Bert Sakmann, MD, PhD.

Inaugural Scientific Director, Max Planck Florida Institute

Winner of the Nobel Prize in Medicine 1991 for discoveries concerning the function of single ion channels in cells

Monday, 07 May 2012

Dr. Sakmann's research has focused on the functional anatomy of circuits in the brain (specifically the cerebral cortex) that form the basis of simple behaviors (e.g. decision making). His research involves the use of large scale, high resolution light- and electron-microscopic techniques to reconstruct the wiring of different cell types in the layers of the brain. The results are used to realistically simulate signal flow in the reconstructed network. Eventually, this may reveal the parts of the network that trigger sensory initiated behavior and lead to new discoveries about the brain's process of learning.

Dr. Sakmann's research group is conducting a program dedicated to creating a three-dimensional map of the normal brain. They are labeling the different cell types with specific fluorescent markers and then imaging and quantifying the neuron distributions. This work will lay the foundation for future studies on brain degenerative diseases, such as Alzheimer's. The research will not only help further our basic understanding of the degenerative disease process, but could also serve as a platform to measure the beneficial changes caused by novel therapeutic approaches such as new drugs and stem cell therapy.

Cortical Column: If You Don't Understand the Function, Do the Anatomy

ABSTRACT: Decision-making based on sensory input can be dependent on representation of a sensory stimulus in only one or a few cortical columns. Thus, soma location, dendrite morphology and presynaptic innervation in a column represent key determinants of functional responses of individual neurons, such as sensory-evoked spiking. We reconstructed the three-dimensional networks formed by thalamocortical afferents from the lemniscal pathway and excitatory neurons of an anatomically defined cortical column in rat vibrissal cortex. We objectively classify nine cortical cell types and quantify the number and distribution of their somata, dendrites and thalamocortical synapses. Somata and dendrites of most cell types intermingle, while thalamocortical connectivity depends strongly upon the cell type and the three-dimensional soma location of the postsynaptic neuron. Correlating dendrite morphology and thalamocortical connectivity to functional responses revealed that the lemniscal afferents can account for cell type- and location-specific subthreshold and spiking responses after passive whisker touch comparable to touch during decision-making. The results provide the first quantitative three-dimensional anatomical description of the cell type-specific lemniscal synaptic wiring diagram and elucidate structure-function relationships of this physiologically relevant pathway at single-cell resolution.