Diencephalon Flashcards
What are the components of the diencephalon?
Thalamus
Subthalamus
Hypothalamus
Label diagram of thalamus and surrounding features.
Label horizontal cross sectional diagram of thalamus and surrounding features.
What divides the thalamus in two?
the 3rd ventricle
Where is the thalamus located in the brain?
ventral to the lateral ventricles.
How is the thalamus organised?
Organised into nuclei (clusters of neurons with similar functions and connections).
Outline the function of the thalamus?
Relay site for numerous inputs/outputs.
Relay centre to cortical sensory areas.
Involved in almost all sesnory systems (except smell)
enhances or inhibits signals (modulatory role).
Diagram outlining somatosensory pathway.
What is the relevant thalamic nucleus for the somatosensory pathway?
Ventral posterior lateral nucleus.
Where do somatosensory fibres cross the midline?
medulla.
What is the role of the intralaminar nuclei?
Project to various medial temporal lobe structures (e.g. amygdala, hippocampus and basal ganglia)
What are the roles of the amygdala, hippocampus and basal ganglia
Amygdala - processing of emotions, fear and anxiety.
hippocampus - memory
basal ganglia - initiation of movement.
What kind of neurotransmitter do intralaminar nuclei have?
glutamate - excitatory.
What problems are associated with loss of intralaminar neurons?
Parkinson’s disease, supreanuclear palsy.
Where is the reticular nucleus found?
Outer covering of the thalamus.
What neurotransmitter do reticular nuclei use?
GABA - inhibitory.
How does the reticular nucleus differ from other thalamic nuclei?
They don’t connect with distal regions, but with other thalamic nuclei - receive inputs from collaterols of their axons from other thalamic nuclei.
What is the role of the reticular nucleus?
Modulate thalamic activity (-ve feedback)
What is the reticular formation?
Set of intercolated pathways in the brainstem - send ascending projections to the forebrain (the ascending reticular activating system)
What are the roles of the reticular formation?
Involved in consciousness, arousal and degree of wakefulness (ARAS)
How do the intralaminar and reticular nucleus relate to the reticular formation?
They both receive inputs from ARAS.
What kind of connections do hypothalami nuclei make?
largely ipselateral.
Name 4 things the hypothalamus modulates.
fighting
fleeing
feeding
fucking
How does the hypothalamus regulate autonomic responses?
Many direct neuronal connections with the ANS
Give 3 things the hypothalamus regulates.
The ANS
the endocrine system.
behaviour.
Identify the paraventricular nucleus.
What is the role of the paraventricular nucleus?
Send projections to ANS and posterior pituitary gland
What are the roles of parvocellular and magnocellular neurones.
Parvocellular - influence the ANS, e.g. to the vasculature, heart and kidneys.
Magnocellular - connect to the anterior pituitary - secretion of oxytosin and vasopressin.
What are the effects of lesions in the paraventricular nucleus?
Loss of inhibitory neurons –> increased feeding and weight gain.
Where is the suprachiasmatic nucleus located?
Just above the optic chiasm.
What is the role of the suprechiasmatic nucleus?
Control of sarcadian rhythms - influencing pineal gland’s release of melatonin.
Influence sleep wake cycle.
What can SCN lesiosn cause?
disrupted sleep cycle.
