Physiology and Biophysics

Seminars

Oct
12
Thu
2017
PBIO Seminar Series: Liangyi Chen @ HSB G-328
Oct 12 @ 9:30 am – 10:30 am

High spatiotemporal resolution, three-dimension fluorescence imaging of biological samples in vivo

Dr. Liangyi Chen Professor Laboratory of Cell Secretion and Metabolism Institute of Molecular Medicine, Peking University, Beijing, China Host: Bertil Hille Abstract: I will give two stories. (i) One story describes unpublished ultrasensitive Hessian structured illumination microscopy that enables ultrafast and long-term super-resolution (SR) live-cell imaging. At a photon dose one order less than point-scanning microscopy, Hessian-SIM has achieved 88-nm and 188-Hz spatial-temporal resolution for live cells imaging and lasted thousands of images without artifacts. Operating at 1 Hz, Hessian-SIM enables hour-long, time-lapse SR imaging with mitigatable photobleaching, highlighting the possibility of achieving SR imaging with commonly used fluorophores for an unlimited period of time. (ii) The second story is our recent Nature Methods paper, our invention of the fast high-resolution miniature two-photon microscope for brain imaging in freely-behaving mice at the single-spine level. With a headpiece weighing 2.15 g and a new type of hollow-core photonic crystal fiber to deliver 920-nm femtosecond laser pulses, the mini-microscope is capable of imaging commonly used biosensors at high spatiotemporal resolution (0.64 μm laterally and 3.35 μm axially, 40 Hz at 256 × 256 pixels). It compares favorably with benchtop two-photon microscopy and miniature wide-field fluorescence microscopy in the structural and functional imaging of Thy1-GFP- or GCaMP6f-labeled neurons. Further, we demonstrate its unique application and robustness with hour-long recording of neuronal activities down to the level of spines in mice experiencing vigorous body and head movements or engaging in social interaction.
Oct
26
Thu
2017
PBIO Seminar Series: Brian Kalmbach @ HSB G-328
Oct 26 @ 9:30 am – 10:30 am
“Of Mice and Men: Intrinsic Membrane Properties of Human Cortical Pyramidal Neurons” Brian Kalmbach, Ph.D. Allen Institute for Brain Science host: Nikolai Dembrow
Nov
2
Thu
2017
2017 Lamport Lecture – Gilles Laurent @ T-739 HSB
Nov 2 @ 4:00 pm – 5:00 pm

Evolution and brain computation

I will introduce our work towards identifying principles of brain function and computation, focused on using comparative approaches and exploiting unusual model systems (reptiles, cephalopods) to study sleep, texture perception and cerebral cortex evolution. Gilles Laurent, PhD, DVM Director Max Planck Institute for Brain Research http://www.brain.mpg.de/home/   4:00 PM Location: T-739, HSB   host: Stan Froehner
Dec
7
Thu
2017
PBIO Seminar Series: Nikolai Dembrow @ HSB G-328
Dec 7 @ 9:30 am – 10:30 am
Title: TBA Nikolai Dembrow, PhD host: Stan Froehner
Jan
9
Tue
2018
PBIO Seminar: Rishidev Chaudhuri @ HSB G-328
Jan 9 @ 9:30 am – 10:30 am
“Cognitive manifolds and their dynamics across states and areas” Rishidev Chaudhuri, PhD. Center for Learning & Memory The University of Texas at Austin Host: Stanley C. Froehner
Jan
16
Tue
2018
PBIO Seminar: Ashok Litwin-Kumar, PhD @ HSB G-328
Jan 16 @ 9:30 am – 10:30 am
“Randomness and structure in neural representations for learning” Ashok Litwin-Kumar, PhD Center for Theoretical Neuroscience Columbia University Host: Stanley C. Froehner
Jan
25
Thu
2018
Canceled – Seminar: Amy Bastian, PhD @ HSB G-328
Jan 25 @ 9:30 am – 10:30 am

Canceled

Dr. Bastian’s seminar will be rescheduled for a later date.

   

Learning and Relearning Movement

Human motor learning depends on a suite of brain mechanisms that are driven by different signals and operate on timescales ranging from minutes to years. Understanding these processes requires identifying how new movement patterns are normally acquired, retained, and generalized, as well as the effects of distinct brain lesions. The lecture focuses on normal and abnormal motor learning and how we can use this information to improve rehabilitation for individuals with neurological damage Amy Bastian, Ph.D. Professor of Neuroscience Johns Hopkins University   Host: John Tuthill  
Feb
1
Thu
2018
PBIO Seminar: Julijana Gjorgieva, PhD @ HSB G-328
Feb 1 @ 9:30 am – 10:30 am
Organizing principles in developing networks and sensory populations Julijana Gjorgieva, PhD Research Group Leader, Max Planck Institute for Brain Research Assistant Professor for Computational Neuroscience, Technical University of Munich Host: Stanley C. Froehner
Science in Medicine – Linda Wordeman @ D-209, HSB
Feb 1 @ 11:30 am – 12:30 pm
“Curious Intersection Between DNA Repair and Microtubule Dynamics” Linda Wordeman, Ph.D Professor Physiology & Biophysics, UW Dr. Linda Wordeman, Ph.D. uses high resolution live imaging to discover how changes in microtubule dynamics influence chromosome segregation and Chromosome INstability (CIN) in cancer cells. Dr. Wordeman will describe, mechanistically, how small changes in microtubule assembly dynamics promote CIN and reveal evidence for unexpected pathways, such as DNA damage repair, that may directly impact cellular mictrotubule dynamics.
Feb
5
Mon
2018
PBIO Seminar: Scott Linderman, PhD @ HSB G-328
Feb 5 @ 9:30 am – 10:30 am

Discovering Structure in Neural and Behavioral Data

Scott Linderman, PhD Department of Statistics Columbia University   Abstract: New recording technologies are transforming neuroscience, allowing us to precisely quantify neural activity, sensory stimuli, and natural behavior.  How can we discover simplifying structure in these high-dimensional data and relate these domains to one another? I will present my work on developing statistical tools and machine learning methods to answer this question.  With two examples, I will show how we can leverage prior knowledge and theories to build models that are flexible enough to capture complex data yet interpretable enough to provide new insight. Alongside these examples, I will discuss the Bayesian inference algorithms I have developed to fit such models at the scales required by modern neuroscience.  First, I will develop models to study global brain states and recurrent dynamics in the neural activity of C. elegans.  Then, I will show how similar ideas apply to data that, on the surface, seem very different: movies of freely behaving larval zebrafish.  In both cases, these models reveal how complex patterns may arise by switching between simple states, and how state changes may be influenced by internal and external factors.  These examples illustrate a framework for harnessing recent advances in machine learning, statistics, and neuroscience.  Prior knowledge and theory serve as the main ingredients for interpretable models, machine learning methods lend additional flexibility for complex data, and new statistical inference algorithms provide the means to fit these models and discover structure in neural and behavioral data. Host: Stanley C. Froehner  
Feb
15
Thu
2018
PBIO Seminar Series: Bernhard Flucher @ HSB G-328
Feb 15 @ 9:30 am – 10:30 am

How and why are the currents of CaV1.1 calicum channels curtailied in skeletal muscle?

The presentation will include structure-function studies on CaV1 channels and analyses of the role of the calcium current in muscle fiber type specification and neuro-muscular junction formation using various mouse models. Bernhard Flucher, PhD Professor Department of Physiology and Medical Physics Medizinische Universität Innsbruck host: Stan Froehner
Apr
26
Thu
2018
Bertil Hille – Distinguished Science in Medicine @ Hogness Auditorium
Apr 26 @ 12:00 pm – 1:00 pm
Distinguished Science in Medicine Lecture Bertil Hille Thurs., April 26, 2018 NOON Hogness Auditorium.
May
3
Thu
2018
2018 Hille Lecture – Doris Tsao @ HSB T-747
May 3 @ 4:00 pm – 5:00 pm
Faces: a neural Rosetta stone Objects constitute the fundamental currency of the brain: they are things that we perceive, remember, and think about.  One of the most important objects for a primate is a face. Research on the macaque face patch system in recent years has given us a remarkable window into the detailed processes underlying object recognition. I will discuss recent findings from our lab elucidating the code for facial identity used by cells in face patches. I will then discuss how this code is used by downstream areas, as well as how the brain computes what constitutes an object in the first place. Doris Tsao Professor of Biology HHMI Investigator California Institute of Technology time: 4:00pm location: T-747, HSB host: Stan Froehner
May
10
Thu
2018
2018 Crill Lecture – J. Anthony Movshon @ HSB T-639
May 10 @ 2:00 pm – 3:00 pm
“Elements of visual form perception” J. Anthony Movshon, PhD

Professor, Department of Ophthalmology

Professor, Department of Neuroscience and Physiology

Thursday, May 10, 2018 2:00 p.m. T-639 HSB
May
17
Thu
2018
PBIO Seminar Series: Brent Doiron, Ph.D. @ HSB G-328
May 17 @ 9:30 am – 10:30 am

New Cortex.  Who dis(inhibition)?

  Brent Doiron, PhD Professor Department of Mathematics University of Pittsburgh host: Adrienne Fairhall seminar abstract: New Cortex.  Who dis(inhibition)?   It is now clear that the inhibitory circuitry within cortical networks is very complex, with multiple cell types interacting with one another and pyramidal neurons in complicated and cell specific ways.  The theoretical community has been slow to adapt to this new circuit reality, and much of our results are obtained from analysis of simpler recurrent excitatory-inhibitory circuits. Two often cited functional roles of inhibition is to: 1) stabilize the dynamics of recurrently coupled excitatory networks, and 2) enact gain control of excitatory neuron responses to a driving stimulus.  In classic excitatory-inhibitory networks mechanisms that place the network in a high gain state necessarily flirt with network instability.  We analyze how recurrent networks of pyramidal neurons (PN), parvalbumin-expressing (PV), somatostatin-expressing (SOM), and vasoactive intestinal polypeptide-expressing (VIP) interneurons compartmentalize stability and gain control through distinct inhibitory and disinhibitory pathways.  This permits a disassociation of stability and gain control in the circuit.  We further show how PC to SOM connections can be crucial in state dependent gain amplification with a simultaneous decrease of shared variability (noise correlations).  In sum, by expanding the complexity of inhibitory architecture cortical circuits can navigate distinct functional roles of inhibition through a “division of labor” with the inhibitory circuit.  This imparts a robustness to the functional operations of the circuit that is absent in the often fine-tuned reduced excitatory-inhibitory framework.
May
24
Thu
2018
PBIO Seminar Series: Ariel Rokem @ HSB G-328
May 24 @ 9:30 am – 10:30 am
seminar: T.B.A. Ariel Rokem, PhD Senior Data Scientist eScience Institute, University of Washington host: Fairhall
May
31
Thu
2018
PBIO Seminar Series: Nicholas Whitehead @ HSB G-328
May 31 @ 9:30 am – 10:30 am
Simvastatin: unexpected or logical therapy for muscular dystrophy? Nicholas P Whitehead, Ph.D. University of Washington host: Stanley C. Froehner
Jun
7
Thu
2018
PBIO Seminar Series: Amy Bastian @ HSB G-328
Jun 7 @ 9:30 am – 10:30 am

Learning and Relearning Movement

Human motor learning depends on a suite of brain mechanisms that are driven by different signals and operate on timescales ranging from minutes to years. Understanding these processes requires identifying how new movement patterns are normally acquired, retained, and generalized, as well as the effects of distinct brain lesions. The lecture focuses on normal and abnormal motor learning and how we can use this information to improve rehabilitation for individuals with neurological damage Amy Bastian, Ph.D. Professor of Neuroscience Johns Hopkins University Host: John Tuthill
Sep
25
Tue
2018
2018 Lamport Lecture – Richard Vallee @ HSB T-639
Sep 25 @ 4:00 pm – 5:00 pm
2018 Lamport Lecture

Cytoplasmic Dynein and Kinesins in Brain Development and Autophagy

Microtubule Motor Proteins Are Involved in a Wide Range of cellular activities.  Recent work in our lab has involved the role of the motor proteins in neuronal migration and neurogenesis in the developing brain.  We have worked out mechanisms by which cytoplasmic dynein, its regulators Nde1 and Ndel1, and LIS1  and the kinesin Kif1a contribute to these functions as well as brain developmental disease. We have also found a new role for the dynein adaptor protein RILP as a master regulator of mTOR-dependent autophagy in neurons. Richard Vallee Professor of Pathology & Cell Biology Columbia University time: 4:00pm location: HSB, T-639 host: Stanley C. Froehner
Oct
4
Thu
2018
PBIO seminar series: Mohan Gupta @ G-328 H.S.B.
Oct 4 @ 9:30 am – 10:30 am
The role of microtubule-generated tension in accurate mitotic chromosome segregation Mohan ‘Moe’ Gupta, Ph.D. Assistant Professor Iowa State University Hosts: Linda Wordeman and Alex Paredez seminar abstract: To ensure genome stability in mitosis, the spindle assembly checkpoint (SAC) delays anaphase if sister chromosomes are not bound to microtubules from opposite spindle poles. Only in this configuration can dynamic microtubules produce tension across sister kinetochores. The interdependency between kinetochore-microtubule attachment and tension has proved challenging to elucidating the role(s) of tension at kinetochores. Thus, whether the SAC responds simply to kinetochore attachment status, or also to tension status remains obscure. Unlike higher eukaryotes, budding yeast kinetochores bind only one microtubule, simplifying the relationship between attachment and tension. To address the role of microtubule-generated tension in checkpoint signaling, we developed a Taxol-sensitive yeast model that allows tension to be reduced by microtubule stabilization in fully assembled spindles with attached kinetochores. Our results reveal that reducing tension on attached kinetochores delays anaphase onset. The tension-specific delay is transient relative to that imposed by kinetochores that are both unattached and tensionless. Furthermore, the mechanism requires only a subset of the core SAC proteins. Our results demonstrate that reduced tension generates a signal to delay anaphase that is temporally and mechanistically distinct from that characterized for unattached kinetochores.
Nov
8
Thu
2018
PBIO seminar series: Ellen Lumpkin @ G-328 H.S.B.
Nov 8 @ 9:30 am – 10:30 am
Exciting touch: Synaptic mechanisms in mamalian touch receptor
Ellen Lumpkin, Ph.D.
Associate Professor of Somatosensory Biology in Physiology & Cellular Biophysics and Dermatology
Columbia University
host: John Tuthill
seminar abstract A rich variety of mechanosensitive cells trigger distinct skin sensations such as pressure, flutter and pain.  A growing body of research indicates that epithelial cells play a key role in sensation by activating or modulating peripheral neurons in healthy skin.  Dr. Lumpkin’s research aims to unveil how epithelial Merkel cells work in concert with the nervous system to generate different qualities of touch sensation.  To tackle this question, her group uses neurophysiology, quantitative neuroanatomy, intersectional mouse genetics and optogenetics.  Recently, they demonstrated that Merkel cells have dual roles in mechanosensation: they transduce sustained pressure, and amplify information transfer during dynamic touch, which encodes shapes and textures.  The seminar will ocus on the molecular signaling mechanisms through which Merkel cells excite sensory neurons.
Nov
15
Thu
2018
PBIO seminar series: Daniel Denman @ G-328 H.S.B.
Nov 15 @ 9:30 am – 10:30 am
Correlated spike time variability, population coding, and synchrony in the early visual system.
Daniel Denman, PhD
Allen Institute
host: Adrienne Fairhall
 
Seminar abstract: In response to repeated presentation of the same stimulus, many visual neurons produce a variable number of spikes. This variability in spike count can be independent, correlated, or anti-correlated between pairs of neurons, and the implications of such correlations on sensory encoding have been extensively explored. In addition, spikes can also occur at variable times within the response (i.e., jitter, or spike time variability). While the magnitude of correlated spike count variability in spike count has been well-studied, the magnitude and sign of correlations in jitter, and any potential implications for visual coding, are not known. In this talk I will present measurements, using high-density electrophysiology (Neuropixels), of correlated jitter within small populations of 20-200 simultaneously recorded neurons across lateral geniculate nucleus and primary visual cortex. I will further discuss proposed mechanisms of correlated jitter and implications for potential and observed synchrony in visual cortical population responses.
Nov
29
Thu
2018
PBIO seminar series: Luke Rice @ HSB G-328
Nov 29 @ 9:30 am – 10:30 am

Mechanism and regulation in microtubule dynamics

Luke Rice, Ph.D.
Associate Professor, Department of Biophysics, UT Southwestern Medical Center
host: Chip Asbury
Seminar abstract: Microtubules are dynamic polymers of αβ-tubulin that have essential roles in intracellular organization and chromosome segregation. The dynamic properties of MTs are central to their function, and they derive from the properties of individual tubulin subunits and their interactions within the MT lattice. Microtubule dynamics is a fascinating problem that tests our ability to integrate ‘one molecule at a time’ views of biochemistry and structure with lower-resolution measurements of collective behavior. My laboratory is focused on bridging this gap by discovering and quantifying the structural and molecular mechanisms that underlie microtubule dynamics and the action of regulatory factors. To provide a new way to study and perturb microtubule dynamics, my laboratory introduced methods for purifying recombinant αβ-tubulin on a scale that permits structural and biochemical studies.  Our work draws on structural, biochemical, and reconstitution studies as well as computational simulations. I will present recent work from my group that is uncovering the mechanisms of XMAP215-family polymerases and CLASP-family rescue factors. These are two cellular factors that regulate microtubule dynamics in different ways despite sharing a common domain organization. At the end of my talk I will presenting ongoing collaborative work in which we are applying interferometric scattering microscopy to observe the microtubule growth at the level of individual αβ-tubulins.
Dec
6
Thu
2018
PBIO seminar series: EJ Chichilnisky @ G-328 H.S.B.
Dec 6 @ 9:30 am – 10:30 am
Toward a high-fidelity artificial retina
EJ Chichilnisky
John R. Adler Professor, Professor of Neurosurgery and of Ophthalmology and, by courtesy, of Electrical Engineering
host: Greg Horwitz
seminar abstract: Retinal prostheses represent an exciting development in science, engineering, and medicine – an opportunity to create devices that exploit our knowledge of neural circuitry in order to replace or even enhance visual function. However, although existing retinal prostheses demonstrate proof of principle in treating incurable blindness, they produce limited visual function. Some of the reasons for this can be understood based on the exquisitely precise and specific circuitry that mediates visual signaling in the retina. These considerations suggest that future devices may need to operate at single-cell, single-spike resolution in order to mediate naturalistic visual function. I will show large-scale multi-electrode recording and stimulation data from the primate retina indicating that, in many cases, such resolution is possible. I will also discuss cases in which it fails, and propose that we can substantially improve ariticial vision in such conditions by incorporating our knowledge of the visual system in bi-directional devices that adapt to the host neural circuity. Finally, I will discuss the potential implications for other neural interfaces of the future.
Dec
13
Thu
2018
PBIO seminar series: Michael Long @ G-328 H.S.B.
Dec 13 @ 9:30 am – 10:30 am
seminar title: TBA Michael Long, PhD Associate Professor, Neuroscience and Physiology NYU, School of Medicine host: Adrienne Fairhall
Feb
21
Thu
2019
PBIO seminar series: Carlos Portera-Cailliau @ G-328 H.S.B.
Feb 21 @ 9:30 am – 10:30 am
Dr. Carlos Portera-Cailliau, UCLA   Host: Andres Barria
Mar
21
Thu
2019
PBIO seminar series: Burns C. Blaxall, Ph.D. @ G-328 H.S.B.
Mar 21 @ 9:30 am – 10:30 am
seminar title: TBA Burns C.Blaxall, PhD, FAHA, FACC, FAPS
Director of Translational Science, Heart Institute Director, Center for Translational Fibrosis Research Co-Director, Heart Institute Clinical Research Core & Biorepository
Cincinnati Children’s Hospital Medical Center Professor, UC Department of Pediatrics   host: Chris Liu
Apr
24
Wed
2019
2019 Hille Lecture – Bernardo Sabatini @ TBA
Apr 24 all-day
time: TBD location: TBD Bernardo Sabatini (Harvard Medical School)     host: Stan Froehner
May
16
Thu
2019
PBIO seminar series: Colleen Clancy @ G-328 H.S.B.
May 16 @ 9:30 am – 10:30 am
Colleen Clancy UC Davis   host: Sharona Gordon
May
23
Thu
2019
PBIO seminar series: Rachel Martin @ G-328 H.S.B.
May 23 @ 9:30 am – 10:30 am
What can we learn about protein solubility and aggregation from a cold fish?
Rachel Martin
Professor Departments of Chemistry and Molecular Biology & Biochemistry UC Irvine
host: Sharona Gordon
seminar abstract: The βγ-crystallin fold that is ubiquitous in the structural proteins of the vertebrate eye lens is an ancient structural motif found in diverse organisms from all three domains of life. In organisms without eyes, e.g. archaea, bacteria, tunicates, and sponges, βγ-crystallins serve as calcium-binding proteins.  In vertebrates, they are primarily found in the eye lens, where they play an important role in controlling the refractive index gradient of this specialized tissue.  The ubiquitous βγ-crystallins of the vertebrate lens are believed to have descended from an ancestral single-domain Ca2+-binding crystallin by a process that included gene duplication resulting in two copies of the double Greek key domain per chain, as well as selection for high refractive index. Because the lens has negligible protein turnover, the crystallins must remain stable and soluble for the lifetime of the organism despite their extremely high concentrations. In particular, we are interested in the resistance to phase separation of the cold-adapted crystallins of the Antarctic toothfish, Dissostichus mawsoni. The eye lens of D. mawsoni is evolutionarily adapted to function in the permanently sub-freezing waters of the Southern Ocean.  This is in contrast to temperate and tropical fishes, and endothermic mammals, the lenses of which undergo liquid-liquid phase separation at low temperatures.  Mammalian lenses phase separate at temperatures between 10 °C and 20 °C – well above the Antarctic’s sub-zero marine environment.  The ability of the toothfish lens to maintain transparency in this frigid environment is particularly remarkable given that fish lenses have a high concentration of constituent proteins ≥1000 mg * mL-1). Recent work in my group focuses on testing the hypothesis that γ-crystallin isoform heterogeneity coupled with cold selective evolutionary pressures contribute to the clarity of the toothfish lens.  We have measured the thermal stabilities and phase diagrams of seven key γ-crystallin lens proteins, and we are able to control the onset of liquid-liquid phase separation by introducing a small number of surface mutations. The implications of our findings with respect to the roles of frustration, ionic interactions, and protein flexibility liquid-liquid phase separation will be discussed.