exam 3 Flashcards
(203 cards)
1
Q
Lower motor neurons and local circuit neurons (interneurons) in the spinal cord and brainstem
**Functions to commend for movement (reflexive or voluntary)
A
subsystem 1
2
Q
a.k.a ventral horn neurons) innervate the skeletal muscles of the head and body
A
lower motor neurons
3
Q
(a.k.a interneurons) receive sensory inputs and descending projections from upper motor neurons
A
local circuit neurons
4
Q
sensory neuron to lower motor neuron without involvement of upper motor neuron in the cortex
A
reflexive
5
Q
sensory neuron to upper motor neuron in the cortex and then to lower motor neuron
A
voluntary
6
Q
____ ___ neurons located in the** ventral horn of the spinal cord gray matter
A
lower motor
7
Q
Upper motor neurons (UMNs) in brainstem or cerebral cortex
A
Subsystem II
8
Q
____ ____ neurons send descending axons to synapse with the local circuit neurons or rarely with the lower motor neurons
A
upper motor
9
Q
___ upper motor neurons are for the initiation of voluntary movements and for skilled movements
A
cortical
10
Q
_____ upper motor neurons are for regulating muscle tone and integrating sensory inputs for postural control
A
brainstem
11
Q
Basal ganglia (a group of forebrain structures)
Prepare upper motor neuron circuits for the initiation of the voluntary
movement and suppress unwanted movement
A
Subsystem III
12
Q
cerebellum
-Detects and attenuates the difference or“motor error” between an intended movement and the actual movement (correct motor error
A
subsystem 4
13
Q
all the motor neurons innervating a single muscle are grouped together into a rod‐shaped cluster called the ____ ____ _____ for that muscle
A
motor neuron pool
14
Q
____ low motor neuron pools innervate the axial (proximal) musculature
A
medial
15
Q
more _____ pools innervate muscles located progressively more laterally in the body
A
lateral
16
Q
___ low motor neuronal pools govern postural control and receive input from brainstem upper motor neurons
A
medial
17
Q
_____ motor neuron pools that innervate the distal extremities are for the execution of skilled behavior and are governed by projections from motor cortex upper motor neurons
A
lateral
18
Q
___ Lower motor neurons innervates the extrafusal muscle fibers that actually generate the forces need for posture and movement
A
alpha
19
Q
____ lower motor neurons innervate intrafusal muscle fibers in muscle spindles and they adjust the gain of muscle stretch reflex
A
gamma
20
Q
the axon from a single α motor neuron branches within muscles to synapse on many extrafusal fibers
**ON EXAM
*ONLY CONTAINS ONE MOTOR NEURON AS OPPOSED TO MANY: MOTOR NEURON POOL
A
motor unit
21
Q
-generate small forces
-most resistant to fatigue
-Low threshold for activation and are tonically active for motor acts requiring sustained effort
A
slow motor units
22
Q
-generate large force
-easily fatigue
A
fast fatigable (FF) motor units
23
Q
-medium force
-resistant to fatigue
A
fast fatigue resistant motor units (FR)
24
Q
gradual increases in muscle tension (or force) results from the progressive recruitment of motor units in a fixed order (S → FR → FF), according to their size
-Low threshold S motor units are recruited first, then FR motor units, and finally, at the highest levels of activity, the FF motor units
A
size principle
25
The number of active motor units and their rate of ____ both increase with voluntary force
firing
26
1. The orderly recruitment of different types of motor units (size principle, S→FR→FF)
2. An increase in lower motor neuron firing frequency
Graded increases in muscle force (tension) are mediated by
27
for muscle stretch reflex, what is the Sensory signal:
muscle spindles, the sensory receptors in most muscles
28
Stretch reflex circuitry is a negative feedback loop used to maintain _____ ____ at a desired value
muscle length
29
____ motor neurons adjust the gain of the muscle stretch reflex
gamma γ
30
what is the sensory signal for authentic inhibition reflex
Golgi tendon organs, the sensory receptors in the tendon
* Afferent fibers of Golgi tendon organs terminate on collagen fibers of the tendo
31
____ ____ organs are mostly sensitive to increases in muscle tension & are relatively insensitive to passive stretch
Golgi tendon
32
when muscles contract is firing rate changing with Golgi tendon or muscle spindle
Golgi tendon
33
Autogenic inhibition reflex regulate ____ _____ to a desired level
muscle tension
34
____ ____ are sensitive to both stretch and contraction of muscle (monitor and maintain muscle length)
muscle spindle
35
____ ____ ___ are sensitive to muscle contraction but relatively insensitive to muscle stretch (monitor and maintain muscle tension)
Golgi tendon organs
36
control the timing and coordination of rhythmic movements
central pattern generators
37
are biological neural networks that produce rhythmic patterned outputs without sensory feedback and without descending upper motor neuron inputs
central pattern generators (CPGs)
38
flexor muscle contracts; the limb is flexed to leave the ground and then brought forward to begin the next stance phase
swing phase
39
extensor muscle contracts; the limb is extended and placed in contact with the ground to propel the animal forward
stance phase
40
t/f Each limb appears to have its a group of central pattern generators for the alternating flexion and extension of the limb during locomotion
FALSE; each limb has its OWN CENTRAL PATTERN GENERATORS
41
Homonymous muscle* contraction, heteronymous muscle* relax
muscle stretch reflex
42
Homonymous muscle* relax, heteronymous* muscle contraction
autogenic inhibition reflex
43
Local circuit neurons and LMNs generate rhythmic firing, flexor and extensor muscles contract alternatively
central pattern generators
44
muscle directly innervated by the sensory afferents
*Homonymous muscle
45
antagonistic muscle not innervated by the sensory afferents
*Heteronymous muscle
46
where is the upper motor neurons located
cortex and brainstem
47
location of upper motor cortex in cortex
1. primary motor cortex
2. premotor cortex
48
location of upper motor cortex in brainstem
vestibular nuclei
2. reticular formatiojn
3. superior colliculus
49
*Axons of UMNs in brainstem* course through the *anterior‐medial white matter* of the spinal cord and terminate on ____ ____ ____ (interneurons and lower motor neurons) in *both sides of the spinal cord
medical cell groups
50
Axons of UMNs in motor cortex course through the lateral white matter of the spinal cord and terminate in ____ _____ _____(interneurons and lower motor neurons) in the contralateral side of the spinal cord
lateral cell groups
51
mediate the expression of skilled voluntary movements of distal extremities (terminate on the contralateral side of the spinal cord)
UMN in motor cortex
52
govern posture and balance mechanisms of axial muscles (terminate on both sides of the spinal cord)
UMNs in brainstem
53
the axons of the upper motor neurons in the motor cortex descend and terminate in the contralateral spinal cord
Corticospinal tract
54
the axons of the upper motor neurons in the motor cortex descend and terminate in the brainstem bilaterally (bulbar refers to brainstem nuclei)
Corticobulbar tract
55
The discharges of a given UMN facilitates contractions of single or several different muscles?
several different muscles
56
the discharges of a given UMN peripheral muscle group is referred to as the ______ ______ of the UMN
muscle field
57
The UMNs in the primary motor cortex controls ______, rather than the contraction of individual muscles
movements
58
_____ movements are mapped in the primary motor cortex
purposeful
59
neurons in the primary motor cortex encode intentions for movements in ____ _____ ____ (within arm’s length)
central personal space
60
the commands to perform precise movement patterns are encoded by the concurrent discharges of a large population of UMNs
population coding
61
four interconnected frontal lobe areas that lie anterior to the primary motor cortex
premotor cortex
62
UMNs in lateral premotor cortex encode intentions (or the selection) for movements that are oriented toward ______ space (beyond arm’s length)
extrapersonal
63
a subset of UMNs in premotor cortex fire in response to not only preparation of a particular movement, but also to OBSERVATION of the particular movement being performed by others
mirror neurons
64
1. Encode movements but not muscle contraction
2. Encode intentions for movements in central personal space
3. These movements are
purposeful/pre‐programmed (behaviorally useful) movements
4. Population coding: each precise movement is encoded by the concurrent discharges of a large population of UMNs relevant to the movement
primary motor cortex
65
encode intentions for movements that are oriented toward extrapersonal space
premotor cortex
65
control the maintenance of balance and the regulation of posture by REFLEXIVE movement
vestibular complex
66
control the maintenance of balance and the regulation of posture by voluntary movement
voluntary
66
control the orientating head and eye movement
superior colliculus
66
what is the Vestibulo‐cervical reflex (VCR) pathway
1.semicircular canals
2. UMNS in MEDIAL vestibular nucleus
3. LMNs in CERVICAL spinal cord
4. neck muscles
5. regulates head pos
67
what is the Vestibulo‐spinal reflex (VSR) pathway
1. otolith organs
2. UMNs in lateral vestibular nucleus
3. LMNs in thoracic and lumbar spinal cord
4. body muscles
5. regulates posture
68
a network of circuits in the core of the brainstem that extends from the rostral midbrain to the caudal medulla
reticular formation
69
what is the corticotreticular pathway
1. UMNs in cortex
2. UMNs in reticular formation
(through reticulospinal tract)
3. LMN in thoracic/lumbar spinal cord
70
Vestibular nuclei and reticular formation both provide information to the spinal cord for posture maintenance but use ____ mechanisms
different
71
UMNs in vestibular nuclei ensure a rapid compensatory ______ ____ response to any existing postural instability
feedback reflex
72
UMNs in reticular formation initiate
_______ ______ adjustments that stabilize posture during ongoing movements
feedforward voluntary
73
Postural control during movement by _____ ____ entails an anticipatory feedforward mechanism
reticular formation
74
Vestibular nuclei generate a ____ ____ response initiated by sensory inputs that detect existing postural instability to adjust posture
feedback reflex
75
what is the cortico-collicular pathway
1. senosry inputs from visual jcortex
2. UMNs in cortex
3. UMNs in superior colliculus
(via colliculospinal tract or UMNs in reticular formation)
4. LMNs in cervical spinal cord
5. orienting head and eye movement (saccade)
76
what does the basal ganglia include
1. Corpus striatum (caudate + putamen)
2. globus pallidus (internal + external)
3. substantia nigra (pars compacta + pars reticulata
4. sub thalamic nucleus
77
what is the education of basal ganglia in control of voluntary motor movement
initiation of intended voluntary movement and suppression of unwanted movement (action selection)
78
does thalamus belong to the basal ganglia ***
no
79
what is the input zone
corpus striatum
80
The basal ganglia receives two major inputs:
1. The glutamatergic input (excitatory) from the ______ _____ (corticostriatal pathway)
2. The dopaminergic input (excitatory or inhibitory) from _____ _____ _____ _____ (nigrostriatal pathway)
1. cerebral cortex
2. substantia nigra pars compacta
81
The inputs are received by ______ ______ neurons in caudate and putamen
medium spiny
82
in caudate and putamen receive inputs from the cerebral cortex, substantia nigra pars compacta (SNc), and local circuit interneurons and send the information to globus pallidus and substantia nigra pars reticulata (output sources)
medium spiny neurons
83
Medium spiny neurons of the putamen and caudate send _____ ______ _____ to the pallidal nuclei, including the globus pallidus and the substantia nigra pars reticulata
inhibitory GABAergic projections
84
Nerve cells in the basal ganglia form a _______ circuit
disinhibitory
85
The main output of the basal ganglia is ______ (tonic inhibition) to prevent unwanted movement
inhibitory
86
When medium spiny neurons (neuron A) receive signals from cortex to command movement, the pallidal neurons (neuron B) are inhibited by activation of the medium spiny neurons, resulting ________ (free from inhibition) of the thalamic neurons (neuron C) and excitation of upper motor neurons (neuron D) to initiate movement
disinhibition
87
____ ____ of the basal ganglia activates “intended” voluntary movement
direct pathway
88
antagonizes the activity of direct pathway to terminate voluntary movement (or suppress competing unwanted movement)
indirect pathway
89
Dopaminergic inputs from SNc on to the striatal medium spiny neurons that make up the _____ and ____ GABAergic pathways
indirect ; direct
90
indirect output pathway has inhibitory D2 dopamine receptors on _____ _____ ____ (D2R‐type MSNs
medium spiny neurons
91
direct output pathway is go or stop?
go
92
Parkinson’s disease is a hypokinetic movement disorder caused by the loss of the dopaminergic neurons in *****______ _____ _____ _____
substantia nigra pars compacta
93
difficulty in expression of movement
hypokinetic
94
Loss of dopaminergic input → increased indirect pathway and diminished direct pathway → more tonic inhibion of thalamus → decreased excitation of motor cortex upper motor neurons → ____ _____ _____ *****
reduced voluntary movement
95
hyperkinetic movement disorder
* In HD, medium spiny neurons that project to the globus pallidus external
degenerate
Huntington's disease
96
expression of unwanted movement
hyperkinetic
97
Loss of inhibitory input from caudate/putamen → abnormally acvaon of globus pallidus external → diminished excitatory subthalamic output to globus pallidus internal → less tonic inhibion of thalamus → increased excitaon of motor cortex neurons → undesired choreiform (“dancelike”) movement in _____
HD
98
what are the 2 main gray matter structures of the cerebellum
1. cerebellar cortex (input zone)
2. deep cerebellar nuclei (output zone)
99
The connections between the cerebellum and other parts of the nervous system are
made by three large axonal pathways
cerebellar peduncles
100
what is the function of the cerebellum
correct motor errors for coordination of ongoing movement
101
lateral part
— Receives input INDIRECTLY from the
cerebral cortex via pontine nuclei
— Concerned with planning and execution of spatial and temporal sequences of highly skilled movements
cerebrocerebellum
102
median/paramedian zone
— Receives input directly from spinal cord
and brainstem
— Paramedian part is concerned with movements of distal muscles, and the median strip along the midline, called VERMIS, is concerned with movements of proximal muscles
spinocerebellum
103
comprises two caudal‐inferior lobes, FLOCCULUS and NODULUS
— Received input from vestibular nuclei
— Concerned with vestibulo‐ocular reflex and the regulation of movements that maintain posture and balance
vestibulocerebellum
104
an afferent pathway
— Comprises axons from neurons in the contralateral pontine nuclei of the pons
middle cerebellar peduncle o
105
an efferent pathway
— Comprises axons from neurons in the deep cerebellar nuclei projecting to upper motor neurons in cortex (through thalamic relay) and in superior colliculus of brainstem
superior cerebellar peduncle
106
contains both afferent and efferent pathways
— Afferent pathways include axons from the vestibular nuclei, the spinal cord, and several brainstem nuclei
— Efferent pathways are axons from deep cerebellar nuclei projecting to vestibular nuclei and reticular formation
inferior cerebellar peduncle
107
what are the 3 deep cerebellar nuclei?
dentate nucleus, 2 interposed nuclei, and fastigial nucleus
108
cerebral cortex provides inputs to ______
cerebrocerebellum
109
Cortical axons do not project directly to cerebellum but synapse on neurons in the ____ nuclei on the same side first
pontine nuclei
110
Pontine nuclei neurons project their axons to cross the ______ and enter the contralateral cerebrocerebellum via the middle cerebellar peduncle
midline
111
Sensory pathways of axons from vestibular nuclei project to
vestibulocerebellum
112
Proprioceptive sensory pathways project to the ______
spinocerebellum
113
stroke in the right cerebrocortex where would it be effected
left
114
stroke in the right cerebellum where would it be effected
right
115
is concerned with ipsilateral representation***
cerebellum
116
concerned with contralateral representation***
cerebral cortex
117
what would happen if there pt has a stroke affected in the inferior olive
motor + learning affected
118
Cerebrocerebellar pathways from dentate nucleus deal with ____ ____ _____
planning voluntary movements
119
Spinocerebellar pathways are directed toward upper motor neurons that govern the execution of ____
movement
120
voluntary movements of limbs
interposed nuclei
121
axial and proximal limb muscle movement
fastigial nuclei
122
what is the pathway for planning of movement
sensory cortex --> cerebrocerebellum --> dentate nucleus --> premotor cortex --> planning of movement
123
what is the pathway for execution of distal muscle movement
proprioception form brainstem/ spinal cord --> spinocerebellum --> interposed nuclei --> primary motor cortex --> execution of distal muscle movement
124
what is the pathway for the execution of axial and proximal muscle movement
proprioception from brainstem/spinal cord --> spinocerebellum --> fastigial nucleus --> brainstem nuclei (superior colliculus and reticular formation) --> execution of axial and proximal muscle movement
125
pathway for Movement of eyes, head, and neck
Vestibular sensory signal (Otolith or semicircular) --> vestibulocerebellum---> vestibularnuclei --> Movement of eyes, head, and neck
126
All input sources to cerebellum are received by ___ cell in the cerebellar cortex
purkinje cell
127
Axons from the main input sources (pontine nuclei, brainstem, spinal cord) are called
mossy fibers
128
convey main inputs
parallel fibers
129
convey modulatory inputs
climbing fibers
130
Purkinje cells are GABAergic so the output of cerebellar cortex is ______ (form cortical inhibitory loop)
inhibitory
131
Deep cerebellar nuclei neurons also receive excitatory inputs from collaterals of mossy fibers, which form the ____ ____ loop
deep excitatory
132
Function for the ____ ____ pathway is to correct motor errors for ongoing movements
parallel pathway
133
Function for the _____ _____ pathway is to encode motor learning and memory
climbing fiber
134
Cerebellar damage causes difficulty producing smooth, well‐coordinated, multi‐jointed movements, referred to as ____ ____
cerebellar ataxia
135
1. Formation of the primordial nervous system:
gastrulation, neural induction and neurulation
2. Initial formation of the major brain regions:
segmentation and patterning
3. Generation of neurons from undifferentiated precursors or stem cells: neurogenesis
4. Migration of neurons from sites of generation to their final positions
events for early brain development
136
Generation of neurons from undifferentiated precursors or stem cells
neurogenesis
137
Initial formation of the major brain regions _____ _____
segmentation and patterning
138
the single‐layered blastula is reorganized into a multilayered structure known as the gastrula
gastrulation
139
epiblasts migrate through the primitive streak to
form the three germ layers (ectoderm, mesoderm and endoderm)
Epithelial‐mesenchymal transition
140
nerve tissues
ectoderm
141
the folding process of ectoderm to develop the neural tube, including formation of notochord, induction of neuroectoderm and neural plate, and transformation of the neural plate into the neural tube
neurulation
142
____ ____cell gives rise to sensory and autonomic ganglia (the PNS)
neural crest
143
Neuroectodermal precursor cells neural tube ____ ____ cells, which have the ability to produce the full range of cell classes in mature nervous tissues, including neurons, astrocytes, and oligodendroglial cells
neural stem
143
The lateral margins of the neural plate fold inward, transforming the neural plate into a _____
tube
144
The cells at the ventral and dorsal midline of the neural tube differentiate respectively into specialized strips of neuroepithelial cells called the ______ and the _____
floor plate and roof plate
145
the floorplate and roofplate are transient structures that provide instructive signals to the developing neural tube: these structures are referred to as the _____
organizers
146
Microglia are derived from hematopoietic stem cells but NOT neural stem cells
t/f
t
147
pathway for neurulation
notochord formation --> induction of neuroectoderm + formation of neural plate --> folding of neural plate form the neural tube and specification of neural crest
148
continue to expand to give rise to the forebrain and midbrain
anterior neural fold
149
(hindbrain) becomes the medulla, pon, and cerebellum
Rhombencephalon
150
neural tube adjacent to the ____ becomes the spinal cord
somites
151
are specified by a BMP gradient at the dorsalmost limit of the neural tube and migrate away from the neural tube
neural crest cells
152
give rise to a variety of progeny, including neurons and glia of the sensory and autonomic (visceral motor) ganglia, neurons of the enteric nervous system
neural crest cells
DRG NEURONS AND SCHWANN CELLS IN PNS
153
neural tubes undergo a series of morphogenic movements that bend, fold, constrict the tube to organize into repeating units (segments) called _____
neruomeres
segmentation
154
cerebral cortex, hippocampus, basal ganglia
telencephalon (Prosencephalon)
155
thalamus and hypothalamus
diencephalon (Prosencephalon)
156
midbrain tegmentum, superior and inferior colliculi
Mesencephalon
157
The segmentation process of the neural tube in the developing brain is controlled by sequential expression of genes which encode ____ ____
transcription factor
158
Segmentation of hindbrain and spinal cord in human is controlled by expression of Hox genes (a subset of homeotic genes) which encode _____ _____ _____
homeobox transcription factors*** --- deals with segmentation
158
Sources of inductive signals for the induction and patterning of the nervous system
1) notochord
(2) floorplate
(3) roofplate
(4) neuroectoderm itself
(5) adjacent mesodermal tissues such as somites
159
molecules able to cause or determine morphogenesis
morphogens
160
the signals DOES NOT have graded effects t/f
false it does in some cases
161
signals drives cellular
differentiation, regulating the transitions between various classes of neural stem cells up to their terminal division for neurogenesis
*nuclear receptors
Retinoic acid
162
___ ___ ___ modulate precursor cell proliferation and
differentiation
fibroblast growth factor
163
FGFs are from ectoderm t/f
f from mesoderm
164
___ ____ ____ play roles in the initial specification of the neural plate (neural induction) and the subsequent differentiation of the dorsal part
-act as dorsalizing signals
bone morphogenic proteins (BMPs)
165
noggin chordin function
secreted from notochord and block BMP4 signaling
166
regulates cell movements for lengthening the neural plate and neural tube
Noncanonical pathway (a.k.a. planar cell polarity pathway)
167
influences precursor cell proliferation, adhesion, and differentiation
canonical pathway
168
can activate two distinct signaling pathways, the “canonical” and “noncanonical” pathways
Wnt ligands
169
if a baby had sonic hedgehog what can the baby not form
cerebral cortex, hippocampus, basal ganglia, thalamus, and hypothalamus (prosencephalon)
170
Mutations of Shh cause____ (failure of the prosencephalon to divide into two cerebral hemispheres)
holoprosencephaly
171
Precursor cells are located in the _____ _____ : the inner most cell layer surrounding the lumen of the neural tube, and a region of extraordinary proliferative activity during neural development
ventricular zone
172
Formation of either new stem cells (self‐renew)
postmitotic neuroblasts
173
New stem cells arise from ______ _____ of neuroectodermal cells (slow division, self‐renew)
symmetric divisions
174
Postmitotic neurons are generated from ____ ____ progenitors (transit amplifying cells) that are molecularly distinct from slowly diving radial glial stem cells
asymmetrically diving
175
_____ of a neuron: the time when a precursor/progenitor cell undergoes the final cell division and generates a neuroblast
Birthdate
176
In the cerebral cortex, most neurons of the six cortical layers are generated in an _____ ____ ___
inside‐out manner
177
the firstborn cells are eventually located in the deepest layers (layer 6) and later born neurons migrate radially, traveling through the older cells and coming to lie superficial to them (located in more superficial layers)
Inside‐out manner
178
Interaction of cell surface ligands, the _____
Interaction of cell surface ligands, the Deltas
179
cell surface receptors ---
are key regulators of neural stem cell decisions to generate either additional stem cells or postmitotic neurons
notches
180
down‐regulate expression of ____ ____ ____ ____ involved in the terminal differentiation of neural cells
bHLH neurogenic transcription factors
181
In Delta‐upregulated cell, expression of bHLH neurogenic transcription factors is also upregulated and this cell differentiates to become _____
neuroblast
182
The neighboring cells, which have Notch activated, downregulate bHLH neurogenic transcription factors and remain as ____ cells or ____ cells
stem or precursor
183
by Delta‐Notch results in “salt and pepper” developmental pattern
-by Delta‐Notch signaling determines generation of neuroblasts
lateral inhibition
184
Two kinds of signals mediate neuronal diversity or glial fate
(1) diffusible inductive signals and (2) local cell‐cell interaction signal; these signals specify cell identify by inducing of *transcriptional code* in each cell
185
Neuronal differentiation is based primarily on local ____ ____ ___ (lateral inhibition of Delta‐Notch signal) followed by distinct histories of transcriptional regulation via a “___” of transcription factors expressed in each cell, specified either by ____ (e.g.: BMP and SHH signals) and ____ ___ ___ ___ (e.g.: Delta‐Notch signal)
cell‐cell interactions; code; diffusible; local cell‐cell signals
186
Different ____ _______ factors have emerged as central factors for subsequent differentiation of distinct neural or glial fates
bHLH transcription
187
____ ____ ____ of neural crest cells at distinct anterior‐posterior locations in the neural tube; is reflected in their final locations in different parts of the body
initial positional identity
188
All neural crest cells begin as neuroepithelial cells and must undergo an
____ ____ ___ transition to downregulate expression of the adhesive genes before migration
epithelial‐to‐mesenchymal
189
what are the neural crest cells in PNS
-enteric ganglia
-DRG
-sympathetic ganglia
190
are specified by a BMP gradient at the dorsalmost limit of the neural tube and migrate away from the neural tube
neural crest cells
191
Neural crest cells give rise to a variety of progeny, including neurons and glia of the ____ and ____ (visceral motor) ganglia
sensory + autonomic
192
the final fates of the neural crest cells are critically dependent on their proper exit (____ ____ ___) + heir subsequent proper migration through terrain that provides _____ and _____ signals
initial positional identity; instructive; trophic signals
193
minority of neurons (most of them are interneurons) and glial cells in the CNS use existing axon pathways as migratory guides
***GABAergic interneurons
Tangential migration
194
The most prominent form of neuroblast migration in CNS is that guided by following the long processes of ___ ____ ___
radial glial cells
195
___ ___ ___ have two major functions in the developing CNS: (1) acting as migratory guides; (2) they are neuronal progenitor (stem) cells in the developing cortex
Radial glial cells
196
(cortical projection neurons)
radial migration
197
Forebrain interneurons are generated in the basal forebrain and migrate ______ into dorsal structures
tangentially
198
influence the detachment of neurons from the radial glia
reelin
