Chapter 5 (The Sensorimotor System) Flashcards
receptor cell
A specialized cell that responds to a particular energy or substance and coverts this energy into a change in the electrical potential across its membrane.
stimulus
A physical event that triggers a sensory response.
labeled lines
The concept that each nerve input to the brain reports only a particular type of information.
generator potential
A local change in the resting potential of a receptor cell that mediates between the impact of stimuli and the initiation of action potentials.
sensory transduction
The process in which a receptor cell converts the energy in a stimulus into a change in the electrical potential across its membrane.
Pacinian corpuscle (lamellated corpuscle)
A skin receptor cell type that detects vibration and pressure.
threshold
The stimulus intensity that is just adequate to trigger and action potential at the axon hillock.
Meissner’s corpuscle (tactile corpuscle)
A skin receptor cell type that detects light touch, responding especially to changes in stimuli.
Merkel’s disc
A skin receptor cell type that detects light touch, responding especially to edges and isolated points on a surface.
Ruffini corpuscle
A skin receptor cell type that detects stretching of skin.
free nerve ending
An axon that terminates in the skin and has no specialized cell associated with it. Free nerve endings detect pain and/or changes in temperature.
range franctionation
The means by which sensory systems cover a wide range of intensity values as each sensory receptor cell specializes in just one part of the overall range of intensities.
somatosensory system
A set of specialized receptors and neural mechanisms responsible for body sensations such as touch and pain.
receptive field
The stimulus region and features that affect the activity of a cell in a sensory system.
adaptation
The progressive loss of receptor sensitivity as stimulation is maintained.
phasic receptor
A receptor in which the frequency of action potentials drops rapidly as stimulation is maintained.
tonic receptor
A receptor in which the frequency of action potentials declines slowly or not at all as stimulation is maintained.
central modulation of sensory information
The process in which higher brain centers, such as the cortex and thalamus, suppress some sources of sensory information and amplify others.
dorsal column system
A somatosensory system that delivers most touch stimuli via the dorsal columns of spinal white matter to the brain.
dermatome
A strip of skin innervated by a particular spinal nerve.
thalamus
The brain regions at the top of the brainstem that trade information with the cortex.
primary sensory cortex
For a given sensory modality, the region of cortex that receives most of the information about that modality from the thalamus or, in the case of olfaction, directly from the secondary sensory neurons.
nonprimary sensory cortex
Also called secondary sensory cortex. For a given sensory modality, the cortical regions receiving direct projections from primary sensory cortex for that modality.
primary somatosensory cortex (S1)
The gyrus just posterior to the central sulcus where sensory receptors on the body surface are mapped. Primary cortex for receiving touch and pain information, in the parietal lobe.
polymodal neuron
A neuron upon which information from different sensory systems converges.
synesthesia
A condition in which stimuli in one modality evoke the involuntary experience of an additional sensation in another modality.
pain
The discomfort normally associated with tissue damage.
nociceptor
A receptor that respons to stimuli (e.g. pain or changes in temperature) that produce tissue damage or pose the threat of damage.
transient receptor potential 2 (TRP2)
A receptor, found in some free nerve endings, that opens its channel in response to rising temperatures.
A delta fiber
A moderately large, myelinated and therefore fast-conducting axon, usually transmitting pain information.
C fiber
A small, unmyelinated axon that conducts pain information slowly and adapts slowly.
anterolateral system (spinothalamic system)
A somatosensory system that carries most of the pain information from the body to the brain.
substance P
A peptide transmitter that is involved in pain transmission.
neuropathic pain
Pain that persists long after the injury that started it has healed. It is caused by damage to peripheral nerves and is often difficult to treat.
cingulate cortex
Also called cingulum. A region of medial cerebral cortex that lies dorsal to the corpus callosum.
analgesia
Absence of or reduction in pain.
endorphin
One of the three kinds of endogenous opioids.
transcutaneous electrical nerve stimulation (TENS)
The delivery of electrical pulses through electrodes attached to the skin, which excite nerves that supply the region to which pain is referred. TENS can relieve pain in some instances.
naloxone
A potent antagonist of opiates that is often administered to people who have taken drug overdoses. It binds to receptors for endogenous opioids.
placebo effect
Relief of a symptom, such as pain, that results following a treatment that is known to be ineffective or inert.
acupuncture
The insertion of needles at designated points on the skin to alleviate pain or neurological inflammation.
movement
A single relocation of a body part, usually resulting form a brief muscle contraction. (Less complex than an act.)
reflex
A simple, highly stereotyped, and unlearned response to a particular stimulus (e.g., an eye blink in response to a puff of air).
act
Complex behavior, as distinct from a simple movement.
motor plan
Also called motor program. A plan for a series of muscular contractions, established in the nervous system prior to its execution.
electromyography (EMG)
The electrical recording of muscle activity.
closed-loop motor control
A control mechanism that provides a flow of information from whatever is being controlled to the device that controls it.
open-loop motor control
A control mechanism in which feedback from the output of the system is not provided to the input control.
ballistic
Referring to a rapid muscular movement that is generally fully preprogrammed and thus not susceptible to error correction during execution.
antagonist
A muscle that counteracts the effect of another muscle.
synergist
A muscle that acts together with another muscle.
skeletal muscle
A muscle that is used for movement of the skeleton, typically under our conscious control.
striate muscle
A type of muscle that has a striped appearance; it is generally under voluntary control.
motoneuron
Also called motor neuron. A neuron that transmits neural messages to muscles (or glands).
neuromuscular junction
The region where adjoining muscle fiber meet; the point where the nerve transmits its message to the muscle fiber.
acetylcholine (ACh)
A neurotransmitter that is produced and released by parasympathetic postganglionic neurons, by motoneurons, and by neurons throughout the brain.
final common pathway
The motoneurons of the spinal cord, so called because they receive and integrate all motor signals from the brain and then direct movement accordingly.
proprioception
Body sense; information about the position and movement of the body that is sent to the brain.
muscle spindle
A muscle receptor that lies parallel to ta muscle and sends impulses to the CNS when the muscle is stretched.
intrafusal fiber
(within spindle) Any of the small muscle fibers that lie within each muscle spinal.
Golgi tendon organ
Any of the receptor within tendons that send impulses to the CNS when a muscle contracts.
stretch reflex
The contraction of a muscle in response to stretch of that muscle.
pyramidal system or corticospinal system
The motor system that includes neurons within the cerebral cortex and their axons, which form the pyramidal tract.
extrapyramidal system
A motor system that includes the basal ganglia and some closely related brainstem structures. Axons of this system pass into the spinal cord outside the pyramids of the medulla.
primary motor cortex (M1)
The apparent executive region for the initiation of movement; primarily the precentral gyrus.
precentral gyrus
The strip of frontal cortex, just in front of the central sulcus, that is crucial for motor control.
nonprimary motor cortex
Frontal lobe regions adjacent to the primary motor cortex that contribute to motor control and modulate activity of the primary motor cortex.
supplementary motor area (SMA)
A region of nonprimary motor cortex that receives input form the basal ganglia and modulates the activity of the primary motor cortex.
premotor cortex
A region of nonprimary moto cortex just anterior to the primary motor cortex.
plegia
Paralysis, the loss of the ability to move.
paresis
Muscular weakness, often the result of damage to the motor cortex.
apraxia
An impairment in the ability to carry out complex movements, even though there is no muscle paralysis.
mirror neuron
A neuron that is active both when and individual makes a particular movement and when that individual sees another individual make the same movement.
basal ganglia
A group of forebrain nuclei, including the caudate nucleus, globus pallidus, and putamen, found deep within the cerebral hemispheres.
cerebellum
A structure located at the back of the brain, dorsal to the pons, that is involved in the central regulation of movement.
ataxia
A loss of movement coordination, often caused by disease of the cerebellum.
decomposition of movement
Difficulty of movement in which gestures are broken up into individual segments instead of being executed smoothly; it is a symptom of cerebellar lesions.
Parkinson’s disease
A degenerative neurological disorder, characterized by tremors at rest, muscular rigidity, and reduction in voluntary movement, caused by a loss of dopaminergic neurons of the substantia nigra.
substantia nigra
A brainstem structure in humans that innervates the basal ganglia and is named for its dark pigmentation.
Huntington’s disease
A genetic disorder, with onset in middle age, in which the destruction of basal ganglia results in a syndrome of abrupt, involuntary writhing movements and changes in mental functioning.
