neuron

Examples of neuron in the following topics:

• Introducing the Neuron

  • The brain is made up entirely of neurons and glial cells, which are non-neuronal cells that provide structure and support for the neurons.
  • There are three primary types of neuron: sensory neurons, motor neurons, and interneurons.
  • Although some neurons do not have any dendrites, other types of neurons have multiple dendrites.
  • There are three major types of neurons: sensory neurons, motor neurons, and interneurons.
  • This diagram shows the difference between: 1) a unipolar neuron; 2) a bipolar neuron; 3) a multipolar neuron; 4) a pseudounipolar neuron.

• Neural Networks

  • Neural networks consist of a series of interconnected neurons, and serve as the interface for neurons to communicate with each other.
  • The connections between neurons form a highly complex network.
  • The method through which neurons interact with neighboring neurons usually consists of several axon terminals connecting through synapses to the dendrites on other neurons.
  • The basic neuronal function of sending signals to other cells includes the capability for neurons to exchange signals with each other.
  • Neurons interact with other neurons by sending a signal, or impulse, along their axon and across a synapse to the dendrites of a neighboring neuron.

• Stages of the Action Potential

  • A neuron affects other neurons by releasing a neurotransmitter that binds to chemical receptors.
  • However, in order for a presynaptic neuron to release a neurotransmitter to the next neuron in the chain, it must go through a series of changes in electric potential.
  • The action potential is a rapid change in polarity that moves along the nerve fiber from neuron to neuron.
  • In order for a neuron to move from resting potential to action potential—a short-term electrical change that allows an electrical signal to be passed from one neuron to another—the neuron must be stimulated by pressure, electricity, chemicals, or another form of stimuli.
  • This process of depolarization, repolarization, and recovery moves along a nerve fiber from neuron to neuron like a very fast wave.

• Network Models of Memory

  • According to network models of memory, the connections between neurons are the source of memories, and the strength of connections corresponds to how well a memory is stored.
  • Others define the unit as a neuron.
  • It is more of a metaphor than an actual biological theory, but it is very useful for understanding how neurons fire and wire with each other.
  • If these neurons stop interacting, the memory's strength weakens.
  • As neurons form connections with each other through their many dendrites, they can form complex networks.

• Introduction to the Nervous System

  • The basic unit of the nervous system is the neuron.
  • Synapses form between the neurons, allowing them to communicate to other neurons or other systems in the body.
  • The general flow of information is that the peripheral nervous system (PNS) takes in information through sensory neurons, then sends it to the central nervous system (CNS) to be processed.
  • The neurons responsible for taking information to the CNS are known as afferent neurons, while the neurons that carry the responses from the CNS to the PNS are known as efferent neurons.

• Neuroplasticity

  • Learning takes place when there is either a change in the internal structure of neurons or a heightened number of synapses between neurons.
  • "Synaptic (or neuronal or axon) pruning" refers to neurological regulatory processes that facilitate changes in neural structure by reducing the overall number of neurons and synapses, leaving more efficient synaptic configurations.
  • Generally, the number of neurons in the cerebral cortex increases until adolescence.
  • Approximately 50% of neurons present at birth do not survive until adulthood.
  • Neurons grow throughout adolescence and then are pruned down based on the connections that get the most use.

• Habituation, Sensitization, and Potentiation

  • One way that the nervous system changes is through potentiation, or the strengthening of the nerve synapses (the gaps between neurons).
  • In neural communication, a neurotransmitter is released from the axon of one neuron, crosses a synapse, and is then picked up by the dendrites of an adjacent neuron.
  • In sensitization, however, there are more pre-synaptic neurotransmitters, and the neuron itself is more excitable.
  • This image shows the way two neurons communicate by the release of the neurotransmitter from the axon, across the synapse, and into the dendrite of another neuron.
  • Communication between neurons occurs when the neurotransmitter is released from the axon on one neuron, travels across the synapse, and is taken in by the dendrite on an adjacent neuron.

• The Peripheral Nervous System (PNS)

  • The CNS includes the brain, brain stem, and spinal cord, while the PNS includes all other sensory neurons, clusters of neurons called ganglia, and connector neurons that attach to the CNS and other neurons.
  • These instructions go to neuromuscular junctions—the interfaces between neurons and muscles—for motor output.
  • Monosynaptic reflex arcs, such as the knee-jerk reflex, have only a single synapse between the sensory neuron that receives the information and the motor neuron that responds.
  • Polysynaptic reflex arcs, by contrast, have at least one interneuron between the sensory neuron and the motor neuron.
  • The human nervous system, including both the central nervous system (in red: brain, brain stem, and spinal cord) and the peripheral nervous system (in blue: all other neurons and receptors).

• Neurotransmitters

  • Neurotransmitters are chemicals that transmit signals from a neuron across a synapse to a target cell.
  • Neurotransmitters are chemicals that transmit signals from a neuron to a target cell across a synapse.
  • A neuron has a negative charge inside the cell membrane relative to the outside of the cell membrane; when stimulation occurs and the neuron reaches the threshold of excitement this polarity is reversed.
  • This allows the signal to pass through the neuron.
  • Explain the role of neurotransmitters in the communication process between neurons

• Cerebral Cortex

  • The cortex is made of layers of neurons with many inputs; these cortical neurons function like mini microprocessors or logic gates.
  • It contains glial cells, which guide neural connections, provide nutrients and myelin to neurons, and absorb extra ions and neurotransmitters.
  • Gray matter is the mass of all the cell bodies, dendrites, and synapses of neurons interlaced with one another, while white matter consists of the long, myelin-coated axons of those neurons connecting masses of gray matter to each other.