Andreas Burkhalter, PhD
Professor, Anatomy & Neurobiology
Our studies of the visual system in mice are aimed at understanding how the visual cortex is subdivided into different areas, how the network of connections between areas develops, how it is organized in the adult and how it is altered by visual experience. Interareal networks are important for visual perception and visually guided actions. The work is focused on identifying cortical areas, defining their hierarchical relationships and studying the circuits that connect lower with higher visual areas. These circuits are formed by feedforward and feedback connections that are composed of excitatory and inhibitory neurons. The goal is to understand how during development the strengths of excitatory and inhibitory synaptic connections are adjusted to generate unique circuit-specific balances of excitation and inhibition.
We are employing a combination of anatomical and physiological techniques. For delineating area maps we are using axonal tracing of connections and extracellular recording of receptive fields to map the topographic organization of visual cortex. To study the structure of synapses and identify their postsynaptic targets we are using neuronal tracers and cell-type specific markers of excitatory and inhibitory neurons and analyses in the confocal and electron microscopes. For determining the mechanisms of synaptic transmission we are using whole cell recording of GFP labeled inhibitory and excitatory neurons in brains slices. An important focus is to find out how during development inhibition in feedforward and feedback circuits become different and to understand the role of visual experience in this process. The long-term goal of our research is to provide a better understanding of the structure, physiology and plasticity of interareal cortical circuits that provide for the cortical representation of visual information and the ion of parts of the visual image for concentrated attention and interpretation.