Glossery Flashcards
1
Q
adult neurogenesis
A
The creation of new neurons in the brain of an adult.
2
Q
amblyopia
A
Reduced visual acuity that is not caused by optical or retinal impairments.
3
Q
Asperger’s syndrome
A
ometimes called high-functioning autism. A syndrome characterized by difficulties in social cognitive processing; usually accompanied by strong language skills.
4
Q
autism
A
A disorder arising during childhood, characterized by social withdrawal and perseverative behavior.
5
Q
behavioral teratology
A
The study of impairments in behavior that are produced by embryonic or fetal exposure to toxic substances.
6
Q
binocular deprivation
A
Depriving both eyes of form vision, as by sealing the eyelids.
7
Q
caspases
A
A family of proteins that regulate cell death (apoptosis).
8
Q
cell adhesion molecule (CAM)
A
A protein found on the surface of a cell that guides cell migration and/or axonal pathfinding.
9
Q
cell death or apoptosis
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The developmental process during which “surplus” cells die.
10
Q
cell differentiation
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The developmental stage in which cells acquire distinctive characteristics, such as those of
11
Q
cell migration
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The movement of cells from site of origin to final location.
12
Q
cell-cell interactions
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The general process during development in which one cell affects the differentiation of other, usually neighboring, cells.
13
Q
chemoattractants
A
Compounds that attract particular classes of growth cones.
14
Q
chemorepellents
A
Compounds that repel particular classes of growth cones.
15
Q
death gene
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A gene that is expressed only when a cell becomes committed to natural cell death (apoptosis).
16
Q
Diablo
A
A protein released by mitochondria, in response to high calcium levels, that activates apoptosis.
17
Q
ectoderm
A
The outer cellular layer of the developing fetus, giving rise to the skin and the nervous system.
18
Q
embryo
A
The earliest stage in a developing animal.
19
Q
fetus
A
A developing individual after the embryo stage.
20
Q
filopodia
A
Very fine, tubular outgrowths from the growth cone.
21
Q
fragile X syndrome
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A condition that is a frequent cause of inherited intellectual disability; produced by a fragile site on the X chromosome that seems prone to breaking because the DNA there is unstable.
22
Q
growth cone
A
The growing tip of an axon or a dendrite.
23
Q
hypoxia
A
A transient lack of oxygen.
24
Q
induction
A
The process by which one set of cells influences the fate of neighboring cells, usually by secreting a chemical factor that changes gene expression in the target cells.
25
inhibitors of apoptosis proteins (IAPs)
A family of proteins that inhibit caspases and thereby stave off apoptosis.
26
lamellipodia
Sheetlike extensions of a growth cone.
27
monocular deprivation
Depriving one eye of light.
28
multiple sclerosis
terally, “many scars”; a disorder characterized by widespread degeneration of myelin.
29
nerve growth factor (NGF)
A substance that markedly affects the growth of neurons in spinal ganglia and in the ganglia of the sympathetic nervous system.
30
neural groove
n the developing embryo, the groove between the neural folds.
31
neural tube
An embryonic structure with subdivisions that correspond to the future forebrain, midbrain, and hindbrain.
32
neurogenesis
The mitotic division of nonneuronal cells to produce neurons.
33
neurotrophic factor
Also called trophic factor. A target-derived chemical that acts as if it “feeds” certain neurons to help them survive.
34
neurotrophin
A chemical that prevents neurons from dying.
35
notochord
A midline structure arising early in the embryonic development of vertebrates.
36
ocular dominance histogram
A graph that portrays the strength of response of a brain neuron to stimuli presented to either the left eye or the right eye.
37
perseverate
To continue to show a behavior repeatedly
38
phenylketonuria (PKU)
An inherited disorder of protein metabolism in which the absence of an enzyme leads to a toxic buildup of certain compounds, causing intellectual disability.
39
process outgrowth
The extensive growth of axons and dendrites.
40
radial glial cells
Glial cells that form early in development, spanning the width of the emerging cerebral hemispheres, and guide migrating neurons.
41
regulation
An adaptive response to early injury, as when developing individuals compensate for missing or injured cells.
42
retrograde degeneration
Destruction of the nerve cell body following injury to its axon.
43
senile dementia
A neurological disorder of the aged that is characterized by progressive behavioral deterioration, including personality change and profound intellectual decline. It includes, but is not limited to, Alzheimer’s disease.
44
stem cellsynapse rearrangement
A cell that is undifferentiated and therefore can take on the fate of any cell that a donor organism can produce.
45
synapse rearrangement
Also called synaptic remodeling. The loss of some synapses and the development of others; a refinement of synaptic connections that is often seen in development.
46
synaptogenesis
The establishment of synaptic connections as axons and dendrites grow.
47
ventricular zone
Also called ependymal layer. A region lining the cerebral ventricles that displays mitosis, providing neurons early in development and glial cells throughout life.
48
zygote
The fertilized egg.
49
adaptation
The progressive loss of receptor sensitivity as stimulation is maintained.
50
adequate stimulus
The type of stimulus for which a given sensory organ is particularly adapted.
51
analgesia
Absence of or reduction in pain.
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anterolateral system or spinothalamic system
A somatosensory system that carries most of the pain information from the body to the brain.
53
capsaicin
A compound synthesized by various plants to deter predators by mimicking the experience of burning.
54
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.
55
cingulate cortex
Also called cingulum. A region of medial cerebral cortex that lies dorsal to the corpus callosum.
56
coding
The rules by which action potentials in a sensory system reflect a physical stimulus.
57
congenital insensitivity to pain
The condition of being born without the ability to perceive pain.
58
dermatome
A strip of skin innervated by a particular spinal root.
59
dermis
he middle layer of skin, between the epidermis and the hypodermis.
60
dorsal column system
A somatosensory system that delivers most touch stimuli via the dorsal columns of spinal white matter to the brain.
61
endogenous opioids
A family of peptide transmitters that have been called the body’s own narcotics. The three kinds are enkephalins, endorphins, and dynorphins.
62
epidermis
The outermost layer of skin, over the dermis.
63
free nerve ending
An axon that terminates in the skin without any specialized cell associated with it and that detects pain and/or changes in temperature.
64
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.
65
hypodermis
Also called subcutaneous tissue. The innermost layer of skin, under the dermis.
66
labeled lines
The concept that each nerve input to the brain reports only a particular type of information.
67
naloxone
A potent antagonist of opiates that is often administered to people who have taken drug overdoses. It binds to receptors for endogenous opioids.
68
neuropathic pain
Pain caused by damage to peripheral nerves; often difficult to treat.
69
nociceptor
A receptor that responds to stimuli that produce tissue damage or pose the threat of damage.
70
Pacinian corpuscle
A skin receptor cell type that detects vibration.
71
periaqueductal gray
The neuronal body–rich region of the midbrain surrounding the cerebral aqueduct that connects the third and fourth ventricles; involved in pain perception.
72
polymodal
Involving several sensory modalities.
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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.
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primary somatosensory cortex (S1) or somatosensory 1
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.
75
range fractionation
A hypothesis of stimulus intensity perception stating that a wide range of intensity values can be encoded by a group of cells, each of which is a specialist for a particular range of stimulus intensities.
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receptive field
The stimulus region and features that affect the activity of a cell in a sensory system.
77
receptor cell
A specialized cell that responds to a particular energy or substance in the internal or external environment, and converts this energy into a change in the electrical potential across its membrane.
78
Ruffini's ending
A skin receptor cell type that detects stretching of the skin.
79
secondary sensory cortex or nonprimary sensory cortex
For a given sensory modality, the cortical regions receiving direct projections from primary sensory cortex for that modality.
80
secondary somatosensory cortex (S2) or somatosensory 2
The region of cortex that receives direct projections from primary somatosensory cortex.
81
sensory pathway
The chain of neural connections from sensory receptor cells to the cortex.
82
sensory receptor organ
An organ (such as the eye or ear) specialized to receive particular stimuli.
83
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.
84
somatosensory
Referring to body sensation, particularly touch and pain sensation.
85
specific nerve energies
The doctrine that the receptors and neural channels for the different senses are independent and operate in their own special ways, and can produce only one particular sensation each.
86
stimulus
A physical event that triggers a sensory response.
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synesthesia
A condition in which stimuli in one modality evoke the involuntary experience of an additional sensation in another modality.
88
thalamus
The brain regions at the top of the brainstem that trade information with the cortex.
89
threshold
The stimulus intensity that is just adequate to trigger an action potential at the axon hillock.
90
tonic receptor
A receptor in which the frequency of action potentials declines slowly or not at all as stimulation is maintained.
91
transient receptor potential 2 (TRP2)
A receptor, found in some free nerve endings, that opens its channel in response to rising temperatures.
92
transient receptor potential vanilloid type 1 (TRPV1)
Also called vanilloid receptor 1. A receptor that binds capsaicin to transmit the burning sensation from chili peppers and normally detects sudden increases in temperature.
93
amplitude
The force sound exerts per unit area, usually measured as dynes per square centimeter.
94
ampulla
An enlarged region of each semicircular canal that contains the receptor cells (hair cells) of the vestibular system.
95
amusia
A disorder characterized by the inability to discern tunes accurately.
96
anosmia
The inability to smell.
97
auditory brainstem implant (ABI)
A type of auditory prosthesis in which implanted microphones directly stimulate the auditory nuclei of the brainstem rather than the cochlea.
98
basilar membrane
A membrane in the cochlea that contains the principal structures involved in auditory transduction.
99
binaural
Pertaining to two ears.
100
Pertaining to two ears.
A hearing impairment that is related to lesions in auditory pathways or centers, including sites in the brainstem, thalamus, or cortex.
101
cilium
A hairlike extension.
102
circumvallate papillae
One of three types of small structures on the tongue, located in the back, that contain taste receptors.
103
cochlea
A snail-shaped structure in the inner ear that contains the primary receptor cells for hearing.
104
cochlear amplifier
The mechanism by which the cochlea is physically distorted by outer hair cells in order to “tune” the cochlea to be particularly sensitive to some frequencies more than others.
105
cochlear implant
An electromechanical device that detects sounds and selectively stimulates nerves in different regions of the cochlea via surgically implanted electrodes.
106
cochlear nuclei
Brainstem nuclei that receive input from auditory hair cells and send output to the superior olivary complex.
107
conduction deafness
A hearing impairment that is associated with pathology of the external-ear or middle-ear cavities.
108
cortical deafness
A hearing impairment that is caused by a fault or defect in the cortex.
109
dendritic knob
A portion of olfactory receptor cells present in the olfactory epithelium.
110
duplex theory
A theory that we localize sound by combining information about intensity differences and latency differences between the two ears.
111
external ear
The part of the ear that we readily see (the pinna) and the canal that leads to the eardrum.
112
frequency
The number of cycles per second in a sound wave; measured in hertz (Hz).
113
fungiform papillae
One of three types of small structures on the tongue, located in the front, that contain taste receptors.
114
foliate papillae
One of three types of small structures on the tongue, located along the sides, that contain taste receptors.
115
glomerulus
A complex arbor of dendrites from a group of olfactory cells.
116
gustatory system
The taste system.
117
hair cell
One of the receptor cells for hearing in the cochlea.
118
hertz (Hz)
Cycles per second, as of an auditory stimulus.
119
inferior colliculi
Paired gray matter structures of the dorsal midbrain that receive auditory information.
120
inner ear
The cochlea and vestibular apparatus.
121
inner hair cell (IHC)
One of the two types of receptor cells for hearing in the cochlea.
122
intensity differences
Perceived differences in loudness between the two ears, which can be used to localize a sound source.
123
latency differences
Differences between the two ears in the time of arrival of a sound, which can be employed by the nervous system to localize sound sources.
124
lateral-line system
A sensory system, found in many kinds of fishes and some amphibians, that informs the animal of water motion in relation to the body surface.
125
medial geniculate nuclei
Nuclei in the thalamus that receive input from the inferior colliculi and send output to the auditory cortex.
126
middle ear
The cavity between the tympanic membrane and the cochlea.
127
mitral cell
A type of cell in the olfactory bulb that conducts smell information from the glomeruli to the rest of the brain.
128
monaural
Pertaining to one ear.
129
olfactory bulb
An anterior projection of the brain that terminates in the upper nasal passages and, through small openings in the skull, provides receptors for smell.
130
olfactory epithelium
A sheet of cells, including olfactory receptors, that lines the dorsal portion of the nasal cavities and adjacent regions, including the septum that separates the left and right nasal cavities.
131
organ of Corti
A structure in the inner ear that lies on the basilar membrane of the cochlea and contains the hair cells and terminations of the auditory nerve.
132
ossicles
Three small bones (incus, malleus, and stapes) that transmit sound across the middle ear, from the tympanic membrane to the oval window.
133
ototoxic
Toxic to the ears, especially the middle or inner ear.
134
outer hair cell (OHC)
One of the two types of receptor cells for hearing in the cochlea.
135
oval window
The opening from the middle ear to the inner ear.
136
papilla
A small bump that projects from the surface of the tongue. Papillae contain most of the taste receptor cells.
137
pattern coding
Coding of information in sensory systems based on the temporal pattern of action potentials.
138
pinna
The external part of the ear.
139
pitch
A dimension of auditory experience in which sounds vary from low to high.
140
place theory
A theory of frequency discrimination stating that pitch perception depends on the place of maximal displacement of the basilar membrane produced by a sound.
141
pure tone
A tone with a single frequency of vibration.
142
round window
A membrane separating the cochlear duct from the middle-ear cavity.
143
semicircular canal
One of the three fluid-filled tubes in the inner ear that are part of the vestibular system. Each of the tubes, which are at right angles to each other, detects angular acceleration.
144
sensorineural deafness
A hearing impairment that originates from cochlear or auditory nerve lesions.
145
spectral filtering
Alteration of the amplitude of some, but not all, frequencies in a sound.
146
stereocilium
A relatively stiff hair that protrudes from a hair cell in the auditory or vestibular system.
147
tastant
A substance that can be tasted.
148
taste bud
A cluster of 50–150 cells that detects tastes. Taste buds are found in papillae.
149
taste pore
The small aperture through which tastant molecules are able to access the sensory receptors of the taste bud.
150
tectorial membrane
A membrane that sits atop the organ of Corti in the cochlear duct.
151
tensor tympani
The muscle attached to the malleus that modulates mechanical linkage to protect the delicate receptor cells of the inner ear from damaging sounds.
152
tinnitus
A sensation of noises or ringing in the ears.
153
tip link
A fine, threadlike fiber that runs along and connects the tips of stereocilia.
154
tonotopic organization
A major organizational feature in auditory systems in which neurons are arranged as an orderly map of stimulus frequency, with cells responsive to high frequencies located at a distance from those responsive to low frequencies.
155
transduction
The conversion of one form of energy to another.
156
tuning curve
A graph of the responses of a single auditory nerve fiber or neuron to sounds that vary in frequency and intensity.
157
tympanic membrane
Also called eardrum. The partition between the external ear and the middle ear.
158
ultrasound
High-frequency sound; in general, above the threshold for human hearing, at about 20,000 Hz.
159
umami
One of the five basic tastes (along with salty, sour, sweet, and bitter), probably mediated by amino acids in foods.
160
volley theory
A theory of frequency discrimination that emphasizes the relation between sound frequency and the firing pattern of nerve cells.
161
word deafness
The specific inability to hear words, although other sounds can be detected.
162
accommodation (sight)
The process of focusing by the ciliary muscles and the lens to form a sharp image on the retina.
163
bipolar cells
A class of interneurons of the retina that receive information from rods and cones and pass the information to retinal ganglion cells.
164
blind spot
The portion of the visual field from which light falls on the optic disc. Because there are no receptors in this region, light striking it cannot be seen.
165
ciliary muscle
One of the muscles that controls the shape of the lens inside the eye, focusing an image on the retina.
166
complex cortical cell
A cell in the visual cortex that responds best to a bar of a particular size and orientation anywhere within a particular area of the visual field.
167
cones
A class of photoreceptor cells in the retina that are responsible for color vision.
168
cornea
The transparent outer layer of the eye, whose curvature is fixed. It bends light rays and is primarily responsible for forming the image on the retina.
169
extraocular muscle
One of the muscles attached to the eyeball that control its position and movements.
170
fovea
The central portion of the retina, packed with the most photoreceptors and therefore the center of our gaze.
171
ganglion cells
A class of cells in the retina whose axons form the optic nerve.
172
horizontal cells
Specialized retinal cells that contact both the receptor cells and the bipolar cells.
173
three basic dimensions of light perception
hue
brightness
saturation
174
iris
The circular structure of the eye that provides an opening to form the pupil.
175
mirror neuron
A neuron that is active both when an individual makes a particular movement and when that individual sees another individual make that same movement.
176
myopia
Nearsightedness; the inability to focus the retinal image of objects that are far away.
177
occipital cortex
Also called visual cortex. The cortex of the occipital lobe of the brain.
178
ocular dominance column
A region of cortex in which one eye or the other provides a greater degree of synaptic input.
179
ocular dominance slab
A slab of visual cortex, about 0.5 mm wide, in which the neurons of all layers respond preferentially to stimulation of one eye.
180
opponent-process hypothesis
The theory that color vision depends on systems that produce opposite responses to light of different wavelengths.
181
opsin
One of the two components of photopigments in the retina.
182
optic chiasm
The point at which the two optic nerves meet.
183
optic disc
The region of the retina devoid of receptor cells because ganglion cell axons and blood vessels exit the eyeball there.
184
optic nerve
Cranial nerve II; the collection of ganglion cell axons that extend from the retina to the optic chiasm.
185
optic radiation
Axons from the lateral geniculate nucleus that terminate in the primary visual areas of the occipital cortex.
186
optic tract
The axons of retinal ganglion cells after they have passed the optic chiasm; most terminate in the lateral geniculate nucleus.
187
orientation column
A column of visual cortex that responds to rod-shaped stimuli of a particular orientation.
188
photon
A quantum of light energy.
189
photopic system
A system in the retina that operates at high levels of light, shows sensitivity to color, and involves the cones.
190
photoreceptor adaptation
The tendency of rods and cones to adjust their light sensitivity to match ambient levels of illumination.
191
photoreceptors
Neural cells in the retina that respond to light.
192
primary visual cortex (V1) or striate cortex
Also called area 17. The region of the occipital cortex where most visual information first arrives.
193
pupil
The aperture, formed by the iris, that allows light to enter the eye.
194
range fractionation
A hypothesis of stimulus intensity perception stating that a wide range of intensity values can be encoded by a group of cells, each of which is a specialist for a particular range of stimulus intensities.
195
receptive field
The stimulus region and features that affect the activity of a cell in a sensory system.
196
refraction
The bending of light rays by a change in the density of a medium, such as the cornea and the lens of the eyes.
197
retina
The receptive surface inside the eye that contains photoreceptors and other neurons.
198
retinal
One of the two components of photopigments in the retina.
199
rhodopsin
The photopigment in rods that responds to light.
200
rods
A class of light-sensitive receptor cells (photoreceptors) in the retina that are most active at low levels of light.
201
scotoma
A region of blindness caused by injury to the visual pathway or brain.
202
visual field
The whole area that you can see without moving your head or eyes.
203
wavelength
The length between two peaks in a repeated stimulus such as a wave, light, or sound.
204
acetylcholine (ACh)
A neurotransmitter produced and released by parasympathetic postganglionic neurons, by motoneurons, and by neurons throughout the brain.
205
act
Also called action pattern. Complex behavior, as distinct from a simple movement.
206
actin
A protein that, along with myosin, mediates the contraction of muscle fibers.
207
alpha motoneuron
A motoneuron that controls the main contractile fibers (extrafusal fibers) of a muscle.
208
amyotrophic lateral sclerosis (ALS)
Also called Lou Gehrig’s disease. A disease in which motoneurons and their target muscles waste away.
209
antagonist
A muscle that counteracts the effect of another muscle.
210
apraxia
An impairment in the ability to begin and execute skilled voluntary movements, even though there is no muscle paralysis.
211
ataxia
An impairment in the direction, extent, and rate of muscular movement; often caused by cerebellar pathology.
212
autoimmune disorder
A disorder caused when the immune system mistakenly attacks a person’s own body, thereby interfering with normal functioning.
213
ballistic movement
A rapid muscular movement that is often organized or programmed in the cerebellum.
214
basal ganglia
A group of forebrain nuclei, including caudate nucleus, globus pallidus, and putamen, found deep within the cerebral hemispheres.
215
central pattern generator
Neural circuitry that is responsible for generating the rhythmic pattern of a behavior such as walking.
216
cerebrocerebellum
The lowermost part of the cerebellum, consisting especially of the lateral parts of each cerebellar hemisphere.
217
closed-loop control mechanism
A control mechanism that provides a flow of information from whatever is being controlled to the device that controls it.
218
decomposition of movement
Difficulty of movement in which gestures are broken up into individual segments instead of being executed smoothly; a symptom of cerebellar lesions.
219
dystrophin
A protein that is needed for normal muscle function.
220
electromyography (EMG)
The electrical recording of muscle activity.
221
extrafusal fiber
One of the ordinary muscle fibers that lie outside the spindles and provide most of the force for muscle contraction.
222
extrapyramidal system
A motor system that includes the basal ganglia and some closely related brainstem structures.
223
fast-twitch muscle fiber
A type of striated muscle that contracts rapidly but fatigues readily.
224
final common pathway
The information-processing pathway consisting of all the motoneurons in the body. Motoneurons are known by this collective term because they receive and integrate all motor signals from the brain and then direct movement accordingly.
225
flaccid paralysis
A loss of reflexes below the level of transection of the spinal cord.
226
gamma motoneuron
Also called gamma efferent. A motor neuron that innervates the contractile tissue in a muscle spindle.
227
Golgi tendon organ
One of the receptors located in tendons that send impulses to the central nervous system when a muscle contracts.
228
huntingtin
A protein produced by a gene (called HTT) that, when containing too many trinucleotide repeats, results in Huntington’s disease in a carrier.
229
Huntington's disease
Also called Huntington’s chorea. A progressive genetic disorder characterized by abrupt, involuntary movements and profound changes in mental functioning.
230
ideational apraxia
An impairment in the ability to carry out a sequence of actions, even though each element or step can be done correctly.
231
ideomotor apraxia
The inability to carry out a simple motor activity in response to a verbal command, even though this same activity is readily performed spontaneously.
232
innervation ratio
The ratio expressing the number of muscle fibers innervated by a single motor axon.
233
intrafusal fiber
One of the small muscle fibers that lie within each muscle spindle.
234
l-dopa
The immediate precursor of the transmitter dopamine.
235
mirror neuron
A neuron that is active both when an individual makes a particular movement and when an individual sees another individual make that same movement.
236
motoneuron
Also called motor neuron. A nerve cell in the spinal cord that transmits motor messages from the spinal cord to muscles.
237
motor plan
Also called motor program. A plan for action in the nervous system.
238
motor unit
A single motor axon and all the muscle fibers that it innervates.
239
movement
A brief, unitary activity of a muscle or body part; less complex than an act.
240
muscle fiber
A collection of large cylindrical cells, making up most of a muscle, that can contract in response to neurotransmitter released from a motoneuron.
241
muscle spindle
A muscle receptor that lies parallel to a muscle and sends impulses to the central nervous system when the muscle is stretched.
242
muscular dystrophy (MD)
A disease that leads to degeneration of and functional changes in muscles
243
myasthenia gravis
A disorder characterized by a profound weakness of skeletal muscles; caused by a loss of acetylcholine receptors.
244
myosin
A protein that, along with actin, mediates the contraction of muscle fibers.
245
neuromuscular junction (NMJ)
The region where the motoneuron terminal and the adjoining muscle fiber meet; the point where the nerve transmits its message to the muscle fiber.
246
nonprimary motor cortex
Frontal lobe regions adjacent to the primary motor cortex that contribute to motor control and modulate the activity of the primary motor cortex.
247
open-loop control mechanism
A control mechanism in which feedback from the output of the system is not provided to the input control.
248
paresis
Partial paralysis.
249
Parkinson's disease
A degenerative neurological disorder, characterized by tremors at rest, muscular rigidity, and reduction in voluntary movement, that involves dopaminergic neurons of the substantia nigra.
250
plegia
Paralysis, the loss of the ability to move.
251
polioviruses
A class of viruses that destroy motoneurons of the spinal cord and brainstem.
252
premotor cortex
region of nonprimary motor cortex just anterior to the primary motor cortex.
253
primary motor cortex (M1)
The apparent executive region for the initiation of movement; primarily the precentral gyrus.
254
primary sensory ending
Also called annulospiral ending. The axon that transmits information from the central portion of a muscle spindle.
255
proprioception
Body sense; information about the position and movement of the body that is sent to the brain.
256
pyramidal system or corticospinal system
The motor system that includes neurons within the cerebral cortex and their axons, which form the pyramidal tract.
257
ramp movement
Also called smooth movement. A slow, sustained motion that is often controlled by the basal ganglia.
258
red nucleus
A brainstem structure related to motor control.
259
reflex
A simple, highly stereotyped, and unlearned response to a particular stimulus (e.g., an eye blink in response to a puff of air).
260
reticular formation
An extensive region of the brainstem (extending from the medulla through the thalamus) that is involved in arousal (waking).
261
reticulospinal tract
A tract of axons arising from the brainstem reticular formation and descending to the spinal cord to modulate movement.
262
rubrospinal tract
A tract of axons arising from the red nucleus in the midbrain and innervating neurons of the spinal cord.
263
secondary sensory ending
Also called flower spray ending. The axon that transmits information from the ends of a muscle spindle.
264
size principle
The idea that, as increasing numbers of motor neurons are recruited to produce muscle responses of increasing strength, small, low-threshold neurons are recruited first, followed by large, high-threshold neurons.
265
slow-twitch muscle fiber
A type of striated muscle fiber that contracts slowly but does not fatigue readily.
266
smooth muscle
A type of muscle fiber, as in the heart, that is controlled by the autonomic nervous system rather than by voluntary control.
267
spasticity
Markedly increased rigidity in response to forced movement of the limbs.
268
spinal animal
An animal whose spinal cord has been surgically disconnected from the brain to enable the study of behaviors that do not require brain control.
269
spinocerebellum
The uppermost part of the cerebellum, consisting mostly of the vermis and anterior lobe.
270
stretch reflex
The contraction of a muscle in response to stretch of that muscle.
271
striated muscle
A type of muscle with a striped appearance, generally under voluntary control.
272
striatum
The caudate nucleus and putamen together.
273
substantia nigra
A brainstem structure in humans that innervates the basal ganglia and is named for its dark pigmentation.
274
supplementary motor area (SMA)
A region of nonprimary motor cortex that receives input from the basal ganglia and modulates the activity of the primary motor cortex.
275
synergist
A muscle that acts together with another muscle.
276
tendon
Strong tissue that connects muscles to bone.
277
vestibulocerebellum
The middle portion of the cerebellum, sandwiched between the spinocerebellum and the cerebrocerebellum and consisting of the nodule and the flocculus.
