Thalamus ad Hypothallamus

Question 1

Where do you find, within the brain, the diencephalon?

Answer 1

Subcortical area, above the brain stem, but underneath the lateral ventricules (3rd vent divides it)-connect to Pitgland
Composed of Thalamus, Subthalamus and hypothalamus
On a coronal section, either side of midline (slighly rostral)-beneath lateral ventricule

Question 2

How is the Thalamus oragnised? What is its basic function?

Answer 2

Discrete nuclei (not to be confused with ganglion)
Numerous different areas-nearly all pathways pass there at some point
Relay site for numerous outputs/inputs (all sensory-except olfactory)
Enhances/restricts signals

Question 3

Why is the thalamus involved in the sensory pathway?

Answer 3

In sensory, input (1st neuron) arrives to dorsal horn, where it synapses up the dorsal column, all the way up to the medulla of brain stem-cross over, and that neuron goes to synapse in Thalamus-and then one goes to somatosensory gyri

Question 4

WHat is the intralaminar nulcei of the thalamus? What neurons do you mostly find there?

Answer 4

Small part in the midline, anterior part of the thalamus
Sprojects to various medial tempral lobe structures-amygdala, Hypocampus (found in bottom of temporal lobe, R/L) and basal ganglia
Mostly glutamatergic neurons-excitatory
Loss of neurons associated with motor issues (parkisins, PCP)

Question 5

Briefly, what is the role of the amygdala, Hypocampus and basal ganglia?

Answer 5

Amygdala-fear and anxiety
Hypocampus-memory
Basal ganglia-movement

Question 6

What is the reticular nucleus? What does it do?

Answer 6

Form the outer covering of the thalamus
GABAnergic neurons
Short neurons connecting to other thalamic nuceli
Recieves inputes from other nuclei-acts to modulate thalamus activity

Question 7

What is the Reticular formation?

Answer 7

Set of interconnected pathways in the brainstem (middle of brainstem where functions isnt defined in current anat)-ascending formations to forebrain-(ascending reticular activating system (ARAS)-seems to keep people conscious/aware, and has role in sleep)
Both Intralaminar and Reticular receive input from ARAS

Question 8

How does the hypothalamus relate to the 3rd ventricule?How is it organised?

Answer 8

Literally makes up the walls and souroundings of the 3rd ventricule-
Again discrete nuclei
Largely ipsilateral (same side) connection with other nuclei
Involved in the 4 F’s

Question 9

What is the function of the hypothalamus?

Answer 9

4 F’s
Directly connected to ANS-
Directly connected to endocrine systems
Control of behaviour

Question 10

What is the paraventricular nucleus? What is it function

Answer 10

Sends projectiong to ANS and Pit Gland
Has Parvocellular gouping - to brain stem- heart and kidney
and Magnocellulars-to Oxytocin, Vasopressin
Very involved in appetite-and lesions can cause loss of ihbitory behaviours
Receieves input from other nuclei

Question 11

What is the suprachiasmatic nucleus?

Answer 11

Just above optic chiasm-supraoptic nucleus a bit more lateral
Role in circadian clocks-connection to sleep/activities, etc
Connects to Paraventricular , but also to pineal gland (Melatonin), and to rest of ANS