Medical Neurosciences: Diencephalon

Front 1

Diencephalon

Back 1

-located rostral to the brainstem, bounded laterally by posterior limb on inner capsule
-Major Subdivisions: Epithalamus (pineal gland), Subthalamus, Hypothalamus, Thalamus, Third Ventricle
-Is divided in half by the third ventricle

Hint 1

Location
Subdivisions

Front 2

Epithalamus

Back 2

-where pineal gland is found

Hint 2

major part

Front 3

Pineal Gland

Back 3

-small, cone-shaped, attached to roof of third ventricle near the posterior commissure
-the epiphysis has glial cells and pinealocytes
-believed to influence circadian rhythm, spontaneous locomotor activity, and feeding and drinking patterns
-calcifies around 20 yoa, and is a good marker for the midline on radiographs
-has incomplete bbb, so can check concentration of compounds in the blood stream

Hint 3

Location
Function

Front 4

Pinealocytes

Back 4

-Secrete hormone melatonin

Hint 4

Secretions

Front 5

Tumors of Pineal Gland

Back 5

-alter the onset of pubertal changes (precocious puberty)

Hint 5

Effects of

Front 6

Subthalamus

Back 6

-located rostral to the midbrain
-contains subthalamic nucleus

Hint 6

Location
Contents

Front 7

Subthalamic Nucleus

Back 7

-involved with motor control
-is a crucial relay of the basal ganglia

Hint 7

Functions

Front 8

Hypothalamus

Back 8

-Includes: mammillary bodies, tuber cinereum, infundibulum, neurohypophysis, optic chiasm, fornix, many major hypothalamic nuclei

Hint 8

Structures

Front 9

Thalamus

Back 9

-separated by thrid ventricle
-separated from hypothalamus by the hypothalamic sulcus, a shallow groove on the ventricular surface
-major source of afferent fibers to the cortex
-relay center to the cerebellum and basal ganglia

Hint 9

location
communication

Front 10

Thalamic Radiations

Back 10

-for communication with the cortex, mainly from regions fo the lateral thalamus to the internal capsule of the cortex

Hint 10

Function

Front 11

Thalamic Nuclei

Back 11

-over 30
-most divided into groups by band of white matter: internal medullary lamina

Hint 11

number
divider

Front 12

Internal Medullary Lamina

Back 12

-band of white matter that divides the thalamic nuclei

Hint 12

purpose

Front 13

Anterior Nuclear Group

Back 13

-anterior pole is pocketed by the internal medullary lamina
-group consists of anterior nucleus, ventral anterior nucleus, lateral anterior nucleus

Hint 13

Thalamic Nuclei
boundaries

Front 14

Medial Nuclear Group

Back 14

-medial and dorsal
-divided by the internal medullary lamina

Hint 14

Divisions

Front 15

Lateral Nuclear Group

Back 15

-Lateral and Ventral
-divided by the interanal medullary lamina

Hint 15

Divisions

Front 16

Centromedian Nucleus

Back 16

-Is within the internal medullary lamina

Hint 16

Location

Front 17

Posterior Region of Thalamus

Back 17

-pulvinar
-lateral geniculate body
-medial geniculate body

Hint 17

Contents

Front 18

Reticular Thalamic Nucleus

Back 18

-surrounds and forms a thin shell on the lateral portion of the thalamus and contains inhibitory neurons
-no extra-thalamic projections (all terminate in thalamic nuclei)
-purely GABAergic
-

Hint 18

Location
Function

Front 19

Anterior Nucleus

Back 19

-Limbic system (hippocampus and amygdala)
-Cingulate gyrus
-Emotion and Short term memory

Hint 19

Thalamic Nuclei
Input
Output
Function

Front 20

Ventral Anterior (VA) Nucleus

Back 20

-Cerebellum, basal ganglia
-motor cortex
-muscle control

Hint 20

Thalamic Nuclei
Input
Output
Function

Front 21

Ventral Lateral (VL) Nucleus

Back 21

-Cerebellum, basal ganglia
-motor cortex
-muscle control

Hint 21

Thalamic Nuclei
Input
Output
Function

Front 22

Ventral Posterior Medial (VPM) Nucleus

Back 22

-medial lemniscus, dorsal trigeminal tract, ventral trigeminal tract, mesencephalic tract
-somatosensory cortex (parietal lobe)
-somatosensation (facial)

Hint 22

Thalamic Nuclei
Input
Output
Function

Front 23

Ventral Posterior Lateral (VPL) Nucleus

Back 23

-medial meniscus, lateral spinothalamic tract
-somatosensory cortex (parietal lobe)
-somatosensation (all non-facial regions)

Hint 23

Thalamic Nuclei
Input
Output
Function

Front 24

Pulvinar

Back 24

-Superior Colliculus
-parietal lobe
-visual association

Hint 24

Thalamic Nuclei
Input
Output
Function

Front 25

Lateral Geniculate Body

Back 25

-Optic Tract
-Occipital Lobe
-Vision

Hint 25

Thalamic Nuclei
Input
Output
Function

Front 26

Medial Geniculate Body

Back 26

-Inferior Colliculus
-Temporal Lobe
-Hearing

Hint 26

Thalamic Nuclei
Input
Output
Function

Front 27

Dorsal Medial Nucleus

Back 27

-Frontal Lobe and limbic system
-frontal lobe
-personality and executive functions

Hint 27

Thalamic Nuclei
Input
Output
Function

Front 28

Reticular Nucleus

Back 28

-Thalamus, cerebral cortex
-thalamus
-thalamic inhibition

Hint 28

Thalamic Nuclei
Input
Output
Function

Front 29

Thalamic Nuclei: Anterior Group

Back 29

-Anterior Nucleus
-Ventral Anterior Nucleus (VA)
-Ventral Lateral Nucleus (VL)

Front 30

Thalamic Nuclei: Ventral Lateral Group

Back 30

-Ventral Posterior Medial (VPM)
-Ventral Posterior Lateral (VPL)

Front 31

Thalamic Nuclei: Posterior Region

Back 31

-Pulvinar
-Lateral Geniculate Body
-Medial Geniculate Body

Front 32

Thalamic Nuclei: Outer Shell of Thalamus

Back 32

-Dorsal Medial Nucleus
-Reticular Nucleus

Front 33

Thalamocortical Circuit

Back 33

-The thalamocortical projection from the principal nuclei is topological: nearby points in the thalamus project to nearby points in the cortex.
-Thalamocortical projection is excitatory (glutamatergic)
-Is reciprocated by a topological and excitatory corticothalamic projection

Front 34

RTN Neuron

Back 34

Can shut down Thalamocortical circuits that are both glutamatergic (excitatory)

Front 35

Thalamus

Back 35

-Integrate, correlate, and relay information (sensory, motor, consciousness, limbic and visual systems, etc)
-Involved with reflexes, and in regulating consciousness, alertness and attention
-is a synaptic point for all sensory impulses with the exception of olfacory signals

Hint 35

Functions

Front 36

Thalamic Nuclei

Back 36

-funciton in methods by which the brain focuses attention and are involved in conscious perception and interpretation of pain

Hint 36

functions

Front 37

Prefrontal Lobotomy

Back 37

-was a treatment for severe psychiatric disorders b/w 1940-1960
-reciprocal connections b/w dorsomedial nucleus of the thalamus and the frontal lobes was interrupted

Front 38

Hypothalamus

Back 38

-part of the wall for the third ventricle
-located ventral to hypothalamic sulcus
-boundaries: anterior-lamina terminalis, superior-hypothalamic sulcus, inferior-optic chism and tracts, posterior-posterior edge of mammillary bodies

Hint 38

location
boundaries

Front 39

Tuber Cinereum

Back 39

-inferior border b/w optic chiasm and mammillary bodies

Front 40

Hypothalamus - Functions

Back 40

-regulates: heart rate, blood pressure, water metabolism, general metabolism, sexual behavior, temperature (posterior hypothalamus), GI activity, etc
-elaboration of emotional responses: aggression, anger, rage, placidity
-modulates autonomic responses

Hint 40

Functions

Front 41

Hypothalamus - Afferents

Back 41

-Forebrain: from limbic system, retina, and others
-Associated pathways: hippocampus to hypothalamus (mammillary bodies) via fornix, amygdala to hypothalamus via stria terminalis
-Brain Stem/Spinal Cord: from a variety of areas/nuclei - reaches hypothalamus via dorsal longitudinal fasciculus

Hint 41

Afferent Input

Front 42

Hypothalamus - Efferents

Back 42

-Sends to same areas from which it recieves input
-exception: mammillary bosies to thalamus via mammillothalamic tract
-Pituitary Gland (hypophysis)

Front 43

Pituitary Gland

Back 43

-neurohypophysis - posterior
-adenohypophysis - anterior

Hint 43

Portions

Front 44

Pituitary - Hypothalamus Connection

Back 44

-neurohypophysis via neural pathways (direct connection)
-adenohypophysis via blood vessels (hypophyseal portal vessels
-hypothalamus contains many well-delineated nuclei which make conections with the pituitary gland

Front 45

Nuclei b/w Neurohypophysis and Hypothalamus

Back 45

-Supraoptic Nucleus (SON)
-Paraventricular Nucleus (PVN)
-These nuclei release neuroendocrine products directly into the general circulation through the vasculature of the posterior pituitary

Front 46

Neurohypophysis - 2 parts

Back 46

-infundibulum
-pars nervosa

Front 47

Adenohypophysis - 3 parts

Back 47

-pars tuberalis
-pars distalis
-pars intermedia

Front 48

Median Eminence

Back 48

-ventral portion of hypothalamus where hypothalamic axons converge to secrete releasing/inhibiting hormones, which act on the pars distalis as signals to release/store hormones

Front 49

Hypophyseal Portal System

Back 49

-superior hypophyseal arteries
-hypophyseal veins
(-portal vein b/w hypothalamus and adenohypophysis)

Front 50

Hypothalamic Nuclei

Back 50

-Supraoptic nucleus
-Paraventricular Nucleus
-Periventricular Nucleus
-Arcuate Nucleus
-Ventral/Medial Nucleus
-Lateral Nucleus
-Suprachiasmatic Nucleus

Front 51

Supraoptic Nucleus

Back 51

-posterior pituitary
-releases oxytocin and vasopressin (ADH)

Hint 51

Connection and Function

Front 52

Paraventricular Nucleus

Back 52

-posterior pituitary
-releases oxytocin and vasopressin (ADH)

Hint 52

Connection and Function

Front 53

Periventricular Nucleus

Back 53

-Anterior Pituitary
-Thyroid releasing hormone

Hint 53

Connection and Function

Front 54

Arcuate Nucleus

Back 54

-Anterior Pituitary
-Growth hormone releasing hormone

Hint 54

Connection and Function

Front 55

Ventral/Medial Nucleus

Back 55

-Anterior Pituitary
-Decreases appetite

Hint 55

Connection and Function

Front 56

Lateral Nucleus

Back 56

-Anterior Pituitary
-increases appetite

Hint 56

Connection and Function

Front 57

Suprachiasmatic Nucleus

Back 57

-Anterior Pituitary
-input: retina
-output: cortex and T1-L2

Hint 57

Connection and function

Front 58

What is the anterior hypothalamus's role in temperature regualtion?

Back 58

-detects increases in blood temp
-activates cutaneous vasodilation and sweating to lower temperature
-lesions result in hyperthermia

Front 59

What is the posterior hypothalamus's role in temperature regualtion?

Back 59

-detects decreases in blood temperature
-activates cutaneous vasoconstriction and shivering to raise temperature
-lesions result in hypothermia

Front 60

What is the lateral hypothalamus feeding center's effect on feeding behavior?

Back 60

-lesion: anorexia
-expresses orexins involved in satiety setpoints

Front 61

What is the function of the ventromedial hypothalamus satiety center?

Back 61

-lesion: overeating

Front 62

What other effects can lesion of the hypothalamus have?

Back 62

Rage