Gareth Leng is the Professor of Experimental Physiology in the Centre for Discovery Brain Sciences at the University of Edinburgh. His multidisciplinary research uses electrophysiology, molecular neuroanatomy, behaviour and computational modelling to investigate hypothalamic neuronal networks. He is particularly interested in pituitary hormones and in the regulation of appetite and obesity.
Prof Leng has just published a book: The Heart of the Brain; The Hormones of the Hypothalamus. In his guest blog, he explains how neuroendocrinologists see the brain differently and why he wrote the book…through a conversation with himself.
Gareth: So, congratulations etc., I’m sure it’s a wonderful book, but before we get to what it’s all about, why did you write it? – apart from fame and fortune, that is.
Gareth: Well (modestly) thanks etc. I’d always wanted to write a book – well, since I was 7. Finally I got the chance to see if I could.
Your students wouldn’t let you into the lab any more so you had some free time?
No. The University abhors a vacuum, and fills all available time with superficially reasonable but pointless demands. The chance came in finding something that I thought was worth saying…
…that you hadn’t said in your last 200 papers?
I hadn’t put it all together.
So, 200 papers without the draggy bits? Quite a short book then. What’s your message?
I wanted to write about what doing science was really like – to talk about the passion and the messiness and the confusions and the mistakes and the mixed messages…
…but not the draggy bits. What’s your message?
I wanted to contrast how neuroendocrinologists understand the brain with the conventional view of the brain as this super, smooth, efficient, dessicated, calculating machine with ten billion neurons and a trillion connections all pinging away.
What do neuroendocrinologists see in the brain that’s different?
Passion and messiness and confusions and mistakes and mixed messages.
That is interesting how exactly?
I don’t think it’s interesting that complicated calculating machines can be good at calculating. To me the challenge in neuroscience is to see how noisy, messy, error-prone systems, self-assembled with quite a lot of randomness, can do clever things, including things that complicated calculating machines are rubbish at.
How is that then? You are pretty noisy and messy yourself but…
A lot comes down to mixed messages. Neurons don’t use just one type of signal – they use many. Some, neurotransmitters, do signal precisely from one neuron to another. Others are local signals, affecting neighbouring cells either of the same type, or of other types, or both; they are signals that pass from one population of cells to another – these are autocrine or paracrine signals. Yet others are released from one population of neurons, spread to large parts of the brain through the extracellular space, and act at distant targets.
Hormones, then, brain hormones?
Exactly. We’ve thought of neuropeptides as another class of neurotransmitters. That’s nonsense. Like hormones they have a massive range of effects, not just on neurons, but on neurons they can have both organisational and activational effects, on gene expression and connectivity as well as on excitability. They can ‘re-program’ their targets in a context-dependent way.
For example – oxytocin as a wild left-field guess?
Yes, oxytocin is a good example. It’s not just released from the pituitary, it’s also released in the brain – but not mainly from nerve endings but from dendrites. That release is governed, not just by electrical activity, but also by peptides that trigger mobilisation of intracellular stores.
Like endocrine cells then?
Oxytocin cells are hybrids of neurons and endocrine cells. They are multifunctional in that the release from dendrites and axons can be regulated independently. They speak in different languages to different listeners.
And so they can do wonderful things…
Oh yes, like generate the synchronised bursts that trigger pulsatile oxytocin release in suckling
…and promote sexual behaviour – lordosis and penile erection?
…and maternal behaviour and bonding in monogamous species?
…and trust and hugs and cuddles…
Just about oxytocin?
No, stress, reproduction, appetite and obesity, plasticity, rhythms, evolution…
How did you go about writing it?
Writing the book was for me a way of testing out whether the message held up – in that sense it is a conversation with myself.
Not like this then?
You’re quite right. No. An argument with myself.
Who did you write it for?
Myself really. I read a lot of science books…
…you start a lot of science books…
…and the ones that engage me handle the science seriously but get an interesting message across – they don’t just say stuff. I tried to write the sort of book that I might read to the end.
Have you read it to the end? What’s the last line?
“The hormones of the hypothalamus- the heart of the brain- […] are the signals of emotional salience, the links between our passions and our reason, the agents of our urges, our hopes, our fears – of the things that make us human.”
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