Abstract
SummaryIntracellular recordings of membrane potential in vitro have defined fundamental properties of synaptic communication. Much less is known about the properties of synaptic connectivity and synaptic transmission in vivo. Here, we combined single-cell optogenetics with whole-cell recordings to investigate glutamatergic synaptic transmission in vivo from single identified excitatory neurons onto two genetically defined subtypes of inhibitory GABAergic neurons in layer 2/3 mouse barrel cortex. We found that parvalbumin-expressing (PV) GABAergic neurons received unitary glutamatergic synaptic input with higher probability than somatostatin-expressing (Sst) GABAergic neurons. Unitary excitatory postsynaptic potentials onto PV neurons were also faster and more reliable than inputs onto Sst neurons. Excitatory synapses targeting Sst neurons displayed strong short-term facilitation, while those targeting PV neurons showed little short-term dynamics. Our results largely agree with in vitro measurements. We therefore demonstrate the technical feasibility of assessing functional cell-type-specific synaptic connectivity in vivo, allowing future investigations into context-dependent modulation of synaptic transmission.
Highlights
Few studies have directly investigated synaptic transmission between identified neocortical neurons in vivo, presumably due to the technical difficulties in obtaining intracellular recordings from connected pairs of neurons in vivo (Matsumura et al, 1996; Crochet et al, 2005; Bruno and Sakmann, 2006; Yu and Ferster, 2013)
There were significant decreases in unitary excitatory postsynaptic potentials (uEPSPs) amplitude in 5 out of 11 PV neurons and 1 out of 6 Sst neurons during UP states, overall we found that uEPSP amplitude was similar across states in both PV neurons (UP 0.41± 0.42 mV; DOWN 0.48 ± 0.33 mV; p = 0.32, n = 11) and Sst neurons (UP 0.38 ± 0.36 mV; DOWN 0.32 ± 0.42 mV; p = 0.56, n = 6) (Figure 3I)
We found that PV and Sst neurons exhibit distinct intrinsic electrophysiological properties and receive local excitatory synaptic input with different connectivity, speed, reliability, and short-term dynamics in vivo
Summary
Few studies have directly investigated synaptic transmission between identified neocortical neurons in vivo, presumably due to the technical difficulties in obtaining intracellular recordings from connected pairs of neurons in vivo (Matsumura et al, 1996; Crochet et al, 2005; Bruno and Sakmann, 2006; Yu and Ferster, 2013). We develop a robust technical approach for measuring synaptic transmission between identified neurons in vivo and apply it to investigate excitatory synaptic transmission between single identified layer 2/3 (L2/3) excitatory neurons and two different types of genetically defined postsynaptic GABAergic neurons
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
