The €60,000 Paul Ehrlich and Ludwig Darmstaedter Prize for Young Researchers is awarded this year to Dr. James Poulet, a brain researcher working in Berlin. The young British scientist has received the award because, as the Scientific Council of the Paul Ehrlich Foundation states, "his research furthers our understanding of the neuronal basis of behavior." The award ceremony will take place today, the 159th birthday of Paul Ehrlich, in the Paulskirche, Frankfurt.
Sensory perceptions result in very precise behavior. We see something and we reach for it. We smell something and we turn up our nose. James Poulet is studying what happens in the cerebral cortex of the mouse when sensory stimuli and motor behavior are interlinked, how the processes influence each other, and which neurons, synapses, and neuronal networks are involved in these responses. To do so, he is using new optical, behavioural and electrophysiological methods, for which the Scientific Council reserves its special praise. "Poulet's work is also of crucial significance for the development of artificial limbs and prostheses," the Council wrote in explaining its decision.
Poulet, who is currently Group Head at the Max Delbrück Center for Molecular Medicine, Berlin-Buch and also works within the NeuroCure Excellence Cluster, has gained attention for his many articles published in prominent scientific journals. He showed why male crickets do not become deaf when they invite females of the species to mate by rhythmically rubbing their forewings together. The chirping we know from warm summer nights is, for the crickets, as loud as a chain saw. The male crickets very specifically "turn down", or inhibit, the neurons responsible for hearing as soon as they begin to chirp and then remove the inhibition as soon as they stop chirping. By switching back and forth between "on" and "off", the crickets protect themselves against deafness but yet are still able to hear the approach of a predator or a rival. Poulet has also identified the neurons that are responsible for this internal feedback process. The process exemplifies how living beings discriminate between self-generated sensory stimuli and external stimuli. A similar feedback loop is activated to ensure that we don't damage our own hearing when we shout and that we are unable to tickle ourselves. James Poulet is furthermore interested in what is generally known as brain states. An example is the transition from dozing to being wide awake. These states are part of the brain's normal functioning. Poulet is investigating how they come about and what their role is in the interlinking of sensory perception and motor behavior.
Background on the award of the 2013 Paul Ehrlich and Ludwig Darmstaedter Prize for Young Researchers to Dr. James F.A. PouletBrain research
This activity is managed at the level of the nerve cells, synapses and neuronal networks in the cortex of the brain, and it leads to some interesting questions that are almost philosophical. How does the brain distinguish between external sensory perceptions and stimulations that arise internally? Did I just call out or did someone else?
These are the questions that Dr. James Poulet from the Max Delbrück Center for Molecular Medicine Berlin-Buch and the cluster of excellence NeuroCure have been studying for more than ten years. Poulet is the winner of this year's Paul Ehrlich and Ludwig Darmstaedter Prize for Young Researchers. The young British scientist has received the award because, as stated by the Scientific Council of the Paul Ehrlich Foundation, "His research furthers our understanding of the neuronal basis of behavior."
The young neurobiologist focuses on voluntary behavior that requires some sort of decision-making process rather than stereotypical reflexes. Taking your hand off a hot surface is a reflex, while responding to a touch is a voluntary reaction. "We want to know how neuronal activities alter behavior," Poulet explains. "We are interested in the causal connection between sensory perception, the activity of neurons and the motor response that results from them." After starting with crickets, Poulet has now turned to mice. He is primarily interested in brain regions called the primary somatosensory and motor cortex. Here sensory perceptions are translated into behavioral responses.
Poulet has now trained the mice to stretch out a forepaw to probe the nearby environment. New optical and electrophysiological techniques are giving Dr. Poulet a look directly into the brains of alert, active mice, allowing him to record and manipulate the activity of specific neurons. "These processes underlie healthy behavior and are disrupted during certain diseases," Poulet says. "If we can determine which neuronal signals underlie sensory perception and how these signals are linked to an appropriate behavioral response, it may give us a key to understanding both healthy and defective activity. Before we can know what is pathological, we should know what is normal."Why can't we tickle ourselves?
On warm summer nights, male crickets attract females by rhythmically rubbing its forewings together at a level that exceeds 100 decibels. That level of noise can be compared to the sound of a chainsaw, the thundering of disco music or the din of a pneumatic drill. "We wondered why male crickets don't go deaf from the noise," explains Poulet. "How do they shut it out?" The young prizewinner demonstrated that as male crickets begin to chirp, they "turn down" or inhibit very specific neurons responsible for hearing; when they stop they remove the inhibition. This "on" and "off" switch protects crickets against deafness – but they can still hear the approach of an enemy. That's crucial because their loud mating call not only attracts interested females but broadcasts a cricket's location to predators and rivals. Poulet and his co-workers identified a precise neuron that tunes down the hearing system – the so-called “corollary discharge neuron.” Other organisms have these neurons as well, but virtually nothing is known about them.
Poulet and his co-workers also investigated how females react to the chirping. Here the question was whether they approach males as a reflex or whether it is a reaction to complex acoustic recognition in the females' brain? Poulet showed that the females display an approach movement in response to individual sounds that resembles a reflex rather than a complex behavioral response. More support for this comes from the fact that once the approach process has been triggered by the right song, females react to any acoustic stimulus. At that point only the sound is important; it doesn't even have to be the right one.What's the difference between dozing and being wide awake?
Dr. Anne Hardy | idw
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