The Simons Collaboration on the Global Brain (SCGB) hosts postdoc/student meetings to bring together trainees interested in neural coding and dynamics to discuss ideas and data. In addition to regional meetings in New York, Boston, and the Bay Area, SCGB holds a virtual series to connect systems and computational neuroscientists independent of geography. We would love to see you at our next meeting! Please see event details and the Zoom link below. SCGB Virtual Postdoc/Student Meeting: https://www.eventbrite.com/e/scgb-global-postdocstudent-meeting-tickets-2094... Wednesday, December 1st, 12pm Eastern Time https://simonsfoundation.zoom.us/j/94767192583?pwd=TXBKNXJQYzdGTmRUZTFlUUYzN... Passcode: 429535 *Olivia Gozel* Postdoctoral Researcher, Doiron Laboratory The University of Chicago *Between-area communication through the lens of within-area neuronal dynamics* Neuronal dynamics range from asynchronous spiking to richly patterned spatio-temporal activity and are modulated by external and internal sources. Numerous experimental datasets show that the shared variability can be well described by a small number of latent variables, indicating coordinated trial-to-trial fluctuations within the population. Besides, cortical areas are connected through long-range excitatory projections, and it has been shown that there exists a communication subspace between connected but distinct brain areas that predicts spiking activity in a downstream area using upstream activity. However, little is known about the effect of neuronal dynamics on interactions between brain areas. Using a layered spiking network with within- and between-layer spatially structured connectivity, we show that pattern formation decreases within-area dimensionality similarly when spatio-temporal patterns emerge within a population or when they are inherited from a connected population. Yet, the fidelity of communication from an upstream to a downstream area, as estimated by a linear reduced-rank regression measure, is affected by the origin of pattern formation. Specifically, downstream activity is poorly predicted by upstream activity when spatio-temporal patterns emerge downstream, while it is particularly well predicted when shared fluctuations are mostly inherited from the upstream area. Interestingly, examination of spiking activity reveals that, even in the scenario with apparent disrupted communication, the downstream area is effectively driven by upstream activity, as expected from the strong feedforward connection strengths between layers. A mismatch in within-area dimensionality between upstream and downstream areas appears to underlie the seemingly weak communication. These results expose the limitations of linear measures when analyzing the flow of information in brain circuits with diverse neuronal dynamics. *Please note that this meeting is open to all neuroscience postdocs and PhD students, regardless of location or SCGB affiliation (sorry, no PIs). *After Q&A with the speaker, we will open breakout rooms for anyone interested in staying to chat, network, or further discuss the talk. In addition to these breakouts, SCGB Scientific Staff will be available for "office hours" to chat and answer questions about SCGB programs and support. Registration on EventBrite is encouraged but not required: https://www.eventbrite.com/e/scgb-global-postdocstudent-meeting-tickets-2094... Please contact Laura Long at llong@simonsfoundation.org with any questions.