Erez Geron

Please join us on Monday, Oct. 3, 2022, for a Neuroscience Seminar. Dr. Erez Geron, Postdoctoral Research Fellow at the Neuroscience Institute, New York University.

Title

When not responding is a response: synaptic weakening as a mechanism for negative neuronal responses and fear learning

Location

Live, in the Bowerman Room, Dobell

Summary

Regional brain activity often decreases from baseline levels in response to external events. These so-called negative responses are a common feature of brain activity, evident in various brain functions, including perception, movement, and higher cognitive functions. Yet, the cellular mechanisms that support negative responses are unclear. To study this, we leveraged the negative response that develops in the primary motor cortex (M1) after classical fear learning to the conditioned tone. We trained mice with the fear conditioning paradigm while imaging their brains with two-photon microscopy. This enabled monitoring changes in neuronal responses to the tone at synaptic resolution while maintaining typical freezing behaviors at later recall tests. We found that M1’s layer 5 pyramidal neurons (L5 PNs; the principal output cells of the cortex) developed negative tone responses within an hour after conditioning, which depended on the weakening of their tone-responsive dendritic spines. Blocking this effect using an optogenetic manipulation of CaMKII activity disrupted negative tone responses and freezing. Thus, by reducing the relative weight of tone-responsive inputs, L5 PNs of M1 acquire negative tone representations and responses, illustrating how area-specific negative responses to external cues can be achieved.

For those who cannot join in person, the presentation will be rebroadcast via Zoom

Join Zoom Meeting

Meeting ID: 918 9333 5776
Passcode: 027444

A pizza lunch with the speaker will be offered to research trainees and students.