- Name: Björn Brembs
- Number of lab members or colleagues (excluding PI): 3 scientists, one technician, varying number of undergraduate students.
- Location: Regensburg, Germany
- Graduation Date: Ph.D. March 2000
- H index: 30
- Grants: About 2.3M€
- Twitter followers: 8000
Hello! Who are you and what are you working on?
I’m a neurobiologist working on the neurobiology of behavior. I study how brains generate spontaneous actions in the absence of external stimuli and how they use feedback to decide what to do next. I use largely invertebrate nervous systems for my experiments, such as flies, snails or leeches.
What’s your backstory and how did you come up with the idea?
I wanted to become a scientist when I started reading books from scientists about their discoveries in high school. I had spent countless hours observing not only the behavior of my pet amphibians, but also of all kinds of animals in the wild, so while all science was attractive, I started studying biology in 1991. I was always broadly interested, so it took a while until I decided I wanted to focus on developmental biology: I found (and still find) the question of how a fertilized egg knew where to grow a head and where a tail tremendously fascinating. However, I quickly realized that the actual lab work in developmental biology consisted largely of pipetting clear liquids and waiting for machines to complete their treatment of the samples. This was fun while it was new, but it grew old very rapidly.
After that, I got hooked on a topic that I had excluded as a specialization already in High School. Neuroscience seemed like it was impossibly complex, despite it also being very interesting, so I decided that Neuroscience was not for me long before I started studying at university. A lecture by Martin Heisenberg in 1994 changed all that. Starting his introduction into the neurogenetics of Drosophila with big questions such as free will and the organization of behavior, he had my undivided attention. While I was affixed to all the exciting things he was telling us about, he also managed to somehow convince me that Drosophila was just the right level of complexity that one could do interesting neuroscience without being completely overwhelmed by the complexity of its nervous system. Knowing what I know now, I’m not so sure any more of that last aspect. 🙂
During one of the courses at the Heisenberg lab, when we were doing operant conditioning experiments, I asked what the neurobiological difference was between operant and classical conditioning. I had learned about these two forms of associative learning in High School as forms of learning discovered by Pavlov and Skinner many decades before I was born. Given the time that had passed since then, I thought I would get a straightforward answer. To my surprise, nobody knew what the difference was or even if there was a difference. This answer got me started in my research career in neuroscience in 1995.
I started reading and became convinced that neurons store all experiences in the same way they store classical memories: synaptic weight changes depending on the evolutionary conserved cAMP-PKA cascades for the discovery of which Eric Kandel would receive the Nobel Prize in 2000. After all, this mechanism was perfectly sufficient to story anything, so why would a nervous system evolve more than one learning system?
I set out to test this hypothesis and in the course of more than a decade I not only learned that I had been wrong, but also that the many different learning systems that neurons possess, likely evolved so that they can interact with each other. These interactions form a dynamic learning web that allows the organism not only to check memories for accuracy and reliability but also to keep its internal model of the world up-to-date by constantly incorporating new experiences.
Please describe the process of learning, iterating, and creating the project
Over the course of several years, I learned that operant and classical conditioning experiments, when set up as analogously as possible (e.g., the animals learn to differentiate between the same two stimuli and are then tested identically after operant and classical training, respectively), do not leave any distinguishable differences in the behavior of the animals. I got the impression that the distinction between the stimuli was the only thing the animals had learned, whether they learned that in a classical or in an operant experiment. However, the process by which this memory was acquired was not equivalent: when equilibrated perfectly, classical conditioning required much more training to eventually yield lower learning scores than operant conditioning (i.e, a form of learning.-by-doing effect).
This was so puzzling that I designed a long series of experiments to test various hypotheses and improve the experimental design in case our results were due to a methodological flaw. However, over several years, I kept getting the same results, despite making the experiments more and more refined and making the behavior more and more equivalent to the learned stimuli: the animals only learned the stimuli and not the behavior, not matter how operant or classical the experiments were in their design.