9511341 Rush Cells in the nervous system transmit information via electrical voltage signals called action potentials. A neuron can fire action potentials repetitively, and information from one neuron to another can be communicated through the frequency at which a neuron fires. One of the goals of this project is to elucidate the mechanisms by which this frequency is modulated. The membranes of most neurons contain a class of channels that allow potassium ions to flow through the membrane. These channels open rapidly following the initial voltage increase during an action potential and then close at a slower rate. This channel type gives rise to a potassium current, the A-current, which inhibits temporarily the voltage increase, and thus serves as an intrinsic mechanism by which the firing frequency is lowered. It has been hypothesized that this current can result in a broad range of firing frequencies in a single cell. Dr. Rush is a mathematician who will study the extent to which A-current modulates firing frequency in the presence of other external influences on the neuron, such as chemical signals released from other neurons. With an understanding of frequency modulation, they will extend their analysis of the A-current to other types of firing patters, namely repetitive burst of action potentials. This type of behavior has been seen in electroencephalograms (EEGs) recorded during certain phases of sleep and during seizures. It is believe that a delicate balance of the A-current and depolarizing currents is important for the generation of such bursts of voltage activity.
