The ability to control the output for a given input is an important feature of neurons as it allows them to respond to a multitude of inputs via the production of a scalable output. Using compartmental models of morphologically accurate reconstructions of feline spinal motoneurons, we examined the ability for motoneurons of the feline spinal cord to alter their input-output properties via the variable activation of persistent inward currents (PICs) due to L-type Ca2+ channels located in hotspots on their dendrites. Traditionally, the activation of PICs is thought to be a threshold-dependent event reliant on the response of hotspots of these channels to a depolarization beyond a specific local voltage. Converse to this belief, we have found that the response of spinal motoneuron PICs is not exclusively voltage-dependent but is also reliant on time-varying fluctuations in membrane potential (noise). Moreover, we show that the activation of PICs in motoneurons is dependent on the location of these dendritic hotspots, which is correlated with cell size. Small motoneurons exhibited delayed activation in response to time-varying input and large motoneurons exhibited no change. The activity of the models was measured via discharge frequency which was due to the activation of dendritically located synapses either firing in a time-averaged (tonic) manner or a Poisson-distributed spike train (transient) with the same overall conductance and distribution as the tonic synapses. These results demonstrate a novel mechanism for the activation characteristics of PICs in motoneurons and, in turn, the ability for the neuron to intrinsically alter its input-output properties. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2009-11-30 14:10:24.905
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OKQ.1974/5346 |
| Date | 07 December 2009 |
| Creators | Garg, ANIRUDHA |
| Contributors | Queen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.)) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Format | 1410630 bytes, application/pdf |
| Rights | This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner. |
| Relation | Canadian theses |
Page generated in 0.0019 seconds