Table 1.
Representative publications for multiple recent advanced MPM techniquesa
| Technique | No. of neurons, range | Recording frequency range, Hz | Depth, μm | Spatial resolution: lateral × axial, μm | Reported application | Features and highlights | Reference |
|---|---|---|---|---|---|---|---|
| eMS2PM: encoded multisite 2PM | 3–15 | 4100–1040 | 300 | 0.7 × 1.4 | Voltage imaging in cultured cells, fast OGB calcium imaging in vivo | Simultaneous recording; less phototoxic; noise increase with increased number of recording sites; limited to 2D scanning; sensitive to motion | Ducros et al., 2013 |
| RAPS: random-access pattern scanning | 16–100 | 490–180 | 300 | 1.0 × 4.1 | High SNR in vivo recordings of calcium transients | 2D-AOD scanning; 1AP detection; sensitive to motion | Grewe et al., 2010 |
| SLAP: Tomographic TPM | 100 | 1016 | 300 | 0.44 × 1.62 | Single-cell voltage imaging, dendritic and axonal calcium recording | Constant frame rate independent of number of sources; tomographic image reconstruction; varying accuracy depending on label distribution; 2D FOV | Kazemipour et al., 2019 |
| ULOVE: 2D-AOD pattern scanning | 1–150 | 15000–100 | 500 | 0.5 × 1.5* | Single-cell imaging of membrane activity in deep neurons during awake behavior | Resilience to motion; high SNR tracking of spikes; 2D FOV | Chavarha et al., 2018 |
| Bessel 2PM: extended focus scanning | 50–400 | 40–10 | 400 | 0.5, 15–400 | High-speed volumetric calcium imaging in vivo in sparsely labeled tissue | Volumetric imaging with extended focus; volume size limited by power; axial dimension reconstructed post hoc | Lu et al., 2017 |
| RAMP: 3D-AOD | 27–411 | 1800–120 | 500 | 0.5 × 1.5* | High-speed calcium recordings from hundreds of neurons | Highest-speed sequential 3D recordings; sensitive to sample motion | Cotton et al., 2013; Nadella et al., 2016 |
| Galvo-Galvo: raster scan with galvanometers | 100–300 | 10–3 | 500 | 0.5 × 1.5* | Calcium imaging in vivo | Well-established technique; available from commercial companies | Denk et al., 1990 |
| TPM-Mux: multibeam multiplexing | 200–800 | 250–60 | 300 | 0.5 × 1.5* | Calcium imaging in vivo in multiple regions | Increased recording throughput by using multiple beams; crosstalk between beams | Stirman et al., 2016; Cheng et al., 2011 |
| Dual-beam TPM: dual-area scan, two beams | 200–600 | 10–3 | 700 | 1 × 9 | Calcium imaging recordings in vivo in multiple regions | Simultaneous imaging of two areas decoupled in X/Y/Z; minimum separation is ∼1 mm center-to-center; requires optical alignment for each experiment | Lecoq et al., 2014; Yang et al., 2016 |
| s-Te-Flo: encoded multibeam scanning | 200–4000 | 160–3 | 500 | 5 × 10 | High-speed calcium recordings in populations of neurons | PSF sculpted to size of neuronal cell body-low spatial resolution; synchronizing pixels to laser pulses | Prevedel et al., 2016 |
| Trepan2p: large FoV and beam multiplexing | 400–5000 | 40–0.1 | 700 | 1.2 × 12 | Dual beam calcium recordings over >9 mm2 FOV | Independent positioning of two beams within 9 mm2; highly reconfigurable in terms of scan size and frame rate; crosstalk between beams | Stirman et al., 2016 |
| 2P-RAM: 25 mm2 FOV | 200–3000 | 44–1.9 | 500 | 1.2 × 5 | Mesoscale imaging of calcium activity in neuronal populations | High collection efficiency; fast z scanning; highly flexible configuration of imaged regions and frame rates; requires prep adaptation to a bulky objective | Sofroniew et al., 2016 |
| Resonant scanner, fast axial scanner | 300–13000 | 30–2.5 | 500 | 0.5 × 1.5* | Calcium recordings in vivo in neuronal populations | Improved frame rate but lower SNR compared with Galvo-Galvo; available from commercial companies | Fan et al., 1999; Pachitariu et al., 2017 |
aRecording capabilities and microscope parameters are listed along with the associated references.
*Spatial resolution values correspond to theoretical values for the objective lenses used in system designs, as PSF sizes were not reported.