meta = &meta;
Archive for March, 2010
How Neurons do Differentiation
0Nature is simply amazing.
Today I learnt…
…how neural networks (think brains) can do differentiation by using temporal inhibition – i.e. by using a delayed signal. In the figure below, the node α will send a signal to two nodes. One of them – β – will pass on an inhibitory signal of the same strength as its input signal, but with a delay. Thus, when β‘s signal gets sent to the final node, α will at the same time be sending its “next” output signal to the final node.
“Differentiation” by using delayed inhibition. Solid lines indicate excitatory signals and the dotted line an inhibitory signal.
Therefore, the final node will receive two signals: the current output of α and the inverted previous output of α. If the final node sums these together its output will therefore be α‘s current value minus its old value – i.e. positive if α‘s output signal is increasing and negative if it is decreasing. Simple and beautiful!
Game of Life
0While reading about cellular automata in preparation for an essay it struck me that I have never actually written Conway’s Game of Life. No, really!
To correct this embarrassing fact I quickly wrote a version in Haskell using the GLUT bindings.
Conway's Game of Life
Code Reading as a Team Activity
1I am currently reading “Coders at Work” by Peter Seibel, a really interesting read for a code monkey like me. The book is full of good tips and experiences from actual coders who learnt by doing. Peter Seibel’s questions are really good – no doubt because he himself is a programmer – and all his interview subject have different and interesting stories to tell.
