chapter 1 Flashcards
action potential
The electrical signal conducted along axons (or muscle fibers) by which information is conveyed from one place to another in the nervous system
afferent
A neuron or axon that conducts action potentials from the periphery toward the central nervous system.
anterograde
Signals or impulses that travel “forward,” e.g., from the cell body to the axon terminal, from the presynaptic terminal to the postsynaptic cell, or from the CNS to the periphery.
anterograde degeneration
- also called Wallerian degeneration
- The loss of the distal portion of an axon resulting from injury to the axon.
Retrograde degeneration
Destruction of the nerve cell body following injury to its axon.
Retrograde messenger
Transmitter that is released by the post-synaptic region, and travels back across the synapse, and alters the functioning of the presynaptic neuron.
Retrograde amnesia
Difficulty in retrieving memories formed before the onset of amnesia.
anterograde amnesia
The inability to form new memories beginning with onset of a disorder.
Retrograde synapse
A synapse in which a signal (usually gas neurotransmitter) flows from the postsynaptic neuron, thus counter to the usual direction of synaptic communication.
Retrograde transmitter
A neurotransmitter that diffuses from the postsynaptic neuron back to the presynaptic neuron.
Retrograde transport
Movement of cellular substances towards the cell body from the axon terminals.
Associational systems
Neural cell circuits that are not part of the relatively defined sensory (input) and motor (output) systems; they mediate the most complex and least well defined brain functions.
Astrocytes
- One of the three major classes of glial cells found in the central nervous system
- important in regulating the ionic milieu of nerve cells and, in some cases, transmitter reuptake
- star shape glial cell with numerous processes (extensions) that run in all directions.
axon
The neuronal process that carries the action potential from the nerve cell body to a target.
axon hillock
-Point at the cell body that is the site of an action potential’s initiation.
- A cone-shaped area from the axon originates out of the cell body.
- Functionally the integration zone of the neuron.
Central nervous system
The brain and spinal cord of vertebrates (by analogy, the central nerve cord and ganglia of invertebrates).
Chemical synapses
Synapses that transmit information via the secretion of chemical signals (neurotransmitters)
cognitive neuroscience
The field of neuroscience devoted to studying and understanding cognitive functions.
Commissures
Axon tracts the cross the midline of the brain
Computational mapping
Central process of assessing and integrating multiple stimulus attributes into an orderly representation that facilitates the extraction and processing of essential information (e.g., the number and configuration of odorant molecules in order to determine the source and nature of smell).
Convergence
- Innervation of a target cell by axons from more than one neuron.
- Neural connections in which many cells send signals to a single cell
-In vision refers specifically to the convergence of both rod and cone photoreceptor cells onto retinal ganglion cells.
cortex
The superficial mantle of gray matter (a sheet-like array of nerve cells) covering the cerebral hemispheres and cerebellum, where most of the neurons in the brain are located.
Cranial nerve ganglia
- The sensory ganglia associated with the cranial nerves
- these correspond to the dorsal root ganglia of the segmental nerves of the spinal cord.
Dendrites
A neuronal process arising from the nerve cell body that receives synaptic input.
Divergence
The branching of a single axon to innervate multiple target cells.
Dorsal root ganglia (DRG)
The segmental sensory ganglia of the spinal cord; they contain the first-order neurons of the dorsal column/medial lemniscus and spinothalamic pathways.