Abstract: Probing multiplexed basal dendritic computations is significant for understanding how neurons process information, which can directly inform advancements in computation and future neuro-inspired AI systems. Basal dendrites of layer 5 cortical pyramidal neurons exhibit Na⁺ and N-methyl-D-aspartate receptor (NMDAR) regenerative spikes and are uniquely poised to influence somatic output. Nevertheless, due to technical limitations, how multibranch basal dendritic integration shapes and enables multiplexed barcoding of synaptic streams remains poorly mapped.  Here, I will describe my group's efforts in combining 3D two-photon holographic transmitter uncaging, whole-cell dynamic clamp, and biophysical modeling to reveal how synchronously activated synapses (distributed and clustered) across multiple basal dendritic branches are multiplexed under quiescent and in vivo-like conditions. I will show that while dendritic regenerative Na⁺ spikes promote millisecond somatic spike precision, distributed synaptic inputs and NMDAR spikes regulate gain. These concomitantly occurring dendritic nonlinearities enable multiplexed information transfer amid an ongoing noisy background, including under back-propagating voltage resets, by barcoding the axo-somatic spike structure. Our results unveil a multibranch dendritic integration framework in which dendritic nonlinearities are critical for multiplexing different spatial-temporal synaptic input patterns, enabling optimal feature binding. Drawing from these biological principles, we envision new algorithms that mimic the brain’s efficiency and adaptability, focusing on principles such as parallel processing, feature binding, and functioning in noisy environments. These insights will deepen our understanding of neuronal integration and pave the way for more sophisticated AI architectures.

Bio: Krishna Jayant is an assistant professor at Purdue University's Weldon School of Biomedical Engineering. His laboratory’s research focuses on delivering biophysically based accounts of behaviorally relevant computations using novel electrical and optical neurotechnologies. Projects in the lab cover various topics, including the examination of synaptic and dendritic computations in individual neurons and network-wide circuit computations that underlie sensorimotor integration, including synucleinopathies.  Dr. Jayant completed his graduate training in electrical and computer engineering at Cornell University, where he worked with Dr. Edwin Kan on bioelectronics. He subsequently completed postdoctoral training at Columbia University with Dr. Rafael Yuste, Dr. Ken Shepard, and Dr. Ozgur Sahin, researching cutting-edge neurotechnologies to probe synaptic and dendritic biophysics. In addition to the NIH Director’s New Innovator Award, Dr. Jayant has been recognized as an NIH NIBIB Trailblazer awardee, a Human Frontiers Science Young Investigator grant awardee, a Ralph E. Powe Junior Faculty Enhancement Award, and is also a recipient of an Air Force Office of Scientific Research DURIP award.

_~ BME Host: Estelle Park _~

Historical BME quote of the week:  "Avoid the habit of driving with your mental brakes on." - Leslie A. Geddes, found of BIomedical Engineering at Purdue, est. 1974

ZOOM LINK: https://us02web.zoom.us/j/87382040456?pwd=cCGi2aEvgQ5nz6lGXTMwqunY0a65JY.1