A Max Planck Florida research team led by Nobel laureate Dr. Bert Sakmann and Dr. Hanno-Sebastian Meyer is conducting basic research that provides new insight into how higher brain functions such as learning, memorizing and decision making, come about at a mechanistic level. To do this they are investigating the structure and function of neuronal circuits in the cerebral cortex, the part of the brain responsible for such higher functions.
Sakmann and Meyer’s research team uses the whisker system of rodents as their model. Information from a rodent’s whiskers is transformed into electrical signals and conveyed to nerve cell networks in the cerebral cortex that are organized in cortical columns (vertical) and layers (horizontal). Input picked up by one whisker is sufficient to trigger a decision, such as whether to make a particular jump based on the width of a gap an animal encounters in pursuit of food.
“It’s a one-to-one relationship; one cortical column processes the information from one particular whisker. So if you understand what is going on in the nerve cell network that comprises a column, you understand how the animal processes whisker input and, thus, the basis of decisions such as to jump or not to jump” Meyer said, adding since columnar and horizontal organization are hallmark features of cortical organization across species, understanding the mechanisms behind the whisker system in rodents could greatly increase our understanding of how the brain works in general.
In the present study, the MPFI researchers were able to locate and obtain 3D positions of all the inhibitory neurons in complete cortical columns (about 2,200 of the 19,100 cells in a column) for the first time and to analyze their distribution. This research fills in an important gap in the current body of knowledge because while much is known about the structure of excitatory, or activating, nerve cells in the cortical columns processing sensory information, and their activity during whisker touch, much less is known about inhibitory neurons. These are the neurons that prevent activation and potentially have a substantial influence on the activity of excitatory nerve cells and that may be responsible for the inactivity of some of the excitatory neurons.