Abstract
One of the large, overarching questions in neuroscience is how learning is manifested in the brain. The prevailing theory is that synaptic connections between
neurons adapt their strength in response to behavioral experiences. A recently discovered
form of synaptic plasticity, behavioral timescale synaptic plasticity (BTSP), has been shown
to form place fields in CA1 pyramidal cells of the hippocampus through a single dendritic
plateau that potentiates synapses active seconds ago. Previous studies indicate that BTSP is
driven by a target signal originating from entorhinal cortex layer 3 (EC3), but this drive
diminishes late in learning as CA1 activity increases. This led to the hypothesis that
dendritic plateau potentials are a cell-specific error signal induced by a mismatch between
CA1 and EC3 activity. We hypothesize that feedback inhibition contributes to error
computation by signaling the activity of the CA1 population to the distal tuft and decreasing
plateau probability when CA1 activity matches EC3 input. In this thesis, I will present
results indicating that oriens lacunosum moleculare (OLM) cells regulate BTSP during
learning through feedback inhibition. Our results demonstrate that OLM cell activity adapts
to match CA1 activity throughout learning, and that manipulating OLM cells alters the
probability of plateau initiation and place field formation.