Lecture 1 Flashcards
Characteristics of PD
Stooped posture and shaky hands
What part of the brain initiates movement
Frontal cortex
Movement is tightly controlled by ___
Basal ganglia
Basal ganglia is a group of ___
Nuclei
What is the basal ganglia involved in
Initiation and smooth performance of ongoing movement
Caudate location
Lateral side of the lateral ventricles
What part of the basal ganglia is connected to the caudate
Putamen
Where do the caudate and putamen connect
Nucleus accumbens
What are the caudate and putamen separated by
Internal capsule
Internal capsule
Nerve tracts that connect various brain regions
Why does the internal capsule appear white
Composed of myelinated axon bundles
Collective name for caudate and putamen
Striatum
Why are the caudate and putamen grouped together
They come from the same embryonic origin
Nuclei adjacent to the putamen
Globus pallidus internal and globus pallidus external
What nuclei is located under the thalamus
Subthalamic nuclei
Where is the substantia nigra located
Midbrain region
How many nuclei make up the substantia nigra
Two
Nuclei of the substantia nigra
SN pars compacta and SN pars reticulata
Ventricles
Cavities in the brain
How are inputs of the caudate and putamen divided
- Input from the cortex
2. Input from the SN pars compacta
Input from the cortex to caudate and putamen name
Corticostriatal inputs/pathway
Input from the SN compacta to caudate and putamen name
Nigrostriatal input/pathway
Neurons of the caudate and putamen
Medium spiny neurons
Characteristic of medium spiny neurons
Huge dendritic trees
Information processed by the medium spiny neurons and other neurons in the caudate and putamen will be sent to ___ and ___ (outputs)
Globus pallidus (internal and external) SN pars reticulata
Which inputs to the caudate and putamen are processed by the medium spiny neurons and other local circuit neurons
Both cerebrostriatal and nigrostriatal
Another name for the globus pallidus
Pallidum
Globus pallidus at rest
Chronically active
What happend when the globus pallidus is active
Puts a break on the thalamus
Can you move the muscle when the globus pallidus is active
NO
Can the thalamus activate the motor cortex when there is a brake from the globus pallidus
No (no movement)
If you want to move, the ___ requests a movement
Cortex
What does the cortex activate when it requests movement
Striatum
What happens when the striatum is activated
The globus pallidus is inhibited (strong brake put on thalamus)
What happens when the globus pallidus puts a strong brake on the thalamus
Thalamus is disinhibited
What happens when the thalamus is disinhibited
Thalamus excites motor cortex to initiate movement
Globus pallidus inhibited = brake is present/absent = thalamus can/cannot talk to motor cortex to initiate movement
Brake is present
Thalamus can talk to the motor cortex to initiate movement
Globus pallidus active (disinhibited) = brake is present/absent = thalamus can/cannot talk to the motor cortex to initiate movement
Brake is absent
Thalamus cannot talk to the motor cortex to initiate movement
___ and ___ monitor and regulate the movement initiated by the cortex
Substantia nigra and subthalamic nucleus
What can the caudate and putamen inhibit besides the globus pallidus
SN reticulata
What happens when the SN reticulata is inhibited
Superior colliculi are disinhibited
What happens when the superior colliculi are disinhibited
The head can move in coordination with the body movement
Basal ganglia pathways divisions
Direct and indirect pathways
Direct pathway is mainly to initiate ___
Voluntary movement
How does the substantia nigra excite the caudate and putamen
D1 receptor subtype
What happens when the caudate and putamen are excited by the substantia nigra
Further disinhibits (activates) the thalamus, and thalamus excites motor cortex to initiate movement
Which SN acts through D1
Compacta
What SN acts through D2
Reticulata
Purpose of the indirect pathway
Suppress inappropriate movement (like a tremor)
What nuclei is part of the indirect pathway
Subthalamic
Why do two indirect pathways prevent movement and the third allows movement
It is not good to prevent all movement (balance)
Organization of the direct and indirect pathways
Center surround
Center of the center surround model
Direct pathway (cortex initiates movement via caudate and putamen)
Surround of the center surround model
Indirect pathway (suppress unwanted movement via subthalamic nuclei)
