Diencephalon and Basal Ganglia Flashcards
What are the stuctures in the subcortical region?
- corpus callosum
- anterior commissure
- corona Radiata
- internal capsule
- diencepahalon (thalamus and hypothalamus)
- pituitary gland
- pineal gland
- hippocampus
- amygdala
- basal ganglia
what is the stucture and function of the corpus callosum
axonal connections between the left and right cerebral hemispheres, principally the frontal and parietal lobes
What is the structue and function of the anterior commissure?
axonal connections between left and right temoral lobes with projection to the amygdala
invovled in the olfactory pathway
what is the corna radiata and internal capsule structure and function?
axonal connections between the cortex and thalamus to the brainstem and spinal cord.
Internal capsule … (parts)
- anterior limb
- genu
- posterior limb
Boomerang shape. – continuation of the homunculus.
Where the axons are funneling to go to the areas needed.
Diencephalon- Thalamus structure and function
- composed of over nuclei
- connected with nearly all structures throughout the nervous system
- relays, integrates and sorts motor, and sensory infomration
- impacts cognitive functions and mood/emotions
Diencephalon- Hypothalamus structures and functions
- links the nervous system to the endocrine system via the pituitary gland
- assists with maintaining homeostasis by controlling autonomic nervous system and regulating hormones
- Detects thirst and hunger
- Determines circadian rhythm/sleep-wake cycle
- Regulated emotions
Pituitary Gland structure and function.
- anterior and posterior portions
- secretes hormones that regulate growth, metabolism, and reproduction
- at the base of the brain, specifically behind the bridge of the nose and directly below the hypothalamus.
Pineal Gland structure and functions.
- Assists with melatonin secreation and managing circadian rhythm
- connects the limbic system to other parts of the brain
- Regulates motor pathways and emotions
- Posterior to the thalamus
Hippocampus structure and functions
- technically part of the temporal lobe
- connected primarily with somatosensory cortex, thalamus, hypothalamus, and brainstem
- Assists with long term memory storage
Amygdala structure and function
- Composed of about nuclei with connections primarily with the cortex, thalamus, hypothalamus, hippocampus, and brainstem
- Encodes information about emotional events
- Modulates cognitive functions such as memory, attention, and perception
The Limbic system structure and function
- An interconnected group of many subcortical structures
- Involved in emotional states, motivated, affect, attention, perception, arousal, perception, arousal, and consiousness, learning, and memory
- Influences endocrine system and autonomic nervous system
Basal Ganglia structures and functions
- Striatum: caudate and putamen
- Globu pallidus: internal segment (GPi) and external segment (GPe)
*Subthalamic nucleus (STN) - Substantia nigra (in midbrain): Pars compacta (Snpc) and Pars reticulate (SNpr)
Anatomy of the basal ganglia - frontal view
Basal Ganglia antomy- transverse view
Basal ganglis - functions and pathways
involved in feedback loops with cerebral cortex, thalamus, and brainstem
Main fucntions
* initiation, termination and control movement
* Eye movemetns
* Behabiors, habits, and procedural learning
* Cognition and mood
Basal Ganglia 3 intrinsic pathways
- direct
- indirect
- hyperdirect
Key principle: at rest unwanted movement from cortex is inhibited by the thalamus. Basal ganglis can either uphold this inhibition or counter it
Direct pathway
=”GO”
inhibition of inhibitory neurons –> facilitates movement
1. Cortex excites putamen via glutamate
2. Putamen inhibits GPi via GABA
3. GPi is unable to inhibit thalamus
4. Thalamus excites cortex via glutamate
5. This results in facilitation of movement
Indirect pathway
= “No Go”
Facilitation of inhibitory neurons -> inhibits movement
1. cortex excites putamen via glutamate
2. putamen inhibits GPe via GABA
3. GPe is unable to inhibit STN
4. STN excites GPi via glutamate
5. GPi inhibits thalamus via GABA
6. This results in inhibition of movement
Hyperdirect pathway
= “STOP”
Facilitation of inhibitory neurons -> inhibits movement
1. Cortex excites STM via glutamate
2. STN excites GPi via glutamate
3. GPi inhibits thalamus via GABA
4. This results in inhibition of movement
What and how is dopamines role in movement?
Faciliates movement
* substantia nigra pars compacta (SNpc) releases dopamine at the putamen
* the putamen has 2 dopamine receptors D1 and D2
* depeneding on which is stimualted different pathways will be activates or inhibited
* Regardless of which receptor, the end result will be facilitation of movement
What is the pathway of the D1 receptor?
SNpc -> dopemine -> D1 receptors -> facilitation of Direct Pathway -> facilitation of movement
What is the pathway of the D2 receptor?
SNpc -> Dopamine -> D2 receptors -> inhibition of indirect pathway -> Facilitation of movement
