Seminar: Prakash Kara, Synaptic, Spiking And Vascular Cortical Maps Of Sensory Stimulus Selectivity

Kara Prakash Flyer

Prakash Kara, Associate Professor of Neurosciences and Ophthalmology at Medical University of South Carolina will be delivering a seminar, Synaptic, Spiking And Vascular Cortical Maps Of Sensory Stimulus Selectivity on December 9th, 2013 at 3:00pm in the John A. Moran Eye Center auditorium.


The Kara lab studies the mechanisms by which sensory feature selectivity arise in local microcircuits of the visual cortex. They use cutting-edge biophotonic and electrophysiological tools such as in vivo two-photon calcium and glutamate imaging of individual synapses and populations of neurons, simultaneous intracellular recording from neurons or astrocytes, and measurement of blood flow in individual microvessels. Due to differences in the organization of visual cortex in rodent vs. non-rodent species, they contrast the feature selectivity across these mammals. Dr. Kara will present new unpublished data on their mapping of orientation selectivity of synaptic inputs, action potentials and blood vessels. Their overall goals in this sub-project are to decipher two key aspects of neurovascular coupling in vivo: the role of synaptic input vs. spiking output in shaping the selectivity of fast hemodynamic responses and whether astrocytes are required for this functional hyperemia. Their novel multi-modal in vivo approach could open new avenues for understanding many neurological disorders that have a neurovascular component, such as those caused by aging, Alzheimer’s, Parkinson’s, and stroke.

Notable Paper: Ras Pathway Inhibition Prevents Neovascularization By Repressing Endothelial Cell Sprouting

JCI cover

A new manuscript in the Journal of Clinical Investigation (on the cover) by Peter D. Westenskow, Toshihide Kurihara, Edith Aguilar, Elizabeth L. Scheppke, Stacey K. Moreno, Carli Wittgrove, Valentina Marchetti, Iacovos P. Michael, Sudarshan Anand, Andras Nagy, David Cheresh and Martin Friedlander at The Scripps Research Institute describes a new technique for treating aberrant growth of blood vessels in the retina from disease processes like “wet” macular degeneration and diabetic retinopathy, two leading causes of blindness.  The approach involves manipulating disease processes with short RNA strands that precisely target microRNAs (anti-microRNAs if you will) to stop the aberrant blood vessel grown without harming the existing retinal vasculature.  The results of this study showed that treatment with microRNAs “blocked aberrant vessel growth without damaging existing vasculature or neurons in three separate models of neovascular eye disease—a proof-of-principle that suggests future treatment based on the same approach may be effective in humans.”

Exciting news indeed.




David Hubel 1926-2013

David Hubel

David Hubel, one of the true giants in the field of neuroscience and visual neuroscience died on September 22nd.  His work on visual cortex helped inform and guide our understanding of how the visual system functions and for that work, he and Torsten Wiesel shared the Nobel Prize in Medicine in 1981.  Most of us in the visual neurosciences have read their work or studied it in textbooks and owe a great debt of gratitude for their insight and efforts to push science forward.

Obituaries are appearing in newspapers around the world, in the NYTimes, Washington Post, The Guardian as well as remembrances in scientific journals like Cell, Science, Scientific American and websites from the NIH and a nice remembrance and background on his work from

For more background of David Hubel’s work, read his Eye, Brain and Vision book or check out the David Hubel Papers.

There will be a memorial to recognize the life of David Hubel, in all its dimensions, open to anyone who wishes to attend. Please join us at 2 pm, November 16 in the Memorial Church at Harvard University.  More details here.


Image courtesy: Harvard Medical School.

Optic Nerve Head Drusen


Drusen in the retina is a common finding in aging retina, forming deposits in the retina between Bruch’s membrane and the retinal pigment epithelium.  Most people over 40 start to accumulate some drusen, but increasing amounts of drusen formation can indicate pathological developments associated with age related macular degeneration, (AMD).  Cristine Curcio has been chasing mechanisms of drusen formation over the years and has the best model for drusen formation that I’ve seen.

Optic nerve head drusen (ONHD) or optic disc drusen (ODD) occurs rarely in the population, about 1% of the population, though there seems to be a genetic association as in families with a history of ONHD, it increases to almost 3.5% of those families.

In todays Grand Rounds on Webvision, we have a classic case of ONHD with typical fundus photographs, but also red-free, autofluorescence, IR and OCT captured by James Gilman of the Moran Eye Center.

A color fundus photograph (CF) shows discreet multiple yellowish calcium deposits in the optic nerve head.  The Red-Free photograph (RF) reveals clearer outlines of the drusen.  The Fundus AutoFluorescence photograph (FAF) shows the highly fluorescent drusen in this patient’s optic nerve.  The infrared image (IR) shows small discreet reflective bodies in the optic nerve. The OCT image (OCT) shows very dense round inclusions in the optic nerve that shadow the OCT signal and indicate the shallow depth and geographic cluster of the drusen.