From Vision to Action: Transforming the brain's decisions into goal-directed motor behavior

• Applicant: Professor Dr. Johann Heinrich Bollmann
• Subject Area: Cognitive, Systems and Behavioural Neurobiology
• Term: from 2017 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 357057764

One of the key challenges of modern neuroscience is to develop a comprehensive, mechanistic understanding of biological information processing in intact brains. Arguably, the most fundamental function of brains across all species is the capacity to make decisions, in the broad sense that the distribution of neural activity in the brain eventually assumes critical states that represent the commitment of an animal to perform one out of several possible actions contingent on integrated sensory information. Rapid perceptual decisions often do not depend on conscious deliberation, but are the result of sensory pattern recognition and classification processes performed by dedicated brain circuitry. A ubiquitous behavioral decision is that between approach and avoidance behavior, in which the behavioral response is selected from one of two mutually exclusive categories, e.g. to approach a prey or to escape predators, and which is therefore vital to maximize chances of survival. Importantly, graded variation of certain stimulus attributes can trigger a switch between response categories, assigning appetitive or aversive value to different ranges of a stimulus property. In the vertebrate visual system, object size and velocity are stimulus attributes critically determining the appetitive or aversive value of moving objects. Subcortical areas in the midbrain, and in particular circuitry in the superior colliculus/optic tectum, are critically involved in both appetitive, target-directed behavior and in object avoidance behavior, suggesting that this is a central hub for stimulus classification and perceptual decision making. Yet, the neuronal mechanisms underlying stimulus classification and response selection are not well understood. At present the size and complexity of mammalian brains make it difficult to directly monitor visually evoked streams of activity throughout the brain at sufficient resolution. Therefore, I propose to study mechanisms of subcortical decision making and response selection in the zebrafish model in which the spatiotemporal dynamics of sensory driven activity can be monitored using opto- und electrophysiological techniques throughout the brain. The objectives of this proposal are (i) to identify the layers and subnetworks within the retinotectal circuitry that perform stimulus categorization and response selection, (ii) to understand the neural command structure encoding the brain's behavioral decisions, and (iii) to unravel the mechanisms how the outcome of the decision process is relayed to downstream motor control centers. The longterm goal of this program is to build a comprehensive model of whole-brain information processing in this tractable vertebrate model, which could ultimately reveal functional principles applicable to mammalian brains on a larger scale.

• DFG Programme: Research Grants