and Freeman, Jeremy and Svoboda, Karel} }