Topic 5: Motor System & Disorders Flashcards
Steps / Functions of the Motor System During Hand Movement
- Visual information required to locate the target
- Frontal-lobe motor areas plan the reach and command of the movement
- Spinal cord carries information to hand
- Motor neurons carry messages to muscles of the hand and forearm
- Sensory receptors on the fingers send a message to the sensory cortex saying that the cup has been grasped
- Spinal cord carries sensory information to the brain
- Basal ganglia judge grasp forces and the cerebellum corrects movement errors
- Sensory Cortex receives that the cup has been grasped
Grip Aperture
In the motor system, grip aperture refers to the degree of opening between the thumb and fingers when grasping an object. Grip aperture is an important aspect of motor control because it reflects the precision of the grip and the amount of force required to manipulate the object.
When an individual reaches out to grasp an object, the grip aperture initially opens to accommodate the size of the object and then closes as the object is grasped. The degree of grip aperture varies based on the properties of the object being grasped, such as its size, shape, texture, and weight.
M1 = Primary Motor Cortex
The primary motor cortex, also known as M1 or the precentral gyrus, is a region of the brain located in the frontal lobe. It is considered one of the most important areas of the motor system, responsible for the planning and execution of voluntary movements in the body.
The primary motor cortex contains a map of the body’s motor representation, known as the motor homunculus. This map represents different body parts, with more cortical space allocated to those that require finer and more precise motor control, such as the hands and face.
What THREE MAIN brain systems contribute to motor system commands?
- Basal ganglia (force)
- Brainstem and spinal cord (movement)
- Cerebellum (accuracy)
Information from the basal ganglia and the cerebellum contributes information to the motor cortex.
Information from the motor cortex, brainstem, and spinal cord sends information to the motor neurons.
Cerebellum (accuracy)
- gets a carbon copy of the original motor program, and compares it to the sensory information it is receive to ensure that the body is in the correct position in space
- makes tweaks and sends information to M1
The cerebellum receives input from various areas of the brain, including the primary motor cortex, and uses this input to fine-tune and coordinate movement. The cerebellum is involved in a wide range of motor functions, including balance, posture, coordination, and precision of movement
Basal Ganglia (force)
Tells the motor system how much force is needed and how long it should be maintained via sensory feedback. (w/o sensory feedback, the motor system will drop the object).
Specifically, the basal ganglia send inhibitory and excitatory signals to the primary motor cortex, which can modulate the excitability of M1 neurons and influence the selection of motor plans. The basal ganglia also play a role in the control of movement sequences and the initiation of movements, and they can influence the speed and amplitude of movements as well.
Disruptions in the basal ganglia can lead to a variety of movement disorders, including Parkinson’s disease, Huntington’s disease, and dystonia, which can result in difficulty with movement initiation, tremors, and other motor impairments.
Information pathways in the brain to execute motor action
Starting at the back of the brain (posterior cortex), information is sent to the prefrontal cortex and passed along back toward the posterior cortex.
1. Posterior cortex provides sensory information to the frontal cortex. The posterior cortex sends goals.
2. Prefrontal cortex PLANS the movement
3. Premotor cortex organizes movement sequences
4. Motor cortex produces specific movements
M1 is shown in blue, this is the final stop and where actions are performed.
Association Cortex / Tertiary Cortex
Association cortical areas are areas that integrate information from a lot of other areas and other systems.
- Posterior cortex is an example of this.
- Visual, somatosensation and auditory info can be used for localization; RECALL the dorsal pathway is referred to as the “where pathway” and is used to help us localize things in space. All the information is sent to this region to help with motor coordination.
- Ventral stream, the “what pathway” is also used, we need to know WHAT we are picking up
- Stimulation in this region doesn’t cause action, but a person will have an intense INTENTION to perform an action.
Somatosensation
Somatosensation is the sensory information that is generated by the skin, muscles, tendons, and joints, as well as the internal organs of the body. It is the sense that allows us to perceive touch, pressure, temperature, pain, and the position and movement of our body parts.
Once the sensory information reaches the brain, it is processed and integrated with other sensory and motor signals to create a perception of the body and the environment. The primary somatosensory cortex, located in the parietal lobe of the brain, is responsible for the initial processing of somatosensory information, and it contains a map of the body’s sensory representation, known as the somatosensory homunculus.
Ventral stream - the WHAT pathway
The ventral stream, also known as the “what” pathway, is a neural pathway in the brain that is involved in object recognition and visual perception of shape, color, and texture. It extends from the primary visual cortex (V1) to the temporal lobe, and is responsible for identifying and categorizing objects in the visual field.
While the ventral stream is primarily involved in visual processing, it can also play a role in motor coordination. This is because object recognition and perception are important for guiding actions and movements in response to visual stimuli.
For example, imagine you are playing catch with a ball. As the ball approaches, your visual system uses the ventral stream to quickly identify the object as a ball and extract information about its size, shape, and movement. This information is then used to guide your motor system in predicting the trajectory and velocity of the ball, allowing you to coordinate your movements to catch it.
Research has shown that the ventral stream is involved in motor planning and coordination, as well as in the perception of action and intention. Damage to the ventral stream can result in deficits in object recognition and perception, as well as in motor coordination and planning.
The general list of brain regions that are involved in motor planning/movement
- dotted line is the central sulcus
Starting anteriorly in the brain:
- Frontal eye field (movement of the eye)
- Premotor cortex
- Primary motor cortex
- Brocas Area (output of language, movement of the mouth)
- Parietal Cortex
Middle of the brain:
- Anterior cingulate (response inhibition)
- Supplementary Motor Cortex (planning, preparation)
How does activity in the brain change in reference to motor actions? (i.e., does the type of motor action illicit different brain activity?)
We tend to see fewer motor areas involved versus when we are required to do much more complex or novel tasks - we see greater engagement in a lot more of the other motor areas.
- blood flow indirectly reports how active the brain regions are
Evidence of preprogrammed actions that are stored in:
The primary motor cortex, and the premotor motor cortex.
Evidence:
- Repertoire of movements (ethological categories - serve a purpose for a particular species in a particular species)
- Similar in premotor (purple area in image) & M1(blue), but more complex available to premotor
- More complex motor programs are found in the premotor cortex; if you stimulate these regions (activate the programs) you will see sweeping actions that can be done (e.g., hand to mouth, with the mouth opening i.e., a feeding action, sequence movement, and you will see this result regardless of the starting position)
- Damage to the premotor disrupts more complex movement
- The end goal is the same ( i.e., a feeding action, sequence movement, and you will see this result regardless of the starting position)
etiological categories
a branch of knowledge dealing with human character and with its formation and evolution
premotor cortex
The premotor cortex is a region of the brain that is located in the frontal lobe, anterior to the primary motor cortex (M1). It is involved in the planning and execution of more complex motor behaviours, such as reaching, grasping, and manipulating objects. The premotor cortex contains a variety of motor programs, or “motor schemas,” that can be activated to produce specific patterns of movement.
When a specific motor program is activated in the premotor cortex, it sends signals to the primary motor cortex to initiate the corresponding movement. Stimulation of the premotor cortex can therefore produce complex, coordinated movements such as sweeping actions, as mentioned in the sentence.
Evarts Study: Movement Coding in M1 (wrist action in monkeys )
Recorded neural activity in the wrist region of M1 while monkeys flexed wrist
Findings:
- M1 neurons plan & initiate movement
- M1 neurons increase firing to increase the force of a movement
- Motor cortex specifies the direction of movement
Elaboration:
- We see signals before the movement has begun, which suggests that M1 is involved in the planning and execution
- The breaks in the red bars helped us to realize that while flexing the wrist we will see activity, but unflex the wrist does not result in activity in these brain regions - DIRECTION SPECIFIC
- Varying weight: activation increases for the increased force that is required
- Investigates how the brain encodes movement information. Specifically, the study aimed to identify how individual neurons in M1 represent different aspects of movement, such as direction, speed, and amplitude.
- Each red bar = representation activation in neurons
Through the use of implanted electrodes and advanced data analysis techniques, Evarts was able to identify specific populations of neurons in M1 that were selectively responsive to different aspects of wrist movement. The study demonstrated that these neurons exhibited a “population code,” in which information about movement direction and other features was distributed across a large number of neurons rather than being represented by individual neurons alone.
Georgopoulos Study: Movement coding in M1 (Arm regions & moving lever in different directions)
Recorded neural activity in the arm region of M1 while the monkey moved the lever in different directions. Single-cell recording.
Findings:
- Each M1 neuron maximally active in a particular direction
- Activity decreased in proportion to displacement from the preferred direction
- Conclusion: Motor neurons calculate the distance & direction of movement
- Different neurons have different directional specificities (notice in the image that you will get a relatively high rate of firing if you’re close to that direction, but notice as you move away from that direction the level of activation decreases.)
- It is not that the neuron is specific to ONLY one direction and will ONLY fire to that direction, it instead seems to have a maximal level of activity for a particular direction. It will still be active if you move away from that preferred direction, but the level of activation really decreases the farther away you get from that preferred direction.
- The greater amount of activation is still seen when a greater amount of force is needed and applied
Neuronal Population Vector Model
- How neurons operate via vectors
- When analyzing how to complete a motor action (i.e., work towards an end goal), there are various pools of neurons in MQ that work together to create a movement of a given body part in a particular direction, with a certain force.
-The Neuronal Population Vector Model (NPV) is a mathematical framework used to analyze and interpret neural activity recorded from populations of neurons.
-The model assumes that neural activity is represented by a vector in a high-dimensional space, with each dimension corresponding to the activity level of one neuron. - PLASTICITY: Implies that there is not a specific motor program, instead, the neuronal pools are dynamic that we can combine in any way we want to generate a movement.
The NPV model can be used to decode the intended movement of an animal or person based on the activity of a population of neurons. The model takes into account the firing rates of individual neurons and the tuning curves that describe how each neuron’s activity relates to the intended movement. The NPV model can also be used to generate predictions about how changes in neural activity will affect movement.
When we say “Motor Plan” or “Motor Cortex,” what region are we referring to? What systems?
- Refers to programs that are being created at higher cortical levels (not basal ganglia, not cerebellum - instead we are talking about M1 and posterior parietal lobe)
- “Motor plan” refers to planning an action and creating an action with an end goal in mind
- Neuromuscular control information: need information about our body, we require feedback
- Sensory feedback: the motor system requires sensory feedback to adjust movement and force, and to maintain actions
- Coarticulation (an example of motor planning): vocal muscles
What are the Cortical Layers in Primary Motor Areas
In the primary motor cortex, layers III, V, and VI contain large pyramidal neurons that are involved in the control of voluntary movements. These neurons project to the spinal cord and brainstem to activate the appropriate motor neurons and muscles during movement. The specific patterns of activity within these layers are thought to reflect the different aspects of movement, such as direction, force, and duration.
The cortical layers in primary motor areas, as well as other areas of the neocortex, are designated as follows:
Layer I: The molecular layer, which is the outermost layer of the cortex and contains few cell bodies but many dendrites and axons of neurons from other cortical layers.
Layer II: The external granular layer, which contains small granular neurons and is primarily involved in the processing of sensory information.
Layer III: The external pyramidal layer, which contains large pyramidal neurons that project to other cortical areas, including the motor cortex.
Layer IV: The internal granular layer, which contains small granular neurons and receives sensory information from the thalamus.
- input of sensory information
Layer V: The internal pyramidal layer, which contains large pyramidal neurons that project to subcortical structures, such as the spinal cord and brainstem, as well as to other cortical areas.
- output of information (larger)
Layer VI: The multiform layer, which contains a diverse population of neurons that project to subcortical structures, such as the thalamus, and are involved in feedback loops between cortical and subcortical areas.
How is “coarticulation” an example of motor planning
- BEING ABLE TO PLAN MOUTH MOVEMENTS AHEAD OF TIME TO SAY THE WORD CORRECTLY
Coarticulation is an example of motor planning because it involves the coordinated movements of multiple articulators, such as the lips, tongue, and jaw, in the production of speech sounds. When we speak, we do not move each articulator separately and independently; rather, the movements of one articulator are influenced by the movements of the others, resulting in a coordinated and efficient motor plan for producing the intended speech sound.
For example, when we produce the word “bat,” the movements of the lips and tongue for producing the “b” sound overlap with those for producing the “a” and “t” sounds. The movements of the articulators are planned in advance based on the intended sound sequence, and coarticulation occurs to optimize the speed and accuracy of speech production. This planning process involves the primary motor cortex and other brain regions involved in motor control and is essential for fluent speech production.
Image: because the left hemisphere is dominant for language, we see a difference in the motor output of mouth movements (for a brief moment in time, the left motor cortex has the information first) so we see the right side of the mouth begins to move first
How far in advance is a motor plan made? How is this shown through reaction time (RT)?
RT (reaction time):
- In terms of motor planning, generally what we see is that when a person begins saying “a cat bit her”, “a big dog ate a bird” and “a man walked down to the river to catch a fish” - the RT is not that different between those three sentences.
- What happens is the motor program appears to begin and get a few steps ahead, then as you create the movement, the planning is continuing as the movement continues
What happens when you are not engaging in a movement, but instead are observing/remembering/imagining a movement?
Martin et al. Study: Increased blood flow to the hand region of the motor cortex when naming tools
Haueisen & Knosche Study: Pianists exhibit activation in the motor cortex when listening to music
Nyberg et al. Study: Similar brain activation during imagined movement & actual movement (e.g., rolling ball on a table) This is shown in the image.
- Look at the areas active in the mental rehearsal: M1, Postieor parietal, prefrontal, BUT THERE IS NO ACITICT IN THE CEREBELLUM because it requires sensory feedback
- Suggest that imaging the movements can help prime some of those motor programs prior to doing the movement and it may benefit performance
Mirror neural system when observing movement
Supplementary Motor Area (SMA)
The SMA is thought to be involved in the formation of an internal model of movements, which allows us to plan and execute complex movements without constant feedback from our senses (i.e., we plan prior to the movement). The pre-motor cortex, on the other hand, is more involved in the control of individual movements and the selection of appropriate movements based on the task at hand.
Preparation for Sequential Movements: The SMA is particularly important for the preparation and execution of sequential movements, such as playing a musical instrument or typing on a keyboard. This may be because the SMA is involved in the formation of motor sequences or the initiation of movement chains.
- SMA is tucked within the interhemispheric fisher
- Involved in motor planning
In the image graph:
- higher numbers are associated with more activation in the SMA region
- During a particular type of movement, the study looked at activation in the SMA region, as well as muscle activation (so the muscle getting ready to go and carry out the action)
- Action initiation: Prior to the START Point (prior to the movement) we see high levels of SMA activation, demonstrating that it is involved in the planning of the action, and is ongoing throughout the action.
- Action initiation: MA is more active when movements are more complex or more novel
- Motor Imagery: SMA is active during the imagery process
What are the regions within the SMA, and what are their associated functions?
- Pre-SMA: anterior regions of SMA (more engaged in initial planning, visual information triggers)
- SMA Proper: posterior regions of SMA (less planning, more about relaying that plan in the engagement of the action)
- Supports the idea that: as you move from more frontal regions, back through the premotor, and finally to the motor cortex, the complexity of the planning is increasing. We get a lot of initial planning and as we move further back in the brain things get a little more complex THEN it is more about really designing the M1 in the execution of the plan.
IMAGE
Participants are reaching out to a fixed object:
- See it – wait – beep - go (reach out to grab it)
- Pre-SMA: a lot of activation when the object is seen, AND when the person reaches out to grab the object
- SMA Proper: there is less activation when the person sees the object (not as much as Pre-SMA), verses activation (more activation than Pre-SMA) when they have to reach out and actually grab the object
Mirror Neurons
Neurons fire when observing others’ movement (also our own) AND when we complete the action physically.
- Activation when imaging an action
- Related to a “complete action” (i.e., encode a complete action); referring to actions with a goal in mind
- Can “fill in the blanks” when part of a movement is absent
- Importance in imitating & understanding others’ actions (goal-directed
- Nurtonsns exist for different types of actions (not all of them, but a majority of them)
- Most of them are transitive, meaning that there is a goal direction, a target associated with the action
- Help us interpret the intention behind other peoples actions
Where are mirror neurons in the brain?
- Hypothesizes that the mirror neuron system is most likely located in the left hemisphere, and is related to language
- Role in self-action, perception of action, self-awareness, & awareness of intention & actions of others; VERY IMPORTANT FOR OUR INTERPRETATION OF OTHERS BEHAVIOURS/ACTIONS
- Important for gestures & verbal language (Broca’s area
- Autism: dysfunction of the mirror neuron system?
Problems with interpreting gestures/intentions appropriately; AND Absence of empathy (ability to see others’ points of view)
IMAGE:
- The human system includes Broca’s area, is distributed - contains areas that are not goal-oriented (i.e., intransitive)
- Purple – hand movements; orange – tool use; blue–upper limb, green – no object manipulated
- Kolb & Whishaw suggest “our cognitive understanding of an action is embodied in the neural systems that produce that action”.
Anterior Cingulate Cortex (ACC)
The anterior cingulate cortex (ACC) is involved in motor planning, specifically in the initiation and control of voluntary movements. Studies have shown that the ACC is active during the early stages of movement preparation, and its activation correlates with the speed and accuracy of motor performance.
The ACC is thought to play a role in the selection and preparation of motor responses based on sensory input and internal goals, as well as in the inhibition of inappropriate responses. For example, research has shown that the ACC is activated when people are required to switch between two different motor responses, indicating that the ACC plays a role in the control of response selection.
- Tomas Paus’s work (motor modulation task): Higher PET activation during learning of task, then less with practice
Anterior Intraparietal Sulcus (AIP)
The anterior intraparietal sulcus (AIP) is a region of the parietal cortex that is involved in motor output and planning, particularly in the context of grasping and manipulating objects.
Studies have shown that neurons in the AIP are selective for the shape, size, and orientation of objects, and that they respond specifically to visual stimuli that are relevant for guiding hand movements. This suggests that the AIP is involved in transforming visual information about objects into motor plans for grasping and manipulating them.
There is functioning mapping of the Anterior Intraparietal Sulcus (AIP); i.e., regions are active for specific types of movement and motions based on function; with emphasis on movements that are visually guided (using visual information for motor planning)
- Emphasis on grasping/aperture
- RECALL: in the parietal lobe we have input associated with vision along the DORSAL stream (i.e., helps us plan where things are - important for pointing, reaching grasping)
Involved in motor control; all along the anterior portion of the Intraparietal Sulcus there is activation for specific types of motor actions (e.g., eye movements, pointing and reaching actions, grasping for something with an end goal to hold it or use it)
Located posteriorly to S1
Dual Channels in the Motor System (from the Anterior Intraparietal Sulcus (AIP))
We have posterior parietal input that comes into the frontal lobe and influences motor planning, and what has been found is that there can be different channels of communication specific to certain types of movements.
The dual channels in the motor system from the anterior intraparietal sulcus (AIP) refer to two distinct neural pathways that originate in the AIP region of the parietal cortex and project to different regions of the frontal cortex involved in motor control.
The first pathway is the dorsal pathway, also known as the “where” pathway or the “action for perception” pathway. This pathway projects from the AIP to the dorsal premotor cortex (PMd) and is involved in visually guided reaching and grasping movements, as well as in transforming visual information about objects into motor plans for action.
The second pathway is the ventral pathway, also known as the “what” pathway or the “action for recognition” pathway. This pathway projects from the AIP to the ventral premotor cortex (PMv) and is involved in the recognition and selection of appropriate actions based on object properties, such as shape, size, and orientation.
Ebbinghaus Illusion
The Ebbinghaus illusion is a visual illusion that involves the perceived size of a circle surrounded by smaller circles. The illusion was first discovered by German psychologist Hermann Ebbinghaus in the late 19th century.
In the Ebbinghaus illusion, two circles of the same size are presented side by side, with one circle surrounded by smaller circles and the other circle surrounded by larger circles. The circle surrounded by smaller circles appears larger than the circle surrounded by larger circles, even though they are actually the same size.
The illusion occurs because the surrounding context of the circles affects our perception of their size. The smaller circles surrounding the first circle make it appear larger by creating a contrast effect, while the larger circles surrounding the second circle make it appear smaller by creating a size contrast effect.
Ebbinghaus Illusion - How does this “trick” the motor regions of the brain?
- All along the anterior portion of the Intraparietal Sulcus there is activation for specific types of motor actions (i.e, reaching actions, grasping for something with an end goal of holding it or using it)
- When looking at this illusion, does our aperture fit with what the true visual information is, or what we perceive the information to be?
- The aperture is not different between the two images; therefore even though our perceptions are subjective, the action is using the true visual sensory information to plan the motor action
Cerebellum (what does it do, and what are the zones involved in processing?)
Helps to coordinate movement, accepts receptive and sensory feedback as motion is ongoing, and is going to compare the original motor program to the sensory feedback, and then send feedback up towards M1 for it to make adjustments and changes.
- very dense, makes up about 50% of neurons in the brain
- Organized ipsilaterally (the right side will process the right side of body information, and the left side will process the left side of the body information)
- Vermis (body midline): right down the center of the body, plays a role in balance and staying upright
- Flocculus: receives Vestibular inputs (input about acceleration in the x,y,z places that will help determine how we’re moving at any point in time, it also helps to maintain movements of the body). Also receives Spinal cord projections (balance)
- Intermediate Zone: processes larger Movement of limbs
- Lateral Zone: processes movement of appendages, motor planning, and multi-joint movement (i.e., decomposition of movement, needing to move shoulder and elbow to carry out a specific action)
- Timing in motor coordination and movement accuracy
- Included auditory information processing
Overshooting (Hypermetria)
In the image, we are looking at an individual who is flexing via a bicep curl.
Ag = Agonist muscle (bicep)
Ant = Antagonist muscle (tricep)
Normal: As you initiate and engage the action you have to relax the antagonist and all the agnostic to pull up. As you start to slow things down, the antagonist needs to now take control and slow that action down. In the image, we see a rhythmic pattern between the muscles.
Damage: we see overshooting and uncoordinated muscle movement. This does not produce smooth action.
This happens when people drink alcohol as well.
Lateral Zone Damage Study: Learning with Prism Goggles
The study involved participants wearing prism goggles that shifted the visual field by a certain amount to one side, causing them to initially reach in the wrong direction when attempting to reach for an object. The participants were then asked to perform a series of reaching tasks while wearing the prism goggles, with the goal of adapting their movements to compensate for the visual shift.
The study compared the performance of participants with lateral zone cerebellar damage to that of healthy control participants. The results showed that the lateral zone cerebellar damage group had difficulty adapting their reaching movements to the visual shift induced by the prism goggles, indicating that the lateral zone of the cerebellum is critical for motor learning and adaptation.
Furthermore, the study showed that the lateral zone cerebellar damage group had difficulty in maintaining the learned movement after the prism goggles were removed, suggesting that the lateral zone of the cerebellum is also involved in the retention and transfer of motor learning.
Basal Ganglia
The basal ganglia play a critical role in motor planning and execution, helping to select and initiate appropriate movements while suppressing unwanted or inappropriate ones. Helps with gate and control of movement.
Neurotransmitters involved:
- DA (dopamine)
- Glutamate (primary excitatory NT)
- Ach
- GABA
Basal Ganglia Disorders: Huntington’s disease
Hyperkinetic = meaning excessive movements
Huntington’s disease = Genetic: HTT gene (huntingtin protein)
- Mutation (dominant allele) produces an abnormal form
- Normal CAG repeats 10 – 35 times (HD: 40 – 120) the mutation gene as ALOT more repetition, therefore more build-up of a protein
- Extremely long form, sliced into smaller fragments, bind together, & accumulate (toxic) to the cells
- Destroys cells in the caudate putamen in particular and this is where the disease begins(ACh & GABA), then affects cortical regions later
Symptom onset ~ 30-50 years of age
- Lift expectancy is 12 years
- Involuntary & exaggerated movements
- Chorea movements (twitching; brief, abrupt, irregular movements)
- Athetosis movements (writhing; slow, convoluted movements) - it is obvious when they are moving, not at rest
- Cortical atrophy: Results in cognitive deficits (e.g., slowed information processing)
Tourette’s Syndrome
Hyperkinetic = meaning excessive movements
- Genetic & environmental factors
- Symptom onset between 2-15 years of age
- Dysfunction in cortical & subcortical regions (i.e., Basal ganglia, thalamus, & frontal cortex)
- Involuntary motor tics
- Involuntary vocal tics (e.g., Inarticulate & articulate, Echolalia (repeating a sound over and over), Coprolalia (myth?))
- Possible abnormalities in cognitive functions supported by the right hemisphere (intelligence is not impacted)
- Treatments include some medications (e.g., haloperidol (antiDA), antiseizure, antidepressants), behaviour therapy (e.g., recognizing tic impulse coming and learning to transition tic into another movement)
Parkinson’s Disease
- Hypokinetic motor disorder: absence of progressive movement
- Genetic & environmental factors
- Loss of DA cells in substantia nigra
- Decreased activation along the nigrostriatal pathway
- Age of onset ~ 60 years of age (can be younger)
- Symptoms (Tremor at rest (CASE), muscular rigidity, involuntary movement (e.g., akathesia), postural disturbance)
- Difficulty initiating & performing movements (e.g., walking)
- Akinesia - Poverty of movement (trouble initiating)
- Bradykinesia - Slow movement (e.g., locomotor)
Cognitive impairments with progressive disease - Treatments: L-dopa, DBS(deep brain stimulation) (treating the symptoms)
Parkinson’s Disease & Handwriting
The image is monitoring the velocity of handwriting when writing “minimum.”
Movements are normally consistent (right graph), on the left side of the image, we see a lack of coordination and initiation.
