Dr. Narges Hosseinmardi

Associate Prof.

Department of Physiology and Neuroscience research center,

Medical School, Shahid Beheshti University of Medical Sciences.

Field potential recording Lab 

  Field potential is the electrical potential- produced by cells that was recorded by extracellular microelectrodes. It represents the integration of synaptic current within a local volume surrounding a single electrode tip. As an action potential is fired in a neuron, channels open on its membrane and the electric current of the ions that flow through them and in the resistive extracellular volume around the neuron generates local changes in extracellular voltage that can be sensed with a recording electrode. Usually, a field potential is generated by the simultaneous activation of many neurons by synaptic transmission because the extracellular signal from a single neuron is extremely small. However, in some areas of the brain, such as the hippocampus, neurons are arranged in such a way that they all receive synaptic inputs in the same area. Because these neurons are in the same orientation, the extracellular signals from synaptic excitation don't cancel out, but rather add up to give a signal that can easily be recorded with a field electrode. This extracellular signal recorded from a population of neurons is the field potential. 

   Commonly, synaptic plasticity events such as long-term potentiation (LTP), long-term depression (LTD), and Depotentiation are investigated by using a stimulation electrode and a single, monopolar field recording electrode. We focus our study of synaptic plasticity to the synaptic response of CA1 pyramidal neurons to Schaffer collateral stimulation in the hippocampus and use this technique to investigate the mechanisms involved in learning and memory, addiction and epilepsy.