Monday, 24 May 2010

A plan?

Another meeting with John today, after getting some feedback from John Jefferys in Neuroscience. The current plan for a framework of modelling and experimentation is as follows:
  1. Take one of the older models of Alzheimer's disease from the mid-1990s (e.g. Willshaw, Tsodyks and Feigel'man, Hasselmo).
  2. Update it with modern learning algorithms (e.g. LEABRA, Contrastive Hebbian Learning).
  3. Use evolutionary computation to set parameters instead of calculating / guessing them (e.g. firing thresholds, Gaussian connectivity radius and density). Fitness function should be adequate "normal" functioning of the network with least amount of energy (= connections?) required.
  4. Use this updated and evolved model to repeat the 1990s experiments of Ruppin and Reggia or Hasselmo (that's already potentially one small contribution to knowledge in the bag). (As a footnote, Ruppin and Reggia's synaptic deletion and compensation model uses biologically implausible uniform compensation values across the whole network instead of adjusting the remaining synapses using the learning algorithm. This is another change worth considering).
  5. Use the model to attempt to dis/prove a more recent medical hypothesis, such as Nikolaev et al. (2009), which will require showing that up to a certain level of deletion the performance actually increases, and then after that level it degrades. (John argues that I should also dis/prove other hypotheses with the same model to be able to show that it's a valid contribution).
This should be enough for a bare minimum PhD thesis, but also opens several avenues for further tinkering or completely different approaches:
  • Starting from different network architectures in (1). e.g. more recent models of schizophrenia or general neocortex models.
  • Implementing other learning algorithms in (2).
  • Broadening the number of parameters which could be evolved in (3), e.g. the distribution of DR6 "death receptors" in (5).
  • Trying out various different things along these lines until I get bored or run out of time!

1 comment:

  1. Yes, I agree with you Mark, but nothing is new in Tory‘s government about Immigration policy. A leopard never changes his spots. Question is why should he Leopard never sport? Tory is still a racism party when it’s come to this issue or policy. They accused the previous government (Labour), state-driven multiculturalism; uncontrolled immigration and the threat of extremism have led to an increase in distrust and segregation, and left us with divided communities. However Tory’s government will be a disaster and would be the enemy of Britain’s politics.
    Back to your point, Statistic shows that, since 1950’s, more than 6.9 million people have come to Australia as new settlers. Their contribution to Australian society, culture and prosperity has been an important factor in shaping their nation. A million more migrants arrived in each of the last four decades. Today, nearly one in four of Australia's more than 21 million populations were born overseas. New Zealand and the United Kingdom are the largest source countries for migrants.
    Also the National statistics state that, the number of people leaving the UK for 12 months or more reached a record high in 2008, with an estimated 427,000 people emigrating. This was up from 341,000 in 2007 and 398,000 in 2006. Not all this numbers were migrated to EU. I agree Britain, benefit from immigration, but not uncontrolled immigration, yes it’s true, but that’s not the best solution David Cameron, is currently consulting on what level to set a non-EU migration cap.
    It’s wrong to say that once the cap is reached, "you can't come to this country if you are not European". If you're Indian, Pakistani, Australian, American, African, Chinese, even if you're a highly-trained medical practitioner or scientist, you can't come in. Because you're from the wrong country.