Lecture 4 - Basal Ganglia and Spinal Cord Flashcards
The basal ganglia is divided into two regions: the ________ and the _________ _______
Striatum & Lenticular Nucleus
The striatum of the basal ganglia consists of what two structures?
Caudate nucleus & the putamen
What are the appearances/orientations of the striatum’s structures?
Caudate - situated inferiority to the lateral ventricle
Putamen - inferior & lateral to the caudate
The putamen can be considered to part of both the ______ and the _____ _____
Striatum & lenticular nucleus
The ________ ________ is strictly part of the lenticular nucleus
Globus Pallidus
A main function of the basal ganglia is to facilitate __________ movements and inhibiting ___________/___________ movement
Desired, undesired or competing
The basal ganglia is not an ___________, but rather is a __________
Initiator, facilitator
What does the motor region of the basal ganglia have in common with the primary motor cortex?
It’s got a lil homunculus!
Where Parkinson’s is associated with a difficultly _______ing movements, Huntington’s is associated with a difficulty _______ing _______ movements
Initiating, inhibiting involuntary
A basal ganglia disorder known as _______ is associated with difficulty inhibiting undesired movements (e.g. tics, verbal, thoughts)
Tourette’s
The function of the direct pathway of the cortical-basal-ganglia-thalamic system is to?
Facilitates or encourages movement
The function of the indirect pathway of the cortical-basal-ganglia-thalamic system is to?
Inhibits or suppresses movement
Describe the process of the direct CBGTC system pathway
- The cortex sends signals to the basal ganglia (specifically, a part called the striatum).
- The striatum then sends inhibitory signals to another part of the basal ganglia called the globus pallidus internal (GPi), which normally inhibits the thalamus.
- When the GPi is inhibited, it stops sending its inhibitory signals to the thalamus.
- This allows the thalamus to send more excitatory signals back to the cortex, promoting movement.
Describe the process of the indirect CBGTC system pathway
- The cortex again sends signals to the striatum.
- The striatum sends inhibitory signals to another part of the basal ganglia called the globus pallidus external (GPe).
- When the GPe is inhibited, it reduces its inhibition on a part called the subthalamic nucleus (STN).
- The STN can then send excitatory signals to the GPi, which increases its inhibitory output to the thalamus.
- This leads to less excitation of the cortex, reducing movement.
Describe the effect of Parkinson’s on the CBGTC system
Affects the direct pathway (bias in favour of the indirect pathway, net effect of inhibition)
Voluntary movement becomes harder to initiate rigidity, slowness of movement
Describe the effect of Huntington’s disease on the CBGTC system
Affects the indirect pathway (bias in favour of the direct pathway, net effect of excitation)
movements are harder to inhibit; choreiform movement - involuntary continuous movements especially of the limbs
Where is the substantia Nigra located?
In the midbrain (aka: mesencephalon)
The substantia nigra produces _______
Dopamine
Direct pathway striatal neurons have _____ dopamine receptors, which are _______ by dopamine
D1, excited
Indirect pathway striatal neurons have ______ dopamine receptors, which are ________ by dopamine
D2, inhibited
In someone with Parkinson’s how does the lack of dopamine influence the nigrostriatal pathway
Excitation of the Direct Pathway: With reduced dopamine, the direct pathway is less activated, leading to decreased facilitation of movement. Patients often experience difficulty initiating movement, known as bradykinesia.
Inhibition of the Indirect Pathway: The indirect pathway, which normally helps suppress excessive movement, becomes overactive. This further inhibits movement and can lead to rigidity and tremors.
The subthalamic nucleus is part of the ________encephalon?
Di
The subthalamic nucleus can be seen as an input nucleus to what structure?
Basal ganglia
What structure has been seen to be a target for deep brain stimulation in Parkinson’s disease?
Subthalamic nucleus
What structure has hard-to-define boundaries anatomically, but is thought to be associated with the basal ganglia regardless?
Nucelus accumbens
The nucleus accumbens is located between what two structures?
Caudate and putamen
The nucleus accumbens mediates what type of behaviour? It plays a role in what?
Goal-directed, addicition
What are the 5 major subcortical white matter tracts?
- Superior longitudinal fasciculus
- Arcuate Fasciculus
- Corpus Callosum
- Internal capsule
- Corona Radiata
The superior longitudinal fasciculus has an important function in ___________________
Language processing
Which of the 5 main white matter subcortical tracts is also known as part of the 4 SLF tracts?
Arcuate fasciculus
What does the arcuate fasciculus connect?
Wernicke’s to Broca’s
The ______ connects the two hemispheres
Corpus Callosum
The corpus callosum is complete by age __, and growth continues until the ____ decade of life
4, 3rd
What are the two major pathways of the corpus callosum?
Forceps Major & Forceps Minor
Where is the forceps major pathway located?
Splenium (posterior part of CC)
Where is the forceps minor pathway located?
Genu (anterior part of the corpus callosum)
The splenium of the corpus callosum connects the ______ lobes of both hemispheres
Occipital
The genu of the corpus callosum connects the ______ lobes of both hemispheres
Frontal