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Microscopy of the diencephalon

Microscopy of the diencephalon. András Csillag In collaboration with Prof. Á. Dobolyi and Dr. V. Vereczki Semmelweis University, Department of Anatomy , Histology and Embryology. The position of the diencephalon in the brain. Parts of the diencephalon. Thalamus Epithalamus

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Microscopy of the diencephalon

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

  2. The position of thediencephaloninthebrain

  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 Mammaliansystem 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 efferentprojections of the motor relaynuclei in theventralcolumn of thelateralnucleargroup (‚ventraltier’ 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-stainedmonkeybrainatthelevel of thecaudalintralaminarnuclei

  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

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

  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 • 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. Essentialdifferencesbetweenthestructure and functions of the thalamus and hypothalamus Thalamus:- welldelineatednuclei- relay and modulation of corticalinputs • Hypothalamus: • Theneuronswithdifferentfunctionsareintermingled, notclearlyseparated • Homeostaticregulatoryfunctionsdonotrequirecorticalprocessing

  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 posteriorhypothalamicregions Tuberal hypothalamic region Posterior hypothalamic region

  36. Neuronalinputstothehypothalamus

  37. Circumventricularorgans – humoralinputs

  38. Extrahypothalamicprojections of hypothalamicnuclei

  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. Neuralelements of homeostaticregulations 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. Hypothalamiccentersthatcontrolfoodintake and body weight

  43. Principle of creatingcircadian (daily) rhythms

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

  45. Neuronalinputs and outputs of thesuprachiasmaticnucleus

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

  47. SUBTHALAMUS - Ventralfromthalamus - Caudal and lateralfromhypothalamus - Prosomere 3 + Peduncularhypo- thalamus (basal part) Main parts: Subthalamicnucleus (Luys) Zonaincerta 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)

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