A neuron processes and transmits information by electrical and chemical signaling (synapses). The adult human brain contains roughly 100-500 trillion synapses.
In a chemical synapse, the presynaptic neuron releases a neurotransmitter that binds to receptors in
the postsynaptic cell (usually embedded in the plasma membrane).
the postsynaptic cell (usually embedded in the plasma membrane).
In an electrical synapse, pre- and postsynaptic cell membranes are connected by channels capable of
passing electrical current, causing voltage changes.
The word synapse comes from synaptein, coined from the Greek syn- (together) and haptein (to clasp).
A neuron is made up of the soma (cell body), one or more dendrites, and an axon.
The cell body of a neuron frequently gives rise to multiple dendrites, but never more than one axon.
An axon is a special cellular extension that arises from the cell body. It can (t)ravel as far as 1 meter
in humans.
in humans.
Dendrites is also a crystal that develops a multi-branching, tree-like form (like snowflake or frost
patterns on a windowpane).
Sensory neurons register touch, sound, light, and other stimuli affecting the cells of sensory organs.
Motor neurons receive signals from the brain and spinal cord, cause muscle contractions, and affect
glands.
Interneurons connect to other neurons within the brain or spinal cord.
At the majority of synapses, signals are sent from the axon of one neuron to the dendrites of another. Exceptions include neurons without dendrites, neurons without an axon, or synapses that connect axon to axon or dendrites to dendrites.
Significant areas of neurogenesis (the creation of new neurons) in adult humans are in the hippocampus (consolidates information from short- to long-term memory) and the olfactory bulb.
The Thalamus relays the actions of the Amygdala, Hippocampus and Hypothalamus and is the control center for the Limbic System.
The Amygdala is responsible for strong negative emotions like rage, fear, and aggression and
positive emotions like affection and love.
The Hippocampus forms long-term memories, interprets memories and may trigger fear and
loathing.
The Hypothalamus controls expression of emotion and can generate feelings of panic and anxiety in
some situations. It also deals with emotions like rage and pleasure.
The Thalamus relays the actions of the Amygdala, Hippocampus and Hypothalamus and is the control center for the Limbic System.
The Amygdala is responsible for strong negative emotions like rage, fear, and aggression and
positive emotions like affection and love.
The Hippocampus forms long-term memories, interprets memories and may trigger fear and
loathing.
The Hypothalamus controls expression of emotion and can generate feelings of panic and anxiety in
some situations. It also deals with emotions like rage and pleasure.
Memory is as much a reflection as it is a progression, a creation of something new.
Sources/Key Words:
Synapse
Neuron and parts -
Soma
Dendrites
Axon
Neurotransmitters
Greek/Roman ideas about memory (e.g. Plato and Aristotle)
19th century memory research
Memory drum (see Georg Elias Muller)
Ebbinghaus - Studies on Memory
Gustav Fechner - Elements of Psychophysics
Frederic C. Bartlett - Remembering: A Study in Experimental and Social Psychology
Adam Zeman - A Portrait of the Brain
