When an excitatory neuron is stimulated, the cell body (presynaptic neuron) creates an action potential which travels down the cell's axon to the synapse, releasing neurotransmitters. These chemical messengers stimulate the adjacent cell--the...

An increase in neuronal ACTIVATION achieved by adding together of a number of postsynaptic potentials (SPATIAL SUMMATION), or by increasing the frequency of individual SYNAPSE discharge (TEMPORAL SUMMATION). See also: EPSP/IPSP; excitatory postsynaptic...

Summation is the addition of a set of numbers; the result is their sum. The "numbers" to be summed may be natural numbers, complex numbers, matrices, or still more complicated objects. An infinite sum is a subtle procedure known as a series. Note that...

Phil Spector's attorney told jurors Thursday in closing arguments of the music producer's murder trial that prosecutors only presented "speculation instead of certainty" as to who pulled the trigger of the gun that was fired inside the mouth of actress Lana Clarkson.Defense attorney Linda Kenney-Baden,...

The defense lawyer for a Florida doctor accused of pledging allegiance to al-Qaida urged a jury Wednesday to ignore references by prosecutors to al-Qaida, Osama bin Laden and terrorism and conclude that there is no real evidence against his client.The lawyer, Ed Wilford, told jurors...

Nepal's Sherpa community held a prayer service in Katmandu on Monday for Sir Edmund Hillary, who conquered Mount Everest and helped thousands of Sherpas living in its foothills by building schools and hospitals.Monks chanted religious verses as mourners draped a khada — a sacred scarf...

Nepal's Sherpa community held a prayer service in Katmandu on Monday for Sir Edmund Hillary, who conquered Mount Everest and helped thousands of Sherpas living in its foothills by building schools and hospitals.Monks chanted religious verses as mourners draped a khada — a sacred scarf...