Bored birds, busy brains: Habituation to song initiates significant molecular changes in auditory forebrain of zebra finch

When we think of habituation, we tend to think of a process in which there is a decrease in psychological and behavioural response(s) over time following an organism’s exposure to a stimulus. Conceptualising habituation in this manner seems to imply the loss of something once an initial learning event has taken place. Although this may accurately describe what occurs at the psychological and behavioural levels, a study by a group of scientists from the University of Illinois (Dong et al. 2010), which examines habituation at the neurobiological level, shows that contrary to this conceptualisation, both initial exposure and habituation to song playbacks initiates a vast array of genetic activity in the zebra finch brain.

The systematic regulation of FoxP2 expression in singing zebra finches has been the subject of previous posts, but there is also a growing literature, of which Dong et al’s study is a part, documenting increases in ZENK gene (which encodes a transcription factor protein that in turn regulates the expression of other target genes) expression in zebra finch auditory forebrain areas in response to playbacks of song or the song of a conspecific. Studies showed that ZENK expression seems to mirror the typical decline in response associated with habituation in that after a certain amount of repetition, presentation of the song that originally elicited upregulation of ZENK no longer did so, and that ZENK returned to baseline levels – although upregulation of ZENK would occur if a different song or an aspect of novelty was introduced (i.e. the original song was presented in a different visual or spatial context).

What Dong et al. have demonstrated by conducting a large scale analysis of gene expression at initial exposure, habituation, and post-habituation stages however, is that unexpectedly profound genetic changes occur as a result of habituation in the absence of any additional novel stimuli following the surge of activity observed during initial exposure to novel song. Thus, the resounding merits of the Dong et al. (2010) study lie in the broadness of their approach, providing a true sense of magnitude with respect to genomic involvement in vocal communication and illuminating important influences that have gone unnoticed by studies with a narrower focus. I summarise the experimental design and findings of the paper below.

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Dawkins and his army of mildy irritating atheists

As many of my friends will know, I’m quite a big fan of Richard Dawkins. But for some reason his website seems to spawn an army of what can only be described as mildly irritating atheists. A particular aspect I frequently bemoan is the necessity of some members to contort a fairly innocuous article into some anti-religious rant. Honestly, it’s unceasing. Take for example this article discussing Neanderthals. Just scroll down to the comments and you’ll be greeted with:

It all just gets you thinking about why the Neanderthals died out. I’ll theorize that their bigger brains found our ancestors’ ravings about our divine origins totally hysterical — and the resulting campaign of genocide simply took the poor buggers off guard.

Funny, yes? Well, no, not when the same joke/theme/structure is applied over and over again. I’ll throw out some more, as I don’t want to single out one individual:

I like to imagine science as a massive guillotine, with creationists frantically trying to stick objects to stop it’s progress. Science may be moving somewhat slowly, but nothing can really stop its progress. (From an article about RNA as a precursor for life on Earth.)

At least one commenter was honest enough to give up any pretence of being interested in the article itself:

When you look at the big picture, Obama has a tough road ahead of him and needs to harvest the support of everyone in America, even that large swath of intolerant, evangelical America, who are Americans none the less. I can’t say that I agree with the choice but I understand it. ( About, um, Quantum computing…)

Maybe it’s a running joke? Or perhaps it’s what you should expect from a website run by Richard Dawkins? Personally, I find these comments serve as an effective cure for insomnia: their repetitive nature will guarantee instant sleep, plus you’ll probably learn something new (from the articles at least). Oh, and one more thing, what’s with Dawkins’ dvd covers:

Does this make your skin crawl?
The serene sea, the steely gaze, the god-like pose. Yes, it makes my skin crawl too.