A large multistory atrium curates movement

Seen on the web, an architectural appreciation of the Shapiro Science Center:

http://hken.ibtimes.com/articles/204391/20110826/carl-j-shapiro-science-center-payette.htm

A large multistory atrium curates movement through the building. Conceived of as a river, the atrium exists as a linear element that allows for quick transit through and into the building while remaining isolated from the sensitive lab spaces within the structure.

The web also reveals a panoramic view of the atrium.

How many neurons does it take to stay cool?

The worm (nematode) C. elegans is a nice model system for studying neuroscience, combining

  • genetic tools that allow genes to be turned on or off, often on a per cell basis, in the whole organism,
  • tools like laser or genetic ablation that allow individual, identified cells to be selectively eliminated,
  • robust behaviors that can be readily measured, and
  • a well defined nervous system consisting of 302 neurons, each of which can be identified, and whoseanatomical connectivity has been established.

In a paper appearing this month in Journal of Neuroscience, Molecular and Cell Biology grad student Matthew Beverly, undergrad Sriram Anbil, and Professor of Biology Piali Sengupta examined the contribution of sensory neurons to controlling thermotaxis in C. elegans. Worms develop a memory of the temperature at which they have been cultivated, and display a robust behavior in which worms placed on a temperature gradient at temperatures higher than their cultivation temperature will crawl back towards colder temperature (negative thermotaxis – see movie). The behavior depends on TAX-4, a channel protein expressed in a subset of the sensory neurons. In this study, the Brandeis researchers asked the question “how many and which of the sensory neurons are required for the worms to perform negative thermotaxis, and are the required sensory neurons the same regardless of the temperature range examined?” (or, in my paraphrase, “how many and which neurons does it take to stay cool?”)

Worm head, showing expression of the calcim indicator GCaMP in ASI and AWA neurons (used in calcium imaging experiments)

As it turns out, the answer is complicated (and readers are encouraged to read the paper). The researchers found that in addition to the previously known thermosensory neurons AFD and AWC, the ASI neurons previously known to be involved in chemosensation play a significant role in regulating negative thermotaxis. Interestingly, the circuits used seem to be degenerate; under one condition, for example, a particular combination of AFD, AWC or ASI is necessary to generate the behavior, although at other conditions, a different combination is required to generate the same behavior.. And only a couple of degrees Celsius makes a difference — the circuit required for negative thermotaxis on a gradient centered at 8oC above the cultivation temperature is different from a gradient centered at 6oC above.

These and other results taken together suggest that even in the worm, a complex circuit has evolved to control crawling behaviors to cope with temperature changes, and that having degeneracy in the underlying circuits may be a common feature that ensures that behaviors crucial to survival are maintained in a variety of environmental conditions..

Beverly M, Anbil S, Sengupta P. Degeneracy and Neuromodulation among Thermosensory Neurons Contribute to Robust Thermosensory Behaviors in Caenorhabditis elegans. J Neurosci. 2011;31(32):11718-27.

Pay attention!

“Pay attention!” That is often very good advice, but sometimes the advice is hard to obey.   The brain’s limited attentional resources can be overwhelmed when attention has to be distributed among multiple objects.  And the challenge is even greater when the objects are moving.  For example, imagine that you’re driving on Route 128 at rush hour.  You must attend not only to your own car’s path, but also to the whims and surprising behaviors of the cars all around you.   Working in my lab, Heather Sternshein and Yigal Agam, two PhD students in the Neuroscience Program, developed a novel electroencephalographic (EEG) technique to study how selective attention is apportioned in a task that can be described as “Route 128-on Sterioids.”   We were especially interested in the neural correlates of failures of attention, the kind of failure that, on the road, might have serious consequences.

Subjects in our experiment watched as ten identical black discs moved about randomly on a computer display for ten seconds.  The hard part was to keep track the entire time of particular, pre-designated target discs –either three, four or five.  Because all ten moving discs were identical, there were no physical features to distinguish target from non-target discs.  At the end of eight seconds, all discs came to standstill, and a subject tried to identify the discs that he or she had been tracking.  The task required attentive tracking of a subset of identical multiple moving objects, something even more challenging than navigating Route 128 at rush hour.

Every once in a while during the eight-second tracking period, one of the ten discs flashed brightly for 100 msec.  Sometimes, the flashed disc was a target disc, that is, one the subject was trying to track; sometimes the flashed disc was a non-target disc, that is, one that the subject could be ignoring.   The flash evoked a response in the subject’s brain, and our EEG system picked up that response from the subject’s scalp.  Knowing that the evoked response would be larger if the flash were delivered to an object that was being attended,  we used responses to target and non-targets as an index of how attention was distributed among the multiple moving objects.  We focused our analysis on electrodes located over occipital and parietal lobes, toward the brain’s posterior.

As expected, the relative sizes of responses to the two kinds of stimuli differed: on average, flashes on target discs evoked larger responses than flashes on non-target discs.  This difference confirmed that on average subjects were paying more attention to targets than to non-targets. But as the number of discs that had to be tracked increased —from three to four to five– subjects found the task increasingly harder, and made more errors when they had to identify the discs that they had been trying to track.  The EEG revealed the neural correlate of these failures of attention.  The difference between evoked responses to flashed targets and flashed non-targets decreased as the number of targets increased.  This shrinking difference between the two sets of neural responses could explain the systematic increase in errors as the the number of targets increased.  As additional items have to be kept track of, it becomes harder for subjects to apportion attentional resources in a way that preserves a sufficient advantage for targets over non-targets.  As a result, subjects make more errors –mistaking non-targets for targets.

We plan to adapt this basic experimental strategy to study the neural basis of attention in various groups whose performance on our task is likely to abnormal:  older adults (who show impaired behavioral performance) and habitual video-game players (who show far-better-than normal performance).  Yigal Agam is now at MGH’s Martinos Center; Heather Sternshein is in the Department of Neurobiology, Harvard University.

Sternshein H, Agam Y, Sekuler R. EEG Correlates of Attentional Load during Multiple Object Tracking. PLoS One. 2011;6(7):e22660..

Postdoc with confessed aversion to genetics

“… now inspiring a new generation of neurophysiologists”

There’s a nice story on the ADInstruments website about Stefan Pulver (PhD ’09) and Nick Hornstein (’11) and the tools they developed in the Griffith lab for “Optogenetics in the Teaching Laboratory” using Drosophila and channelrhodopsin-2. Stefan is currently in Cambridge (England) doing a postdoc, and Nick is starting his MD/PhD at Columbia real soon now.

recent papers by undergraduate alumni

We like to keep track of what our alumni are up to. Listed below, some recent papers showing what our undergraduate researchers from years past who are hitting their academic stride (grads from 7-14 years ago)  are up to now.

If you are an alum of the Brandeis Sciences, and would like to share what you are up to, email karel @ brandeis dot edu or join the Brandeis Sciences group at linkedin.com

Genetics Training Grant Symposium to be held Sep 2

The Genetics Training Grant at Brandeis (GTG) is an important part of the graduate programs in Molecular & Cell Biology and Biochemistry & Biophysics, teaching students to critically evaluate both their own research and the scientific literature, while also developing their communication skills. The annual symposium, organized and hosted by the GTG students, is central to this mission. This year’s GTG Symposium is entitled “Signal Transduction: Insights gained from diverse species”, and will take place on September 2.  Four distinguished scientists will be presenting their recent work:

  • Gary Ruvkun (Harvard Medical School), our Keynote Speaker, will speak about neuroendocrine control of C. elegans development, metabolism and longevity;
  • Marcia Haigis (Harvard Medical School) will present her work on mitochondrial sirtuins and aging;
  • Morris White (Children’s Hospital Boston) will talk about the molecular basis of mammalian insulin-like signaling in the pathophysiology of metabolic disease;
  • Cynthia Bradham (Boston University) will present work on secondary axis specification and patterning in the sea urchin.

These talks will be followed by a Poster Session and Reception (see schedule). Current and former GTG trainees will be presenting posters from 3:40 to 5:00 PM in the Shapiro Science Center Atrium, All life sciences graduate students are encouraged to present posters.

The entire event is free and open to the public.  For planning purposes, we ask anyone attending the symposium and/or presenting a poster to pre-register by August 24th, 2011. Poster titles will be available after registration is complete.

Please join us for this exciting symposium showcasing genetics at Brandeis.

Snider named ACS Fellow

Charles A. Breskin Professor of Organic Chemistry Barry Snider has been named a Fellow by the American Chemical Society (ACS). ACS members are selected as fellows to recognize and honor their outstanding achievements in and contributions to science, the profession, and ACS. Fellows will be inducted at the ACS National Meeting in Denver on Aug. 29. Snider’s work in recent years has focused on total synthesis of natural products, a dazzling array of which are shown on his website: Recent stories on this blog discussing new syntheses from the Snider lab include:

 

 

Long receives HHMI fellowship to develop new protein degradation strategy

Marcus Long, a 3rd yr PhD student in the Graduate Program in Biochemistry who works in the Hedstrom Lab, has been awarded a Howard Hughes International Student Predoctoral Research Fellowship for 2011-2013. This award, which is open only to students at selected universities, is given to roughly 40 international students in the life sciences per year in the US. The receipt of this award reflects strongly on the quality of research conducted in Brandeis, and particularly the interdisciplinary approach taken by principal investigator, Prof. Liz Hedstrom. Application for the award requires a clear research plan, which in this instance involves a novel protein degradation strategy (called IMPED), which was pioneered by Prof Hedstrom and her laboratory. Marcus will play his part in a collaborative effort  (alongside lab mates Rory Coffey, Devi Gollapali and established Hedstrom Group collaborators) to understand the mechanism and limitations of this new methodology.

Mehmet Fisek (BS/MS ’08), an alumnus of the Marder lab and undergraduate Neuroscience program at Brandeis, was also among the 48 winners named. Mehmet is currently doing graduate research in Rachel Wilson’s lab in the Dept. of Neurobiology at Harvard, working on olfactory neurophysiology in Drosophila.

See also story at Brandeis NOW.

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