Welcome to our MaxWell Monthly Must-Reads blog. A new year also means new publications to highlight and new topics to discover. This year as well, for our monthly must-reads, we will choose a theme per month and select five papers that we think are worth reading.
Last year we covered a range of topics from Human iPSC-Derived Neurons to a special COVID-19 edition called Neurons and Viruses. In our first edition of 2021, we have decided to focus on Functional Connectivity in Neuronal Networks.

As we know, neurons connect and form functional networks, in vitro. Microelectrode array (MEA) technology enables simultaneous recording of action potentials from thousands of synaptically connected neurons. Furthermore, this technology makes it possible to quantify the degree of connectivity in in vitro neuronal networks, by functional connectivity metrics. Functional connectivity metrics are computed by assessing the correlation between action potential time series and can be measured in neuronal samples, featuring 2D or 3D cell cultures. We feature the article written by Abbott et al. which uses a CMOS-nanoelectrode array to measure extracellular recordings of direct synaptic signals. Please find a summary below.

Extracellular recording of direct synaptic signals with a CMOS-nanoelectrode array.
by Jeffrey Abbott, Tianyang Ye, Keith Krenek, Rona S. Gertner, Wenxuan Wu, Han Sae Jung, Donhee Ham and Hongkun Park. Lab on a Chip. July 2020.

Abbott et al. demonstrate that a complementary metal-oxide-semiconductor (CMOS) nanoelectrode array (CNEA) can extracellularly measure direct synaptic connections in rat neurons. The authors identified ∼1 pA extracellular synaptic signals at the region where pre-synaptic axons and post-synaptic dendrites/somas overlap. Functional connectivity among neurons was confirmed by synaptic signal following the axon propagation signal, and respective time correlation analyses. Electrical stimulation was successfully used to reproducibly evoke network activity and to measure neuronal synaptic connectivity strength, in response to drug application blocking AMPA receptors. Action potential time series correlation analyses alone can not identify direct synaptic connections, Abbott et al. presented a method for measuring extracellular synaptic signals at the region where presynaptic axons and the post-synaptic soma/dendrites colocalize.

Read the paper here.

Although we decided to highlight the article by Abbott et al., we selected four scientific articles that also delve into the topic of functional connectivity in neuronal networks. These can be found below:

  1. Modular microstructure design to build neuronal networks of defined functional connectivity.
    by Csaba Forró, Greta Thompson-Steckel, Sean Weaver, Serge Weydert, Stephan Ihle, Harald Dermutz, Mathias J. Aebersold, Raphael Pilz, László Demkó and János Vörös. Biosensors and Bioelectronics. December 2018.
    Read the paper here.
  2. Large-Scale Mapping of Axonal Arbors Using High-Density Microelectrode Arrays.
    by Torsten Bullmann, Milos Radivojevic, Stefan T. Huber, Kosmas Deligkaris, Andreas Hierlemann and Urs Frey. Frontiers in Cellular Neuroscience. September 2019.
    Read the paper here.
  3. Cerebral organoids at the air–liquid interface generate diverse nerve tracts with functional output.
    by Stefano L. Giandomenico, Susanna B. Mierau, George M. Gibbons, Lea M. D. Wenger, Laura Masullo, Timothy Sit, Magdalena Sutcliffe, Jerome Boulanger, Marco Tripodi, Emmanuel Derivery, Ole Paulsen, András Lakatos and Madeline A. Lancaster. Nature Neuroscience. March 2019.
    Read the paper here. 
  4. Emergence of Rich-Club Topology and Coordinated Dynamics in Development of Hippocampal Functional Networks In Vitro.
    by Manuel S. Schroeter, Paul Charlesworth, Manfred G. Kitzbichler, Ole Paulsen and Edward T. Bullmore. Journal of Neuroscience. April 2015.
    Read the paper here.

We hope you enjoyed the first Monthly-Must-reads of the year! If you would like to be featured in one of the editions, feel free to contact us!

In case you would like to know how MaxWell Biosystems technology can help your experiments, please schedule a call with one of our specialists here: https://calendly.com/mxw