[CTN] Seminar: Ernst Neibur, Tues Oct 19, 3:30

[Matthijs van der Meer]

Hello,

Please join us for next Tuesday's CTN seminar by Dr. Ernst Neibur. Title
and abstract follow below, but please read on for a few small changes.

To encourage post-talk discussion, some of the refreshments will only
appear *after* the talk, and I would like to invite you to submit a
single slide, to go into a looping slideshow following the talk.

These slides were a success at my PhD institute's seminar series, as a
way for people to keep up with what others are working on, and to spark
new conversations and even collaborations. I personally have gotten
several useful suggestions this way.

Anything from a very specific issue you want ideas on, a recent result,
or a general description of past or future work, is good. Students are
especially encouraged to participate; for your slide to be included,
please send me an image file (png, jpg, ...) on the day before the
seminar (Monday the 18th) at the latest.

An example slide is here:
http://www.vandermeerlab.org/MvdM_OctSeminarSlide.png. Feel free to
contact me with questions or suggestions.

Cheers,

- Matt


PS: if you are interested, the uWaterloo Neuroscience journal club
(http://groups.google.com/group/uw-neuro) meets this Thursday to discuss
some of Dr. Neibur's work.



Tues Oct 19th - PAS 2464 at 3:30

Speaker: Ernst Neibur (Johns Hopkins)

Title: Up states are critical, Down states are subcritical

During sleep, under anesthesia and in vitro, cortical neurons in
sensory, motor, association and executive areas fluctuate between Up and
Down states (UDS) characterized by distinct membrane potentials and
spike rates. While Down states are quiescent, Up state activity
resembles that of REM sleep and wakefulness, suggesting similar network
processing. Another network phenomenon observed in preparations similar
to those that exhibit UDS, such as anesthetized rats, brain slices and
cultures devoid of sensory input, as well as awake monkey cortex, is
self-organized criticality (SOC). This is characterized by activity
``avalanches'' whose size distributions obey a power law with critical
exponent of about -3/2 and branching parameter near unity. We report an
intimate connection between the two phenomena, SOC and UDS. We show
analytically that networks of leaky integrate-and-fire neurons with
short-term synaptic depression typically have 2 stable activity levels
corresponding to UP and Down states, and that Up states are critical and
Down states are subcritical. Our analytical results are confirmed by
simulations of networks with different connectivity structures which
also switch spontaneously between Up and Down states.