1. Microscopy of the diencephalon
András Csillag
In collaboration with Prof. Á. Dobolyi and Dr. V. Vereczki
Semmelweis University, Department of Anatomy, Histology and Embryology

2. The position of the diencephalon in the brain

3. Parts of the diencephalon
Thalamus
Epithalamus
Pineal body
Habenula
Trigonum habenulae
Habenular nuclei
Stria medullaris
Habenular commissure
Metathalamus
Medial geniculate body
Lateral geniculate body
Subthalamus
Subthalamic nucleus
Zona incerta
H fields of Forel
Hypothalamus

4. Midsagittal (A) and frontal (B) sections of midbrain

5. Thalamic subdivisions of human brain
Williams et al., (1989) Gray’s Anatomy, Churchill Livingstone

6. Functional groups of thalamic nuclei
Mammalian system
Nucl. ventralis post. VPL/VPM
SENSORY THALAMUS
MOTOR THALAMUS
Ventral tier nuclei (VA/VL)
Anterior nuclei
VISCERAL AND LIMBIC THALAMUS
Intralaminar nuclei
Midline nuclei
Mediodorsal nucleus

7. Nuclear groups and nuclei of the thalamus

8. Frontal sections of the thalamus
Anterior section Middle section

9. Functional classification of thalamic nuclei
Specific nuclei: specific input, project to specific part of the cortex
- sensory relay nuclei: VPL, VPM, CGL, CGM
- motor relay nuclei: VA, VL
- limbic relay nuclei: AV, AD, AM
Associate nuclei: cortical input, project to associate areas of the cortex
MD, LD, LP, pulvinar
Non-specific nuclei: ascending input, diffuse projection to the cortex
midline and intralaminar nuclei
Nuclei not projecting to the cerebral cortex
n. reticularis thalami, n. parafascicularis, n. subparafascicularis

10. Cortical projections of (specific and associate) thalamic nuclei
mediosagittal view lateral view

11. Specific sensory relay nuclei

12. The VPL relays sensory inputs from the body to the cerebral cortex

13. The VPM relays sensory inputs from the head to the cerebral cortex

14. Relay of gustatory inputs to the cortex takes place in the VPMpc

15. Somatotopy in the VPM/VPL

16. Specific motor relay nuclei

17. Afferent and efferent projections of the motor relay nuclei in the ventral column of the lateral nuclear group (‚ventral tier’ nuclei)
Specific thalamic motor relay nuclei: Ventral anterior nucleus (VA) Afferents (inputs): basal ganglia (pallidum) Efferents (projections): premotor and supplementary motor cortex Ventral lateral nucleus (VL) Afferents (inputs): cerebellum (dentate nucleus) Efferents (projections): primary motor cortex (precentral gyrus )

18. Neuronal circuit of information relay in the specific thalamic nuclei

19. State-dependent modes of relay cell function

20. Midline and intralaminar nuclei of the thalamus

21. The IMMC Complex 1. Midline thalamic nuclei: Paraventricular
Parataenial
Intermediodorsal
Rhomboid
Reuniens
2. Mediodorsal nucleus
3. Intralaminar nuclei:
Rostral group Central medial
Paracentral
Central lateral
Caudal group Centre médian
Parafascicular

22. Midline thalamic group: paraventricular nucleus
Input from preoptic area
Output to medial orbitofrontal cortex
Output to dorsomedial hypothalamus (DMH)
Input from (output to ?) midbrain periaqueductal gray (PAG)

23. Mediodorsal thalamic nucleus
Output to prefrontal cortex and anterior cingulate cortex
Output to amygdala
Reciprocal (?) connections with lateral hypothalamus and PAG

24. Intralaminar thalamic group
Output to non-limbic (visceral, sensory and motor) cortices
Output to (mainly) dorsal striatum
Output to hypothalamus ?
Output to reticular thalamic nuclei
Nissl-stained monkey brain at the level of the caudal intralaminar nuclei

25. Major inputs and projections of midline and intralaminar thalamic nuclei
Spino-reticulo-thalamic
tract
– part of the „ascending
reticular activating
system”, a regulator of
cortical alertness
bal alsók: O:\ A_PM\Előadások-ppt\Human brain \rajz1-09Sept-2valtA.jpg + rajz1-09Sept-2valtB.jpg (mérete: 6,35x6,63 cm; pozíciója: 1,2; 10,83 cm)
középen: O:\A_PM\Előadások-ppt\ September\Kandel_page342-5valtozat1-ures.jpg + Kandel_page342-5valtozat2-piros.jpg (méret: 17,53x7,12 cm; pozíció: 9,1; 1,47 cm)
jobb felső: O:\A_PM\Előadások-ppt\Human brain \rajz sarga.jpg + rajz pirossal.jpg (méret: 6,19x6,6 cm; pozíció: 17,48; 1,74)
jobb középső: O:\A_PM\Előadások-ppt\_Fájdalom, 2010\Duvernoy_page23.jpg
jobb alsó: Insula.jpg
innen másolva: O:\A_PM\Előadások-ppt\2011,insula (Fájdalom,Debrecen)\Fájdalom-Debrecen,2011.ppt\27. dia

26. Cortical efferents of thalamic nuclei
CGL LD
PULV. LP
VPL+VPM VL VA DM
CGM

27. Thalamic reticular nucleus: a regulator of the relay function of specific thalamic nuclei

28. GABAergic inhibitory neurons in the thalamus

29. The hypothalamus Thalamus Epithalamus Metathalamus Subthalamus
Pineal body
Habenula
Trigonum habenulae
Habenular nuclei
Stria medullaris
Habenular commissure
Metathalamus
Medial geniculate body
Lateral geniculate body
Subthalamus
Subthalamic nucleus
Zona incerta
H fields of Forel
Hypothalamus

30. Essential differences between the structure and functions of the thalamus and hypothalamus
Thalamus: - well delineated nuclei - relay and modulation of cortical inputs
Hypothalamus:
The neurons with different functions are intermingled, not clearly separated
Homeostatic regulatory functions do not require cortical processing

31. Antero-posterior regions of the hypothalamus

32. Medio-lateral zones of the hypothalamus

33. Nuclei in the medial zone of the hypothalamus

34. Anterior hypothalamic region

35. Tuberal and posterior hypothalamic regions
Tuberal hypothalamic region
Posterior hypothalamic region

36. Neuronal inputs to the hypothalamus

37. Circumventricular organs – humoral inputs

38. Extrahypothalamic projections of hypothalamic nuclei

39. Hypothalamo-spinal tract and other descending pathways regulating vegetative functions

40. Regulatory functions of hypothalamic nuclei
Vegetative regulations
Neuroendocrine regulations
Salt and water balance
Food intake and body weight
Temperature
Circadian rhythms
Sleep
Reproduction

41. Neural elements of homeostatic regulations
NTS: nucleus of the solitary tract, PBN: parabrachial nucleus, RF: reticular formation,
DMX: dorsal motor vagus nucleus, ILN: intermediolateral column (nucleus) of the spinal cord

42. Hypothalamic centers that control food intake and body weight

43. Principle of creating circadian (daily) rhythms

44. Circadial regulation of neural functions PACEMAKER: SUPRACHIASMATIC NUCLEUS (SCN)

45. Neuronal inputs and outputs of the suprachiasmatic nucleus

46. 5. control of circadian rhytms: retinohypothalamic tract
Medial zone
Suprachiasmaticus nucleus (VIP) : retinohypothalamic tract of rat
(Scale: 100 µm. OX= optic chiasm;SCH=suprachiasmatic nucleus)

47. SUBTHALAMUS - Ventral from thalamus
- Caudal and lateral from hypothalamus
- Prosomere 3 + Peduncular hypo-
thalamus (basal part)
Main parts:
Subthalamic nucleus (Luys)
Zona incerta
Fields of Forel

48. EPITHALAMUS Habenular nuclei
Septohabenular pathway (stria medullaris thalami)
Retroflex fascicle (fasciculus retroflexus) – habenulo-interpeduncular pathway
Retroflex fascicle – border between prosomers 1 and 2
Part of the limbic system,
From stress evasion to value-based decision making,
Connections with the basal ganglia and the serotonergic system of brainstem (raphe nuclei)