Basal Ganglia - Friedman - Exam 1 Flashcards
Basal Ganglia Functions:
Action selection
Plan and movement sequences
Integrate cortical inputs
Cognitive goals
Emotional goals
Survival oriented motivations
Moment by moment sensory inputs
Substrate for ____ learning
Substrate for ___ behaviors (why people get addicted)
Substrate for reward
Basal Ganglia Functions:
Action selection
Plan and movement sequences
Integrate cortical inputs
Cognitive goals
Emotional goals
Survival oriented motivations
Moment by moment sensory inputs
Substrate for procedural learning
Substrate for habitual behaviors (why people get addicted)
Substrate for reward
There are a set of circuits that run through all the structures in the basal ganglia. They all have different functions.
Which three did Dr. Friedman talk about and what are their functions?
___ loop: has to do with cognitive function, attention, making decisions about what to do next, changing behaviors.
___ loop: has to do with emotional behaviors.
___ loop: body movement loop.
These loops are not independent of each other. Instead, they overlap.
There are a set of circuits that run through all the structures in the basal ganglia. They all have different functions.
Which three did Dr. Friedman talk about and what are their functions?
Pre-frontal loop: has to do with cognitive function, attention, making decisions about what to do next, changing behaviors.
Limbic loop: has to do with emotional behaviors.
Motor loop: body movemebt loop.
These loops are not independent of each other. Instead, they overlap.
There are two parts in the motor loop of the basal ganglia:
What are they?
Indirect loop: inhibiting loop
Direct loop: allowing loop
All voluntary movements are planned and carried out by what structure?
Cerebral cortex
At any given time, multiple plans and multiple movements are being programmed by the cortex.
The cortex sends its info to the ___ ____.The __ ___ does some sort of processing and in the end, selects a movement. The purpose of the __ ____ is to select a movement.
All of the input from cortex to ganglia is to the ____. This structure is made up of the ___ and ___. For the motor system, the input is the ___).
At any given time, multiple plans and multiple movements are being programmed by the cortex.
The cortex sends its info to the BG.The BG does some sort of processing and in the end, selects a movement. The purpose of the BG is to select a movement.
All of the input from cortex to ganglia is to the striatum. This structure is made up of the caudate and putamen. for the motor system, the input is the putamen
Dopamine is a NT and it comes from the ___ ___ part of the basal ganglia.
Substantia niagra
The D1 receptors (exictatory or inhibitory?) projects directly to the ___ ___ ___. The __ __ is the output of the basal ganglia and projects to the thalamus within the direct/indirect system of the basal ganglia. The __ __ inhibits the thalamus and causes movement/no movement?
The D1 receptors (exictatory) projects directly to the globus pallidus internus. The globus pallidus internus is the output of the basal ganglia and projects to the thalamus within the direct system of the basal ganglia. The globus pallidus inhibits the thalamus and causes movement.
The D1 neurons in the putamen inhibit the globus pallidus, then the thalamus is released and it excites the motor cortex, causing ___
The D1 neurons in the putamen inhibit the globus pallidus, then the thalamus is released and it excites the motor cortex, causing movement.
All of the neurons within the basal ganglia are inhibitory except for two: neurons from the __ and __
All of the neurons within the basal ganglia are inhibitory except for two: neurons from the thalamus (VA/VL) and STN (subthalamic nucleus)
The pathway that starts from the D2 containing neurons is more complicated. It projects to the ____ segment of the __ ___ (this normally inhibits the subthalamic nucleus).
But, when D2 is released, the ___ segment of the __ __ gets inhibited, causing the ___ nucleus to become activated.
The ____ nucleus activates the internal segment of the globus pallidus, which causes inhibition of the thalamus, and therefore, a decrease in ___ (there is a leash on the dog).
So, when the ___ pathway is predominant, you do not get movement. When the ___ pathway is predominant, you get movement.
The pathway that starts from the D2 containing neurons is more complicated. It projects to the external segment of the globus pallidus (the GpE normally inhibits the subthalamic nucleus).
But, when D2 is released, the external segment of the globus pallidus gets inhibited, causing the subthalamic nucleus to become activated.
The subthalamic nucleus activates the internal segment of the globus pallidus, which causes inhibition of the thalamus, and therefore, a decrease in movement (there is a leash on the dog).
So, when the indirect pathway is predominant, you do not get movement. When the direct pathway is predominant, you get movement.
You must have an active thalamus exciting the cortex to get ____. Movement can only occur when the output of basal ganglia is ____.
Movement.
Movement can only occur when the output of the basal ganglia is reduced.
The substantia nigra has two parts:
- pars compacta - contains dopamine neurons
- pars reticula (SMR) - it is just like the internal segment of the globus pallidus. They both project to the thalamus.
The ___ pathway of the BG faciliates movement. The ___ pathway of the BG suppresses unselected movements.
The direct pathway of the BG faciliates movement. The indirect pathway of the BG suppresses unselected movements.
The indirect and direct pathway of the BG are chemically distinct.
The ___ pathway uses:
D1 receptors
Substance __
Dy____
Projects to __ segment of the globus pallidus.
The ___ pathway uses:
D2 receptors
Enk__
Projects to __ segment of the globus pallidus.
The indirect and direct pathway of the BG are chemically distinct.
The direct pathway uses:
D1 receptors
Substance P
Dynorphin
Projects to internal segment of the globus pallidus.
The indirect pathway uses:
D2 receptors
Enkephalin
Projects to external segment of the globus pallidus.
With Huntington’s Disease, a degenerative disease of the __ __ and cortex, the ___ neurons degenerate first (aka D2 neurons).
With Huntington’s Disease, a degenerative disease of the BG and cortex, the enkephalon neurons degenerate first (aka D2 neurons).
The subthalamic nucleus’s role is to excite ____ segment of the globus pallidus, and ___ movement.
The subthalamic nucleus receives tonic inhibitory input from the ___ segment of the ___ ___.
The STN can also receive direct cortical inputs, which inhibits movement. This is called the __direct pathway.
The subthalamic nucleus’s role is to excite internal segment of the globus pallidus, and inhibit movement.
The subthalamic nucleus receives tonic inhibitory input from the external segment of the GP.
The STN can also receive direct cortical inputs, which inhibits movement. This is called the hyperdirect pathway.
__ ___ is a sheet of neurons in the midbrain between the cerebral peduncles and tegmentum of midbrain.
The dorsal part of the sheet houses the dopamine.
The ventral parts, the pars reticulata, and just like the ones in the the internal segment of the GP, are GABAnergic or inhibitory. So. the dopamine neruons project back into the striatum, but also to the entire BG. It is these guys who die in Parkinsons disease.
Substantia Nigra is a sheet of neurons in the midbrain between the cerebral peduncles and tegmentum of midbrain.
The dorsal part of the sheet houses the dopamine.
The ventral parts, the pars reticulata, and just like the ones in the the internal segment of the GP, are Gaba nergic or inhibitory. So the dopamine neruons project back into the striatum, but also to the entire BG. It is these guys who die in Parkinsons disease.
Which one, A or B, is the one with Parkinson’s Disease?
A
Dopamine neurons accimulate melanin, giving the SNc a dark color (NORMAL)
The loss f pigmentation shows the loss of dopamine neurons (the left one)
T or F?
Dopamine faciliates movement through both indirect and direct pathways.
T
D1 receptors are excitatory. Dopamine activates the direct path, which activates mvmt.
D2 receptors are inhibitory. Dopamine inhibits the indirect path, which activates mvmt.
One alternative to treating Parkinson’s disease is Deep Brain Stimulation, which inactivates specific targets in the brain by electrical stimulation.
Given what you know about the circuitry of the basal ganglia, what structure would you inactivate to help with the hypokinetic symptoms of PD?
You could inactivate the subthalamic nucleus (prevent the release of glutamine, which activates GPI, which, when activated, releases inhibitory neurons to the thalamus, preventing movement).
You could also inactivate the Globus Pallidus internus. If you inactivate GPi, the thalamus is not held on a leash anymore, so it causes movement.
Medium spiny neurons (MSNs), also known as spiny projection neurons, are a special type of ___-nergic inhibitory cell representing 95% of neurons within the human striatum, a structure located in the basal ganglia. Medium spiny neurons have two primary phenotypes (i.e., characteristic types): __-type MSNs of the direct pathway and ___-type MSNs of the indirect pathway
Medium spiny neurons (MSNs), also known as spiny projection neurons, are a special type of GABA-ergic inhibitory cell representing 95% of neurons within the human striatum, a structure located in the basal ganglia. Medium spiny neurons have two primary phenotypes (i.e., characteristic types): D1-type MSNs of the direct pathway and D2-type MSNs of the indirect pathway
Two types of cholinergic receptors are:
muscarinic and nicotinic
Cholinergic interneurons predominantly excites the __ pathway.
This balances the inhibitory effect of dopamine (inhibitory effect of dopamine on the ___ pathway causes movement).
The ___ ___ can amelioriate akinesia of PD by blocking excitatory effects of cholinergic interneurons.
Cholinergic interneurons predominantly excites the indirect pathway.
This balances the inhibitory effect of dopamine (inhibitory effect of dopamine on the indirect pathway causes movement).
The muscarinic anticholinergics can amelioriate akinesia of PD by blocking excitatory effects of cholinergic interneurons
When there is no dopamine, you get this excitatory effect of ACh on the indirect pathway, which would inhibit __ – not a good thing for someone with PD. If you can block that, you would facilitate ___ – a good thing for people with PD.
When there is no dopamine, you get this excitatory effect of ACh on the indirect pathway, which would inhibit mvmt – not a good thing for someone with PD. If you can block that, you would facilitate mvmt – a good thing for people with PD.
