Meeting Abstract
S6-1.2 Saturday, Jan. 5 Computation Meets GnRH Neurons: Compartmental Modeling ROBERTS, Carson B; University of Texas at San Antonio carson.b.roberts@gmail.com
Gonadotropin-Releasing Hormone (GnRH) neurons in mice have small somata and exceedingly long dendrites. These morphological characteristics can strongly influence the electrical behavior of GnRH neurons. Thus, changes in dendritic structure can potentially influence hormone secretion. In order to study the impact of the GnRH neuronal morphology on their output, we have developed full-morphology models of GnRH neurons. We have developed models with active and with passive dendrites. For distances from the soma of over 300 microns, excitatory synapses appear unable to drive spiking with purely passive dendrites. However, when our models are tuned to match measured electrophysiology with dendrites capable of initiating and propagating action potentials, then the most distal portions of the dendrites appear more efficient than the soma at driving spiking in response to synaptic input. We have also used our models to extend the results from dynamic current clamping, an approach that does not lend itself to studying synaptic integration in dendrites. Using our compartmental models to distribute synaptic inputs along the dendrite, we show that time delays (due to propagation of post synaptic potentials arising on dendrites); alter temporal and spatial integration in GnRH neurons. Finally, we have shown that dendrite length in model GnRH neurons dramatically alters the efficacy of spike generation due to a key intrinsic phenomenon in neurosecretory neurons. Specifically, the magnitude of generated after-depolarization potentials, and their effect on repetitive firing, is strongly dependent on dendrite length, independent of whether the GnRH dendrite is active or passive. Thus, the electrical filtering properties that are seen in neurons with complex dendritic arbors are also a defining feature of firing patterns in GnRH neurons despite their simpler morphological characteristics.
