Test 3 (Lectures 17-25) Flashcards
1
Q
The biggest and most important relay station in the CNS
A
Thalamus
2
Q
These pathways travel from the periphery to the center
A
Ascending pathways
3
Q
These pathways travel from the center to the periphery
A
Descending pathways
4
Q
Ascending and descending pathways have 3 common features
A
- Presence of synaptic relays.
- Integration of information.
- Topographic organization
5
Q
Information can be amplified or attenuated by
A
Synaptic relays
6
Q
Topographic organization refers to
A
motor and sensory maps
7
Q
First order neurons
A
Primary afferent neurons
8
Q
Second-order neurons
A
Relays between first-order neurons and brain centers;
Typically in the spinal cord and the brain stem
9
Q
Third-order neurons
A
Commonly in thalamic nuclei.
10
Q
Afferent fibers enter the spinal cord through the
A
dorsal columns
11
Q
Pathway of the dorsal column-medial lemniscus pathways
A
Dorsal columns-spinal ganglion-medulla-thalamus-cortex
12
Q
The ascending fibers of the dorsal column pathways terminate in these medullary nuclei
A
Cuneate nucleus
Gracile nucleus
13
Q
This tract consists of the axons of neurons that lie in the dorsal and intermediate parts of the gray matter. The axons decusate and travel along the contralateral side of the spinal cord.
A
The spinothalamic tract
14
Q
Conveys the sensations of touch, pressure, temperature, and pain
A
The spinothalamic tract
15
Q
Consists of the dorsal spinocerebellar tract (DSCT), ventral spinocerebellar tracts (VSCT), rostral spinocerebellar tract (RSCT), the cuneocerebellar tract, and the spino-olivary-cerebellar tract (SOCT).
A
The spinocerebellar tracts
16
Q
Ascends in Clarke’s column. Carries proprioception information from the lower extremities. Projects onto nucleus Z and the VPL thalamus.
A
Dorsal spinocerebellar tract (DSCT)
17
Q
Carries proprioceptive information from the upper extremities
A
Cuneocerebellar tract
18
Q
Ascends laterally in the ventral horn. Carries flexor reflex afferent information from lower extremities and afferent signals.
Only active during active movements
A
Ventral spinocerebellar tract (VSCT)
19
Q
Carries flexor reflexor afferent information from upper extremities and also afferent signals.
Only active during active movements.
A
Rostral spinocerebellar tract (RSCT)
20
Q
Ascends in the ventrolateral fasciculus directly to the reticular formation
A
Spinoreticular tract
21
Q
Plays a role in controlling the sense of pain
A
Spinoreticular tract
22
Q
Consists of two major groups of axons which split into separate tracts
A
Pyramidal tract
23
Q
These axons from the pyramidal tract go down the spinal cord
A
The corticospinal tract
24
Q
These axons leave the pyramidal tract and innervate the motor nuclei of the cranial nerves
A
The corticobulbar tract
25
M1 stand for
primary motor area
26
30% from the primary motor area
30% from the premotor and supplementary motor areas
40% from the somatosensory areas
Pyramidal tract
27
Contains most of the fibers (80%) that decussate at the brain stem. Has direct projections to both interneurons and motoneurons.
Lateral corticospinal tract
28
Contains most of the fibers that do not decussate. Mostly controls axial trunk muscles.
Ventral corticospinal tract
29
Exits at the pyramids. Controls cranial nerves (facial muscles, articular, etc.)
Cotricobulbar tract
30
Originates in the red nucleus
The rubrospinal tract
31
Receives input from the motor cortex, the cerebellum, and the olives.
The rubrospinal tract
32
Decussates at the midbrain and descends adjacent to the lateral CST. Has projections onto the olives.
The rubrospinal tract
33
Is suspected of being of major importance for motor control
The rubrospinal tract
34
Is part of the cerebellum-red nucleus-olive-cerebellum loop
The rubrospinal tract
35
Receives inputs from the cerebellum and the labyrinth.
The vestibulospinal tracts
36
Rises from the neurons in Deiter's (lateral vestibular) nucleus.
Lateral vestibulospinal tract
37
Originates in the medial vestibular nucleus
Medial vestibulospinal tract
38
Descends ipsilaterally to the lumbar level. Makes connections with interneurons.
Lateral VST
39
Plays a role in the control of posture
Lateral VST
40
Descends ipsilaterally to the mid-thoracic level. Makes connections with interneurons.
Medial VST
41
Plays a role in postural control through control of head position
Medial VST
42
Travels ipsilaterally to spinal interneurons. Has mostly inhibitory effects.
Medial reticulospinal tract
43
Travels to interneurons in the ventral spinal cord. Provides postural control of the proximal extensor muscles.
Lateral reticulospinal tract
44
Suspected of bringing about the startle reaction
The reticulospinal tract
45
Comes from neurons in the superior colliculus.
The tectospinal tract
46
Decussates and plays a role in motor reactions to visual stimuli by controlling head orientation to visual stimuli through control of the neck muscles.
The tectospinal tract
47
Comes from neurons in the midbrain.
| Its function is a mystery.
The interstitiospinal tract
48
How many cranial nerves are there?
12
49
Sense of smell
Olfactory nerve (cranial nerve I)
50
Information from the retina
Optic nerve (cranial nerve II)
51
Motor control of the oculomotor muscles, pupillary reflexes
| cranial nerve III
Oculomotor nerve (cranial nerve III)
52
Motor control of the oculomotor muscles
| cranial nerve IV
Trochlear (cranial nerve IV)
53
Control of jaw movements during speech; sensory information from teeth
Trigeminal nerve (cranial nerve V)
54
Motor control of the oculomotor muscles
| cranial nerve VI
Abducens (cranial nerve VI)
55
Control of facial muscles, including lip and eyelid movments; minimal sensory function.
Paralysis of the nerve is known as Bell's palsy
Facial nerve (cranial nerve VII)
56
Hearing and balance
Vestibulocochlear nerve (cranial nerve VIII)
57
Motor control of the pharynx; control of speech
Glossopharyngeal nerve (cranial nerve IX)
58
Control of autonomic functions of the whole body
| Wandering nerve
Vagus nerve (cranial nerve X)
59
Innervation of trapezius, helps control head movements
Spinal accessory nerve (cranial nerve XI)
60
Control of tongue movements; speech
Hypoglossal nerve (cranial nerve XII)
61
Soul is responsible for thinking (cognition); body obeys soul and laws of nature. Considered mind a uniquely human feature independent of the body. Theorized by Descartes.
Dualism
62
All features of human behavior are reflected in measurable physical properties of neurons and synapses (everything can be measured, including specific memory sites)
Reductionism
63
Function of a complex system is an emergent property of all the system elements and cannot be assigned to certain changes in neurons and synapses. The mind is an emergent part of the body. not a separate feature.
Neodualism
64
Semantic and episodic memories; facts and events
Declarative memories
65
Declarative memories are stored in
Hippocampus, medial temporal lobe, diencephalon
66
Procedural, non-associative, and associative memories
Nondeclarative memories
67
Habituation and sensitization
Non-associative learning
68
Skills, habits
Nondeclarative memories
69
Nondeclarative memories are stored in
Amygdala, cerebellum, basal ganglia, cortex
70
Learning not to respond to a stimulus following its multiple presentations (usually, when it is not very meaningful)
Habituation
71
The restoration or recovery of a habituated response (usually requires a new, strong stimulus)
Dishabituation
72
Learning to respond to smaller magnitudes of a stimulus (usually, if it is very meaningful)
Sensitization
73
Non-associative learning and associative learning
Implicit memory
74
Associative learning is a subtype of
Non-declarative memory
75
Involves creating a relationship between two stimuli
Associative learning
76
Generally studied in animals and involves food as a stimulus/reward
Associative learning
77
Example of associative learning
Conditioning
78
Associating a response with a stimulus based on repetitive presentations
Classical conditioning
79
Ringing a bell is associated with getting food; the animal has no initiative
Classical conditioning
80
Considered a conditional reflex, not an inborn reflex
Classical conditioning
81
Searching for an action that leads to a desired consequence; active exploration.
Operant conditioning
82
Even monosynaptic reflexes can show this
Operant conditioning
83
Requires thousands of repetitions
Operant conditioning
84
Example of non-declarative memory
Motor skills and motor learning
85
Typically involves a motor program
Motor skills and motor learning
86
Four stages of memory
Encoding
Storage
Consolidation
Retrieval
87
Putting an event into an internal code
Encoding
88
Maintaining the code over time
Storage
89
The process that makes the temporarily stored and still liable information more stable
Consolidation
90
Using a key (intrinsic or extrinsic) to recover the code/event
Retrieval
91
Typically an acoustic, visual, or somatosensory code
Encoding
92
Limited capacity (7 +/- 2 "pieces"); decay; followed by consolidation or loss of memory. Effectiveness is typically a few minutes or hour
Storage
93
Allocates attentional resources to the verbal and visuospatial subsystems, also monitors, manipulates, and updates stored memory representations.
Executive control process
94
Can be consolidated into long-term memory
Short-term memory
95
Processing a sensory stimulus may lead to creating a short-term memory trace in parallel with producing an effector (motor).
Memory consolidation
96
Pros for synapses serve as the site for memories
The phenomena of long term potentiation and long term depression in the cerebellum and hippocampus.
97
Cons against synapses serving as memory sites
Disposable synapses don't exist
| Long term potentiation is too short according to animal studies
98
Lashley says that
each neuron takes part in many memories
99
partial loss of memory
Amnesia
100
Causes of amnesia
Brian injury, stroke, encephalitis, electric shock, etc.
101
Types of amnesia
Anterograde
| Retrograde
102
Affects the ability to recollect events that occurred after an injury
Anterograde amnesia
103
Affects the ability to recollect events that occurred prior to an injury
Retrograde amnesia
104
Caused by chronic alcohol abuse or thiamine deficiency
Korsakoff's syndrome
105
Characterized by defective retrieval of memories. Partial cues or prompts cause the brain to fill in the gaps in whatever way it can
Korsakoff's syndrome
106
Type of progressive dementia that causes problems with memory, thinking, and behavior.
Alzheimer's
107
Earliest sign is inability to remember newly learned things
Alzheimer's
108
Patients with lesions in this brain structure will solve the same puzzle over and over as if it was a new puzzle every time
Hippocampus
109
Important in storing declarative memory
Hippocampus
110
Crucial for transferring short term memories to long term memories
Hippocampus and medial temporal lobe
111
Long hypothesized to store long-term effects of training, specifically motor memories
Cerebellum
112
Likely occurs in interneurons controlling reflex arcs
Spinal memory
113
An engineer would find human movements to be suboptimal. Why?
Because muscles fatigue, get injured, the electromechanical delay, etc.
114
Human movements are produced by force generating structures called
Muscle
115
Muscles are relatively ____ in their actions.
slow
116
Muscles interact with the nervous system in a _____ fashion.
non-linear
117
The body is highly
adaptable
118
The requirements of most everyday tasks
To move a limb or the whole body to a particular point in space
119
Movements requires two things:
Rotation at one or several joints
| Force production using the muscular system
120
Finding a joint configuration corresponding to the location of the endpoint. Considers different joints, different joint actions, sequencing of actions, etc.
Inverse kinematics
121
Finding patterns of joint torques.
Inverse dynamics
122
The CNS produces active changes in _____ _____ by sending signals to the muscle
muscle force
123
Depends on neural signals sent to the muscles and external loading conditions
Force
124
Computes signals sent to spinal neurons and considers the activation of alpha motoneurons through reflex pathways
CNS
125
Developed by Schmidt in the 1970s
Generalized motor program
126
Brain stores "movement formulas" expressed as mechanical patterns associated with particular actions
Generalized motor program
127
Has support from experiments which demonstrate invariant timing patterns when movement is sped up or slowed down
Generalized motor program
128
These can be changed in a program
Parameters
129
Stay the same in the same motor program; is different in different programs
Invariant features
130
In this model, the CNS computes control signals that produce adequate force patterns
Internal models
131
The 2 factors the brain has to account for in the internal model:
1: All the steps involved in transforming neural signals into mechanical variables.
2: Time delays in information transmission from the brain to muscle and from peripheral receptors to the brain
132
These internal models is similar to feedback
Inverse models
133
These internal models is similar to feedforward
Direct models
134
Compute descending neural commands based on a desired mechanical effect
Inverse models
135
Computations are made from sensory signals that deliver some outdated information
Inverse models
136
Computed signals from the brain reach muscles after substantial time delay
Inverse models
137
Compute the effects of current neural commands on the state of the periphery
Direct models
138
Takes into account possible changes in muscles and limbs due to time delays in the neural pathways
Direct models
139
The common explanation for how internal models work is
The internal model is quickly updated (recomputed) based on feedback signals
140
The problem with internal models
The brain does not have an amazingly quick and accurate computational process.
141
One signal, one response
Simple reaction
142
Different signals with specific responses to each signal
Choice reaction
143
If an agonist-antagonist pair of muscles are relaxed, one will shorten and one will lengthen as the joint moves to a new position. This would require active force production to prevent the joint from moving back to the original position. However, neural structures can modify the spring like properties of muscles. This is known as the ______.
Equilibrium Point Hypothesis
144
The central control structures shift muscle activation thresholds and readdress posture stabilizing mechanisms to a new posture. These mechanisms turn from posture stabilizing into movement producing. This is an example of:
A dynamic system
145
Has the ability to resolve the posture-movement paradox
Equilibrium point hypothesis
146
During active movement, neural commands re-address afferent signals from proprioceptors to the new posture. These signals allow the movement to occur and are used to stabilize the new posture.
Central control structures shift physiological variables associated with muscle activation thresholds and re-address posture stabilizing mechanims to a new posture.
Principle of reafference
147
The central controller finds a unique solution each time a problem emerges
Redundancy
148
Central controller facilitates groups of equally acceptable solutions rather than unique solutions
Abundancy
149
A common approach to the problem of motor redundancy
Optimization
150
Allows selection of a unique solution to a problem
Optimization
151
Particular function of a system's performance the controller tries to keep optimized, commonly at a minimum or maximum value
Cost function
152
Time derivative of acceleration
Jerk
153
Leads to smooth trajectories with a bell shaped velocity profile and a symmetrical double-peaked acceleration
Minimum jerk criterion
154
Bernstein's kinematic study of professional blacksmiths found more variability in the _____ than in the _______.
joints; trajectory of the hammer
155
Multiple possibilities
Abundancy
156
Instead of searching for unique solutions, the controller can facilitate similar solutions that can solve the task
Abundancy
157
A task specific organization of elements, while each element within a structural unit is itself a structural unit at a different level of the analysis
Structural unit
158
Purposes of structural units
Synergies
159
Extrinsic patterns reflecting a synergy under particular external conditions
Behaviors
160
Based on a structural unit that consists of a neural network uniting different extremities.
Locomotion
161
Motion of the arms or legs is based on a structural unit comprising
individual joint rotations
162
Each joint rotation is based on a structural unit involving
muscle actions as elements
163
Each muscle is a structural unit of it
motor units
164
What would happen if the far motor neuron in a muscle stopped firing?
Muscle force drops, the muscle lengthens.
As the muscle lengthens, muscle force increases due to an increased activation of the remaining motor neurons due to the tonic stretch reflex.
165
If two fingers work in parallel to produce 20 N of force, the could accomplish this in three different ways
25/75%
50/50%
75/25%
166
Controller do not prescribe what each element should do in a synergy, they only set the overall task and organize feedback loops to assure task stability. This is opposite of an internal mode.
Hierarchy of a structural unit
167
According to the uncontrolled manifold hypothesis, the controller acts in
a space of elemental variables
168
In the uncontrolled manifold hypothesis, a subspace is termed
the uncontrolled manifold
169
These variables do not have to be controlled within the sub-space
Elemental variables
170
Within space, the controller selects a subspace corresponding to a desired value of a performance variable of the whole system.
The controller then tries to limit variability of elemental variables outside the subspace while allowing relatively large variability within the subspace
Uncontrolled manifold hypothesis
171
This is within the uncontrolled manifold. Does not affect performance variables and therefore may be relatively large
Good variability
172
This is outside the uncontrolled manifold. Changes important performance variables and needs to be kept low
Bad variability
173
An inverted pendulum in the field of gravity
Posture
174
Maintenance of body alignment and spatial orientation in order to put the body in a position to enable effective movement
Postural control
175
A position that is resistant to disturbance or returns to its normal state after disturbance
Stability
176
Sources of problems with postural control
High center of mass/center of gravity
Multiple joints
Small support area (1 square foot)
177
The location of the center of gravity of a human being in the normal standing position varies with
body build, age, and sex
178
Female's center of gravity is ___ of standing height.
55%
179
Male's center of gravity is ___ of standing height.
57%
180
The center of gravity can be considered to be almost directly over the center of pressure when
in quiet standing
181
The point at which the force vector for ground reaction force is applied
Center of pressure
182
Sway increases under these conditions:
Closed eyes
Standing on a narrow support
Age, disorder
183
Sway decreases under these conditions:
Light finger touch (to virtually any part of the body)
| Holding an object connected to the external world
184
Center of gravity must remain within the base of support in order to maintain
equilibrium
185
It is easier to maintain center of gravity with a
larger base of support
186
Migration of the reference point, with respect to which equilibrium is instantly maintained
Rambling
187
Likely a reflection of a central search process (supraspinal process)
Rambling
188
Likely a reflection of the mechanical properties of the effectors and reflex loops (subspinal process)
Trembling
189
The body oscillates about a reference point, while
the reference point migrates for reasons that are not well understood.
190
One of the least prominent senses
Sense of balance
191
Are innvervated by the peripheral ends of bipolar sensory neurons in the ampullary nerve
Vestibular hair cells
192
The ampullary crest is covered by a gelatinous, diaphragm-like mass called the
cupula
193
The structure that aids in balance
Vestibular apparatus
194
Sensitive to angular acceleration of the head
Semicircular canals
195
The fluid in the semicircular canals move when the head
rotates
196
Action potentials are generated when fluid acts on the ____ and displace hair cells.
cupula
197
Sensitive to linear acceleration of the head
Otoliths
198
The zone in the utricle where the floor is thickened and contains hair receptors
Macula
199
Is covered with a gelatinous substance containing crystals of calcium carbonate (otoliths)
Macula
200
Otoliths deform the floor and bend the hair cells which generate action potentials when
The head is tilted or accelerated in a certain direction
201
Vestibular nuclei occupy a large part of the
medulla
202
Innervated by the 8th cranial nerve via Scarpa's ganglion. Neurons here are bipolar.
Vestibular apparatus
203
What is necessary to maintain posture?
1. Adequate perception of a reference point or reference vertical.
2. Timely generation of appropriate muscle torques.
3. Control of posture under external and internal perturbations.
204
There are many different sources of
postural perturbations
205
Some of these are caused by our own movements
postural perturbations
206
Many voluntary movements are associated with changes in the activity of postural muscles, even
before the movement begins
207
These minimize perturbations to vertical posture
Anticipatory postural adjustments (APAs)
208
Time delay of anticipatory postural adjustments
< 0 ms
209
Time delay of muscle elasticity
0 ms
210
Time delay of monosynaptic reflexes
30 ms
211
Time delay of polysynaptic reflexes
50 ms
212
Time delay of preprogrammed reactions
70 ms
213
Time delay of voluntary action
150 ms
214
A fast arm movement by a standing person is a source of postural perturbation because of
joint coupling
215
A fast shoulder flexion creates reactive torques that try to tilt the body
backward
216
Are generated prior to a perturbation
Anticipatory postural adjustments
217
If perturbations are predictable,
it is easier to anticipate
218
Perturbation are typically associated with
an action by the person
219
Produces forces/torques acting against the expected perturbation
Anticipatory postural adjustments
220
Anticipatory postural adjustments are always
suboptimal
221
Slow forward or backward translations lead to this in young participants:
Ankle strategy
222
Slow forward or backward translations lead to this in older subjects:
Hip strategy
223
When standing on a narrow surface or during fast translations, young participants employ
Hip strategy
224
Leads to larger horizontal displacement of the center of mass
Ankle movement
225
Is more effective, but increases the risk
Ankle strategy
226
Is a task-specific organization of many elements (elemental variables) by a controller
Synergy
227
Its purpose is to stabilize a value or a pattern of an important performance variable or of several variables.
Postural synergies
228
A combination of control signals sent to several muscles to ensure stability of a limb or whole body either in anticipation of a predictable postural perturbation or in response to an actual perturbation
Postural synergy
229
In the two pockets hypothesis of brain pockets, motor commands are split into action and postural commands are done
separately, but simultaneously
230
In the one pocket hypothesis of brain pockets, motor commands are done
at the same time
231
Are the source of kinesthetic information
Proprioceptors
232
Awareness of the position of the body segments in space and in relation to each other
Kinesthesia
233
Allows us to perform movements without continuous visual control, to adjust patterns of control variables, and perform tasks requiring multi-limb coordination
Kinesthesia
234
Under isometric conditions, muscle activation increases lead to an increase in the gamma-system activity. This leads to an increase in the firing level of muscle spindle sensory endings. How might the CNS interpret this?
The CNS may interpret this as a joint motion corresponding to an increase in muscle length.
235
Why would one possibly see the same average firing level of muscle spindle sensory endings at different joint positions under non-isometric conditions?
An increase in muscle activation level leads to muscle shortening. This leads to an increase in gamma-system activity.
236
How are muscle fibers shortened and tendons stretched under isometric conditions?
Under isometric conditions, an increase in muscle activation level leads to an increase in muscle fiber stiffness.
237
The sum of products of muscle forces and corresponding lever arms
Joint torque
238
Leads to a change in the lever arm
Joint movement
239
Is dependent on both muscle force and joint angle
Joint torque
240
Why would a system within the human body appear to be imperfectly designed?
Something has probably been overlooked or misinterpreted
241
Accurate kinesthetic information is likely to emerge through participation of signals from
various sensors
242
A copy of a voluntary motor command
An efferent copy
243
Efferent copies participate in deciphering the mixed information from peripheral receptors. This helps to
reduce the cognitive load
244
Spindle activity is dependent on
gamma activity
245
Gamma activity is dependent on
the current descending motor command
246
Is based on signals from proprioceptors
Kinesthetic perception
247
Information provided by each proprioceptor is
insufficient to extract values of joint angles or torques
248
Combined information from several proprioceptors is
sufficient to extract values of joint angles or torques
249
Is an activity leading to a change in the location of the body in external space
Locomotion
250
4 important characteristics of locomotion
Velocity
Stride length
Relation between the support and swing phases
Relative timing of the extremities (gait)
251
The two different views of locomotion
Motor programming
| Dynamic systems
252
Central pattern generator is part of
motor programming
253
Hypothetical neural structure that generates neural activity, activity is transformed into rhythmic muscle activity, leading to rhythmic behavior
Central pattern generator
254
Rhythmicity of locomotion is caused by interaction of neural activity and the periphery
Dynamic systems
255
According to Sherrington, locomotion was a pattern produced by
alternating reflex responses
256
According to Sherrington, voluntary movement is a result of
modulating reflexes
257
This view has been shown to be false
Sherrington's view
258
Rhythmic motor pattern of locomotion was produced by a special neural network (CPG) that could produce activity even in the absence of reflexes
Brown's view
259
This view is still supported today
Brown's view
260
A hypothetical structure in the CNS that can generate patterned (rhythmical) activity
Central pattern generator (CPG)
261
Can be driven by "higher" centers as well as by peripheral information
Central pattern generator
262
4 problems with the CPG
Undefined "higher center"
Peripheral input could change the pattern of gait activity
Difficult to determine if changes in gait are produced by higher center or peripheral input
Many important variables lack a good definition
263
Leads to rhythmic movements of the cat's limbs
Stimulation of the cat's reticular formation
264
Different levels of stimulation to the reticular formation could
slow down or speed up locomotion
265
Found in the upper cervical region of the spinal cord
Locomotor strip
266
Electrical stimulation of certain brain (and spinal) areas can induce
Locomotion
267
Changes with the strength of the stimulation
Gait
268
Can also be induced by treadmill motion and by intraspinal drugs (GABA)
Locomotion and gait changes
| fictive locomotion
269
How many central pattern generators are likely contained in the spinal cord
1, 2, or even 4 CPGs
270
Can be driven by descending and ascending signals
Central pattern generator
271
Does not necessarily require a signal
Central pattern generator
272
Can produce different gaits
Central pattern generator
273
Better explains issues of stability particularly in medial and lateral directions
Dynamic systems approach
274
System for movement production including the CNS, effectors and the connections with the CNS, and the environmental forces and sources of sensory information, can be modeled with complex, non-linear equations
Dynamic systems approach
275
Success in describing inter-limb and inter-joint coordination
Dynamic systems approach
276
The equations developed by this approach can describe these rather complex changes in behavior
Dynamic systems approach
277
Lacks coordination; all details of coordination are delegated by the ultimate controller
Motor programming
278
Coordination can emerge without supreme problem solver, but it lacks control
Dynamic systems
279
All elements are linked, and there is an upper neural structure that can send descending signals
Combination of the different approaches to locomotion
280
The approaches to locomotion
Motor programming
| Dynamic systems
281
Step initiation
1. The stepping foot must be unloaded.
| 2. The body must start moving in the direction of the planned step.
282
When the stepping foot is unloaded,
body weight is shifted to the supporting foot.
283
What happens when the body starts moving in the direction of the planned step?
1. Center of pressure shift starts 0.5 seconds before the stepping leg leaves the ground.
2. In the M/L direction, COP shifts toward the stepping foot and then back toward the supporting foot.
3. COP also shifts backward in the A/P direction.
4. This backwards shift creates a moment of reactive force that rotates the body forward.
284
Occurs during locomotion
Corrective stumbling reaction
285
Can be induced by a mechanical stimulus to the foot
Corrective stumbling reaction
286
Represents a complex pattern of EMG changes
Corrective stumbling reaction
287
Leads to a quick step over the obstacle
Corrective stumbling reaction
288
What are some general changes in the neuromotor system that occur due to aging?
```
Strength decline
Longer reaction time
Impaired control of posture/gait
Impaired accurate control of force/movement
Unintended force production
```
289
Behavioral changes with aging
Weakness
Slowness
Higher variability
Larger postural sway; delayed APAs
290
With aging, strength tends to
decline
291
With aging, reaction times tend to
increase
292
With aging, control of posture and gait becomes
impaired
293
With aging, the accurate control of force and movement becomes
impaired
294
As age increases, there is more ____ force production.
unintended
295
With age, muscles become
weaker
296
With age, movement becomes
slower
297
With age, joint variability is
higher
298
With age, postural sway becomes
larger
299
With age, anticipatory postural adjustments are
delayed
300
With age, antagonist co-contraction becomes
higher
301
With age, safety margins become
higher
302
The central changes with movements and aging
```
Longer reaction time
Slower movements
Higher antagonist co-contraction
Higher safety margins
Changed synergies
```
303
With age, the number of apha-motoneurons
declines
304
This is a consequence of the decline in motoneurons in aging:
There are fewer motoneurons, meaning that on average, motonuerons are larger in size and slower
305
When smaller motor units are absent, there is
poor control of low forces
306
With less motor units, force production is
not as smooth
307
With age, twitch contraction time increases from 100-150 ms to
125-200 ms
308
With age, muscle mass is
reduced and partly replaced by fat/connective tissue
309
With age, cross-sectional area is
reduced
310
With age, normalized force (MVIC/cross-sectional area) is
reduced
311
With age, neural activation
depends on the muscle
312
With age, co-activation of antagonist muscles are
increased by 30%
313
Do all muscles show similar force losses?
No. Distal muscles are more affected, typically.
314
With age, H-reflex amplitude is
slightly reduced (may show a delay)
315
With age, the tendon tap reflex is
slightly reduced (may show a delay)
316
With age, polysynaptic reflexes are
reduced
317
With age, simple reaction time is
increased
318
With age, postural sway is
increased
319
Anticipatory postural adjustments are delayed with aging due to
loss of asynchronous involvement
320
With age, preprogrammed reactions are
decreased and delayed
321
Do older people tend to use ankle or hip strategy for postural control?
Hip strategy
322
How does training in older people effect forces?
Induces higher forces
323
How does training in older people effect antagonist co-contraction?
Lowers antagonist co-contractions
324
How does training in older people effect cross-sectional area?
Induces small changes in cross-sectional area through neural adaptations.
325
Characteristics of gait in older people?
Short, slow strides; wide base
326
__ of those over 60 have gait problems, reduced arm swing, stiff turns, and tendency to fall.
15%
327
Postural reflexes are impaired in __ of elderly over 80 years of age.
70%
328
With age, recovery after perturbation is
impaired
329
With age, spontaneous and induced sway are
exaggerated
330
The posture of elderly:
flexed in neck and trunk, extended in knees and elbows
331
Why can it be said that humans are born "prematurely?"
Their nervous system is not fully developed.
332
At birth, the brain weighs approximately
300 grams
333
After birth, myelination proceeds over
the first 6 months of life in the cephalocaudal direction.
334
These sensory systems are mature at birth
Kinesthetic system
| Vestibular system
335
This sensory system is not mature at birth. Why?
Visual system
| The optic nerve axons are still being myelinated
336
Visual acuity of newborns
20/200 to 20/400
337
The motor systems of newborns consist of
primitive reflexes (sucking, grasping); atypical monosynaptic reflexes
338
Current thinking is that the actions of newborns of kicking, rocking, arm waving, etc. are
preceding the emergence of new functional patterns such as walking and reaching.
339
Cause of Down Syndrome
Trisomy 21 or mosaicism
340
Life expectancy of Down Syndrome
Over 60 years
341
Reaction time in Down Syndrome is
longer
342
Movement time in Down Syndrome is
longer
343
Trajectories in Down Syndrome are
irregular
344
Joint variability in Down Syndrome is
higher
345
The movement patterns of this disease are similar to elderly movement patterns
Down Syndrome
346
When do Down Syndrome patients have a preference for co-activation patterns?
During movements
During preprogrammed reactions
During anticipatory postural adjustments
347
During grip taks, people with Down Syndrome have a
high safety margin
348
Down Syndrome patients can show significant improvement in motor performance with
training and rehabilitation
349
In Down Syndrome patients, cerebellum weight is typically reported as
low
350
This brain structure is important for coordination
Cerebellum
351
The clumsiness of Down Syndrome patients is though to be
a deliberate choice by the brain - a safety catch
352
Can Down Syndrome patients show improvements in the ability to coordinate effectors?
Yes
353
Can Down Syndrome patients show improvement in general indices of motor performance (speed and force)?
Yes
354
Most common pervasive developmental disorder
Autism
355
Resistance to change is seen in
Autism
356
Difficulty in verbal expression is seen in
Autism
357
Autistics are sometimes distressed for
unclear reasons
358
Have difficulty mixing with others
Autism
359
Have a lack of responsiveness to words
Autism
360
Sustained odd play is seen in
Autism
361
Physical over activity or extreme under-activity is seen in
Autism
362
Gross and fine motor skills in autistics tend to be
uneven
363
Causes of autism
Unknown
364
Contributing factors to autism
Genetic
Certain medical conditions
Harmful substances during pregnancy
365
With autism, cerebellum weight is sometimes reported as
low
366
Causes of developmental coordination disorder (DCD)
Unknown
367
More common in boys; prevalence of 5%
Developmental coordination disorder (DCD)
368
Typical features of developmental coordination disorder
```
Tripping
Running into others
Dropping objects
Unsteady gait
Speech problems (sometimes)
```
369
Cocontraction levels in DCD are
increased
370
Safety margins (grip forces) in DCD are
increased
371
The cerebellum in developmental coordination disorder is typically
smaller
372
The developmental delays seen in DCD
Delays in:
Sitting up, crawling, walking
Deficits in handwriting and reading
Problems in fine and gross motor skills
373
ALS (Lou Gehrig's disease) affects
the neuron cell body in the motor cortex
374
Cervical or lumbar radiculopathy affects the
spinal root
375
Axonal neuropathy affects the
axon
376
Guillain-Barre syndrome and multiple sclerosis affects the
myelin
377
Myasthenia gravis affects the
neuromuscular synapse
378
Muscular dystrophy or myopathy affects the
muscle
379
Muscular dystrophies affect mostly
males
380
Muscular dystrophy is a ____ disease.
genetic
381
Progressive weakness and degeneration of skeletal muscles
Muscular dystrophy
382
This form of muscular dystrophy typically affects children
Duchenne dystrophy
383
This form of muscular dystrophy typically affects adolescents
Becker dystrophy
384
Mutation of a gene responsible for dystrophin, a protein involved in maintaining integrity of muscle fibers
Duchene dystrophy and Becker dystrophy
385
Clinical symptoms at 2 to 6 years; all muscles are affected
Duchenne dystrophy
386
This form of muscular dystrophy is characterized by the subject being late to walk and having a waddling, unsteady gait
Duchenne dystrophy
387
Respirator dependence by the age of 20
Duchenne dystrophy
388
Clinical symptoms appear at adolescence
Becker dystrophy
389
Slower disease progression; longer life expectancy
Becker dystrophy
390
Most common adult form of muscular dystrophy
Myotonic dystrophy
391
Prolonged episode of muscle activity after its voluntary contraction
Myotonia
392
This muscular dystrophy commonly affects finger and facial muscles
Myotonic dystrophy
393
Characterized by high-stepping, floppy-footed gait (gait drop)
Myotonic dystrophy
394
Long face; drooping eyelids
Myotonic dystrophy
395
Types of peripheral neuropathies
Mononeuropathies
Diabetic neuropathies
Polyneuropathies
396
Slowed conduction in a single nerve
Mononeuropathies
397
Reduced amplitude of motor and/or sensory potentials
Mononeuropathies
398
Signs of denervation
Mononeuropathies
399
Types of mononeuropathies
```
Carpal tunnel syndrome
Entrapment of the ulnar nerve
Brachial plexus lesions
Peroneal pressure palsy
Tarsal tunnel syndrome
Sciatica
```
400
Entrapment of the median nerve at the wrist
Carpal tunnel syndrome
401
Most common mononeuropathy
Carpal tunnel syndrome
402
Can be entrapped near the elbow
Ulnar nerve
403
Mostly seen in muscles innervated by median and ulnar nerves
Brachial plexus lesions
404
Affects the peroneal nerve
Peroneal pressure palsy
405
Affects the tibila nerve
Tarsal tunnel syndrome
406
Affects the sciatic nerve
Sciatica
407
Long-term complications of diabetic neuropathies
Peripheral sensory neuropathy
Peripheral motor neuropathy
Loss of autonomic nerve function
Atrophy of peripheral tissues
408
Consequences of diabetic neuropathies
Loss of balance and coordination
| Increased probability of falls, fractures, bruises, etc.
409
Reduced recruitment; conduction block; may result in permanent axonal loss
Guillain-Barre syndrome
410
Common recovery, but nerve conduction velocity may remain slow
Chronic inflammatory demyelinating polyneuropathy
411
ALS and poliomyelitis are classified as
Neuronal degenerations
412
Enterovirus destroys anterior horn cells; EMGs show chronic denervation; may lead to weakness and pain
Poliomyelitis
413
A postpolio syndrome
Poliomyelitis
414
problems with swallowing
Dysphagia
415
Problems speaking or forming words
Dysarthria
416
Tight and stiff muscles
Spasticity
417
Exaggerated reflexes
Hyperreflexia
418
Early symptoms include twitching, cramping, or stiffness of muscles; muscle weakness affecting an arm or a leg; slurred and nasal speech; or difficulty chewing or swallowing
ALS
419
Patients have increasing dysphagia, dysarthria, spasticity, and hyperreflexia
ALS
420
Causes of spinal cord injury
Motor vehicle accidents (36%)
Violence (28.9%)
Falls (21.2%)
421
Partial loss of voluntary control of muscle activity
Paresis
422
Total loss of voluntary motor control
Plegia
423
Two extremities are involved - forelimbs or hindlimbs
Para
424
Half of the body (left or right) is involved
Hemi
425
All four extremities are involved
Quadri
426
With positive signs of spasticity (hyperreflexia)
Spastic
427
Without positive signs of spasticity (areflexia)
Flaccid
428
Quadriplegia is commonly seen in
Cervical injuries
429
Ventilator may be required when the injury is
above C4 level
430
Shoulder and biceps control, no wrist or hand control
Injuries at C5
431
Wrist control, but not hand function
C6 injuries
432
Can straighten arms; dexterity problems with hand and fingers
C7 and T1 injuries
433
Commonly paraplegia
Thoracic-Lumbar injuries
434
Hands not affected
Thoracic-lumbar injuries
435
Poor trunk control; lack of abdominal muscle control
T1 to T8 injuries
436
Good trunk control and good abdominal muscle control; sitting balance is very good
T9 - T12 injuries
437
Decreasing control of hip flexors and legs
Lumbar and sacral injuries
438
Demyelination of CNS axons
Multiple sclerosis
439
Macrophages and mononuclear cells strip away myelin
Multiple sclerosis
440
Effects of MS on the optic nerve
Sudden onset of blurred vision
Dull ache in the eye
Impaired acuity (rarely blindness)
441
Unilateral deafness can happen when MS affects the
olfactory and auditory nerves
442
MS can impair balance when it afffects
the brain stem pathways
443
MS can cause intentional tremors when it affects
the brain stem pathways
444
MS can cause ataxia when it affects the
brain stem pathways
445
MS can cause dysarthria when it affects the
brain stem pathways
446
MS can cause facial weakness and numbness when it affects the
brain stem pathways
447
MS can cause unilateral opthalmoplegia when it affects the
brain stem pathways
448
When MS affects the spinal cord, is it commonly high in
the posterior columns
449
MS can cause tingling in hands and arms when it affects the
spinal cord
450
If the spindle afferents are affected by MS in the spinal cord, it can cause
discoordination
451
IF MS affect nerves innervating the lower limbs in the spinal cord, it can cause
instability of stance
452
If MS affects the pyramidal tract, it can cause
heaviness
dragging of legs
weakness, even acute paraplegia
spasticity
453
Fatigue in MS is viewed as
very different feeling than generic fatigue
454
Fatigue in MS can be disproportionate
to the amount of effort
455
Evoked potentials with MS are
delayed
456
An MRI to assess MS can show
plaques on affected tracts
457
Spontaneous improvements with MS are
typical
458
MS can be treated with
```
Hormone thereapy
Diet modification
Hyperbaric oxygenation
Immunosuppressive treatment
Antispastic treatment
```
459
Prognosis for MS
Very uncertain
460
First MS episode may be followed by
20 years of no symptoms, and then MS strikes again
461
Older persons and males with MS
do worse
462
Parkinson's disease has these affects on single-joint movements
Slowness
High variability
High sensitivity to accuracy requirements
463
Parkinson's disease has these affects on multijoint movements
```
Impaired interjoint coordination
Less smooth (high jerk)
Impaired compensation for interaction torques
High variability
Sensitivity to accuracy requirements
```
464
Parkinson's disease causes anticipatory postural adjustments to be
reduced
465
Parkinson's may cause reduced APAs because of
bradykinseia (small perturbations during movement)
466
The gait in Parkinson's tends to be
shuffling
467
If stripes are painted on the floor, Parkinson's patients will show a
more normal looking gait when walking over the stripes
468
Why is the Parkinson's gait a shuffling gait?
It is likely an adaptation to postural problems. It leads to smaller contact forces
469
Atrophy of caudate nucleus
Huntingdon's disease
470
A neurodegenerative disorder
Huntingdon's disease
471
Huntingdon's is
hereditary (the gene has been located)
472
Huntingdon's usually starts in
midlife
473
Is characterized by chorea and dementia
Huntingdon's
474
Huntingdon's usually sees death after
15-20 years
475
Huntingdon's disease has these clinical features
Motor disorders
Depression
Irritability
Loss of social skills
476
Generalized, irregular, restless, often pseudopurposive movements (Fidgeting hand movements, dancelike gait, clumsiness, slurry speech, etc.)
Chorea in Huntingdon's disease
477
Chorea in Huntingdon's disease tends to involve
all parts of the body
478
At early stages, it can be suppressed voluntarily and looks like restlessness or movements under emotional stress
Chorea
479
At later stages, it can be masked by rigidity and bradykinesia
Chorea
480
Cerebellar disorders are characterized by
Delays in movement initaition
Incomplete and inaccurate movement forms
Muscle strength is diminished somewhat
481
Abnormalities of stance and gait are seen in
Cerebellar disorders
482
Rhythmic tremor of the body or head [rocking or rotational movement] a few times per second
Titubation
483
Titubation is seen in
Cerebellar disorders
484
Rotated or tilted postures of the head
Cerebellar disorders
485
Disturbances of extraocular movements
Cerebellar disorders
486
Decompostion of movement
Cerebellar disorders
487
Ataxia is characteristic in
cerebellar disorders
488
Ataxic dysarthria is seen in
cerebellar disorders
489
Copper deposits in the brain (cortex and basal ganglia) and also in the liver and other organs
Wilson's disease
490
Wilson's disease is probalby
genetic
491
Wilson's disease can be seen in
young persons
492
Wilson's disease has these clinical signs
```
Tremor
Slurred speech
Masklike face
Shuffling gait
Stooped posture
```
493
A nonprogressive disorder in young children
Cerebral palsy
494
Cerebral palsy causes these motor disorders
Discoordination
Spasticty
Dystonia
Dysarthria
495
Epilepsy, mental retardation, and visual disturbances can be seen in some, but not all cases of
Cerebral palsy
496
Cerebral palsy can be caused by
```
Labor complications
Preterm birth, low birth weight
Hypoxia
Genetic factors
Infections during pregnancy
Commonly seen CNS congenital malformations
```
497
This type of cerebral palsy affects the majority of patients
Spastic cerebral palsy
498
Scissor gait
Spastic cerebral palsy
499
This type of cerebral palsy may affect face muscles
Athetoid cerebral palsy
500
Characterized by uncontrollable, slow, writhing movements
Athetoid cerebral palsy
501
Usually increases during stress and disappears when asleep
Athetoid cerebral palsy
502
Affects the quality of balance and depth perception
| Unsteady walk with wide-base gait
Ataxic cerebral palsy
503
Cerebral palsy can present with mixed forms. Most common is
Spastic + athetoid
504
Should one try to improve motor patterns or function?
Function
505
If an atypical motor pattern is optimal for an atypical person
Hands off!
506
If exercise through discomfort will efficiently improve motor performance
Hands on!
