Neurotransmission is initiated when an action potential travels down the axon and invades the presynaptic bouton, depolarizing the membrane. This depolarization immediately triggers calcium entry through voltage-gated calcium channels within the active zone of the synapse, initiating exocytosis of neurotransmitter. Ion channels that generate and sculpt the presynaptic action potential are also of fundamental importance for determining synaptic strength. Critically, the voltage waveform of the action potential determines both the opening time and driving force for calcium influx. Small changes in calcium entry have an outsized effect on the magnitude of neurotransmission as the two factors are related by a power law. Many neurological diseasesare believed to arise from pathologies of voltage-gated ion channel function, particularly many forms of juvenile seizures as well as disorders such as autism and schizophrenia. Utilizing and developing optogenetic measurements to illuminate the underpinnings of “channelopathies”at the molecular level is the ultimate goal of my work as a researcher.

I completed my undergraduate work at Reed College as a biology major. Later, I joined Dr. Patrik Rorsman's lab at the University of Oxford to study beta-cell physiology and type 2 diabetes mellitus. Currently, i am engaged in postdoctoral studies in Dr. Timothy Ryan's lab at Cornell University investigating calcium channel trafficking and synaptic physiology. I am interested in all types of cell signaling among other aspects of cell, molecular and systems biology.

Hoppa MB, Lana B, Margas W, Dolphin AC, RyanTA. α2δ expression sets presynaptic calcium channel abundance and releaseprobability. Nature. 2012 May 13;486(7401):122-5.

Hoppa MB, Jones E, Karanauskaite J, Ramracheya R, Braun M, Collins SC, Zhang Q, Clark A, Eliasson L, Genoud C, Macdonald PE, Monteith AG, Barg S, Galvanovskis J, Rorsman P. Multivesicular exocytosis in rat pancreatic beta cells. Diabetologia. 2012 Apr;55(4):1001-12

Collins SC, Hoppa MB, Walker JN, Amisten S, Abdulkhader F, Bengtsson M,Fearnside J, Ramracheya R, Toye AA, Zhang Q, Clark A, Gauguier D, Rorsman P. Progression of diet-induced diabetes in C57Bl6J mice involves functional dissociation of Ca2+ channels from secretory vesicles. Diabetes. 2010 May;59(5):1192-201.

Hoppa MB, Collins S, Ramracheya R, Hodson L, Amisten S, Zhang Q, Johnson P, Ashcroft FM, Rorsman P. Chronic palmitate exposure inhibits insulin secretion by dissociation of Ca(2+) channels from secretory granules. Cell Metabolism. 2009 Dec;10(6):455-65. 

Karanauskaite J, Hoppa MB, Braun M, Galvanovskis J, Rorsman P. Quantal ATP releasein rat beta-cells by exocytosis of insulin-containing LDCVs. Pflugers Archives2009 Jun;458(2):389-401.