Two-Photon Imaging of Calcium in Virally Transfected Striate Cortical Neurons of Behaving Monkey

Abstract

Two-photon scanning microscopy has advanced our understanding of neural signaling in non-mammalian species and mammals. Various developments are needed to perform two-photon scanning microscopy over prolonged periods in non-human primates performing a behavioral task. In striate cortex in two macaque monkeys, cortical neurons were transfected with a genetically encoded fluorescent calcium sensor, memTNXL, using AAV1 as a viral vector. By constructing an extremely rigid and stable apparatus holding both the two-photon scanning microscope and the monkey's head, single neurons were imaged at high magnification for prolonged periods with minimal motion artifacts for up to ten months. Structural images of single neurons were obtained at high magnification. Changes in calcium during visual stimulation were measured as the monkeys performed a fixation task. Overall, functional responses and orientation tuning curves were obtained in 18.8% of the 234 labeled and imaged neurons. This demonstrated that the two-photon scanning microscopy can be successfully obtained in behaving primates.

Neuron Cells Uptake of Polymeric Microcapsules and Subsequent Intracellular Release

“…Further work on microcapsules using neurons can concern neuron delivery, [34] imaging [35] as well as studying cell signaling, injury and recovery, [36] as well as substrates [37,38] for cells [39] including those with nanoparticles. [40,41] Also, using direction-specific release [42] and anisotropic [43] and anisotropic multicompartment [44] capsules it should be possible targeting cellular organelles.…”

Infrared neural stimulation of primary visual cortex in non-human primates

“…In order to increase our understanding of neural circuitry of the brain, scientists continue to improve methods for assessing neural function through the development of new neurostimulation and detection techniques (Han et al, 2009; Heider et al, 2010; Jackson and Fetz, 2011). These new techniques with clinical potential are often first vetted in non-human primates before their clinical implementation in humans (Velliste et al, 2008).…”

Design of an implantable artificial dural window for chronic two-photon optical imaging in non-human primates

“…1A). Previously reported functional imaging experiments in primates have relied on either: A) acute experimental preparations with a large craniotomy [7], [4], or B) microprobe objective lenses designed to penetrate through a small craniotomy [9]. Microprobe objectives feature short working distances (∼200µm), limited field of view, and low numerical aperture (0.2 NA), and are sub-optimal for imaging below layer 1 in primate cortex.…”

“…To obtain optical access to primate cortex, previously reported approaches replace a small portion of natural dura with a silicone artificial dura (AD). This approach has successfully been employed for intrinsic optical imaging [7], optogenetic stimulation [8], and acute calcium imaging [4], [9]. Building upon these techniques, we developed a novel optical imaging chamber which facilitates 2P imaging in non-human primates, with a chamber geometry optimized to accommodate large lenses.…”