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Olfactory system, Amygdala and Hippocampus

Olfactory system, Amygdala and Hippocampus. Maryann Martone, Ph. D. NEU257. The Limbic System.

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Olfactory system, Amygdala and Hippocampus

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  1. Olfactory system, Amygdala and Hippocampus Maryann Martone, Ph. D. NEU257

  2. The Limbic System “The hypothalamus, the anterior thalamic nucleus, the cingulate gyrus, the hippocampus and their interconnections, constitute a harmonious mechanism which may elaborate the functions of central emotion as well as participate in the emotional expression.” -James Papez, 1939 • Broca, Papez, Kluver and Bucy • Parts of the brain underlying emotional behavior • Associated with the olfactory system; rhinencephalon = “smell brain” http://www.hallym.ac.kr/~de1610/nana/chp-12n.htm#II

  3. Limbic Structures • Hippocampus • Amygdala • Olfactory system Terminology assistance: http://www.umanitoba.ca/faculties/medicine/anatomy/neuro/gloss/gloss.htm http://braininfo.rprc.washington.edu/mainmenu.html

  4. From the Digital Anatomist website

  5. From the Digital Anatomist website

  6. Olfactory System thalamus.wustl.edu/ course/lim5.gif From the Digital Anatomist website

  7. Olfactory Cortex • Also cortical amygdaloid nucleus and periamygdaloid area • Projects to ventral striatum, MD thalamus, insula and orbitofrontal cortex • Pyriform cortex = 1˚ olfactory cortex • Allocortex, paleocortex • 3 layered From the Digital Anatomist website

  8. Olfactory Cortex http://www.hallym.ac.kr/~de1610/nana/chp-12n.htm#II

  9. Olfactory Cortex Monkey brain From the Digital Anatomist website

  10. Rodent Brain

  11. Amygdala most closely associated with emotional behavior • “Angst and the Amygdala • “Fear, faces, and the human amygdala.” • “The neurobiology of psychopathy” • “Emotion, decision making, and the amygdala” • “Neuroanatomy of autism” • “The functional neuroanatomy of PTSD: a critical review” • “Neurobiology of escalated aggression and violence.” • Pub Med search for “Amygdala”

  12. The Amygdala • Burdach 1819: the amygdaloid complex (“almond”) • Johnston 1923: central, medial, cortical, basal nuclei • Price 1980’s: basolateral, cortical, central medial nucleus • De Olmos and Heimer 1991: extended amygdala • Swanson 1998: there is no amygdala

  13. The amygdaloid complex • Over 20 divisions/nuclei, depending on whom you talk to • 500-1000 different connections identified (Swanson) • Swanson: “The amygdala is neither a structural nor a functional unit of the cerebral hemispheres; instead, its cell groups participate in at least four distinct, though interconnected, functional systems or differentiations of the corticostriatopallidal system…. Terms such as 'amygdala' and 'lenticular nucleus' combine cell groups arbitrarily rather than according to the structural and functional units to which they now seem to belong..” • L. W. Swanson: The amygdala and its place in the cerebral hemisphere, PNAS 985: 174, 2003.

  14. Amygdaloid complex Amygdala

  15. One view(based on Heimer, 1996) • Basolateral • Similar to cortex • Projects to ventral striatum • Has pyramidal like cells • Receives input from primary sensory cortex, polysensory cortex and thalamus • Connections are reciprocal • Cortical • Olfactory amygdala • Receives direct input form olfactory system, both the olfactory bulb and olfactory cortex • Central Medial group • Main output of amygdaloid complex • Input from hippocampus, orbitofrontal, insula, anterior cingulate cortex as well as basolateral group • Projects to hypothalamus, brainstem via stria terminalis and amygdaloventral fugal pathway • Part of “central autonomic network”

  16. Major afferents to the amygdaloid complex Figure 23-18 Major inputs to the basolateral (blue), central (red), and medial (green) nuclei of the amygdala (Am). Only inputs from visual association cortex to the basolateral nuclei are shown, although there are similar projections from most or all unimodal sensory areas. The inputs from limbic cortex to the basolateral nuclei also include a major projection from the insula, which is not present in this view. B, brainstem (periaqueductal gray, parabrachial nuclei, other nuclei); Hy, hypothalamus; S, septal nuclei; T, thalamus (multiple nuclei). (Modified from Warwick R, Williams PL: Gray's anatomy, Br ed 35, Philadelphia, 1973, WB Saunders.) From Nolte Downloaded from: StudentConsult (on 1 March 2011 06:45 AM) © 2005 Elsevier

  17. Major efferents to the amygdaloid complex Figure 23-21 Major outputs from the basolateral (blue), central (red), and medial (green) nuclei of the amygdala (Am). These take three routes: (1) the stria terminalis, which reaches the septal nuclei (S) and hypothalamus (Hy); (2) the ventral amygdalofugal pathway (see Fig. 23-20B and C) to the hypothalamus (Hy), thalamus (T; mainly the dorsomedial nucleus), widespread areas of ventromedial prefrontal and insular cortex, ventral striatum (VS), olfactory structures, and various brainstem sites (B); and (3) direct projections to the hippocampus (HC) and temporal and other neocortical areas. Only visual cortical areas are shown, although there are similar projections to most or all primary and unimodal sensory areas. (Modified from Warwick R, Williams PL: Gray's anatomy, Br ed 35, Philadelphia, 1973, WB Saunders.) Downloaded from: StudentConsult (on 1 March 2011 06:45 AM) From Nolte © 2005 Elsevier

  18. cal.vet.upenn.edu/neuro/server/ slides/ns_075-BNST.jpg Connections of the central medial group • Extended amygdala: Central medial group shares continuity and similarity with parts of substantia innominata and bed nucleus of the stria terminalis

  19. Summary of Forebrain Systems • Cortical vs subcortical • According to Swanson, the forebrain can be understood in terms of two systems: • Cortex and cortical (basal) nuclei • Cortex: glutamate projection neurons • Projections to striatum • Interconnections with thalamus • Striatal: GABA projection neurons • Pallidal: GABA ---> Thalamus --> Cortex

  20. The Hippocampus • Greek: “Sea Monster” • Another terminology tangle • Allocortex/ archicortex • Hippocampal formation (after Amaral and Witter) • Dentate gyrus • Hippocampus proper “Cornu ammonis” • Subicular complex • Subiculum • Presubiculum • parasubiculum • Entorhinal cortex

  21. “C” shaped structure in medial temporal lobe http://www.hallym.ac.kr/~de1610/nana/chp-12n.htm#II From Digital Anatomist

  22. Development http://www.hallym.ac.kr/~de1610/nana/chp-12n.htm#II From Digital Anatomist From Digital Anatomist

  23. Gross Anatomy • Septal-temporal poles • Fornix • Fimbria, body, columns Rodent Supracommissural hippocampus=supracallosal gyrus, indusium griseum Human

  24. Connections • Afferents: • Much of cortex is reciprocally connected to entorhinal cortex • Cholinergic and GABA input via septal nuclei • Amygdala • VTA, LC, Raphe • Efferents • Via the fornix • Precommissural: septal nuclei • Post-commisural: mammillary bodies (to anterior thalamic nucleus via mammillothalamic tract)

  25. Cytoarchitecture • Two interlocking cell fields • Dentate gyrus • hippocampus Human Rodent

  26. so sp • Stratum oriens • Stratum pyramidale • Stratum lucidum • Stratum radiatum • Stratum lacunosum-moleculare • ml=molecular layer sl sr sl-m ml Hilus www.deltagen.com/.../nervous/ cerebrum_hippo_10x.htm CA1-CA3: pyramidal neurons Dentate Gyrus: granule cells

  27. Cajal, 1901 Intrinsic connections fornix http://www.angelfire.com/yt/yas709neuroscience/hippocampus.htm

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