Friday, March 21, 2021, 1-2:30 PM (ET)
Estuardo Robles, PhD
Assistant Professor
Department of Biological Sciences
Title: A conserved midbrain circuit drives spatial summation in the zebrafish visual system
We have identified a population of visual neurons in the zebrafish midbrain with properties uniquely suited to monitoring changes in luminance across the entire visual field. Genetically targeted functional imaging of pyramidal neurons (PyrNs) in the optic tectum revealed that they exhibit large, compound receptive fields that span both retinal hemifields. We are currently using cell type-specific transgenics to functionally characterize the two known sources of synaptic input to PyrNs: retinal ganglion cells (RGCs) and neurons in torus longitudinalis (TL), a second-order visual area conserved among ray-finned fish (actinopterygians). Our preliminary data support a model in which RGC input specifies ON and OFF PyrN response classes, whereas TL input endows PyrNs with large, compound receptive fields that span both retinal hemifields. These findings reveal a novel function for TL in mediating binocular integration and spatial summation in the zebrafish visual system.
Daniel Gonzales, PhD
HHMI Hanna Gray Fellow, Postdoctoral Fellow
Weldon School for Biomedical Engineering
Title: Nano and microscale technologies for mapping subcellular activity
From nanoscale synapses up to network-level activity, complex computations occur at every spatial scale in the mammalian brain. A mechanistic understanding of cognition requires monitoring neural activity across these spatial scales. Here, I will discuss our efforts to develop nano- and micro-scale technologies that enable multi-scale neurophysiology from the cortical surface. These high-density, flexible grids conform to the brain surface and target the activity of apical dendrites from L2/3 and L5 pyramidal neurons, which are critical for stimuli detection and reward reinforcement. Simultaneously, we use silicon shanks or two-photon imaging to capture deep-layer cortical activity, yielding a platform for monitoring neurophysiology across spatial scales in behaving animals. While the application of this platform to interrogate cognition is diverse, we are specifically investigating how dendritic dynamics shape cortical associations as animals learn to discriminate different forms of multi-whisker touch. Our work links multiple spatial scales of the brain and informs how subcellular dynamics guide emergent properties at the population level.
Following research talks, Chris Rochet, Director of the Purdue Institute for Integrative Neuroscience, will lead an open discussion on finding faculty and postdoc positions.
Details for attending this virtual seminar:
https://purdue-edu.zoom.us/j/
Meeting ID: 949 6617 2668
Passcode: 941761
