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Rhinencepalon

Rhinencepalon. Smells are surer than sounds and sights to make your heart-strings crack. - Rudyard Kipling. Olfactory system. Conveys specific visceral sensation ( smell ) via n. olfactorius. Does not relay in the thalamus .

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Rhinencepalon

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  1. Rhinencepalon

  2. Smells are surer than sounds and sights to make your heart-strings crack. - Rudyard Kipling

  3. Olfactory system • Conveysspecific visceral sensation (smell) vian. olfactorius. • Does not relay in the thalamus. • Connections withthalamus, hypothalamus, amygdaloid complex&hippocampal formation.

  4. Structure of the olfactory system І. Receptor cells • Chemoreceptors. • Aboutо25 billionson each side. • Located in thenasal mucosa. • Regenerate. • 1st order neuronsin the olfactory pathway. • Bipolar neurons,unmyelynated axons formnn. оlfactоrii. • Inbulbus olfactorius the axons synapse withthe mitral cellsin olfactory glomerulus.

  5. Nervi olfactorii

  6. II. Bulbus olfactorius • Onlamina cribrosaofos ethmoidale • Entered by olfactory nerves. • 6-layered structure. • 4 cell types: • periglomerular- inhibitory • tufted- efferent (ІІ order) • mitral- efferent (ІІ order) • granule - inhibitory • Glomerulus– polysynaptic structure, ensuringconversionof olfactory impulseson the mitral cells.

  7. Bulbus olfactorius

  8. Bulbus olfactorius -клетъчен състав

  9. Synaptic organization ofbulbus olfactorius Dendrodendrite synapses Glutamate (excitory) GABA (inhibitory)

  10. Types of synapses Lateral inhibition.

  11. ІІІ. Tractus olfactorius: • insulcus olfactorius. • Axons of mitral and tufted cells. • nucl. olfactorius anterior (modulator): • terminates intrigonum olfactorium. ІV. Stria olfactoria lateralis • to primary olfactory cortex throughlimen insulae V. Stria olfactoria medialis • toarea subcalosa andgyrus paraterminalis

  12. Tractus olfactorius

  13. VІ. Olfactory corex • Primary • onuncus(area 34afterBrodmann). • fibers fromstria olfactoria lateralis. • containsprepiriform&periamygdaloid areas. • connectins withnucl. medialis dorsalis of thalamus, hypothalamus, hipocampal formation. • Secondary • entorhinal areaofgyrus parahippocampalis (area 28). • Impulses from primary areas. • efferents to hippocampus. • Orbitofrontal cortex • Impulses fromnucl. medialis dorsalis thalami • conscious preception of smell.

  14. Olfactory corex

  15. Orbitofrontal cortex We need our orbitofrontal cortex to make intelligent choices. Its individual cells code for value. Ann Thomson, Nature Neuroscience

  16. Pathways in the olfactory system

  17. Limbic system

  18. Limbic system • Morphological substrate of emotionsand behaviour. • Role inemotional behavior, feeding, defensive reaction, sexual behaviour, memoryand learning. • Functions mediated throughhypothalamus andautonomic system. • Containscortical&subcortical (nuclei) structures.

  19. Affective behavior Emotion Happiness and Grief

  20. Introduction Concept Broca (1877) - ‘La Grand Lobe Limbique’ Papez (1937) - ‘Limbic Circuit’ - emotion MacLean (1952) - ‘Limbic System’ – visceral brain Nauta (1972) - ‘Septo-hypothalamo-mesencephalic continuum’

  21. PAUL BROCA (1824-1880) JAMES PAPEZ (1883-1958)

  22. Limbic system • - Term ofPaul MacLean (1952) • - Visceral brain • Triple concept • of brain evolution • Hypothalamus • Nucleus accumbens • Nucleus amygdaloideus • Cortex orbitofrontalis • Some psychiatric implications on • physiological studies on fronto- • temporal portions of limbic system • (visceral brain). Electroencephalogr • Clin Neurophysiol 4: 407-418, 1952 Paul D. MacLean (1913- )

  23. Parts of the limbic system Olfactory cortex Spinal cord & Brain stem Septo-(Preoptico)-Hypothalamo- Mesencephalic Continuum Hippocampal formation Area septalis Hypothalamus Midbrain Amygdaloid complex Limbic system

  24. Expression of emotion Septo- hypothalamo- mesencephalic continuum

  25. Parts of the limbic system Basal forebrain Substantia Innominata Nucleus Basalis на Meynert Pallidum Ventralis Nucleus Accumbens (Septi) Regio Septalis Area Septalis GyrusParaterminalis Gyrus Subcallosus Nuclei Septalis Dorsal, lateralandmedial Nuclei Septalis Nucleus Stria Diagonalis Broca Nucleus Stria Terminalis Corpus Amygdaloideum Pars Corticomedialis Pars Basolateralis Nucleus Centralis TELENCEPHALON Lobus Limbicus Gyrus Fornicatus Gyrus Cingulatus Gyrus Parahippocampalis Hippocampal Formation Hippocampus Gyrus Dentatus Subiculum Hippocampal Rudiments Gyrus Fasciolaris Indusium Griseum Cortex Olfactorius (Rhinencephalon) - Lobus Piriformis Cortex Prepiriformis Cortex Periamygdaloideus Cortex Entorhinalis

  26. Lobus Limbicus Класификация на кората Isocortex - Neocortex Allocortex Archicortex Hippocampus Gyrus Dentatus Paleocortex BulbusOlfactorius Lobus Piriformis Mesocortex (Juxtallocortex, Periallocortex, Mesallocortex) GyrusCinguli Lobus Limbicus Gyrus Fornicatus GyrusCinguli Gyrus Parahippocampalis AreaEntorhinalis Isthmus Hippocampal Formation Hippocampus Proper (Ammon’s horn) Gyrus Dentatus Subiculum Hippocampal Rudiments GyrusFasciolaris Indusium Griseum

  27. Parts of the limbic system

  28. Limbic cortex • Onmedial aspectof the hemispheres • Archicortex • In some partspaleo- &neocortex. • External ring • Internal ring

  29. Limbic cortex External ring -gyrus cinguli -area subcallosa -gyrus parahippocampalis -uncus. Internal ring -gyrus paraterminalis -indusium griseum - Hippocampal formation.

  30. Hippocampal formation Hippocampus Proper (Ammon’s horn, Cornu Ammonis) Gyrus Dentatus Subiculum

  31. Hippocampal formation Hippocampus –cortical fold in the lateral ventriclecaused bysulcus hippocampi - 3-layeredarchicortex -stratum pyramidale - efferents, formingalveus andfimbria hippocampi -stratum moleculare • stratum radiatum • Subiculum (paleocortex) - affrents from hippocampus - efferents to corpora mamillaria and nucl. anterior thalami Parasubiculum (paleocortex) - transition togyr. parahippocampalis

  32. Hippocampal formation 1. uncus 2. gyrus dentatus 3. fornix 4. corpus callosum 5. gyrus fasciolaris 6. sulcus hippocampalis 7. gyrus parahippocampal 8. sulcus collateralis

  33. Hippocampal formation(lateral view)

  34. Hippocampal formation(medial view)

  35. Hippocampal formation - Archicortex Archicortex - 3 layers Hippocampus Proper Str. Moleculare Str. Pyramidale Str. Polymorphe Gyrus Dentatus Str. Moleculare Str. Granulare Str. Polymorphe Subiculum Transientbetweenhippocampal archicortex and entorhinal paleocortex

  36. Classification of the cortex Isocortex 6-layered cortex homotypicaland heterotypical Allocortex Paleocortex olfactory cortex - lobus piriformis Archicortex 3-layered - hippocampal formation

  37. Archicortex - after Ramon y Cajal 7. stratum moleculare 6. stratum lacunosum 5. stratum radiatum 4. stratum pyramidalis 3. stratum oriens 2. alveus 1. ependyma

  38. Hippocampus and memory Х.M. - пациент с антеградна и ретроградна амнезия, възникнала след мозъчна операция за лечение на епилептични припадъци.

  39. Connection in the hippocampal formation 1. Internal connections trisynaptic pathway 2. Afferent connections perforantandalveolar pathway 3. Efferent connctions fornix

  40. Internal connections Classical 3-neuron pathway 1. Енторинална кора (perforant pathway)  granule cell ofgyrus dentatus 2. Granules cells (mossy fiber)  CA3 pyramid cells 3. Pyramid cells (Schaffer collateral)  CA1 pyramid cells  subiculum  cortex entorhinalis

  41. Afferents From Cortex Entorhinalis Alveolar pathway from medial EC to CA1 and Subiculum Perforant pathway from medial EC to CA1, CA2, CA3 & Gyrus Dentatus

  42. Efferents FORNIX Alveus Fimbriae Crus Commissurа Corpus Column

  43. Efferents Fornix - from pyramid cells of hippocampus & subiculum - 1.2 million fibers Postcommissiral Fornix – basic bundle toCorpus Mammillare Thalamus Anterior Nuclei Septi Lateralis Hypothalamus Tegmentum of midbrain

  44. Efferents Precommissural Fornix – smaller - mainly from hippocampus proper to Nuclei Septi Area Preoptica Lateralis Area Hypothalamica Anterior Nucleus Striae Diagonalis Broca Nucleus Accumbens Medial aspect of frontal lobe Nucleus Caudatus &Putamen Amygdala & Claustrum

  45. Summary of connections Afferent Entorhinal Cortex Alveolar pathway medial EC to CA1 and Subiculum Perforant pathway from lateral EC to CA1, CA2, CA3 and GyrusDentatus GyrusDentatuse Mossy fiber - CA3 - Schaefer fiber (CA3-CA1) Others Hypothalamus, Nuclei Septi, Substantia Innominata Midbrain Efferent FORNIX from pyramid cells hippocampus & subiculum Alveus, Fimbriae, Crus Commissure, Corpus, Column Precommissural Fornix to Nuclei Septal, Nucleus Accumbens Area Hypothalamica Anterior Nucleus Olfactorius Anterior Postcommissural Fornix to Corpus Mammillare Thalamus Anterior Hypothalamus Nucleus Striaе Terminalis

  46. Subcortical limbic structures 1. Amygdaloid complex 2. Mammillary body 3. Septal area 4. Nucleus anterior, nucleus medialis dorsalis & nuclei intralaminares thalami 5. Nucleus accumbems 6. Substantia innominata 7. Nuclei habenulae 8. Hypothalamus 9. Midbrain limbic nuclei

  47. Amygdala L. almond K. F. Burdach’s term

  48. Amygdaloid complex

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