Monday . . . .
Tuesday . . . . 1:00 - 2:00
Wednesday . .
Thursday. . . . 10:00 - 12:00
Friday. . . . . . Others by appt.
Biographical Information:Generating an appropriate behavior requires that neural circuits alter their output in response to changes in the internal (e.g. hungry vs. sated, stressed vs. calm) and external (e.g. food or predator nearby) environment. Changes in circuit output result largely from sensory input and input from other regions of the central nervous system (CNS). These inputs commonly converge onto descending modulatory projection neurons, which then integrate the incoming information and in turn alter the intrinsic properties of individual neurons and the strength of connections among circuit neurons. We aim to identify mechanisms of integration at the level of descending inputs and determine how the resulting activity in the projection neurons enables the selection and generation of a specific motor circuit output and thus an appropriate behavior.
In order to achieve this goal, we are using a model system called the crustacean stomatogastric nervous system. While the circuits underlying rhythmic behaviors across species have many similarities, the model system we use is unusually accessible due to the small number of neurons and their large size, enabling detailed cellular-level studies of systems-level questions. Using multiple neurophysiological approaches, pharmacology, single neuron dye-fills for anatomical tracing and for photo-ablation, we can take advantage of this small system to address our questions. For example, we can determine not only how modulating the strength of a connection between cells alters single neuron activity but also its role in altering the output of an entire motor pathway.
We are currently addressing these issues by determining how distinct circuit outputs are triggered by two extrinsic inputs (sensory and CNS), via their convergent yet distinct actions on the same two projection neurons, and the consequences for muscle targets of this circuit. We are also investigating the role of feedback pathways. Many circuits throughout all nervous systems provide feedback to their inputs. However, little is known regarding the function of circuit feedback and whether it is subject to modulation. Recently, we found that the strength of feedback synapses is indeed subject to modulation by sensory and higher order inputs. Thus, we now aim to determine the function of circuit feedback and its modulation, in regulating projection neuron responses to sensory inputs including the consequences for motor circuit output.