Darren Logan

Genetics of Instinctive Behaviour

Darren leads the Genetics of Instinctive Behaviour group at the Wellcome Trust Sanger Institute. This group is aiming to understand social interactions such as aggression, sex and parenting. To investigate these experimentally his team studies how mice react to specialised odour signals (such as pheromones), and then identify the genes that process these cues from their detection in the nose to the resultant behaviour. As most instinctive behaviours are common among mammals, the genes that build the important neural circuits in the mouse brain are likely to be similar to those in humans, even if the exact social signals differ between species.

Following a degree in Biochemistry from the University of Bath, Darren earned a PhD in Edinburgh, at the MRC Human Genetics Unit. He then spent five years studying mouse behaviour at The Scripps Research Institute in California, before joining the Sanger Institute Academic Faculty in 2010. Darren is also an investigator for the MRC Centre for Obesity and Related Metabolic Diseases, studying how the behavioural aspects of feeding and appetite influence obesity.


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My research
Darren Logan 1:21 min - 8,463 kb
"I am a Junior Faculty member here and my lab is interested in the genetics of instinctive behaviour and so really what we are interested in is how genes inform behaviour and that's a really difficult question because humans, like a lot of animals, are very complex beings, and while they have a set of genes in their genome, those genes interact with the environment to result in the actual behaviour that's involved and so it's really hard to study with humans, so instead we study the behaviour of mice. My main question really is two-fold. One is how does the sense of smell work? Of course it’s one of our five senses, it’s the one we probably know least about and it’s really, I think, important to fully understand these because all of our behaviours are really an integration of absorbing information through all of our senses, mixing them together in our brain and then releasing some appropriate behaviour. The second thing I’m interested in is how all of these neurons that transmit the senses integrate together to release that behaviour and in my lab we are focussing on the olfactory sense simply because we can map the individual neurons a lot easier than a lot of the other senses. This allows us the ability to then map the genes on to the neurons and then really understand how that patterns the brain to result in instinctive and other behaviours.
Studying behaviour in mice
Darren Logan 1:31 min - 9,477 kb
"Well mice actually have a whole range of behaviours, they’re remarkably complex little creatures. The ones I am particularly interested in are aggression, that’s male/male aggression. So mice, like humans, tend to be very territorial and dominant of each other and so when two mice meet, male mice meet, they will often have a little fight until one determines he’s the boss of the other one. We’re also interested in fear behaviours, so we have found recently that mice when they detect odours from cats or snakes or other predators will respond with fear. What’s interesting about this is that the mice do so in an innate way. These mice have never seen a cat or a snake before and yet they are innately afraid of these cats or snakes, which tells us there is something in their genes that encodes this pathway that allows them to be afraid. So, parenting behaviour is a really interesting behaviour for mice because mice, like humans, invest a lot of their time looking after their young after they are born. In fact in the first few days or so, female mice spend almost all of their time attending to their young. So in my lab, we have looked at suckling behaviour, so that is how mice once they are born will take their first feeding from their mother and continue to do so. A lot of these behaviours like aggression and sexual behaviours are highly stereotyped, so that’s great for us to study because the stereo type nature of their behaviour means that we can really change the genes a little bit and see how that affects the behaviour. "
Why look at sensory behaviours?
Darren Logan 0:50 min - 5,270 kb
What’s interesting about sensory biology is that it’s very, very labile. That is, all of our senses by their very nature are very exposed to the environment and that means that the impact of genes can be very well disguised by the environmental or nurturing factor. However the genes are there, and the genes are building a blueprint of which the environment moulds into a sensory system and I think this is perhaps why so little is known about many of the genes that are involved in the sensory systems because they are so massed by the environmental impact. So I feel that by taking the approach we are, we are really targeting the genes that are most obvious through instinctive behaviours, this will allow us to identify genes we can then apply to other more subtle behaviours that have a perhaps smaller genetic impact, but a genetic impact none the less.
Why did you come to work at the Sanger Institute?
Darren Logan 1:19 min - 8,224 kb
"Why I came to the Sanger Institute, is because as I said before, I study the behaviour in mice and mice behaviour is really interesting because it evolved mainly via olfaction or pheromones. And the interesting thing with mice pheromones is that they have this gene family that regulates these called the vomeronasal receptors. Very little is known about them; there is maybe about 300 genes of which we know very little. So I came here principally to study these genes and the resources at the Sanger Centre allows me to knock these genes out in mice and study their behaviour and there’s very few places in the world that has the ability and resources to do that. So this place by integrating genome resources with behaviour in science allows us to really tackle this question, where no one else really could. I’m a firm believer in collaborating. I think that the Sanger Institute is in a very strong and unique position to allow us to collaborate because it’s really written into the mandate of what we do here. I collaborate with a lot of people, with people I have worked with before, I continue working with them. But I also think it is important because we work with animals that by sharing the animals that we do generate, means that less have to be made worldwide, which I think’s a really important part of maintaining our responsibility towards animal welfare. "
Why are you interested in the genetics of behaviour?
Darren Logan 0:53 min - 5,576 kb
I think the reason I am interested in the genetics of behaviour is because the ultimate question really is to understand the neural circuits that mediate behaviours. And so if you think of humans, a lot of behavioural disorders are really in response to the inability to detect cues and respond to them correctly. So diseases particularly like schizophrenia, where people may hear phantom noises or phantom voices, or autism where people don’t respond to the correct cues. In terms of autism for example, it is very much an instinctive response that we have to cues but of course it’s really hard to study because every human is so different. So the one way to study this is to look at genetics. So our long term goal I would say is to identify neural circuits that mediate behaviour. One way to do that is to identify genes that build these circuits
How do you study mice behaviour?
Darren Logan 0:50 min - 5,198 kb
On a day to day basis in our lab, we really design these vectors, what we call vectors, these are pieces of DNA that allow us to target specific genes in the mouse and we build these and then we hand them off to another team who will then make these mice for us that are lacking specific genes. Once we have these mice we can then test them in various, what we call, behavioural paradigms, and this is really very simple social interactions so we may take mice and ask, do these mice respond to females with aggression or with sexual behaviour? Or we may take a mother and ask does she look after her pups well or less well than a regular mouse? And by testing these mice against regular mice, or mice with their full compliment of genes, we can then really ascertain whether or not these genes that we are interested in really affect behaviour.
The importance of smell
Darren Logan 0:59 min - 6,121 kb
I think it’s surprising that most people tend to put little value in their olfactory system and its only when people lose it that it really becomes clear how important it is to us. One interesting thing about the olfactory system is that it is incredibly tightly regulated and integrated with our ability to taste, and in fact most of what we define as taste is really smell. So those who lose their ability to smell often can’t distinguish flavour. In fact, most flavours are just distilled down into five very simple flavours, that’s like salty or sweet, but the real subtlety of flavour is lost. And so people who lose that ability will often become depressed, lose their libido for example, and so hopefully our work will also impact on this andwe hope to define the very basic molecular mechanisms and genes that influence smell and once we do that we may be able to look at treatments to help people who have lost their sense of smell, to begin to smell again.
What are pheromones?
Darren Logan 1:11 min - 7,383 kb
"Pheromones are chemical cues that are emitted by one species and detected by a member of the same species, that elicits an innate behaviour. This was defined in the 1950s by two gentlemen who found the first pheromone which was a cue in moths and they spent many years trying to identify this. They mushed up thousands of moths, probably tens of thousands of moths, and essentially came back with a tiny, tiny little amount of this first pheromone which they wrote a paper on. A lot of people ask if humans have pheromones and that’s a question we are not quite sure about the answer to yet. What’s certainly clear is that a lot of the pheromones you can buy online aren’t true pheromones, but there are some suggestions that some human behaviours may be influenced by odours. Whether these are pheromones or not is a matter of debate. There is a very famous pheromonal effect called the Vandenbergh effect, which is the ability of males to promote oestrus in young females. And so the idea of this is that males will have more fertile females around them if they can promote females to be mature. "