Processing of spatial information during goal directed behavior in the carrion crow endbrain

Abstract

Goal directed behavior, as opposed to habitual or conditioned behavior, is believed or known to have a causal effect that brings the agent closer to a goal. In order to be able to perform goal directed behavior, at least these three steps of processing are necessary: first, sensory information must be integrated, maintained and analyzed for possible behavioral response. This maintenance and analysis of information takes place in working memory. Secondly, as a result of the analysis in working memory, the motor response can be planned. Finally, the motor plan is executed, actualizing the goal directed behavior. This thesis investigates the involvement of the avian endbrain area Nidopallium caudolaterale (NCL) in processing of spatial information for goal directed behavior. We trained carrion crows (Corvus corone) on two different behavioral protocols, in which they either had to remember the spatial location of an object or prepare a movement to a spatial location. While the animals were engaged in these protocols, we recorded the activity of single neurons in the NCL. Single neurons in NCL selectively increased their firing rates during visual presentation of different spatial locations, encoding the spatial sensory input. In addition, NCL neurons also maintained this selectivity over a memory delay in the absence of visual stimulation. Similar maintained selectivity was previously interpreted as a correlate for working memory. Another population of NCL neurons selectively encoded the location of a future motor response, while the crows were planning the movement. Finally, NCL neurons represented the movement direction during execution of the behavioral response. These findings demonstrate that NCL is involved in sensory encoding and maintenance of spatial information in working memory. In addition, NCL also takes part in planning of motor responses and encodes the direction of motor response during execution. Our findings parallel previous findings in the mammalian prefrontal cortex (PFC) which is also involved in both spatial working memory and motor planning. Although birds and mammals show drastically different brain architectures, the avian NCL and mammalian PFC are astoundingly similar in the processing of spatial information. This thesis emphasizes the previously proposed functional analogy between NCL and PFC.