The Fourth Online Consciousness Conference

A call for papers is up here.

In celebration of Ada Lovelace day...

I encourage you all to take a look at Maggie Boden's work. Her book The Creative Mind was probably one of the main reasons I moved back to psychology and cognitive science, as opposed to purely being interested in the philosophy of mind.

Need an introduction to artificial intelligence?

Stanford is offering a free course here, taught by Sebastian Thrun and Peter Norvig. Norvig in particular is one of the biggest names in AI - the textbook that he and Stuart Russell wrote, Artificial Intelligence: A Modern Approach, is essentially the classic in the field - (Thrun is also ridiculously highly cited, even if I'm less familiar with his work) and the syllabus for the course looks like it covers a lot of ground.

Registration is open until the 9th of October, with the class actually starting on the 10th of October, so sign up if you're interested!

Jane Austen was a Bayesian

... well, no, she wasn't, actually (as far as I'm aware), although the quirkily named paper Prior and Prejudice [PDF] in August's issue of Nature Neuroscience introduces Bayesian inference by appeal to her work. It's an interesting overview of two studies which appeared in the August and July issues of Nat. Neuroscience, and "create convincing links between psychophysical performance and neuronal representations using the formalism of Bayesian inference"; Fischer and Pena's Owl's Behavior and Neural Representation Predicted by Bayesian inference and Girschick et al.'s Cardinal rules: visual orientation perception reflects knowledge of environmental statistics.

Rats and the "Wave of Death"

Bit of a morbid topic for this post, but an article examining what happens in the brains of decapitated rats recently came to my attention. To be fair to the scientists involved, they're investigating whether euthanasia by decapitation is humane, but the idea still seems somewhat... grim.

Issues of personal queasiness aside, the paper did find something interesting;

Remarkably, after 50 seconds (awake group) or 80 seconds (anesthetized group) following decapitation, a high amplitude slow wave was observed. The EEG before this wave had more power than the signal after the wave. This wave might be due to a simultaneous massive loss of membrane potentials of the neurons. Still functioning ion channels, which keep the membrane potential intact before the wave, might explain the observed power difference.

This "wave of death" is suggested by the authors to reflect "the ultimate border between life and death". The question arises as to whether this wave is irreparably damaging to the cells involved, something which the authors apparently intend upon researching in future.

On a somewhat related note, the authors also argue that conscious brain activity probably vanishes a scant few seconds after decapitation, making the process a reasonably humane method of disposing of unwanted rodents.

A related study, published more recently, develops a computational model to attempt to account for this "wave of death" phenomenon. Of particular note is the end of the paper, where they argue against the wave as a biomarker of clinical death;

Irreversible functional damage due to oxygen and
glucose deprivation most likely occurs from damage to synapses,
rather than from cell death itself. In line with this perhaps
surprising result, cells from neocortical slices from adult human
brain obtained several hours postmortem, can survive for weeks in
vitro. We therefore reject the claim in the paper by van Rijn
et al. that this particular phenomenon can be used clinically to
determine brain death. In fact, this wave does not imply death,
neither of neurons nor of individuals.
In summary, our simulations and the data presented from
experimental physiology show that the ‘‘Wave of Death’’ reflects
the sudden change in membrane potential due to anoxic
depolarization, that is a direct result of the Hodgkin-Huxley
dynamics and ion concentrations. Although the wave is indeed a
typical signature of the final membrane voltage changes of neurons
suffering from severe oxygen and glucose deprivation, it is not a
biomarker for irreversibility.

A pair of pretty interesting papers, all round. Hopefully they'll inspire some fascinating follow-up research.

References:
Rijn CMv, Krijnen H, Menting-Hermeling S, Coenen AML (2011) Decapitation in Rats: Latency to Unconsciousness and the ‘Wave of Death’. PLoS ONE 6(1): e16514. doi:10.1371/journal.pone.0016514

Zandt B-J, ten Haken B, van Dijk JG, van Putten MJAM (2011) Neural Dynamics during Anoxia and the “Wave of Death”. PLoS ONE 6(7): e22127. doi:10.1371/journal.pone.0022127

Blocking in Learning

Sometimes I stumble across a really simple concept that I feel like I should have known, and perhaps even at one point did know. "Blocking" is just one of those concepts, which I found in David Shanks' Annual Review of Psychology paper Learning: From association to cognition.

The basic idea is pretty simple. In classical conditioning, when a neutral stimulus is presented alongside an unconditioned stimulus that generates an unconditioned response, that neutral stimulus normally becomes a conditioned stimulus that causes a conditioned response. The classic example is, quite obviously, Pavlov's dogs; the smell of food (US) caused salivation (UR). When a bell was rung (NS) at the same time as the dogs' food was served, the dogs eventually began to salivate when they heard the bell - a conditioned response. The dogs had learnt to associate the bell with being fed.

That's all well and good. If, however, a second neutral/conditioned stimulus is introduced after an association has been made between CS1 and the US, and presented consistently with CS1, then little to no association will be made between CS2 and the US. To demonstrate with a thought experiment; if I make an association between, say, eating peanuts and having an allergic reaction, then experiencing an allergic reaction after eating peanuts and drinking beer won't make me associate beer with an allergic reaction. The association between CS2 (beer) and US (allergic reaction) has been blocked.

It's simple enough, but I found the effect interesting due to the implications it raises as to how the learning process actually works in humans and other organisms.

The BPS on the APA's DSM

So the British Psychological Society have published a response to the American Psychiatric Association's development of the DSM-5, the forthcoming edition of what is frequently (and perhaps worryingly) referred to as the "bible" of mental illness. The response is public and worth, at the very least, a quick read. Some points I found noteworthy;

"The Society recommends a revision of the way mental distress is thought about, starting with recognition of the overwhelming evidence that it is on a spectrum with 'normal' experience, and that psychosocial factors such as poverty, unemployment and trauma are the most strongly-evidenced causal factors. Rather than applying preordained diagnostic categories to clinical populations, we believe that any classification system should begin from the bottom up – starting with specific experiences, problems or ‘symptoms’ or ‘complaints’."

"While some people find a name or a diagnostic label helpful, our contention is that this helpfulness results from a knowledge that their problems are recognised (in both senses of the word) understood, validated, explained (and explicable) and have some relief. Clients often, unfortunately, find that diagnosis offers only a spurious promise of such benefits. Since – for example – two people with a diagnosis of ‘schizophrenia’ or ‘personality disorder’ may possess no two symptoms in common, it is difficult to see what communicative benefit is served by using these diagnoses. We believe that a description of a person’s real problems would suffice."

On gender dysphoria;

"Of particular concern are the subjective and socially normative aspects of sexual
behaviour. We are very concerned at the inclusion of children and adolescents in
this area. There is controversy in this particular area – the concept of a ‘diagnosis’ of
a ‘psychiatric disorder’ disputed.

Labelling people who need help as ‘ill’ may make supportive and therapeutic
responses more difficult."

On neurocognitive disorders;

"We have no specific comments on these disorders, other than to say that, in our
opinion, the use of diagnostic labels has greater validity, both on theoretical and
empirical grounds in these areas."

On paraphilias;

"We believe that classifying these problems as ‘illnesses’ misses the relational
context of problems and the undeniable social causation of many such problems. ... of particular concern are the subjective and socially normative aspects of sexual behaviour. It is a matter of record that homosexuality used to be considered a symptom of illness. The Society would not be able to support considering sexual differences as symptoms of illness.

We, finally, have severe misgivings about the inclusion of “Paraphilic Coercive
Disorder” in the appendix. Rape is a crime, not a disorder. Such behaviours can, of
course, be understood, but we disagree that such a pattern of behaviour could be
considered a disorder, and we would have grave concerns that such views may offer
a spurious and unscientific defence to a rapist in a criminal trial."