Cortical functional subnetworks in the fosGFP+ mouse
Final Report Abstract
A common feature of sensory processing in cortex is the response heterogeneity of neighboring excitatory pyramidal neurons, especially in superficial layers 2/3. In our project we hypothesized that a subset of layer 2 excitatory neurons in the mouse whisker somatosensory barrel cortex, distinguished by expression of the activity-dependent fosGFP reporter gene, would be preferentially activated by whisker stimulation. In fact, two-photon targeted dual whole-cell recordings showed that principal whisker stimulation elicits similar amplitude synaptic responses in fosGFP-expressing (fosGFP+) and non-expressing (fosGFP–) neurons. FosGFP+ neurons instead displayed shorter latency and larger amplitude subthreshold responses to surround whisker stimulation. Using optogenetic thalamic stimulation we determined that these neurons are targeted by axons from the posteromedial nucleus (POm), a paralemniscal thalamic nucleus associated with broad receptive fields and widespread cortical projections. Therefore in this part of the project we showed that fosGFP expression discriminates between single- and multi-whisker receptive field layer 2 pyramidal neurons. We went on to investigate monosynaptic connections between pyramidal neurons in vivo in the fosGFP mouse. We made multiple whole-cell recordings from connected and unconnected pyramidal neurons in vivo from fosGFP+ and fosGFP– neurons in layer 2/3. As a first study, we included these data with monosynaptic connections collected from other mouse lines to make one of the first studies of excitatory neuron monosynaptic connectivity in vivo. We continue to analyze and investigate sensory responses and spontaneous activity in connected and unconnected fosGFP+/– neurons.
Publications
- (2013) Barrel cortex function Prog. Neurobiol., 103: 3-27
Feldmeyer D., Brecht M., Helmchen F., Petersen C.C., Poulet J.F.A., Staiger J.F., Luhmann H.J., Schwarz C.
(See online at https://doi.org/10.1016/j.pneurobio.2012.11.002) - (2014) Cortical fosGFP expression reveals broad receptive field excitatory neurons targeted by POm. Neuron, 84: 1-14
Jouhanneau J.S., Ferrarese L., Estebanez L., Audette N., Brecht M., Barth A.L. and Poulet J.F.A.
(See online at https://doi.org/10.1016/j.neuron.2014.10.014) - (2014) Keeping an eye on cortical states. Neuron, 84:246-248
Poulet J.F.A.
(See online at https://doi.org/10.1016/j.neuron.2014.10.005) - (2015) In vivo monosynaptic excitatory transmission between layer 2 pyramidal neurons. Cell Reports, 13: 1-9
Jouhanneau J. S. Kremkow, J. Dorrn, A. and Poulet J.F.A.
(See online at https://doi.org/10.1016/j.celrep.2015.11.011) - (2015) Matching cell type to function in cortical circuits. Neuron. 87:249-251
Estebanez, L., Kremkow J. and Poulet J.F.A.
(See online at https://doi.org/10.1016/j.neuron.2015.06.039)
