Research
Our laboratory studies neuronal excitability and network dynamics in a small central pattern generating circuit, the crustacean stomatogastric ganglion (STG).
The objective is to uncover fundamental principles that govern neural processing across animal and human nervous systems. The choice of model system comes with distinct experimental advantages, as the circuits studied contain only a small number of individually identified neurons with known synaptic connectivity. Furthermore, the STG produces very regular rhythmic activity in vitro, patterns that are straightforward to quantify and assess under different experimental conditions and in response to manipulations.
The stomatogastric nervous system (STNS) consists of a series of ganglia that are involved in the control of rhythmic foregut ("stomach") movements.
The whole system as shown above can be dissected off the stomach and kept alive in an experimental dish for many hours or even days. The commissural ganglia (CoGs) and the upaired oesophageal ganglion (OG) contain descending neurons that project to the stomatogastric ganglion (STG). The STG contains two interacting groups of neurons that comprise the central pattern generating circuits for the control of the gastric mill (the internal stomach "teeth") and the pyloric filter apparatus. Most of these cells are motor neurons that project through the motor nerves to stomach muscles.
Neurons and the circuits they form produce electrical activity in a fairly complex way that cannot be understood simply on the basis of the synaptic wiring diagram. Neuronal signaling is shaped by a multitude of nonlinear dynamic properties that operate on multiple time scales. The gating properties of ion channels, short-term synaptic plasticity, neuromodulation, as well as long-term regulatory mechanisms, all contribute to activity- and time-dependent changes in excitability. We are using various electrophysiological techniques (extra- and intracellular recording, voltage clamp, current clamp, dynamic clamp, etc.), molecular biology, confocal microscopy, computational modeling and dynamical systems mathematical approaches to characterize these phenomena. We also perform cell ablations and have pioneered the use of realistic voltage waveforms in the measurement of ion channel and synaptic currents.