Electronic Thesis and Dissertation Repository


Master of Science




Dr. Stan Leung


Long-term potentiation at the distal apical dendrites of CA1 pyramidal cells. This study investigated whether a theta burst stimulation (TBS) tetanus could induce long-term potentiation (LTP) at the distal apical dendrites via the temporoammonic (TA) pathway and the nucleus reuniens (RE)-CA1 pathway. Neuromodulation by dopamine (DA) and acetylcholine (ACh) during LTP in the TA synapse was also investigated. Extracellular potentials were recorded in hippocampal CA1 of urethane-anaesthetized mice. LTP was induced in the TA and RE-CA1 synapses. DA and ACh were also found to have neuromodulatory roles in LTP of the TA-CA1 synapse. Mice deficient in their ability to produce vesicular ACh transporter showed a reduced ability for LTP. Co-stimulation of the ventral tegmental area (VTA) during the TA tetanus did not affect LTP; DA antagonist haloperidol injected prior to the TA tetanus also did not affect LTP. However, co-stimulation of the TA pathway and VTA after haloperidol injection reduced LTP. Therefore, LTP may be induced in vivo at the distal apical dendrites, and this plasticity at the TA synapse is modulated by DA and ACh.