Thalamus and Hypothalamus Flashcards
Which parts does diencephalon consist of?
thalamus, subthalamus, hypothalamus
Label the diagram
Label the diagram
Describe the position of the thalamus
sits ventral to the lateral ventricles, is divided in two by 3rd ventricle, organised into discrete nuclei (Clusters of neurons with similar functions and connections.)
What are the functions of the thalamus?
- relay for numerous inputs/outputs
- key relay centre to cortical sensory areas
- involved in almost all sensory systems (except olfactory)
- enhances or restricts signals
LO 20 Thalamic nuclei: explain the functional significance of the thalamic nuclei
Thalamic nuclei classified based on connection with pf nuclei with cortex
- Specific: connected to primary cortical areas
- Association: connected to association cortex
- Reticular: NOT connected to cortex (but intrathalamic connection with all thalamic nuclei)
- Intralaminar: connected to ALL cortical areas
Describe 3 features of intralaminar nuclei.
- project to various medial temporal lobe structures:
- amugdala: emotions, fear, anxiety
- hippocampus: memory
- basal ganglia: movement
- mostly glutamergic neurons (contain glutamate hence mostly excitatory)
- loss of neurons in this region associated with progressive supranuclear palsy (PSP) and Parkinson’s disease
LO 20 Describe the features of reticular nucleus
- forms outer covering of the thalamus
- majority of neurons are GABAergic (Eg inhibitory)
- unlike other thalamic nuclei: dont connect with distal regions but with other thalamic nuclei
- receive inputs from collaterals of their axons from thalaamic nuclei
What is reticular formation?
- Set of interconnected pathways in the brainstem
- Send ascending projections to forebrain nuclei: Ascending reticular activating system (ARAS) -
What is ARAS? What is it responsible for?
Ascending reticular activating system (ARAS)
- involed in consciousness and arousal
- increased activity=increases wakefulness
- both intralaminar and reticular nucleus receive inputs from ARAS
Describe some features of the hypothalamus.
- Divided into two by 3rd ventricle
- Collection of individual nuclei with distinct functions
- Largely ipsilateral (same side) connections with other nuclei
- Involved in 4 F’s (Fighting, Fleeing, Feeding, Mating)
What are the functions of the hypothalamus?
- Direct connections with autonomic nervous system (by neurons in hypothalamic paraventricular nucleus with direct projections to pre-autonomic neurons in spinal cord)
- connections with endocrine system (hypothalamic-pituitary axis)
- control of behavior
Label the diagram
paraventricular nucleus diagram
What are the functions of paraventricular nucleus?
- sends projections to autonomic nervous system and posterior pituitary gland (diagram)
- involved in feeding behavior
What is the function of suprachiasmatic nucleus?
Regulates circadian rhythm
