Johannes (Jonny) Kohl’s first encounter with the city of London did not go smoothly. The then-prospective grad student found the city overwhelming. “I guess the village boy came through,” he recalls.
Instead, he opted to enroll in the graduate program at the MRC Laboratory of Molecular Biology in Cambridge, UK and continued on to a postdoc in the Dulac Lab at Harvard, where he researches the neural circuitry underlying parenting behavior in mice. Today, he splits his time between Harvard and the UK, where he conducts research as a Sir Henry Wellcome Fellow in Tiago Branco’s lab at the Sainsbury Wellcome Centre for Neural Circuits and Behaviour at University College London.
“The cool thing about the Crick is that there are no departments,” Kohl says. “This sort of approach seems to create extensive collaborations….It’s an amazing place, and I’m quite excited to join it.”
London has grown on him, too. “The city is amazing, even if you’re not a city person,” he says. “The diversity is just insane.”
Interacting with many different people and cultures has always been part of Kohl’s modus operandi as a scientist. An avid conference-goer, one of his resolutions is to attend at least one “weird conference” in a non-neuroscience field per year, just to shake things up.
His conversations at conferences often inform his benchwork.“We have this bias in science, especially with the current publishing landscape, that only positive findings get published, and we are missing this huge underbelly of negative findings,” Kohl explains. “So everytime I go to a poster, I speak to someone, and they tell me what didn’t work. So you can actually save a lot of time and energy by talking to people like that.”
Initially, Kohl didn’t set out become a scientist. Growing up in the small village of Etzelwang, Bavaria in Germany, he didn’t see science as a career path. “Growing up there was extremely nice, because you’re surrounded by a lot of nature, and you have a lot of freedom,” Kohl says.“Obviously, once you’re a teenager, it becomes extremely boring.”
At 19, he headed to university in the Bavarian town of Bayreuth. He quickly found that biochemistry didn’t satisfy his itch to interact with living organisms. “It was all test tubes and molecular reactions and all of that. I didn’t find it hands-on enough,” he says.
Kohl decided to change majors while traveling through the Americas during a sweltering day in the city of Pucallpa, Peru. “It was too hot to do anything, so we just sat around in the internet cafe and Googled,” he recalls. His Internet wanderings always seemed to lead back to neuroscience topics. After more Googling, he transferred to the neuroscience program at University of Magdeburg.
At Magdeburg, he worked in various labs in order to find out where his interests lay. “It was by exclusion, rather than by some distant calling,” he says. Eventually, he realized that he enjoyed looking at how groups of cells functioned as circuits, as opposed to studying individual cells or the brain as a whole.
When he arrived at Cambridge, he joined a lab headed by Gregory Jefferis, who studies olfactory processing in fruit flies. Kohl’s PhD research investigated the effects of a sex pheromone called cVA, which previous research had identified as important in male courtship.
“This pheromone does opposite things in males and females,” Kohl explains. “When males smell cVA, they are utterly turned off. But it promotes attraction in females.”
Investigating how cVA is processed differently between males and females required recording activity from tiny neurons in the fly brain. “It was hell at first,” Kohl says. “It took me about two years to get the first proper recording, because these neurons are very small. They are only about 3-5 microns in diameter.”
However, a summer course in neurobiology at Wood’s Hole gave him a second wind. Kohl documented a neural circuit switch which reroutes pheromone signals between the sexes. It was governed by a single transcription factor that could flip this switch from the female to the male position (and vice versa).
Soon after that, he met MCB professor Catherine Dulac at a neuroscience conference in Toronto. She was presenting on a set of neurons in a brain region called the medial preoptic area (MPOA) that seems to control parenting in mice. Kohl was intrigued.
“Virgin females are spontaneously parental,” Kohl explains. “When they see a mouse pup for the first time in their life, there’s a good chance that they’ll take care of it.” Male virgin mice, in contrast, are typically infanticidal but become paternal in the weeks after mating.
“What they found is that when you ablate these [MPOA] neurons, the parental behavior is gone,” he adds. And by optogenetically activating these neurons “they could convert infanticidal virgin males into a parental state.”
Kohl struck up a conversation with Dulac and arranged to visit her lab later that year. One visit was all it took to convince Kohl. “We have very open conversations about everything,” he says. “She gives people a lot of time and a lot of freedom. So for my style of science, that was absolutely perfect.” In 2014, after wrapping up his PhD, Kohl relocated to Cambridge, Massachusetts.
The number of MPOA neurons is relatively small (several thousands), and it was unclear how such a small cluster of neurons could coordinate a complex social behavior like parenting. Kohl’s first task was to figure out which neural circuits these neurons were embedded in. To do so, he needed to trace the signals going into and coming out of these neurons.
“What we found was that these neurons talk to more than twenty areas, and they also receive input from more than twenty areas…..this was intimidatingly complex,” Kohl says.
Researchers once believed that such high levels of connectivity were rare, but technological advances in synapse-mapping have revealed that it’s not unusual. “There is this absolutely incredible degree of connectivity between essentially all brain areas,” Kohl says. “It’s like a small village where everyone ends up talking to everyone.”
However, the risk he took in tackling a complex topic paid off. “Jonny’s work in the lab led to a beautiful and monumental dissection of the brain circuits underlying parenting behavior in male and female mice,” says Professor Catherine Dulac. “The level of analysis reached by Jonny’s experiments on behavior circuit dissection is quite unprecedented, and led to a landmark paper in Nature earlier this year.”
This work on parenting behavior inspired Kohl to write an essay that recently garnered the Eppendorf & Science Prize for Neurobiology, an international essay competition that highlights promising young neurobiologists. His essay will be published in the journal Science, and he will also receive $25,000 in prize money. “It was very unexpected,” he says of winning the Eppendorf Prize. “I’m still completely thrilled.”
His postdoctoral work also attracted attention from the Society for Neuroscience (SfN). They will honor him with the Peter and Patricia Gruber International Research Award at the 2018 Society for Neuroscience conference.
Starting in early 2019, his lab at the Crick will explore how pregnancy and other physiological states change neural circuits in female mice. “I’m fascinated with instinctive behaviors that are seemingly hard-wired,” he says. “We’re realizing that even these circuits are profoundly influenced by animals’ physiological states.”
He’s currently looking for people to join his lab and encourages people to apply.