Impedance Tomography of Aplysia Abdominal Ganglion
Using Multichannel Micro-electrode Arrays
Collaborator: Dr. Rosalind Sadleir
For years, researchers have studied impedance changes in
neural tissue resulting from increased neuronal activity.
Here, we explore this relationship using voltages recorded
on a 60-channel micro-electrode array. Specifically, we
show that increased action potential firing events (spikes)
produced changes in the average impedance of the tissue. In
each trial, changes in the amplitude of a sinusoidal
carrier wave caused by an injected subthreshold current
were analyzed in order to determine these impedance
changes. Higher frequency data, obtained after the carrier
wave was removed, were analyzed to determine the location
and frequency of spike events. We here validate the utility
of the 60-channel micro-electrode array for this purpose
and outline future, more detailed experiments.
Schematic representation of recording and stimulation system used to study impedance changes during neural activity of an Aplysia abdominal ganglion.
Aplysia Californica and schmatic diagram of neural system. The abdominal ganlion mediates the response to tactile stimulation of the siphon or mantle shelf which produces a characteristic withdrawl response often studied for the effects of sensitization and habituation.
Example of a spike during 1.2 seconds of baseline recordings (top), during application of the 10 A current source (middle), and following application of the LMS filter (bottom panel).