Midterm review Flashcards
1
Q
What is the degrees of freedom problem?
A
-Redundancy in the motor system
-There are a number of dimensions in which systems can independently vary
-So, there are infinitely many different arm postures that allow you to hold your hand in any given position
2
Q
What are the 2 principles of motor behaviour?
A
- Movement Preparation
- Movement Execution
3
Q
What is the definition of reaction time?
A
The interval of time from when one decides to
execute a movement until the movement is initiated
Where the decision to act is typically provided by a sensory stimulus
4
Q
What are 4 factors that influence reaction time?
What is hicks law?
A
- Stimulus intensity
- # of choices (Hick’s law)
- Stimulus-response compatibility (congruent vs incongruent)
- Response complexity (Henry & Rogers)
Hicks law:
RT increases by a similar amount every time the
number of alternatives is doubled
RT is related to the quantity of information processed
5
Q
What are 4 factors that influence movement time?
What is Fitt’s task?
A
- Speed accuracy trade-off
(Accuracy is inversely related to speed)
2.Movement parameters
(Acceleration and velocity scale with movement distance. Longer the movement = greater the velocity and acceleration.)
(We tend to like linear trajectories (movement efficiency)
- End-state comfort effect
(A movement is planned such that initial discomfort and instability is tolerated for the sake of later comfort and stability)
4.Motor Equivalence
(The brain can generate similar movements using different patterns of muscle activity, e.g. the same hand path with different contributions from wrist and elbow; or similar script written large or small, or with the right or left hand or a foot.)
Fitts’ Task
examine relation between:
* movement time
* movement amplitude
* target width
6
Q
Where does motor equivalence happen in the brain?
Where does the brain send signals for motor equivalence?
What is motor equivalence useful for?
A
Motor-planning centres in the brain specify high-level, abstract properties of a movement, such as its shape.
They let downstream centres work out the details (e.g.muscle activation patterns) for achieving those properties.
Those details may vary, yet still achieve the desired properties
May help solve the Degrees of Freedom Problem
7
Q
What does the study of motor control entail?
A
Entails exploring how the central nervous system (CNS) produces purposeful, coordinated movements in its interaction with the rest of the body and with the environment.
8
Q
Why is the study of motor control important?
A
Optimize sport performance
Use as a rehabilitation tool after injury
Use as a treatment tool for chronic disease
Help with the aging population
9
Q
What is the difference between the behavioural and neurophysiological study of motor control?
A
Behaviour:
“Black Box” processes lead to observed behaviour
Neurophysiology
Specific neural activities lead to observed behaviour
10
Q
What are the 2 components of memory?
A
Working memory and long-term memory
11
Q
What is the 3-stage model?
A
- stimulus identification
(Receives information from senses, identifies and classifies information, extract relevant information) - response selection
(Decide on a plan of action, translate between stimulus and response) - response programming
(Organize and prepare a response, send appropriate motor commands)
12
Q
What 2 things do mental operations occur between?
What type of operations process information?
Is this time-consuming?
What are 3 things that will affect processing?
A
mental operations occur between reception of stimulus and production of response
cognitive operations process information
processing is time consuming
- stimulus characteristics will affect processing
- complexity of decision making will affect processing
- complexity of response will affect processing
13
Q
What are some benefits of the behavioural model of studying motor control?
A
1.We are studying behaviour
2.Can have subjects do complicated paradigms
3.Inexpensive
Need to validate tasks for future use
14
Q
What are the 7 components of the basic neuron?
A
Dendrites
Cell Body
Axon Hillock
Axon
Myelin sheath
Node of Ranvier
Presynaptic Terminal
15
Q
What does EEG measure and how does this signal occur?
How do we measure EEG?
What are 2 reasons that it is clinically useful?
A
movement of ions inside, across, and outside neural cell membranes creates electrical currents in excitable tissue
electrical currents travel to scalp surface
measure electrical potentials with electrodes placed on scalp
1.Clinically useful as distinct brain states show
characteristic EEG signal
2.Clinically useful in determining the focus of epileptic seizure
16
Q
How can we eliminate background EEG signal?
A
Background EEG signal can be removed by trial averaging revealing the response of a brain region to stimuli
17
Q
What is an event-related potential?
What are it’s 2 uses?
A
electrical potentials (voltage changes) recorded from the scalp are specifically time-locked to a sensory, motor, or cognitive process
1.used to determine time-course (and location) of processes in the brain
2.provide an electrophysiological window into brain function
18
Q
What is the quantity measured by EEG?
What is the temporal resolution of EEG?
What is the spatial resolution of EEG?
How much does it cost?
What is 1 of its advantages?
What are 2 of its disadvantages?
A
Quantity measured:
electric potential on the scalp surface
Temporal Resolution:
ms
Spatial Resolution:
cm
Cost:
cheap
Advantage:
easy to record
Disadvantage:
signals are smeared before they reach the scalp, limited to activity in brain cortex surface (without corresponding anatomical structures)
19
Q
What does MEG measure and how does this signal occur?
A
- electrical neural currents within the dendrites create magnetic fields
- measurement of magnetic fields of the brain
20
Q
What is the quantity measured my MEG?
What is the temporal resolution of MEG?
What is the spatial resolution of MEG?
How much does it cost?
What is 1 advantage of MEG?
What is 1 disadvantage of MEG?
A
Quantity measured:
components of the magnetic field
Temporal Resolution:
ms
Spatial Resolution:
cm
Cost:
expensive
Advantage:
Clean signals
Disadvantage:
Insensitive to radial currents
21
Q
What is the difference between MRI and fMRI?
A
MRI studies brain anatomy.
Functional MRI (fMRI) studies brain function.
22
Q
What does fMRI measure and why is it important?
A
- measures changes in blood oxygen levels (BOLD response)
*Blood-oxygen-level dependent
- BOLD is closed related to changes in neural activity
23
Q
What is the quantity measured by fMRI?
What is the knowledge gained by fMRI?
What is the temporal resolution of fMRI?
What is the spatial resolution of fMRI?
How much does it cost?
What is 1 advantage of fMRI?
What are 2 disadvantages of fMRI?
A
Quantity measured:
ratio between oxy- and deoxyhemoglobin
Knowledge gained:
activated areas
Temporal Resolution:
sec
Spatial Resolution:
mm
Cost:
expensive
Advantage:
3D-volume resolution
Disadvantage:
low temporal resolution, no straight forward analysis
24
Q
In what situation would you use either EEG/MEG or fMRI?
A
If you want high temporal resolution with less spatial resolution, use EEG/MEG
If you want high spatial resolution with less temporal resolution, use fMRI
25
What is injected to get a PET scan?
What does the result of this produce in the blood?
What does the PET scan measure?
* injection (or inhalation) of a radioactive solution, in which atoms emit positively charged electrons (positrons)
* positrons interact with electrons in the blood to produce photons of electomagnetic radiation
* scanner used to determine the location (and levels) of these photons in brain areas
26
What animal was single-unit recording tested on?
What is the quantity measured by single unit recording?
What is the temporal resolution of single unit recording?
How much does single unit recording cost?
What is 1 advantage of single unit recording?
What is 1 disadvantage of single unit recording?
Monkeys
Quantity measured:
single neuron activity
Temporal Resolution:
ms
Cost:
expensive
Advantage:
Cleanest signals
Disadvantage:
Training of animals
27
What does the TMS device involve?
What does TMS measure?
What does TMS do?
What are 3 pros and 3 cons of using TMS?
Coil placed over target brain region
Cognitive (sensorimotor) failures recorded
Focused oscillating magnetic fields can
activate or suppress neural activity across the
skull.
Pluses:
Non-invasive.
Allows direct manipulation of neural activity.
Single pulses affect brain activity for only a few
seconds.
Minuses:
Repeated pulses can change brain activity for
weeks
Sensation can be disturbing
Spread of activation/inhibition
28
What is contained within the soma/cell body?
What is the function of dendrites?
What is the function of axons? How long are they?
What is the purpose of the myelin sheath?
What is the purpose of the presynaptic terminal?
Soma (cell body) – contains nucleus, cytoplasm,
organelles, metabolic center
Dendrites – receive information
Axon – transmits information (0.1 to 3 meters long)
Myelin sheath – covers the axon to increase
transmission speed
Presynaptic Terminal – communication site
29
What is the main function of neurons?
What are the 4 functional components of a neuron?
Neurons perform computations, they transform
information.
The functional components of a neuron:
an input component (dendrites)
an integration component (axon hillock)
a transmission component (axon)
an output component (synapse)
30
What is the definition of membrane potential?
What is the definition of an action potential?
Membrane potential:
difference in net electrical charge on
either side of the membrane
An action potential is a short-lasting event
in which the electrical membrane potential
(of a cell) rapidly rises and falls
31
What is the resting potential of a membrane in mV?
What is the membrane potential when an action potential is released in mV?
-70mV
+30mV
32
What are the 4 main different types of neurons?
Where is the cell body of a sensory neuron?
What do motor neurons connect to?
What are the 2 differences between local interneurons and projection interneurons?
Sensory Neuron
Motor Neuron
Local Interneuron
Projection interneuron
Sensory neurons have a cell body in the middle and gets its input from sensory receptors rather than neurons
Motor neurons connect to a muscle rather than another neuron and have the ability to activate muscle fibers
Local interneurons have no myelin sheath, input and output are neurons, and they travel shorter distances
Projection interneurons have a myelin sheath and travel longer distances
33
What about the spinal cord changes at different levels?
What proportion changes within the spinal cord at different levels? Why does this occur this way?
The internal and external appearances of the spinal cord vary at different levels.
The proportion of gray matter (neuron cell bodies) to white matter (axons) is greater at sacral levels than at cervical levels.
At sacral levels very few incoming sensory fibers have joined the spinal cord, whereas most of the motor fibers have already terminated at higher levels of the spinal cord.
34
What is within the white matter of the spinal cord?
What is within the grey matter of the spinal cord?
Which horn of the spine do sensory inflow come in and motor commands go out?
What is the difference between and medial and lateral aspects of the spinal cord?
What is the difference between the dorsal and ventral aspects of the spinal cord?
White matter
(nerve fibres/axons)
Grey matter
(cell bodies)
Sensory inflow comes in the dorsal horn
Motor commands goes out the ventral horn
The medial aspect is on the inside of the spinal cord and the lateral aspect is on the outside of the spinal cord
The dorsal aspect is on the back of the spinal cord and the ventral aspect is on the front of the spinal cord
35
Which fibers in the spinal cord are receptors and effectors?
What is within the central canal of the spinal cord?
What is the role of the interneuron within the spinal cord?
Sensory fibers are receptors and motor fibers are effectors
The central canal has cerebro-spinal fluid
Connect the dorsal root (sensory fibers) and the ventral root (motor fibers)
36
What do neurons in the medial gray matter control?
What do neurons in the lateral ventral horn control?
Neurons in the medial gray matter control axial muscles (trunk) & proximal muscles (e.g. shoulder & elbow movers).
Neurons in the lateral ventral horn control distal muscles (e.g. wrist & fingers).
37
Where do axons of projection neurons in the spinal cord ascend to?
Where do axons of motor neurons in the spinal cord exit to?
Where do propriospinal neurons in the spinal cord reach to?
Where do interneurons in the spinal cord project to?
Axons of projection neurons ascend to the brain
Axons of motor neurons exit the central nervous
system to innervate muscles
Propriospinal neurons reach distant spinal
segments
Interneurons project within their own or adjacent
spinal segments
38
Where do axons of projection neurons in the spinal cord ascend to?
Where do axons of motor neurons in the spinal cord exit to?
Where do propriospinal neurons in the spinal cord reach to?
Where do interneurons in the spinal cord project to?
Axons of projection neurons ascend to the brain
Axons of motor neurons exit the central nervous
system to innervate muscles
Propriospinal neurons reach distant spinal
segments
Interneurons project within their own or adjacent
spinal segments
39
What 2 things is the input signal graded on for neuron firing?
What does the trigger zone integrate in regard to neuron firing? In what situation is an action potential generated? How does an increase in amplitude after the action potential is triggered affect the action potential? What determines the number of action potentials?
The input signal is graded in amplitude and duration, proportional to the amplitude and duration of the stimulus.
The trigger zone integrates the input signal into a trigger action that produces action potentials that will be propagated along the axon. An action potential is generated only if the input signal is greater than a certain spike threshold. Once the input signal surpasses this threshold, any further increase in amplitude of the input signal increases the frequency with which the action potentials are generated, not their amplitude. The duration of the input signal determines the number of action potentials.
40
Are action potentials all or none? What is the same about every action potential?
What happens when the action potential reaches the cell membrane? What does the total number of action potentials determine?
Action potentials are all-or-none. Every action potential has the same amplitude and duration. Since action potentials are conducted without fail along the full length of the axon to the synaptic terminals, the information in the
signal is represented only by the frequency and number of spikes, not by the amplitude.
When the action potential reaches the synaptic terminal, the cell releases a chemical neurotransmitter that serves as the output signal. The total number of action potentials in a
given period of time determines exactly how much neurotransmitter will be released by the cell.
41
What 2 diseases affect neuron firing?
What specifically does each disease damage and what is the effect?
Amyotrophic lateral sclerosis (ALS)/Lou Gehrig's disease:
-degeneration of motor neurons
-lose the ability to initiate and control voluntary movement
Multiple sclerosis:
-Damage of the myelin sheath
-Visual, motor, and sensory problems
42
What are the 3 main types of movements?
Reflex
Rhythmic
Voluntary
43
What are 3 examples of reflex movement?
Do reflexive movements depend on context?
Are they fast or slow?
Are they voluntary or involuntary?
Examples: cough, blink, stretch reflex
1.Stereotyped: always roughly the same response to the same simple stimulus; i.e. not very sensitive to context
2.Fast-responding: some reflexes respond in just 10 ms
3.Involuntary: happen without conscious planning, but may be modified or suppressed voluntarily
44
What are 3 examples of rhythmic movement?
What are rhythmic movements driven by?
Examples: chewing, breathing, locomotion
Often driven by circuits in brain stem and spinal
cord which can function autonomously but are
influenced by higher centres (e.g. headless
chickens, "walking" newborns)
45
What is unique about voluntary movements as opposed to other movements?
Many of these voluntary movements have to be learned (whereas reflexes usually don’t, though even reflexes can be changed by learning)
46
What is a test used for the monosynaptic pathway?
Hammer test
Hammer stretches quadriceps, Muscle spindles(stretch receptors) in the quadriceps send a signal to the sensory neuron, signal is moved to the alpha motor neuron and the knee is extended.
47
How do stretching and slacking of intrafusal fibers affect the monosynaptic reflex pathway?
Sensory Receptors (Muscle Spindles):
stretch of intrafusal fibers causes:
increased firing rate of afferent neuron
slackening of intrafusal fibers causes:
decreased firing rate of afferent neuron
48
What are the 3 different types of signals in the monosynaptic reflex pathway?
What are the 4 components of each signal?
What is unique about one of the different types of signals?
Sensory signals, motor signals, muscle signals
Input
Integration
Conduction
Output (behavior)
Sensory signals receive a stimulus
49
What is the jendrassik maneuver?
*Interlocking the fingers is used to distract the
subject
*Often a larger reflex response will be observed when the patient is distracted, because the maneuver may prevent the patient from consciously inhibiting or influencing his or her response to the hammer.
50
How do we stimulate the Hoffman reflex?
What is the pathway of the Hoffman reflex?
What tool do we use to measure the Hoffman reflex?
* electrically stimulate nerve, starting at low intensities
* recruit large sensory afferents
* sensory afferents synapse with motor neurons in spinal cord
* EMG (Electromyography) response provides
indication of magnitude of reflex response
51
What does EMG measure?
What 2 summations of action potentials does EMG record?
What is it a tool for?
measure surface electrical potentials from
the muscle
EMG – spatial and temporal summation
of many motor unit action potentials
tool to study characteristics of muscle
activation
52
What is the definition of "gain of" system?
What is the difference between a high gain and low gain system?
What type of signal is usually involved in a low gain system?
"Gain of" System
* Ratio of output to input
* High gain
larger response for a given input
* Low gain
smaller response for a given input
(usually involves an inhibitory signal)
53
What is a common feature of all types of locomotion?
Many different forms of locomotion have evolved to enable animals to move from one place to another including walking, galloping, crawling, swimming, flying.
A common feature of all these forms of locomotion is rhythmic and alternating movements of the limbs.
54
Where is the motor pattern for stepping produced?
What level of the nervous system is used for locomotion?
The motor pattern for stepping is produced at the spinal level.
Rhythmthic & alternating (repetitive) pattern of locomotion allows it to be controlled automatically at relatively low levels of the nervous system without intervention by
higher centres.
55
What is the difference in muscle activation for the stance phase and swing phase of locomotion?
stance phase: hip extensors active, flexors inactive
swing phase: hip flexors active, extensors inactive
56
What knowledge was gained from the cat experiment when the spine was severed?
Transection of the spinal cord at the lower thoracic level does NOT eliminate stepping movements, nor the oscillating muscle
activity associated with locomotion.
57
What are central pattern generators?
How is the rhythmic pattern of locomotion produced?
Neural networks within the spinal cord generate the rhythmic alternating activity in the flexor and extensor muscles - referred to as central pattern generators or CPG.
Basic rhythmic pattern of locomotion is produced by alternately inhibiting flexor and extensor interneurons
58
Are higher brain centres important for locomotion?
What are 3 deficits in locomotion for deafferented animals?
Although the neural circuitry of the spinal cord can generate rhythmic bursts of reciprocal activity in flexor and extensor neurons in the legs, descending influences from higher brain centres are also important in the control of
locomotor activity.
Deficits in deafferented animals include strange gait, no weight support, and can’t initiate stepping (need external stimulus to produce locomotion, ex. a rolling treadmill).
59
How does a spinal cord injury occur and what are the results?
What is the most common type of spinal cord injury?
What does severe spinal cord injury usually cause?
Spinal cord injury (SCI) occurs when a traumatic event results in damage to cells within the spinal cord or severs the nerve tracts that relay signals up and down the spinal cord.
Most common are lacerations (severing or tearing of some nerve fibers, such as damage caused by sports injury, car accident or a gun shot wound)
Severe SCI often causes paralysis (loss of control over voluntary movement and muscles of the body) and loss of sensation and reflex function below the point of injury, including autonomic activity such as breathing and other
activities such as bowel and bladder control.
60
What are the 4 ways to classify a spinal cord injury?
Complete/incomplete
Injury level
Sensory/motor dysfunction
Muscle function
61
What are the 2 components of the central nervous system?
Brain + spinal cord = Central Nervous system
62
What are the 4 parts of the central nervous system?
Cerebral cortex
Cerebellum
Brain stem
Spinal cord
63
What are the 4 parts of the brain stem?
Diencephalon
Midbrain
Pons
Medulla
64
What 3 areas of the body does the brain stem control the motor function of and receive sensation from?
What does the brain stem serve as the point of entry for?
What part of the nervous system has its reflexes mediated by the brain stem?
Where does the brain stem carry information to?
What is the brain stem home to?
What type of output does the brain stem mediate via the reticulospinal pathway?
Concerned with sensation from and motor control of the head, neck and face
Point of entry for several specialized senses (hearing, balance, taste)
Mediate reflexes of autonomic nervous system (e.g. heart rate, digestion, respiratory rate, salivation, perspiration, pupillary dilation, micturition (urination), and sexual arousal)
Carries sensory and motor information to other division of the CNS
Home to the reticular formation: a diffuse network of neurons that (1) receives a summary of the much of the sensory information entering the spinal cord and brain stem, (2) is
important in influencing the arousal of the organism
mediates motor output (via the reticulospinal pathway)
65
What is unique about the reticulospinal pathway?
How do individual axons project in the reticulospinal pathway?
What 3 types of neurons influence muscles in the reticulospinal pathway
One of the phylogenetically oldest descending motor pathways
Individual axons project widely, coordinating different regions of spinal cord
Contact interneurons, long propriospinal cells, & some motor neurons influence muscles
66
What 2 things does the medulla regulate?
What 3 things does the medulla receive input about?
What 2 types of muscles does the medulla control?
1.Regulates blood pressure and respiration
2.Receives input regarding taste, hearing and maintenance of
balance
3.Involved in control of neck and facial muscles
67
What does the pons relay information about?
What 3 things is it involved in?
1.Relays information about movement and sensation from the
cerebral cortex to the cerebellum
2.Involved in respiration, taste and sleep
68
What does the midbrain form linkages between?
What is the "nucleus of the midbrain"
What 2 types of information does the midbrain process?
1.Forms linkage between parts of motor system (cerebellum,
basal ganglia, and cerebral hemispheres)
2.Substantia Nigra = nucleus of midbrain
3.Involved in processing of auditory and visual information
(control of eye movements)
69
What is the minimum amount of time for olympic sprinters to react to the gun?
Why is this the case and what is the pathway?
100 ms
It takes a minimum of 100 ms for the signal to travel from the auditory receptors, to the cortex, to the brain stem and then to the spinal cord
70
What is a characteristic of a startle response?
What muscles are responsible for this response?
How loud does the stimulus have to be?
What neurons is the startle response mediated by?
diffuse protective response consisting of a characteristic set of
muscle actions (flexion).
Sternocleidomastoid, Orbiculus oculi, Masseters, Wrist flexors
elicited by a loud (>100 dB) acoustic stimulus
Mediated by neurons in reticular formation
71
What do premotor time and motor time represent?
Premotor time:
represents “central processing” time – information processing
activity involved in preparation
Motor time:
represents muscular processes -initial contractile activity required
to overcome inertia
72
What are the 3 phases of the tri-phasic muscle activation pattern?
first agonist burst (AG1):
-precedes movement onset
-burst amplitude and duration are dependent on movement amplitude
-burst amplitude reflects force
antagonist burst (ANT):
-burst amplitude and timing influenced by movement extent and velocity
-earlier onsets with small, fast movements may represent ‘braking’
second agonist burst (AG2):
-influenced by strategy
-helps to “clamp” limb at target position
73
How do we know that certain movements are caused by the startle reflex?
Where are the movements stored?
* RTs too short to involve initiation via cortical mechanism
movement is prepared in advance and stored in sub-cortical areas
startle triggers prepared movement without cortical involvement
74
What part of the brain does the startle activate?
Where is the movement program stored?
Where is the movement program carried?
* Startle activates midbrain reticular formation
* Movement program stored in midbrain reticular formation
* Program carried to appropriate muscles by reticulospinal tract
75
What are the 5 parts of the basal ganglia?
What 2 parts make up the striatum?
Caudate nucleus
Putamen
Globus pallidus
Subthalmic nucleus
Substantia nigra
Caudate nucleus and Putamen make up the striatum
76
How do the basal ganglia and cerebrum act on motor areas of the cortex?
Basal ganglia & cerebellum act indirectly on motor
areas of the cortex
77
What are the 2 connections of the basal ganglia to the cortex and how does each affect the thalamus?
How does each impact movement?
Direct path (Decrease inhibition of thalamus):
-Leads to less inhibition of the thalamus, i.e. striatum inhibits GPi
which in turn inhibits its normal (inhibitory) action on the thalamus, thus leading to greater excitation from the thalamus to the cortex
-Allows one to sustain actions or initiation of action
Indirect path (Increase Inhibition of thalamus):
-Excites the GPi thereby increasing its inhibition of the thalamus
-Suppresses (unwanted) movements
78
What are the 4 parts of the direct path of basal ganglia to the cortex?
Direct path:
1. striatum
2. GPi (internal)
3. thalamus
4. cortex
79
What are the 6 parts of the indirect path of basal ganglia to the cortex?
Indirect path:
1. striatum
2. GPe (external)
3. STN
4. GPi
5. thalamus
6. cortex
80
What type of motor activity does the basal ganglia select/maintain and what type of activity does the basal ganglia suppress?
What does the basal ganglia control?
What effect does it have on movements?
What is it involved in with regard to movement?
What does the basal ganglia function on autopilot for?
What type of contractions does it help monitor/coordinate?
1.Selecting and maintaining purposeful motor activity while
suppressing unwanted or useless movements
2.Controls force production
3.Fine tunes movements (like cerebellum)
4.Involved in making movements smooth
5.Autopilot for well-learned movements, timing and
switching, planning, learning
6.Helps monitor and coordinate slow, sustained
contractions related to posture and support
81
Name all of these common symptoms of damage to the basal ganglia?
1. T...(blank) - involuntary oscillatory movements
2. A...(blank) - slow, writhing movements of the hand
3. C...(blank) - abrupt movements of limb and facial
muscles
4. B...(blank) -violent, flailing movements
5. D...(blank) - persistent abnormal posture
1. Tremors - involuntary oscillatory movements
2. Athetosis - slow, writhing movements of the hand
3. Chorea - abrupt movements of limb and facial
muscles
4. Ballism - violent, flailing movements
5. Dystonia - persistent abnormal posture
82
What are the 2 components of the diencephalon and what does each do?
Diencephalon:
1. Thalamus: integrates motor (and sensory) information
2. Hypothalamus: homeostasis and reproduction
83
What are the 2 segments of the Globus pallidus?
External and Internal segment
84
(Caudate, Putamen, Globus Pallidus)
What nuclei do these 3 make up?
What other 2 parts of the basal ganglia are clinically included?
How much are these structures connected?
Subcortical nuclei: caudate, putamen, globus pallidus
Clinically includes subthalamic nucleus & substantia nigra
These structures are highly interconnected anatomically
85
What 2 components of the brain does the basal ganglia have a connection to?
Does the cerebral cortex have direct connections to motor areas?
Connections to:
1. Thalamus
2. Brain Stem Nuclei
Cerebral Cortex
(Direct connections are not to motor areas)
86
What was Parkinson's disease initially described as by James Parkinson in 1817?
“shaking palsy” – James Parkinson (1817)
... Involuntary tremulous motion, with lessened muscular power, in parts, not in action and even when supported, with a propensity to bend the trunk forwards, and to pass from a walking to a running
phase, the senses and intellect being uninjured.
87
What percent of the population is affected by Parkinson's Disease?
Which gender is affected more by Parkinson's Disease?
What is the age of onset for Parkinson's Disease?
What are some factors that cause the onset of Parkinson's Disease?
What is the physiological cause of Parkinson's Disease?
~ 1/4 million people nationwide suffer from PD
Affects 0.1-1% of population: it’s one of the most common
neurological diseases
Strikes men slightly more than women
Age of onset: found most often in patients over 50 with ~10% of
patients afflicted with “young-onset” PD under 40
Exact cause unknown
Many researchers believe that several factors combined are
involved: accelerated aging, environmental toxins, and genetic
predisposition
BUT results from the degeneration of dopaminergic neurons in the substantia nigra: NOT ENOUGH DOPAMINE
88
What process do we see physiologically with Parkinson's?
How much of this process is gone in Parkinson's?
How much of this process must be gone for symptoms to arise and is Parkinson's early or late onset?
See deterioration of dopaminergic cells in SNpc
Normally lose a bit every year due to aging, but in Parkinson’s
patients have > 70% gone
Symptoms arise after > 80% dopaminergic neurons loss (so
late onset)
89
What is Parkinson's caused by?
What does this lead to?
What is Hypokinetic Disorder?
Caused by degeneration of pathways from SNpc to rest
of basal ganglia and thalamus
Leads to a decrease in the excitatory input to the cerebral
cortex from the thalamus through both direct and indirect
pathways
Hypokinetic Disorder: reduced amount of voluntary movement
90
What are 4 typical sympotoms of Parkinson's Disease?
What does this cause difficulty with?
How does Parkinson's Disease affect posture?
What 3 gait disorders are characteristic of Parkinson's Disease?
What percent of patients with Parkinson's Disease also have Dementia and what are the 2 effects of this?
Typical symptoms: tremor, rigidity, and akinesia, bradykinesia
Difficulty of initiating and carrying out complex voluntary
movements
Postural instability or impaired balance and coordination
includes a stooped posture, reduced postural reflexes and a
tendency to fall down easily
Gait disorders:
tend to walk with short shuffling steps
Go from walking to running; stopping in a doorway (freezing of gait)
Body may be bent forward and unsteadiness on turns
Dementia:
- 20-60% of individuals
- Cognitive and motoric slowing
- Executive dysfunction and poor memory retrieval
91
When is Tremor most apparent in Parkinson's Disease?
Tremor is most apparent at rest (4-5 tremors per second)
92
What is the definition of rigidity in regard to Parkinson's Disease and what does it arise from?
Rigidity:
muscular stiffness & decreased muscle tone are demonstrated by increased resistance to passive movements of the joints, such as elbow, wrist, and neck
Results from simultaneous contraction of flexors and extensors, which tends to lock up the limbs.
93
What is the difference between Akinesia and Bradykinesia in regard to parkinson's disease?
Akinesia: difficulty initiating voluntary movement, as though the brake can’t be released
Bradykinesia: slowness in executing movement
94
What is the goal with treatments for Parkinson's Disease?
What are the 4 types of treatments for Parkinson's Disease?
Increase effective dopaminergic transmission
1.L-Dopa: increases the amount of dopamine available
2.Exercise
-Calisthenics, Cycling
3.Surgical interventions
-Pallidotomy, lesion of the globus pallidus
-Eliminate neural circuits responsible for abnormal
movement production
4.Deep Brain Stimulation
-Surgery that electrically stimulates part of the brain
95
What are the 2 results of a Pallidotomy in regard to treating Parkinson's Disease?
1.some recovery of function
2.faster movements & faster deceleration as home in on target
96
What is the Latin term for cerebellum?
How much information does the cerebellum handle?
What percent of the brain's neurons does the cerebellum have compared to how much volume of the brain it takes up?
Does the cerebellum have more axons going into it or leaving it?
What 2 cortical areas does the cerebellum talk to?
How do the neurons of the cerebellum project?
The cerebellum is Latin for little brain
It handles a lot of information
Contains > 50% of all the brain's neurons (while it
constitutes only 10% of the total brain volume)
40 times more axons project into the cerebellum than exit it
Talks to both sensory and motor cortical areas
Neurons project ipsilaterally
(ipsilateral = belonging to or occurring on the same side of the body)
97
Where is the cerebellum located?
What are the 3 inputs of the cerebellum?
What is the 1 output of the cerebellum?
Located behind the brainstem and below the cerebral cortex (occipital lobe)
Input:
1. Spinal cord
2. Brainstem
3. Cerebral Cortex
Output:
(primarily) motor regions of brain stem and cerebral cortex (via the thalamus)
98
What is contained within the frontal lobe of the brain?
What is this cortex responsible for?
FRONTAL LOBE:
contains MOTOR CORTEX
Planning, reasoning, movement (map of the body) and
some aspects of speech
99
What is the contained within the occipital lobe of the brain?
What is this cortex responsible for?
OCCIPITAL LOBE:
Seat of the VISUAL CORTEX
Deals with visual information
100
What is the function of the parietal lobe of the brain?
What does it work closely with?
PARIETAL LOBE:
Handles skin based proprioceptive information
(heat, cold, pressure & pain)
Works closely with the motor areas.
101
What is the function of the temporal lobe of the brain?
TEMPORAL LOBE:
Speech, hearing and Language
102
What are the 4 sensations that touch can send as input to the somatosensory cortex?
Touch
Sensations:
1.Localize the position that is touched
2.Recognize vibration and determine its frequency and
amplitude
3.Resolve spatial detail by touch (e.g. texture, spacing of two
points touched simultaneously)
4.Recognize the shape of objects grasped in the hand
103
What are the 5 sensory mechanoreceptors that are sensitive to touch?
5 sensory mechanoreceptors that are sensitive to touch:
1.Hair Receptors
2.Meissner’s Corpuscles
(Superficial layers of skin)
3.Merkel Cells
4/5.Pacinian Corpuscles/Ruffini Endings
(Deep subcutaneous tissue, Large in size, less in terms of absolute number compared to superficial receptors)
104
How are hair receptors activated?
How are Meissner's Corpuscles activated?
How are Merkel Cells activated?
How are Pacinian Corpuscles activated?
How are Ruffini Endings activated?
What is common about how all the touch receptors are activated and what type of receptors are they?
Hair Receptors: position changes of hairs
Meissner’s Corpuscles: stroking, fluttering
Merkel Cells: pressure, texture
Pacinian Corpuscles: vibration
Ruffini Endings: stretch of the skin
Receptors are activated with mechanical stimulus
(mechanoreceptors)
105
What type of fields do touch receptors have?
What happens if a stimulus is within the field of a touch receptor?
In what 2 ways do touch receptors vary? What does this allow you to do?
Location of receptors:
Receptors have receptive fields
If a stimulus is within the field of a receptor, it activates
the receptor
Receptive fields vary in size and location, gives rise to ability to discriminate between two stimuli
106
What does two-point discrimination measure and how does it vary?
Two-point discrimination varies throughout the body surface
Measures the minimum distance at which two stimuli are
processed as distinct stimuli
107
What does Homunculous mean?
What is the amount of area in the cortex dependent on?
Homunculus:
- “little human”
-areas of the human brain map to certain areas of the body
-amount of area in cortex, dependent on the amount (density)
and importance of somatosensory input from that area
108
What are the 3 other inputs to the somatosensory cortex aside from touch?
2. Pain
3. Temperature
4. Proprioceptive input
109
How are Proprioceptive input and Kinesthesia similar
Sherrington (1906): Proprioception = sense of body position and
orientation in space (6th sense)
Bastian (1880): KINESTHESIA = conscious perception
of movement
Today: synonyms (mean the same thing)
110
What are the 3 sensations of proprioceptive input
Sensations:
1. Sense of Position and Movement in the limbs
2. Sense of Force (effort and heaviness)
3. Sense of Timing of muscular contractions
111
Where are the 4 sensory mechanoreceptors for proprioceptive input found in the body?
Sensory mechanoreceptors found in:
1. Joints: sensitive to extreme joint angles
2. Tendons: Golgi tendon organs detect tension/force
3. Skin: Somatosensory receptors detect position of limbs
(specifically the fingers)
4. Muscles: Muscle Spindles detect limb position and
movement
112
What are the 4 somatosensory maps in S1?
4 Somatosensory Maps in S1
Each one represents (processes) different information:
3a: proprioceptive input
3b: skin (touch)
1: skin (touch)
2: combination of input
113
Where do Primary afferents originate from?
Where do Secondary afferents originate from?
Primary Afferents (1a) originate from bag and chain fibers
Secondary Afferents (II) originate from chain fibers and
static bag fibers
114
What do afferents from bag fibers signal and what type of response do they give?
How do afferents from chain fibers fire and what type of response do they give?
Afferents (1a) from bag fibers signal velocity of stretch
phasic response: proportional to rate of change in muscle length
Afferents (1a and 2) from chain fibers fire in proportion to muscle’s length
tonic response: proportional to muscle length
115
What is the "pinocchio illusion" and what does it involve?
Vibration of the muscle spindles
Pinocchio illusion:
-Vibrate tendon (80-100 Hz)
-Activate muscle spindles
-Perception – muscle has stretched
-Feel muscle containing the stimulated spindles is longer
than it really is
-False biceps spindle input + tactile input from fingertip and
nose
116
What are the 2 principles of control systems?
Open-loop
Closed-loop: feedback
117
What is the major characteristic of open loop control?
What is an example with an object? what is another name for open loop control?
What is an example with the body?
In open-loop control, a movement is launched toward some target, and cannot be corrected thereafter
e.g. a cannonball or ballistic missile can't be steered once it's been launched (that's why another name for open-loop control is ballistic control)
A biological example is a quick movement like a punch: if it's fast, it can't be redirected when the target dodges
118
What are the 2 main ingredients of open-loop control?
1.The controller generates a command to bring about the
desired state
2.If it errs or malfunctions, or if the system is disturbed,
there will be no correction, e.g., a quick movement like a
punch can't be redirected en route
This is the main disadvantage of open-loop control
119
What is the major characteristic of closed-loop control?
What are the 2 examples with objects?
What is an example with the body?
A feedback system constantly monitors its own progress and adjusts its control accordingly
*ROLE (TIME) FOR FEEDBACK*
e.g. a heat-seeking missile detects the current direction of its target and steers toward it. Another example is a thermostat, which monitors room temperature and adjusts the furnace
accordingly
A biological example is balance: we constantly monitor our posture, using our inner ears, vision and proprioception, and adjust our muscles to keep ourselves upright
120
What computes the error in closed-loop control?
A comparator computes the error: the difference between the desired state and the actual state reported by feedback
121
What creates the command in closed-loop control?
A controller creates a command to reduce the error:
e.g., if desired elbow angle is 90º of flexion and the actual angle is 70º, then the error is 20º and the command flexes the elbow
As the elbow continues to flex, the actual state draws closer and closer to the desired, and so the error becomes steadily smaller
When the arm reaches its desired position, the error becomes zero, and the flexion command shuts off so the arm stops in the desired position
122
What happens if something disturbs the system in closed-loop control?
If something disturbs the system away from its desired
position, the feedback signal will report it to the comparator.
The resulting error signal will cause the controller to correct the disturbance.
123
What is a role for proprioception in movement?
Deafferentation
124
Taub & Berman (1968):
deafferented monkeys could still move
(e.g., climb, reach, grasp)
performance was clumsy and inaccurate
Bizzi & Polit (1978):
after deafferentation, monkeys could still
perform point to target
movements not as accurate
What was these 2 researchers conclusions about proprioception in deafferented monkeys?
Taub & Berman (1968):
deafferented monkeys could still move
(e.g., climb, reach, grasp)
performance was clumsy and inaccurate
Bizzi & Polit (1978):
after deafferentation, monkeys could still
perform point to target
movements not as accurate
*Proprioceptive feedback was not necessary for movement production but important for finer control*
125
What was the condition of the patient named "GL"?
What happened in her case?
(Don't need to answer, just read passage)
Deafferented patient
The patient GL, whose results are reported here was followed by
the Doctor Yves Lamarre at the Hôtel Dieu hospital in Montréal.
She was 27 years old when suffering in 1975 from a first episode
of acute polyneuropathy with a complete paralysis including the
respiratory muscles. A diagnostic of Guillain-Barré was made.
She left the hospital three months later. It took three more
months for complete functional recovery that allowed her to meet
again her normal professional and familial activities even
becoming mother of a child.
A second episode of extensive sensory polyneuropathy
occurred suddenly four years later (April 1979) which affected
selectively the large myelinated sensory fibers; There was no
paralysis but only a transient muscular weakness that vanished
after two months. In contrast the severe sensory impairment
affecting her whole body below the nose remained totally
unchanged over the years until now.
Clinically she has a total loss touch, vibration, pressure and
kinesthetic senses and no tendon reflexes in the four limbs, the
trunk being more moderately affected. Pain and temperature
sensations are present which indicate selective impairment of the
large diameter peripheral sensory myelinated fibers.
126
What did Blouin et. al discover with the pointing task in relation to deafferentation?
Blouin et al. (1993): pointing task
with vision of the arm, the patient performed as accurately
as normal participants but without vision of the environment (unstructured environment) or the arm while moving, the deafferented patient consistently undershot the target
127
What did Wadman et. al discover with control of rapid limb movements in relation to deafferentation?
Control of Rapid Limb Movements
Wadman et al. (1979)
-studied tri-phasic EMG patterns during rapid, target-directed movements.
-rapid elbow extension movement to a target
-on some trials, movement was blocked
128
Under what conditions is antagonist muscle activity pre-planned?
movements in which antagonist onset occurs later than
100 ms after initial agonist onset:
-preparation of the antagonist occurs on-line, after
initiation of agonist activity
movements in which antagonist activity begins within
100 ms of agonist onset:
-antagonist control is preplanned along with the agonist
129
What is the role of proprioception in movement?
What are 2 distinct limitations of proprioception in movement?
What does proprioceptive feedback provide information about?
Can carry out certain limb movements in the absence of
proprioceptive feedback (carry out movements in open
loop manner, or use feedback from other senses)
BUT distinct limitations:
1.DEGREE OF ACCURACY
2.Cannot maintain a constant force or position with complete deafferentation
PROPRIOCEPTIVE FEEDBACK PROVIDES IMPORTANT
INFORMATION REGARDING SPATIAL ACCURACY
WHILE A MOVEMENT IS STILL IN PROGRESS
130
What are the 6 components of the eye from innermost to outermost?
Optic nerve
Retina
Fovea
Lens
Iris
Cornea
131
What are the 2 types of photoreceptor cells in the eye?
What are the 4 types of neurons in the eye?
(Photo)Receptor cells:
Rods
Cones
Neurons:
Horizontal
Amacrine
Bipolar
Ganglion
132
What are the 4 types of receptors in the eye from shortest to longest wavelength?
Blue cones
Rods
Green cones
Red cones
133
Where are cones located in the eye?
How many different types of cones are there?
How sensitive are cones to light?
In the fovea
3 types of cones
Lower sensitivity to light (Day Vision)
134
Where are rods located in the eye?
How many different types of rods are there?
How sensitive are rods to light?
In the periphery
1 type of rod
Very sensitive to light (Night Vision)
135
Where do 90% of retinal projections go to?
What are the 2 other targets of retinal projections and what do they control?
90% of retinal projections go to lateral geniculate nucleus
(thalamus)
Other targets:
1. Superior Colliculus:
controls eye movements
2. Pre-tectum:
controls pupillary responses
136
What is the difference between perception and action in regard to the function of vision and what do these processes subserve?
Perception vs. Action
Visual Perception (Perception):
-processes that subserve the recognition and identification of objects and events and their relations
-provides foundation for visual-cognitive processes
Visual-Motor Control (Action)
complex processes that subserve the control of movement or action
137
What are the 2 different systems of vision?
What was the initial research question in regard to vision?
Vision for Perception and Action
Issues for vision:
-does the brain have a unitary visual system to serve
visual perception and action?
… or …
-does the brain have separate systems to serve
perception and action?
138
What did Schneider (1969) originally believe the 2 vision systems were?
Cortical System:
-enables organism to identify a stimulus
-“what” system
Midbrain System:
-enables organism to localize and orient to stimulus in
space
-“where” system
139
What were 3 tasks that monkeys who had their visual cortexes removed able to complete?
monkeys with visual cortex removed are able to perform certain
visual tasks:
avoid obstacles
grasp objects
grasp a moving object
140
What did patient DB suffer from?
What did the surgery remove?
What was the result for his vision?
suffered from severe migraines due to tumor in right visual cortex
surgery removed striate cortex in right hemisphere
blind in left visual field
– could not experience visual stimuli
141
What is the definition of blindsight?
What is cortical blindness?
What do blindsight patients report?
What is this mediated by?
Blindsight:
“seeing” what you don’t see
cortical blindness – damage to visual cortex
blindsight patients report having no visual experience –
but can respond accurately on visual tasks
mediated by sub-cortical visual pathways to extra-striate
(non-primary) visual cortex
142
What did Ungerleider and Mishkin (1982) believe the 2 visual systems were and which cortex did they believe these processes occurred in?
“what” system
-perception of qualities and features of objects
-processing in the INFERIOR-TEMPORAL CORTEX
“where” system
perception of spatial location and relations of objects
processing in the POSTERIOR PARIETAL CORTEX
143
What did monkeys with inferior-temporal lesion show impairment in?
monkeys with inferior-temporal lesion show impairment in visual pattern recognition or object discrimination
144
What did monkeys with posterior parietal lesion show impairment in?
monkeys with posterior parietal lesion show impairment in spatial
discrimination or landmark discrimination
145
What were the 2 major components of the Ungerleider and Mishkin (1982) model?
What were the 2 emphasized points of the U & M model?
Ungerleider & Mishkin (1982):
- “what” vs. “where” systems
-inferior-temporal and posterior parietal lesions disrupts
two different circuits:
what circuit
where circuit
emphasis of U & M model:
-distinction based primarily on stimulus features or attributes
-focus on processing of the stimulus input and not on visual-motor control
146
What did Milner and Goodale (1995) believe the 2 visual systems were and which stream did each of these systems take place?
“what” system:
-VENTRAL (inferior-temporal) stream
-visual processing for formation of perceptual and cognitive
representations
“how” system:
-DORSAL (posterior parietal) stream
-visual processing for the on-line control of goal-directed
actions
147
What are 2 major differences between the Ungerleider & Mishkin model vs the Milner & Goodale model in regard to the 2 visual systems?
Ungerleider & Mishkin (1982):
what vs. where
emphasis based on analysis of visual input
Milner & Goodale (1995):
what vs. how
emphasis based on the purpose of visual input
-purpose of cognition and conscious perception
-purpose of visually-guided action
148
What did patient DF suffer?
What did patient DF develop?
What were the 2 results of this condition?
What can patient DF do and not do?
Patient DF:
-suffered anoxia from CO poisoning
-developed visual form agnosia
“vision without shape”
1. preserved color and texture discrimination
2. impaired form, shape, size discrimination
patient DF can search for colour but shows deficits for orientation
149
What vision stream of patient DF was damaged and what was the result?
What vision stream was preserved and what was the result?
cerebral damage in areas associated with the ventral
stream (ventrolateral occipital cortex)
interrupt visual processing required for perception and
recognition
preserved areas associated with dorsal stream
preserved visual processing for purpose of visual-motor
control
150
What vision stream of patient RV was damaged and what was the result?
What vision stream of patient RV was preserved and what was the result?
R.V.’s Pathology
cerebral damage in areas associated with the dorsal
stream (posterior parietal cortex)
interrupt visual-motor processing required for visually-guided action
preserved areas associated with ventral stream
preserved visual processing for purpose of perception and object recognition
151
Where is the site of damage for Visual Agnosia? How does this damage affect perception and action?
Where is the site of damage for Optic Ataxia? How does this damage affect perception and action?
Site of damage for visual agnosia is the ventral pathway
Perception is lost but action is ok
Site of damage for optic ataxia is the dorsal pathway
perception is ok but action is lost
152
What is the definition of saccades?
How are saccades initiated?
What is the velocity of saccades?
Saccades:
-rapid, ballistic, eye movements
-initiated voluntarily or reflexively
-high velocity (600-700 º / sec)
153
What is space/position constancy?
What are 2 characteristics of saccadic suppression?
Space / Position Constancy:
visual world remains stable when we move our eyes
Saccadic Suppression:
-brief period of reduced sensitivity to spatial displacement
during execution of a saccade
-general suppression of motion signals
154
What are the 2 different saccades when moving towards a target?
What is the goal of a saccade?
Saccade to Target:
*initial saccade
*secondary, corrective saccade
*attempt to get the image of target to fall on or near fovea
155
What moves first in eye-hand coordination?
When is eye movement typically completed?
Eye-Hand Coordination
when reaching to a target in the peripheral visual field:
eye often moves first, followed by head and hand
eye movement is typically completed while hand is still
moving
156
What are 2 things that are reduced by saccadic suppression?
Saccadic Suppression:
1.reduction in visual sensitivity during saccadic eye
movements
2.reduced awareness of visual events (e.g., changes in target
location) that occur during saccades
157
Wha 3 things did the test done by Pelisson et al (1986) called "movement corrections to displaced targets" show?
examination of aiming accuracy showed that limb
movement was modified to the new target position
subjects did not perceive and were unaware of the
change in target position
dissociation between conscious perception and action
158
What was the PPC test?
What were the results of the PPC test?
What were the 4 conclusions of the PPC test?
* point to target as quickly and accurately as possible
* target jumps at start of movement
* aware of target jump
* instructions are to:
a) GO to new target location
b) STOP the movement
a) GO to new target location
- subjects adjust movement trajectory to new location
b) STOP the movement
- movement trajectory turns toward new location before
being aborted
1.Hand is guided by events outside of conscious
awareness
2.movement corrections to displaced targets
3.corrections made even when one does not want to correct his or her movement
4.Corrections mediated by the PPC
-dissociation between conscious perception and action
159
What is the Ebbinghaus illusion and what were the results?
Illusory size distortions
Aglioti et al. (1995)
* size distortion in Titchener circles (Ebbinghaus illusion) affected subjects’ perception
* examination of grip aperture showed proper scaling according to size of circle
* dissociation b/w conscious perception and action
160
What is the influence of a delay in grip aperture?
(dont need answer, just read passage)
“ ... visuomotor networks in the dorsal stream operate in ‘real
time’: these networks appear not to be engaged unless the target
object is visible at the exact moment the response is required. In other situations (e.g. memory-driven actions or advance movement preparation), the control of action passes to other systems that access a representation of the target object laid down by the perceptual mechanisms of the ventral stream.”
161
What does memory-guided action rely on?
memory-guided action:
relies on ventral stream
162
What is the definition of a single sensory modality input?
What is the definition of a unimodal association area output?
What is the definition of a multimodal association area output?
Input:
Single sensory modality: visual or somatosensory input
Output:
Unimodal association area: integrate information for a
single sensory modality
Multimodal association area: integrate information from
more than one sensory modality
163
Where is the multimodal association area in the brain?
Posterior association area
164
What are the 4 inputs to the multimodal association area?
What are the 3 functions of the multimodal association area?
Input:
Somatosensory cortex
Visual cortex
Auditory Cortex
Hippocampus
Function:
Visuomotor integration
Selective attention
Spatial perception
165
What are 3 things that happen when primary sensory areas are damaged?
What are 3 things that are affected by damage to the multimodal association area?
Primary Sensory Areas:
Blindness, deafness, lack of tactile (proprioceptive) sensibility
Multimodal Association Area:
Visuomotor integration
Selective attention
Spatial perception
166
What happens when there is damage to the right PPC?
What happened in the story of Ellen who had damage done to her right PPC?
What is this condition called?
What are 2 important books on this syndrome?
Damage to Right PPC – bizarre deficits
Ellen, a stroke patient, before the mishap, was described
as “Martha Stewart perfect”. (e.g. her clothes and makeup
were always perfectly done)
Afterward, this was still true for the right half of her face
(lipstick, mascara, rouge, etc applied correctly and hair
styled), but not for the left half of her face. Her hair was
not combed on the left and no make-up was applied. “It
was almost as though someone had used a wet towel to
erase all of the makeup on the left side.”
Furthermore, while eating she ignores food on the left
side of the plate and does not seem to see any objects in
her left visual field.
Neglect syndrome
"Left neglected" and "the man who mistook his wife for a hat"
167
What are the 3 deficits that are characteristic of neglect syndrome when there is damage to the right PPC?
deficit in spatial perception
deficit in self-image of left side of body
also have left-side paralysis
deficit in perceiving external world on the left
168
What are 5 symptoms characteristic of personal neglect syndrome?
1.Does not “see/recognize” the left side of the body
2.Will not dress, undress or wash the affected side
3.May deny or disown their left arm or leg
“ Who put this arm in bed with me?”
4.Lose a discrete part of self-awareness
5.Deny paralysis
169
What is the definition of spatial neglect syndrome?
What is the definition of representational spatial neglect syndrome?
What does this suggest and how could this be the case?
Neglect extends from personal space, to space
external from body
Left visual field is neglected in an internal representation
Cannot access and recall images associated with the left
side of the body
Suggests memory of extra personal space is stored with
a body-centered frame of reference
Memories for each half of the visual field are accessed
through the contralateral hemisphere
170
What is the central tenet of spatial neglect syndrome?
Right hemisphere has a particular role in spatial
representations (but this is not mirrored in the left side)
171
What are the 2 diseases that are caused by damage to the left hemisphere?
Damage to Left PPC – dominant hemisphere
1.Aphasia = disorder of language
2.Apraxia = impaired performance of learned motor
responses
Even though:
1. No motoric problems (no muscle weakness)
2. No sensory loss
3. No loss of motivation
172
What is the definition of ideo-motor apraxia?
Ideo-motor apraxia – inability to carry out simple motor
activity in response to verbal command (e.g. “smile”).
Deficits most pronounced when asked to imitate and
pantomime gestures
ex.Show me how you would slice bread. Patient makes a fist and pounds table. When bread and knife are presented, then the patient improves but is still not very good at the task
173
What is the definition of ideational apraxia?
What kind of tasks does this cause of a problem with?
Does this happen contraleterally or ipsilaterally?
What is another cause for this issue beside damage to the PPC?
Ideational apraxia – impairment in carrying out a sequence of movements that are components of a behavioural script, while being able to carry out each one alone (e.g., use of a tool appropriately) SERIAL ORDER PROBLEM.
Problems with attention demanding tasks
Can have ideational apraxia in both contralesional and
ipsilesional limbs
Can also be caused by frontal lobe damage especially in
the pre-motor areas
174
What areas of the contralaterl hemisphere are essential for skilled movemoents?
Where do these areas receive information from?
Which pattern of limbs do parietal lesions cause ideational apraxia in?
* Premotor cortical (PMC) areas of the contralateral
hemispheres are essential for skilled movements
* PMC receives input from the parietal cortex where action
representations are stored.
* Parietal lesions can thus cause ideational apraxia in
both contralesional and ipsilesional limbs
175
What is another way to examine cerebral lateralization?
What does this involve and what is it a treatment for?
What is the prodecure called?
What does this allow you to study?
Is there inter-hemispheric communication or inhibition?
Split Brain Patients
Sectioning of corpus callosum as a treatment for
medically intractable epilepsy
This procedure is called callosotomy
Can study the separate contributions of the left and
right hemispheres to various abilities/tasks
No inter-hemispheric communication or inhibition
176
What is the definition of Bimanual coordination?
How do bimanual movements compare to unimanual movements?
What does this bimanual coordination involve?
Having two limbs perform an action (at the same time)
Bimanual movements are much more complex than
Unimanual movements
involve neural crosstalk across the corpus callosum
177
What is the definition of movement interference and what are 2 ways we can test it?
How does the brain control the movement of two limbs
(each controlled by different hemispheres)?
Often see: Movement Interference
Consider patting your head and rubbing you belly
While sitting at your desk, lift your right foot off the floor
and make clockwise circles with it.
Now, while doing this, draw the number "6" in the air with
your right hand.
Your foot will change direction!!!
178
What is the definition of executive control?
What does the plan for executive control involve?
executive retrieves a motor program from memory implements plan on cortical motor strip
details of plan might refer to changes in motor units, muscles, joints, a-g coactivation
how many variables must the executive control?
179
What are 2 ways we can define the degrees of freedom variable?
A variable that is free to vary
Variable in a system that has to be controlled
180
How many degrees of freedom are at the shoulder joint?
How many degrees of freedom are at the elbow joint?
How many degrees of freedom are at the radio-ulnar joint?
How many degrees of freedom are at the wrist joint?
shoulder joint: 3 degrees of freedom
elbow joint: 1 degree of freedom
radio-ulnar joint: 1 degree of freedom
wrist joint: 2 degrees of freedom (up/down and left/right)
181
How many degrees of freedom must we control to have complete control of the movement of the joints?
if a degree of freedom = movement about a joint
must control 7 degrees of freedom
7 values must be specified for complete control of movement
about the joints
shoulder joint: 3 degrees of freedom
elbow joint: 1 degree of freedom
radio-ulnar joint: 1 degree of freedom
wrist joint: 2 degrees of freedom
3+1+1+2=7
182
How many degrees of freedom must we control to have complete control of the movement of the muscles?
if degree of freedom = muscle
30+ degrees of freedom to control
183
How many degrees of freedom must we control to have complete control of the motor units?
if degree of freedom = motor unit
1000’s of degrees of freedom to control
184
What was Bernstein's (1967) degrees of freedom problem?
What was his solution?
Degrees of Freedom Problem:
too many independent DFs make control difficult
how do we control and coordinate the many degrees of freedom?
solution:
attempt to reduce the functional degrees of freedom as part of the
control strategy
185
How do we reduce the number of degrees of freedom?
Functional Linkages or Constraints
establish functional linkages over the individual degrees of
freedom
linkages functionally reduce the number of DFs that have to be
controlled
186
What was the question that Kelso, Southard & Goodman posited about Bimanual coordination?
What was the answer to the question?
Bimanual Coordination
Kelso, Southard, & Goodman (1979)
how will a person perform when asked to produce movements of the upper limbs to targets, each of which varies in amplitude and accuracy?
-person will form functional linkages (groupings) between muscles that are constrained to act as a single unit
-reduce the number of DFs to be controlled
187
What is the equation for Fitt's law?
Fitts’ Law
Linear equation: y = b + mx
MT = a + b * Log2 [2A / W]
MT = movement time
A = movement amplitude (distance)
W = target width
Log2(2A / W) = index of difficulty of movement
188
What does Fitt's law describe the relation between?
What do movement requiring greater accuracy demand?
Fitts’ Law
describes logarithmic relation between movement time and accuracy demands of movement
movements requiring greater accuracy:
longer movement times to allow processing time to detect errors and make corrections
speed at which movement completed depends on target moving to – degree of accuracy necessary
189
What are functional groupings of muscles constrained to act as?
What kind of coupling happens between limbs?
functional groupings of muscles (muscle linkages or muscle collectives) that are constrained to act as a single, functional unit
Temporal and Spatial Coupling between limbs
190
What is the definition of coordination in relation to degrees of freedom?
… is a problem of mastering the very many degrees of freedom involved in a particular movement - of reducing the number of independent variables to be controlled
