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The process begins with a wave of electrochemical excitation called an action potential traveling along the membrane of the presynaptic cell, until it reaches the synapse. The electrical depolarization of the membrane at the synapse causes channels to open that are permeable to calcium ions.
In this process, a mechanically gated ion channel makes it possible for sound, pressure, or movement to cause a change in the excitability of specialized sensory cells and sensory neurons. [9] The stimulation of a mechanoreceptor causes mechanically sensitive ion channels to open and produce a transduction current that changes the membrane ...
Metabotropic receptors, which are also called G-protein-coupled receptors, act on an ion channel through the intracellular signaling of a molecule called a G protein. Each of these channels has a specific reversal potential , E rev , and each receptor is selectively permeable to particular ions that flow either into or out of the cell in order ...
An electrochemical wave called an action potential travels along the axon of a neuron. When the wave reaches a synapse, it provokes release of a puff of neurotransmitter molecules, which bind to chemical receptor molecules located in the membrane of another neuron, on the opposite side of the synapse.
The dopamine neurons of the dopaminergic pathways synthesize and release the neurotransmitter dopamine. [2] [3] Enzymes tyrosine hydroxylase and dopa decarboxylase are required for dopamine synthesis. [4] These enzymes are both produced in the cell bodies of dopamine neurons. Dopamine is stored in the cytoplasm and vesicles in axon terminals.
The release of dopamine from the mesolimbic pathway into the nucleus accumbens regulates incentive salience (e.g. motivation and desire for rewarding stimuli) and facilitates reinforcement and reward-related motor function learning; [3] [4] [5] it may also play a role in the subjective perception of pleasure.
The light causes a conformational change in a protein called rhodopsin. [1] This conformational change sets in motion a series of molecular events that result in a reduction of the electrochemical gradient of the photoreceptor. [1] The decrease in the electrochemical gradient causes a reduction in the electrical signals going to the brain.
Additionally, outputs from the motor system can be used to modify the sensory system's response to future stimuli. [1] [2] To be useful it is necessary that sensory-motor integration be a flexible process because the properties of the world and ourselves change over time. Flexible sensorimotor integration would allow an animal the ability to ...