What are the functions of the basal ganglia? 3
- Modulate voluntary motor activity
- look at the “big picture” to produce a behavior; integrates the sum of cortical activity to one behavioral output.
— Decision to move; direction of movememnt; amplitude of movement; motor expression of emotions - Proceduralizes movement and behavior (make it more efficient) -> habits
What are the parallel curcuits used in the basal ganglia?
Motor circuit: controls body and eye movement
Associative/cognitive circuit: involved in higher level cognitive function
Limbic circuit: involved in emotional and motivational processing
** All of these act at the same time and not individually and modify/streamline movement to purpose. They also give “personality” to our movement.
What is the release-inhibition model in the basal ganglia?
The release-inhibition model is the pathways used in all three parallel circuits that requires the release of thalamic inhibition to allow cortical output.
Direct pathway:
- Inhibits the globus pallidus internal -> release of inhibition on the thalamus
- Allows more motor output
- Facilitates target-oriented movement
Indirect pathway:
- Strengthens inhibition on thalamus.
- Less motor output
- “Brakes” the normal function of the direct pathway
- Inhibits potentially competing movement
** Both pathways work together to streamline movement to make it target-oriented and efficient.
Draw the pathway for the indirect and direct pathway for the basal ganglia.
Look on the slides
Name the structures needed in the basal ganglia parallel circuits.
All: Ventral striatum (Caudate nucleus, Putamen, Nucleus Accumbens); Globus Pallidus (External, Internal); Substantia Nigra; Subthalamic nucleus; thalamus
Circuits:
Motor: (putamen)
- Supplementary motor; premotor; primary motor; Primary sensory; sensory association
Associative (nucleus accumbens/ caudate):
Prefrontal; temporal; posterior parietal cortex; prestriate cortex?
Limbic (nucleus accumbens):
Frontal association area; Anterior cingulate obitofrontal lobe; amydala; hippocampus
Name dopamine receptors and how they affect the basal ganglia.
Dopamine fires when there is movement.
D1 receptor = excitatory
- In the direct pathway to strengthen more purposeful movement
D2 receptor = inhibitory
- Weaken indirect pathway to allow more superfluous movement
What does the motor circuit in the basal ganglia modulate?
- Motor performance **
— Measured and coordinates motor - Regulate gaze and orientation of eye
- procedural aspects of movement **
— Recall sequences of movement
— Innervated by the substantia nigra - Forms habits
What does the associative circuit in the basal ganglia modulate?
- Planning complex motor activity
- Learns sequences of motor sequences
— Learned enough, it gets recalled by the motor circuit - Dopaminergic projection helps for motivation, reward, goal-oriiented movements/cognitive processes in here
What does the limbic circuit in the basal ganglia modulate?
- Motor expression of EMOTION (body language)
— Postures, gestures and facial expressions related to emotions - Affective-motivational behavior
- Reward-oriented behaviour
- Dopaminergic signaling to nucleus accumben
— working memory processes and cognitive processes
—**Incentive-based learning is dependent on assigning accurate salience (dopaminergic signaling) to external stimuli
Name the lobes and structures within the cerebellum.
Anterior lobe:
- Vermis
Flocculonodular lobe:
- Flocculus
- Nodule
Posterior lobe:
Pathways:
Superior cerebellar peduncle
Middle cerebellar peduncle
Inferior cerebellar peduncle
What does the cerebellum do?
- Receives and interprets (nonconscious) PROPRIOCEPTIVE information
- coordinates BALANCE, linked to the vestibular nuclei
- coordinates FINE MOVEMENT, eye-hand coordination
- PREDICTS sensory consequences of movement
Name the type of information processed in the cerebellum and where does the information project to.
- Vestibular information
- Project to the paravermis and flocculonodular lobes through the inferior cerebellar peduncle
- Informs position of head and body in space
- orient eye movments during locomotion - Propriocetive information
- Project to the anterior lobe and vermis
- Information from…
— Spinal border cells go in the anterior spinocerebellar tract through the superior cerebellar peduncle
— Propiception from Clarke’s column and cuneocerebellar fibers go in the anterior spinocerebellar tract through the inferior cerebellar peduncle - Cortical information
- Project to the cerebellar hemispheres
- Cortex -> pontine nuclei -> pontocerebellar tract -> (middle cerebellar peduncle) -> cerebellar hemispheres
- Helps with fine motor control of upper extremity, dexterous hand movement, hand-eye coordination - Olivecerebellar fibers
- Project to the entire cerebellar cortex through climbing fibers
What are the different regions of the cerebellum during development? What order do they develop in?
- Archicerebellum/vestibulocerebellum - Trunk control
(Found in the flocculornodular lobe aned vermis) - Paleocerebellum/Spinocerebellum - Syngergistic movement of extermities
(Found in the anterior lobe and vermis) - Neocerebellum/cerebrocerebellum - Toptographical representation of the extremities, contains areas for eye movement and speech, coordination of intricate and complex movement
(found in the posterior lobe)
What are the cerebellar loops and what do they allow?
- Vestibulocerebellar loop
- Spinocerebellar loop
- Cerebrocerebellar loop
Allows for…
- Coordinated, balanced and smooth movement
- Anticipation of movement
- Predictions that feed back to the cortex
- Calculate trajectories/behavioural outcomes and react accordingly
Draw the vestibulocerebellar loop. What information does it take?
Vestibular nuclei
🔻
Paravermal area/flocculonodular lobe
🔻
Fastigial nucleus -> Vestibular nuclei -> spinal cord
🔻
Reticular formation
🔻
spinal cord
- Visual and proprioceptive information -> balance
Draw the spinocerebellar loop. What is the purpose of this loop?
Look on slides.
- Refining and correting movement patterns
Draw the cerebrocerebellar loop. What is its purpose?
Look on slides.
- To automate processes and predict movement outcomes
What is part of the hypotheses on cerebellar function?
a) Prediction, sequencing of movement, proceduralization of movement
b) Compile past outcomes, form habits, time coordination
c) Adust movement errors, generate internal nodes, prediction
d) Motivational movement, learning movement, emotional processing
C
When one drinks too much alcohol, what type of lesion can occur? What are the symptoms of this?
Lesion of the Purkinje cells can occur. The anterior lobe is most sensitive to this poisoning.
Symptoms
- Gait ataxia
John is having trouble grabbing a can of soda. When he tries to grab it, it is either too far or too close to his hand. What does he have? What kind of lesion could he potentially have?
- John shows symptoms of dysmetria
- Dysmetria can be a result of a lesion to the neocerebellum which can also show symptoms of the following: dysdiadochokinesia, impaired speech, nystagmia?
nystagmus and difficulty walking are all signs of…
1. Midline cerebellar disease
2. Being drunk
3. Lesion to vermis
4. Lesion to the FN node
5. 2 of the above
6. 3 of the above
7. All of the above
- Midline cerebellar disease, lesions to the vermis or FN node will show signs of these.
Use an ananlogy to explain the differences between the STATE, LEVEL, and CONTENT of consciousness. Associate the different brain structures involved in consciousness to your analogy
Example: vinyl player
Content of consciousness: vinyl disc / Cortex because the different type of music would be the type of thoughts the person would have
State of consciousness: power button / Thalamus because the power button determines what goes in and out of the consciousness
Level of consciousness: Volume / Reticular formation because the volume shows how strong of a alertness the person is.
How does the thalamus modulate information from the driver input? Draw the pathways.
- Driver input goes into the thalamus.
- The thalamus sends the input to the cortex
- The cortex sends feedback on the information to the thalamic reticular nucleus.
- The thalamic reticular nucleus inhibits the thalamus to modulate the information received by the cortex. (negative feedback loop)
What is the purpose of the Glasgow Coma scale
It assesses motor and verbal responses to determine the level of consciousness of a person
