Measuring the Brain in Time & Space

In this episode, we discussed methods to measure brain activity and the important trade-off between spatial (where) and temporal (when) resolution. We also explored the relative significance of understanding brain activity in space vs. time, and finally went on to talk about some novel methods that are breaking this barrier and achieving both high spatial and temporal resolution.

While imaging methods can be used to visualise brain activity across space, they give little information about the temporal dynamics of activity; whereas electrophysiology methods are used to measure electrical activity with high temporal precision, but are usually restricted in what they can tell us about where the activity is occuring.

Here is a great figure summarising the major techniques used in neuroscience research and their spatio-temporal resolution:

Grinvald, A., Hildesheim, R. VSDI: a new era in functional imaging of cortical dynamics. Nat Rev Neurosci5, 874–885 (2004). https://doi.org/10.1038/nrn1536

Large-scale methods:

• Summary of MRI vs. EEG: https://imotions.com/blog/learning/research-fundamentals/eeg-vs-mri-vs-fmri-differences/

Electrophysiology methods:

• Patch-clamp: https://en.wikipedia.org/wiki/Patch_clamp

• Neuropixels 2.0: A miniaturized high-density probe for stable, long-term brain recordings (Steinmetz et al., 2021) https://www.science.org/doi/10.1126/science.abf4588

Calcium imaging:

• Wide-Field Calcium Imaging of Neuronal Network Dynamics In Vivo (Nietz et al., 2022) https://www.mdpi.com/2079-7737/11/11/1601/pdf

Voltage imaging:

• VSDI: a new era in functional imaging of cortical dynamics (Grinvald & Hildesheim, 2004) https://www.nature.com/articles/nrn1536

• Optical voltage imaging in neurons: moving from technology development to practical tool (Knöpfel & Song, 2019) https://doi.org/10.1038/s41583-019-0231-4