Neurons have several major compartments, including soma, dendrite, and axon. The shapes of these compartments varies depending on the functionality of the neuron:
Image from Dr. C. George Boeree. [Learn more...]
An action potential is a transient change in the membrane potential of a cell, which is generated by the flow of ions across the cell membrane. Action potential occurs in excitable cells including neurons and muscle cells. Different types of excitable cells emit action potentials with distinct shape and amplitude. Action potential is considered to play a central role in transmitting information between cells.
Neurotransmitters are chemicals that transmit signals across synaptic cleft, the gap between a neuron and a target cell. Neurotransmitters are packed into small packages name vesicles. Vesicles are located in the presynapic terminal and are release into the synaptic cleft following the opening of voltage gated calcium channels, which is generally caused by an action potential. The neurotransmitters then bind to the receptors on the postsynaptic terminal. Different neurotransmitters bind to different receptors and may cause different responses (activation or inhibition) in the target cell.
Using a microelectrode placed to the vicinity (extracellular recording) or inside a neuron (intracellular recording), one can measure the change of membrane potential of a neuron. Recoding of single neurons is an important technique in understanding neural activity. Single neuron recording has great temporal and spatial resolution; however recoding a large number of neurons simultaneously can be difficult.
A neural network is a circuit formed by a group of connected (physically or by neural signals) neurons that performs certain functionality. On a micro level, several connected neurons can perform sophisticated tasks such as mediate reflexes, process sensory information, generate locomotion and mediate learning and memory. More complex networks (macrocircuits) consist of multiple imbedded microcircuits. Macrocircuits mediate higher brain functions such as object recognition and cognition. [Learn more...]
Calcium carries out many important physiological functions. Among other functionalities, calcium influx following an action potential causes the release of neural transmitters. Fluorescence dye labeled calcium can be injected into neural tissue. The changes of fluorescence recorded from the neural tissue are proved to be directly corresponding to neural activity (i.e. action potentials). Through calcium imaging one can study the neural activity of a population of neurons simultaneously, which is critical in uncovering the function of neural networks. [Learn more...]