Bettina Schnell
Max Planck Institute for Neurobiology of Behavior – caesar, Bonn
Germany
Neuronal control of flight turns in Drosophila
Flies perform rapid turns termed saccades to change direction during flight, which constitute an important aspect of their behavior. However, how these turns are controlled by the brain is still poorly understood. Saccades can be elicited by looming stimuli mimicking an approaching object such as a potential predator, but can also be initiated spontaneously.
We study the neuronal mechanisms underlying the control of saccades during flight with a focus on descending neurons (DNs) that transmit information from the brain to the ventral nerve cord. Using whole-cell patch-clamp recordings during head-fixed flight in Drosophila, we have identified DNs whose activity is correlated with flight saccades (measured as changes in wing stroke amplitude in our preparation), some of which receive direct input from looming-sensitive visual projection neurons. To study the actual contribution of these DNs to the control of saccades, we use genetic tools to manipulate their activity during both head-fixed and free flight.
For this, we have developed a setup that allows us to track the flies’ behavior during free flight while presenting visual stimuli or optogenetically activating DNs. This work provides an entry point into understanding how sensory information is transmitted to the motor system to control an important behavior of the fly.
Songbird brain circuits for skilled vocal and non-vocal behaviors
From typing an email to swinging a tennis racket, learned motor sequences are commonplace in our everyday lives. In humans, these complex behaviors are often associated with the use of tools, but how tool use is controlled at the level of the neural circuit remains virtually unexplored.
To gain traction on this issue, we first consider our previous work on the neuronal mechanisms underlying a different complex learned behavior: the courtship song of the zebra finch (Taeniopygia guttata). Next, we demonstrate that the zebra finch shares its songbird-typical brain structures dedicated to vocal control (i.e., the “song system”) with the carrion crow (Corvus corone) – another songbird species that readily learns to use tools in the laboratory.
In the crow brain, the well-characterized song system is anatomically paralleled by identified areas involved in voluntary head movement control, which we have mapped out using tract-tracing methods. These premotor areas are likely involved in controlling our crows' behavior in a task that requires them to employ a stick tool to reach for food pellets in a fully automated behavioral setup. By tracking their movements with high-speed video cameras, we demonstrate both the reproducibility and the sensory feedback-driven adaptability of the crows' tool use. This new behavioral paradigm and an anatomical atlas of the crow's premotor system will enable us to identify the neuronal underpinnings of tool use control in the crow brain, uncovering network coding principles underlying skilled action sequences.
