Toward a Neurobiology of Corvid Tool Use

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 – collectively referred to as the “general motor system” – which we have mapped out using tract-tracing methods. These premotor areas are likely involved in controlling our crows' tool use 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 areas will enable us to identify the neuronal underpinnings of tool use control in the crow brain, uncovering network coding principles underlying flexible skilled action sequences.