If you decide to take a short noon walk
And pass the cliffs that mark the edge of Muir,
You’ll see the labs founded by Jonas Salk
A worthy home for a bright professor–
Ed Callaway, let me tell you ‘bout him!
For a masterfully shaped talk Tuesday
Be sure you don’t miss Of mice and monkeys:
A journey into the visual system
Where we’ll learn of the circuits that relay
Signals telling cortex what the eye sees.
Pursing the mechanisms behind
Functional cortical activity,
He has pioneered mapping techniques and
Helped us understand connectivity.
To trace the complex circuits creating
The visual cortex, a new marker,
For cells connected synaptically,
Was created and has been worth the slaving.
The rabies virus vector was winner
Moving ‘cross synapses retrogradely.
But here’s the cool part kids, pay attention.
Without glycoprotein (G) the virus
Can only spread through direct connection
Thus mapping neural inputs, lucky us!
To know which inputs cause inhibition,
Cell-specific markers become crucial.
So the vector was further improved to
Make its envelope glycoprotein fit in
A receptor, not found in a mammal,
But expressed in the target cell by you!1
An example of targeting the Glycoprotein (G)-deficient rabies vector to infect cells where the TVA-receptor, which binds to an envelope glycoprotein on the rabies virus, is expressed. Taking advantage of selective expression of Camk2a-Cre in CA1 pyramidal neurons, the rabies vector was injected into the hippocampi of Camk2a-Cre:TVA double transgenic mice to study which neurons have direct synaptic connections with the CA1 pyramidal neurons. In A and B, fluorescent neurons have been infected with the rabies virus.2
Rabies vectors, and high-tech imaging
Callaway has many tricks up his sleeve.
He’s shown inputs to layer 2/3 exciting,
If they’re from layer 5, but not always
If they’re from layer 4 or layer 2/3.
Wow, that’s some fine-tuned specificity!3
If this wets your whistle, just wait a few days.
Both talk and food are complimentary
Tuesday, 4 PM at CNCB.
Kelsey is a first year student in the Neurosciences Graduate Program and started the MD/PhD Program in 2012. She is doing her thesis work in Dr. Subhojit Roy’s lab. Outside of work, she enjoys singing and soccer but struggles with iambic pentameter.
1. Osakada F. and Callaway E.M. (2013). Design and generation of recombinant rabies virus vectors. Nature Protocols. 8, 1583-1601.
2. Sun Y., Nguyen A.Q., Nguyen J.P., Le L., Saur D., Choi J., Callaway E.M., and Xu X. (2014). Cell-Type-Specific Circuit Connectivity of Hippocampal CA1 Revealed through Cre-Dependent Rabies Tracing. Cell Reports. 7.1, 269-280.
3. Yoshimura Y., Dantzker J.L.M., and Callaway E.M. (2005). Excitatory cortical neurons for fine-scale functional networks. Nature. 433, 868-873.