Plaut McClelland Grandmother vs Distributed Sparse
<p>Dec 1, 2009 2:02 PM
 
SPARSE coding means only a few units (read neurons) respond  (to one thing or to unrelated things)
 
Quiroga , Kreiman ,  Koch, Fried  estimate that  2 million neurons represent an object in the HC =
.2% of  1 billion HC neurons and other areas in MTL.  and each neuron may respond to
50 to 150 objects.
 
SPARSITY means the fraction of neurons in a population that are activated by something.
 
PERPLEXITY:  is the degree to which the things a neuron responds to are unrealted.
 
When we speak of person X's grandmother  we are speaking of one such entity,
a specific person ... like Mrs Ethyl Watts Shaffer... Jay's maternal GM.
 
Consider TOAST... a particular piece of toast.  Do we have a single neuron which fires for
every piece of toast we have ever encountered, everydog, every face etc.  NO.</p>