Biology Commons^™

Flexibility Vs Consistency: Quantifying Differences In Neuromodulatory Elicited Patterns Of Activity, Elizabeth M. Cronin

Dissertations

Central pattern generating circuits underly fundamental behaviors such as respiration or locomotion and are under the influence of neuromodulators. The presence of neuromodulators is thought to confer flexibility to these circuits to generate distinct patterns of activity to meet distinct behavioral needs. Network output flexibility can be achieved by distinct classes of neuromodulators, those which have convergent cellular actions but divergent circuit actions or by those which have divergent cellular actions but convergent circuit actions.

Both classes of neuromodulator exist in the stomatogastric nervous system of the crab Cancer borealis and influence the activity of a central pattern generating circuit …

Regulation Of Voltage-Gated K+ Currents In Motor Neurons: Activity-Dependence And Neuromodulation, Dalia Salloum

Dissertations

Neuronal output is shaped by extrinsic modulation as well as modulation of intrinsic properties of individual neurons, mediated by activity-dependent changes in the expression levels of voltage-gated ionic currents. Activity-dependent regulation of ionic currents is a mechanism by which electrical output of a neuron feeds back onto the expression of its own ion channels to alter cellular excitability in response to stimuli. Neurons alter their intrinsic properties to achieve long lasting changes involved in development, learning and memory formation and vital functions of organ systems such as locomotion and digestion. At the same time, plasticity of neuronal excitability driven by …

Biophysical Mechanisms Of Frequency-Dependence And Its Neuromodulation In Neurons In Oscillatory Networks, David Michael Fox

Dissertations

In response to oscillatory input, many isolated neurons exhibit a preferred frequency response in their voltage amplitude and phase shift. Membrane potential resonance (MPR), a maximum amplitude in a neuron’s input impedance at a non-zero frequency, captures the essential subthreshold properties of a neuron, which may provide a coordinating mechanism for organizing the activity of oscillatory neuronal networks around a given frequency. In the pyloric central pattern generator network of the crab Cancer borealis, for example, the pacemaker group pyloric dilator neurons show MPR at a frequency that is correlated with the network frequency. This dissertation uses the crab …

Determining How Stable Network Oscillations Arise From Neuronal And Synaptic Mechanisms, Diana Martinez

Dissertations

Many animal behaviors involve the generation of rhythmic patterns and movements. These rhythmic patterns are commonly mediated by neural networks that produce an oscillatory activity pattern, where different neurons maintain a relative phase relationship. This thesis examines the relationships between the cellular and synaptic properties that give rise to stable activity in the form of phase maintenance, across different frequencies in a well-suited model system, the pyloric network of the crab Cancer borealis. The pyloric network has endogenously oscillating ‘pacemaker’ neurons that inhibit ‘follower’ neurons, which in turn feed back onto the pacemaker neurons. The focus of this thesis …