Category: Uncategorized

• CSHL computational vision: day 4

  Today was a little less intense than yesterday, mercifully. Geoff Boynton Geoff did a tutorial on signal detection theory and estimating psychophysical measures in Matlab. He emphasized that given the signal detection model, it is easy to find good estimates using Bayesian inference. Whenever the observer’s response is binary, you should use the binomial likelihood…

  June 23, 2012

• CSHL computational vision: day 3

  Heavy day today. These notes might be slightly more rambling than usual, apologies. Eero Simoncelli Eero (pictured above) delivered a lecture focusing on encoding, and specifically on efficient coding . From Barlow (1961): Sensory relays recode sensory messages so that their redundancy is reduced but comparatively little information is lost. He pointed out that this…

  June 22, 2012

• Action in perception

  Mu-Ming Poo delivered a talk at the MNI a few years back on his work on spike-timing dependent plasticity (STDP). He mentioned that to get good ideas for new experiments, you should start by reading old rather than current literature (in his case, the works of Donald Hebb). His reasoning was that the questions raised…

  May 19, 2012

• Taking the mean of angles

  Stylianos Papaioannou sent me an email asking how to take the mean of several angles. These angles are actually phases derived from a Hilbert transform. So let’s say that you have a vector of angles x where the values are between 0 and 2pi. It’s not possible to take mean(x) as the mean of the…

  February 22, 2012

• Optimizing GLM hyperparameters through the evidence

  I wrote earlier about a recent paper by the Pillow lab which uses priors optimized through the evidence (aka marginal likelihood) to estimate spatially and frequency-localized receptive fields. It seems that evidence optimization might be seeing something of a revival as a technique for estimating model hyperparameters. I just posted an update on my GLM…

  December 7, 2011

• Comp Neuro News: a news aggregrator

  Comp Neuro News is a social news website about computational neuroscience recently created by Ian Stevenson and Jeff Teeters from UC Berkeley. It’s the same idea as Reddit or Digg: users submit links which are then upvoted by interested members, yielding a constantly refreshing list of interesting articles. Not much activity currently, but I’m sure…

  November 23, 2011