04. Definitions Flashcards
Define neuron
A single cell in the nervous system
Define nerve
a bundle of many neurons
Sensory neurons
carry information from sensory organs into the central nervous system
Motor neurons
carry messages out from the central nervous system to operate muscles and glands
Interneurons
entirely within the central nervous system. Carry messages from one set of neurons to another (vastly outnumber sensory and motor neurons)
Axon terminal
end of a branch of an axon. Shaped like a small swelling. Designed to release chemical transmitter molecules onto other neurons, motor cells or glandular cells
myelin sheath
A casing of fatty cells wrapped tightly around the axon of some neurons
Action potentials
Neural impulses; the all-or-nothing electrical bursts that begin at one end of the axon of a neuron and move along the axon to the other end
Cell membrane (encloses each neuron)
The thin, porous outer covering of a neuron or other cell that separates the cell’s intracellular fluid from extracellular fluid.
Resting potential
charge across the membrane of an inactive neuron, it is the source of electrical energy which makes an action potential possible
Synapse
Junction between axon terminal and the cell body or dendrite. The functional connection through which neural activity in the axon of one neuron influences the action of another neuron, a muscle cell, or a glandular cell.
Neurotransmitter
A chemical substance released from the axon terminal of a neuron, at a synapse, that influences the activity of another neuron, a muscle cell, or a glandular cell; also called a transmitter.
Excitory synapse
A synapse at which the neurotransmitter increases the likelihood that an action potential will occur, or increases the rate at which they are already occurring, in the neuron on which it acts
Inhibitory synapse
A synapse at which the neurotransmitter decreases the likelihood that an action potential will occur, or decreases the rate at which they are already occurring, in the neuron upon which it acts.
Neurogenesis
The creation of new neurons in which neuronal stem cells divide and replicate themselves by mitosis.
selective cell death (apoptosis)
Early developmental process in which neurons die.
mirror neurons
Neurons in the brain that become active both when the individual makes a particular motion and when the individual sees another individual making that same motion. These neurons are believed to facilitate observational learning. Found in the cerebral cortex
transcranial magnetic stimulation (TMS)
A procedure for temporarily altering the responsiveness of a localized area of the cerebral cortex by creating a magnetic field over that brain area. It is also used as a treatment for depression.
positron emission tomography (PET)
A method for visually displaying brain activity that is based upon the uptake of a radioactive form of oxygen into active areas of the brain.
functional magnetic resonance imagining (fMRI)
A method for visually displaying brain activity that is based on the fact that protons in certain molecules can be made to resonate and give off radio waves indicating relative amounts of neural activity in each portion of the brain.
cranial nerve
A nerve that extends directly from the brain.
spinal nerve
A nerve that extends directly from the spinal cord
somatosensation
The set of senses that derive from the whole body—such as from the skin, muscles, and tendons—as opposed to those senses that come from the special sensory organs of the head.
sympathetic division of the autonomic motor system
The set of motor neurons that act upon visceral muscles and glands and mediate many of the body’s responses to stressful stimulation, preparing the body for possible “fight or flight.”
parasympathetic division of the autonomic motor system
The set of motor neurons that act upon visceral muscles and glands and mediate many of the body’s regenerative, growth-promoting, and energy-conserving functions.
Spinal cord
connects spinal nerves to the brain and organises some reflexes such as walking, running, etc.
pattern generators
Networks of neurons that stimulate one another in a cyclic manner and thereby produce bursts of action potentials that wax and wane in a regular, repeating rhythm. They help to control rhythmic sequences of muscle movements, such as those involved in walking, running, flying (in birds), or swimming (in fish)
Subcortical strurctures
The lower more primitive parts of the brain
brainstem
The primitive, stalk-like portion of the brain that can be thought of as an extension of the spinal cord into the head; it consists of the medulla, pons, and midbrain
Medulla
The lowest portion of the brainstem, bounded at one end by the spinal cord and at the other by the pons. It is responsible, with the pons, for organizing reflexes more complex than spinal reflexes.
Pons
The portion of the brainstem that is bounded at its lower end by the medulla and its upper end by the midbrain and is responsible, with the medulla, for organizing reflexes more complex than spinal reflexes.
Midbrain
The upper portion of the brainstem, bounded at its lower end by the pons and at its upper end by the thalamus, that contains neural centers that organize basic movement patterns.
cerebellum
The relatively large, conspicuous, convoluted portion of the brain attached to the rear side of the brainstem; it is especially important for the coordination of rapid movements.
basal ganglia
The large masses of gray matter in the brain that lie on each side of the thalamus; they are especially important for the initiation and coordination of deliberate movements.
Thalamus
The brain structure that sits directly atop the brainstem; it functions as a sensory relay station, connecting incoming sensory tracts to special sensory areas of the cerebral cortex.
limbic system
An interconnected set of brain structures (including the amygdala and hippocampus) that form a circuit wrapped around the thalamus and basal ganglia, underneath the cerebral cortex. These structures are especially important for the regulation of emotion and motivation and are involved in the formation of long-term memories.
Amygdala
A brain structure that is part of the limbic system and is particularly important for evaluating the emotional and motivational significance of stimuli and generating emotional responses.
Hippocampus
A structure in the limbic system of the brain that is essential for encoding explicit memories for long-term storage.
occipital lobes
The rearmost lobes of the cerebral cortex, bounded in front by the temporal and parietal lobes; they contain the visual areas of the brain.
temporal lobes
The lobes of the cerebral cortex that lie in front of the occipital lobes and below the parietal and frontal lobes and that contain the auditory areas of the brain.
parietal lobes
The lobes of the cerebral cortex that lie in front of the occipital lobes, above the temporal lobes, and behind the frontal lobes; they contain the somatosensory areas of the brain.
frontal lobes
The frontmost lobes of the cerebral cortex, bounded in the rear by the parietal and temporal lobes; the frontal lobes contain the motor area and parts of the association areas involved in planning and making judgments.
primary motor area
An area in the rear part of the frontal lobe of the cerebral cortex that is directly involved in the control of movements, especially finely coordinated movements of small muscles, as in the fingers and vocal apparatus
primary sensory areas
Specialized areas of the cerebral cortex that receive input from sensory nerves and tracts by way of the relay nuclei in the thalamus. They include the visual area (in the occipital lobe), auditory area (in the temporal lobe), and somatosensory area (in the parietal lobe)
association areas
(perception, thought and decision making) Areas of the cerebral cortex that receive input from the primary or secondary sensory areas for more than one sensory modality (such as vision and hearing) and are involved in associating this input with stored memories, in the processes of perception, thought, and decision making.
premotor areas
Portions of the brain’s cerebral cortex that lie directly anterior to (in front of) the motor area. They provide neural programs for producing organized movements.
prefrontal cortex
The front-most portion of the frontal lobe of the brain’s cerebral cortex.
hormone
Any chemical substance that is secreted naturally by the body into the blood and can influence physiological processes at specific target tissues (such as the brain) and thereby influence behavior.
androgen
A category of hormones, including testosterone, which are produced by the testes in male animals and are normally thought of as “male hormones.” These hormones are also produced at lower levels by the adrenal glands, in females as well as in males.
corpus callosum
A massive bundle of axons connecting the right and left hemispheres of the higher parts of the brain, including the cerebral cortex.
aphasia
Any loss in language ability due to brain damage.
What are the two best studied aphasia’s
Broca’s (non-fluent) aphasia, Wernicke’s (fluent) aphasia
Broca’s aphasia
A specific syndrome of loss in language ability that occurs due to damage in a particular part of the brain called Broca’s area; it is characterized by telegraphic speech in which the meaning is usually clear but the small words and word endings that serve grammatical purposes are missing; also called nonfluent aphasia.
Wernicke’s aphasia
A specific syndrome of loss of language ability that occurs due to damage in a particular part of the brain called Wernicke’s area. Speech in a person with this disorder typically retains its grammatical structure but loses its meaning due to the speaker’s failure to provide meaningful content words (nouns, verbs, adjectives, and adverbs); also called fluent aphasia
long-term potentiation (LTP)
A process by which repeated activation of synapses results in strengthening of those synapses.
encephalization quotient (EQ)
Formula for evaluating the expected ratio between brain weight and body weight for animals.
