Presenting Author:
Michael Fiske, B.A.
Principal Investigator:
Gianmaria Maccaferri, Ph.D.
Department:
Physiology
Keywords:
Subiculum, paired recordings, epilepsy, pyramidal neuron, burst, synaptic connectivity, synapse, anatomy, dendrites, re... [Read full text]
Location:
Third Floor, Feinberg Pavilion, Northwestern Memorial Hospital
B162 - Basic Science
Paired recordings in the subiculum reveal local excitatory microcircuits
Information exchange between neurons is accomplished using sequences of action potentials that result from the integration of local microcircuits. Unraveling the connectivity of these microcircuits and how they contribute to network activity is vital for understanding how information is relayed through the brain. Interestingly, despite its role as the main output region of the hippocampus, the microcircuity of the subiculum remains understudied. Additionally, recent evidence suggests that the subiculum is involved in generating both interictal and ictal activity in epileptic patients, providing impetus to study how these microcircuits contribute to disease. Most work involving the subiculum has focused on the excitable properties of the constituent pyramidal cells, which can be classified as either regular spiking or bursting. However, little is known about the regional synaptic connectivity. We sought to physiologically and anatomically characterize the excitatory connections of the subiculum at the individual neuron level. Using paired whole cell recordings, we have shown significant levels of connectivity between the principal cells of the subiculum. Connections were observed between bursting to bursting, regular to regular, bursting to regular, and regular to bursting neurons. These synaptic connections are excitatory and mediated by AMPA receptors at resting potential. The EPSP kinetics were similar between connection patterns, but the connection probability was highest when bursting cells were the post-synaptic target. Additionally, anatomical reconstruction of recorded cells allowed us to map the location of putative synapses. Ultimately, this work will provide insight into the population dynamics of the subiculum, which is vital for understanding the physiology of the subiculum and its role in epilepsy.
