Dynamical Systems Seminars

Fall 2026

The Dynamical Systems seminar is held on Monday afternoons at 4:00 PM in CCDS 548 . There will be a brief tea in CCDS 548 at 3:45PM.

• September 14th Jie Zang (Brown University)
  Title: Sequential chaotic oscillations in excitatory-inhibitory threshold-linear networks
  Abstract: Metastable states, a phenomenon observed in brain dynamics and many other systems, have been proposed as a key feature of healthy brain function, reflecting a balance between integration and segregation. However, it remains unclear how to capture this behavior within a dynamical-systems framework. In this paper, we propose sequential chaotic oscillations (SCOs), arising in excitatory-inhibitory threshold-linear networks (E-I TLNs), as a candidate dynamical mechanism for sequential metastability. As a simple form of chaotic itinerancy, SCOs occur under constant input and consist of a sequence of metastable states whose transition order can be predicted by the underlying graph. To identify the parameter regime for SCOs, we develop new graph rules for E-I TLNs and use them to characterize the fixed point structure of E-I TLNs on paths and cycles. Our results show that the emergence of SCOs requires unstable singleton fixed points and sufficiently strong inhibition. In addition to SCOs, we find that E-I oscillations need not be synchronized. Motivated by this, we introduce a decomposition into the z-mode and the mean mode, which capture excitatory differences and overall network activity, respectively. These modes are then used to distinguish attractors associated with the full-support fixed point of E-I TLNs on cycles.

• September 21st Greg Handy (U of Minnesota - Twin Cities)
  Title: Glial ensheathment of inhibitory synapses drives hyperactivity and increases correlations
  Abstract: Recent evidence shows that glial cells actively modulate neuronal dynamics. A recent study notably found that during and after anesthesia, microglia ensheath inhibitory synapses, disrupting neurotransmitter flow. In this talk, I will develop computational models that explore how this ensheathment affects neuronal dynamics. Extending a microscale synaptic cleft model, I show that ensheathment accelerates synaptic transmission but reduces its strength. I will then integrate this microscale model into a large network of exponential integrate-and-fire neurons, which introduces heterogeneous synaptic parameters determined by glial proximity, and extend linear response theory to analyze firing rates and noise correlations. I will show that this model reproduces the experimental finding that increased glial ensheathment of inhibitory synapses leads to hyperactivity and predicts significant increases in power spectrum magnitude across task-relevant frequencies, suggesting glial-driven synaptic plasticity is an underappreciated mechanism for modulating cortical dynamics.
  

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• September 28th Weiqi Chu (U. Mass. Amherst)
  Title: TBA
  Abstract: TBA

• October 5th TBA ()
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• October 12th No Seminar - Indig. People's Day ()
  Title: TBA
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• October 19th Mark Levi ()
  Title: TBA
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• October 26th TBA ()
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• November 2nd TBA ()
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• November 9th Saleh Sina (Harvard University)
  Title: TBA
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• November 16th Binan Gu (Worcester Polytechnic Institute)
  Title: TBA
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• November 23rd Semyon Dyatlov (MIT)
  Title: TBA
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• November 30th TBA ()
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• December 7th TBA ()
  Title: TBA
  Abstract: TBA

  Directions to BU Math Dept.

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  Speakers from previous years

  

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