Neuromorphic Chips Boahen Sci Am May 2005 pdf
<p>Dec 17, 2007 8:26 PM
 
This is the FULL TEXT for the Sci Am article by Kwabena Boahen.
Neuromorphic Chips  May 2005.  (He is from Ghana; was at U Penn when paper was printed.)
 
retina is .5 mm thick.  5 layers.
One million ganglion cells per retina.
 
1991  Misha Mahovald and Carver Mead ... 3 layer retina.
 
Kwabena also went thru Carver's lab .
 
Kareem Zaghloul did 5 layer retina in 2001 in Boahen's lab as PhD student.
His chip  Visio1.
 
page 58:  activity of each neuron represented by a voltage output.
 
The chip emulates the way voltage-activated ion channels cause ganglion cells to spike -
with + feedback which causes a spike one a threshold is reached.
 
Viosio1 uses <b>60 mwatts.</b>
 
Visio1 provides <b>3600 ganglion cell output</b> should provide near normal vision.
 
Two more of his grad students went further.
They developed an artific. tectum chip (the tectum (frogs) is like the colliculi (tegmentum) in humans).
The problem is ... how do you do the mapping from retina to tectum.
They did wiring automatically by having voltage of firing ganglion cells diffuse around it when they
reach the tectal chip and then "softwire" those neurons to adjacent ganglion cells.
After a while,  cells in the tectal chip have localization of orientation (all cells within the same
neighborhood have similar orientation fields.)
 
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