Imaging neuromodulators with high spatiotemporal resolution using genetically encoded indicators

Genetically encoded sensors enable micro- and nano-scopic decoding of transmission in healthy and diseased brains

“…Two families of GPCR-based dopamine (3,4-dihydroxyphenethylamine or DA) sensors, human D 2 dopamine receptor-based GRAB DA [25,36] and human D 1 dopamine receptor-based dLight [26,37] sensors, are engineered (Table 1). GRAB DA1m , GRAB DA1h , GRAB DA2m , and GRAB DA2h are the green versions of genetically encoded DA sensors, while rGRAB DA1m and rGRAB DA1h belong to [26,37]…”

“…the first red versions of genetically encoded neuromodulatory transmitter sensors [25,36]. dLight sensors also have multiple versions with somewhat different properties [26,37]. The top-performing GRAB DA2m and dLight 1 registered robust dopaminergic signals from populations of cells in the striatum [32,36] and basal amygdala [38], which receive the heaviest dopaminergic innervations with probably largest dopaminergic signals [38][39][40].…”

Emerging technologies to study glial cells

“…A few examples of these studies include: time lapse intravital imaging of microglia that revealed their rapid dynamics and response to injuries (Davalos et al, 2005;Nimmerjahn et al, 2005); visualization of OPCs showing their self-repulsive behavior during adult proliferation (Hughes, Kang, Fukaya, & Bergles, 2013); and imaging of astrocyte processes with Ca 2+ sensors demonstrating time-correlated Ca 2+ responses to neuronal activation (Bindocci et al, 2017). The palette of tools has continued to blossom with refined and potent techniques such as targeted two-photon holographic activation of channelrhodopsins in individual cells (Papagiakoumou et al, 2010) and genetically encoded optical voltage and neurotransmitter sensors (Abdelfattah et al, 2019;Marvin et al, 2013;Patriarchi et al, 2019), which in the future will allow a more sophisticated in vivo dissection of the role of glial cells within complex neuroglial networks. Altogether, in vivo imaging techniques expand capabilities for elucidating the interactions between neuronal and non-neuronal cells in health and disease.…”

A Bright and Colorful Future for G-Protein Coupled Receptor Sensors

“…Our hope is that, with time, a careful evaluation of the side-effects of GPCR sensor expression will elucidate best experimental practices that can allow us to make the most out of these tools without significantly altering the system under investigation. For a more in-depth discussion of the limitations of these tools please refer to our previously published protocols (Patriarchi et al, 2019). All things considered, we envision a bright future for GPCR sensor development, with important achievements to be expected along at least three directions.…”