Neuroscience 1A LC9 Limbic System PDF

UNIVERSITY OF NORTHERN PHILIPPINES NEUROSCIENCE 1A LC9 [NEUROSCIENCE1A] 1.9 LIMBIC SYSTEM – Dr. Steve Arellano COLLEGE OF MEDICINE, BATCH 2026 LIMBIC SYSTE...

UNIVERSITY OF NORTHERN PHILIPPINES NEUROSCIENCE 1A LC9 [NEUROSCIENCE1A] 1.9 LIMBIC SYSTEM – Dr. Steve Arellano COLLEGE OF MEDICINE, BATCH 2026 LIMBIC SYSTEM: The Structure and Functions of Limbic System Transcribers: Quilana, Reyes, Rodriguez, Editors: Rivera, Rosalin Dr. Steve Arellano | Nov. 2022 B. TWO MAIN STRUCTURES OF THE LIMBIC SYSTEM OUTLINE 1. Hippocampal formation I. THE LIMBIC SYSTEM A. Limbic System - Consolidation of short-term memory into long term B. Two Main Structures of the Limbic System memory in order for these events or memories to be C. Function of the Limbic System stored and retrieve in the future. II. THE LIMBIC LOBE A. Components of the Limbic Lobe - Includes: B. Hippocampal Formation a. Hippocampus proper B1. Structures Associated with the Hippocampal Formation b. Dentate Gyrus B2. Hippocampus Formation c. Subiculum B3. Intrinsic Circuit of the Hippocampal Formation C. Papez Circuit 2. Amygdala / Amygdaloid Body D. Function of Hippocampal Formation in Memory - Regulates emotional expression via modulation of the III. AMYGDALA hypothalamus A. Divisions B. Efferent and Efferent Projections to the Amygdala C. Functions of the Amygdala C. FUNCTION OF THE LIMBIC SYSTEM IV. BRAINSTEM CENTERS ASSOCIATED WITH LIMBIC SYSTEM FUCNTION 1. Species preservation – done by reproduction and V. PATHWAYS OF THE LIMBIC SYSTEM associated instinctive behavior 2. Self-preservation – done thru feeding, behavior and I. THE LIMBIC SYSTEM aggression 3. Expression of fear, motivation, & other emotions A. LIMBIC SYSTEM 4. Memory Limbic means border or margin 5. Learning Limbic system includes a group of structures that lie in the -Emotional background of intellect - to balance the border zone between the cerebral cortex and the incognitive mechanism hypothalamus -A lot of the internal organs of the body are being Can only be seen when the brain is cut sagitally controlled by the limbic system including endocrine and Interconnects the telencephalon, diencephalon, & brain stem nervous system. Major function: modulate the hypothalamus II. THE LIMBIC LOBE (L. limbus, ‘border’) e.g. eye - It is the part of the eye where the horizon or the boundary between the dark colour and the white one. -Limbic lobe is a border between mesencephalon and prosenencephalon Characterized by Paul Broca, 1878 Formed a transition border intervening between diencephalon and the telencephalon Components: 1. Subcallosal gyrus (Neocortex) Figure 1. Sagittal Section of the Brain showing the Limbic System 2. Cingulate gyrus (Mesocortex) 1. cingulate gyrus – lesions result in akinesia, mutism, 3. Parahippocampal gyri (Neocrtex) apathy and indifference to pain 4. Hippocampal formation (Archicortex) 2. subcallosal arca 3. parahippocampal gyrus Figure 2. The Components of the Limbic Lob 4. dentate gyri 5. hippocampus proper 6. subiculum 7. amygdaloid body 8. septal area 9. nuclei of the thalamus & hypothalamus Figure 2. The components of Limbic Lobe Page 1 of 9 [NEUROSCIENCE1A] 1.9 LIMBIC SYSTEM – Dr. Steve Arellano A. COMPONENTS OF THE LIMBIC LOBE B. HIPPOCAMPAL FORMATION Component Layers Cell Bodies Dendrites Axon Terminals Hippocampus Molecular Pyramidal Cell *Granule Cells of I. Subcallosal Gyrus Proper (Deepest) Apical Dentate Gyrus Consists of gray matter, which underlies the basal surface of Dendrites (Mossy Fibers) *Perforant Pathway the rostral part of the corpus callosum *Septohippocampal Curves superiorly around the genu of the corpus callosum, Tract *Pyramidal cell axon as the cingulate gyrus collateral branches Extends posteriorly, superior to the corpus callosum, as the cingulate gyrus *Pyramidal *Pyramidal Cells The cingulate gyrus in turn continues as the (Middle) *Interneurons *Polymorphic *Pyramidal parahippocampal gyrus (Superficial) cell basal dendrites Dentate Gyrus *Molecular Some *Apical *Perforant Pathway II. Hippocampal Formation (Outer) dendrites *Alveus Extend from your amygdala, anteriorly to the splenium to of granule cells *Collateral branchesof granule cells the corpus callosum posteriorly Consists of archicortex *Granule Cell Granule Cells Function: recent memory and learning (Middle) Interneurons Three Regions *Polymorphic (Deepest) 2. Hippocampus proper Subiculum Three-Layered Aka: hippocampus, Ammon’s Horn, cornu ammonis, Cortex next to Hippocampus sea-horse shaped, comma shaped 3. Dentate gyrus Six-Layered Cortex Next To 4. Subiculum Parahippocam Neuroanatomical connections: pal Gyrus 1. Entorhinal cortex 2. Supracallosal gyrus (Indusium griseum) Table 2. Components of the Hippocampal Formation 3. Fasciola cincera (Gyrus fasciolaris) HIPPOCAMPUS PROPER 4. Septal area Gk. Hippocampus, “seahorse‟ III. Cortical Components of the Limbic Lobe Ancient cortical structure that forms a comma-shaped Part of Cortex Components Phylogenetically ancient cortical structure that forms a Archicortex comma-shaped prominence on the floor & medial wall of Hippocampal the temporal horn of the lateral ventricle formation: Ventricular surface: coated with ependymal layer 1. Hippocampus -Ependymal layer - they are involve in production, proper resorption, and circulation of CSF. 2. Dentate gyrus Allocortex 3. Subiculum -Lateral ventricle – contains CSF Coronal section: appears similar to a seahorse as a result Paleocortex of its arched form. Piriform cortex ofthe C-chaped outline in coronal section, resembles a ram‟s parahippocampal horm & is called Ammon‟s horm (cornu Ammonis or CA) gyrus Mesocortex Juxtallocortex Cingulate gyrus Neocortex Subcallosal gyrus Isocortex Parahippocampal gyrus Table 1. The Cortical Components of the Limbic Lobe Figure 3. The Hippocampal Formation sea-horse-like shape Page 2 of 9 [NEUROSCIENCE1A] 1.9 LIMBIC SYSTEM – Dr. Steve Arellano Input sources to the Output targets of the Components: hippocampus hippocampus 1. Apical dendritic trees Indusium griseum Septal nuclei i. Belong to hippocampal pyramidal cells Cingulate gyrus Lateral preoptic area 2. Axon terminals (hypothalamus) i. belong to granule cells Septal nuclei Anterior part (hypothalamus) ii. cell bodies reside in the: Entorhinal cortex Mamillary body Granule cell layer (dentate gyrus) Perforant pathway (entorhinal Dentate gyrus Anterior nuclear group (thalamus) cortex) Parahippocampal gyrus Midbrain tigmentum Septohippo campal tract (septal Contralateral hippocampus Habenuclei area) Pyramidal cell axon collateral branches(pyramidal cell layer Table 3. Input Sources and Output Targets of the Hippocampus ii. Be of the hippocampus) 2. Pyramidal Layer Middle layer Most prominent layer of the hippocampal formation Consist of pyramidal cells Dendrites ramify in the molecular layer, their axons pass in the opposite direction, across the polymorphic layer, & then course in the alveus, finbria, & fornix *Schaffer collaterals Pyramidal cell axon collateral branches Cross the polymorohic & pyramidal Figure 4. The Hippocampus at the Transverse Section layers to reach the molecular layer of theTemporal Lobe where they form synaptic contacts with the dendrites of other pyramidal neurons -when you have cells in a specific layer, it will not stay there. It will involve other layers. How? By extending its axon or dendrites. 3. Polymorphic Layer Superficial layer Shares structural characteristics with the deepest layers ofthe neocortex Lies deep to the alveus -alveus – found in the region as the hippocampus or thelimbic syster pivoting posteriorly and superiorly. Figure 5. The 3-Layered Hippocampus Proper and Dentate Consists of interneurons, as well as, Gyrus are called the Cornu Ammonis (Ammon’s Horn) pyramidal celldendrites and axon collateral branches LAYERS OF THE HIPPOCAMPAL ARCHICORTEX Components: 1. Molecular Layer Deepest layer a. Interneurons (neurons connecting -But when you reach dentate gyrus, molecular layer will be interveningtwo or more neurons) the superficial most later. It will reverse because it is b. Pyramidal cell dendrites (from the pivoted. There is an inversion process. pyramidallayer where their cell Location: core of the hippocampal formation bodies are located) c. Axon collateral branches Page 3 of 9 [NEUROSCIENCE1A] 1.9 LIMBIC SYSTEM – Dr. Steve Arellano DENTATE GYRUS C. Fasciola cinerea (Gyrus Fasciolaris) (L. dentate, “tooth-shaped‟) (L. fasciola, “band”; cinereus, “ashen-hued”) - Structure that is opposite to hippocampus proper. Transitional zone of intervening cortex that joins the Notched band of cortex that in interposed between dentate gyrus with the indusium griseum theupper aspect of the parahippocampal gyrus & the fimbria D. Septal area Layers of the Dentate gyrus: Located in the telencephalon (forebrain) 1. Molecular Layer Well developed in humans Outer -it makes us unique from the lower forms of animals. It has Small population of nerve cell bodies & something to do with memory, behaviour, and decision granulecell dendrites making. 2. Granule layer *Septal nuclear complex Middle v. Nuclei are gathered rostral to the anteriorcommissure Corresponds to the pyramidal layer of the vi. Two main groups: hippocampus 1. Media septal nuclei Cell bodies of the granule cells 2. Lateral septal nuclei 3. Polymorphic Layer Deep layer B2. HIPPOCAMPUS FORMATION Consists of interneurons Afferent fibers to the hippocampus proper arise from: 1. Indusium griseum 2. Cingulate gyrus SUBICULUM 3. Septal gyrus 4. Entorhinal cortex Transitional zone 5. Dentate gyrus Displays a three layered archicortex next to the 6. Parahippocampal gyrus hippocampus 7. Contralateral hippocampus Progressively becomes a more elaborate six-layered Efferent fibers from the hippocampus proper: (classic layering of cortex) neocortex as it approaches the o Axons anterior to the anterior commissure terminate at: parahippocampal gyrus a. Septal nuclei Receives information relayed by the hippocampal pyramidal cells b. Lateral preoptic area (hypothalamus) c. Anterior part (hypothalamus) o Axons posterior to the anterior commissure: B1. STRUCTURES ASSOCIATED WITH THE HIPPOCAMPAL a. Mammillary body FORMATION b. Anterior nuclear group (thalamus) c. Tegmentum (midbrain) A. Entorhinal Cortex (Brodmann’s area 28) d. Habenular nuclei -Located in the temporal lobe *Hippocampo-Entorhino-Neocortical Pathway Located ventral to the amygdaloid body & anterior half of viii. Pathway involved in the consolidation of episodic the hippocampal formation memories. Gives rise to the most prominent input to the dentate ix. Consolidation means it strengthen so that these gyrus via: memories will stay forever in the brain so that in future 1. Perforant pathway retrieval, you can have it. iii. Arise from the lateral part of the entorhinal cortex 2. Alvear pathway B3. INTRINSIC CIRCUIT OF THE HIPPOCAMPAL FORMATION iv. Arise from the medial part of the entorhinal Components of the hippocampal formation: cortex 1. Hippocampus B. Indusium griseum (Supracallosal gyrus) 2. Dentate gyrus Represents a portion of the hippocampal formation that 3. Subiculum remained attached to the corpus callosum during its Axons from the Entorhinal cortex development - Form the perforant (lateral) & alvear (medial) pathways Dorsally it curves around the splenium of the corpus - Terminates in the molecular layer callosum and then merge with the dentate and - Send collaterals to the CA1 & CA3 zones parahippocampal gyrus by way of Fasciola cinerea. Provides the major input to the hippocampal formation Page 4 of 9 [NEUROSCIENCE1A] 1.9 LIMBIC SYSTEM – Dr. Steve Arellano C. PAPEZ CIRCUIT James Papez in the 1930s Its initial segment is a projection primarily from the subiculum to the medial mammillary nucleus via the post commissural fornix Neuroanatomical basis of emotion Anatomical structures a. Hippocampus b. Fornix (member of the limbic system that also pivot located posterior to the thalamus) c. Mamillary body (located posterior-anterior to thalamus) d. Anterior Nucleus (anterior part of thalamus) e. Mamillothalamic tract f. Cingulate gyrus Figure 7. Diagram Showing the Human Memory System - Implicit (non-declarative) events from the past that we experienced but we are not capable of elaborating or we cannot relate this to other people. It is just there. In the future, this will just guide you or get you away from danger. - Explicit (declarative) you can talk about this kind of memories. Experience in the past that is until now, it is present. You can culminate and write. E.g., you know when is your birthday or when did you graduate. - Episodic: e.g., you know when and what is going on in your birthday. - Semantic: it strengthens the episodic memory. E.g. your friend knows your birthday because at the same day, he/she won the lottery. Figure 6. Diagram Showing the Pathway of Papez Circuit Lesions in the hippocampal formation - Inability to transfer immediate & short-term memory into D. FUNCTION OF HIPPOCAMPAL FORMATION IN MEMORY long-term memory - You will now have forgetfulness Learning Learning and Memory processes may be interrupted by: − Manner by which knowledge is acquired 1. Trauma Memory 2. Cerebral anoxia (vascular event like stroke) − Process by which knowledge is stored and is retrievable 3. Alzheimer‟s disease (degenerating disease) in the future -presence of neurofibrillary tangles, neurotic plaque, and Classification of Memory: neuronal loss in specific brain region 1. Immediate Memory 4. Korsakoff‟s syndrome (acquired drug-related − Where newly learned information is initially stored forgetfulness) (seconds) − Amnestic confabulatory syndrome involving the 2. Short-term memory hippocampus. − Where newly learned information is initially stored (minutes) III. AMYGDALA 3. Long-term memory Aka: amygdaloid body, amygdala complex, amygdala nuclei − Recently learned information are reinforced, conveyed, (G. amygdalon, “almond”) & stored for a prolonged period of time Almond-shaped group of nuclei deep to the uncus of the − Mediated by the hippocampal formatio parahippocampal gyrus A. DIVISIONS 1. Basolateral (VL) nuclei (larger) 2. Corticomedial (DM) nuclei (smaller) 3. Central nuclei Page 5 of 9 [NEUROSCIENCE1A] 1.9 LIMBIC SYSTEM – Dr. Steve Arellano Basolateral (ventrolateral) nuclei Efferent Projections from the Amygdala: - Receives afferent fibers 1. Stria terminalis - Phylogenetically the newest - Small fiber bundle that arises primarily from cells of - Projects to: the corticomedial group 1. Dorsomedial nucleus (thalamus) - Fibers from the corticomedial nucleus to the septal 2. Basal nucleus of Meynert nuclei & hypothalamus 3. Ventral striatum - Lies between the thalamus and the caudate nucleus - Influences functions of the hypothalamus 2. Amygdaloid pathway Corticomedial (Dorsomedial) nuclei - Fibers from the central nucleus to the brainstem - Receives afferent fibers - Fibers from the basolateral nucleus to the thalamus, - Phylogenetically the oldest ventral striatum, & basal nucleus - Terminal of the olfactory fibers - Project to the VL nucleus (hypothalamus) Afferent Projections to the Afferent Projections to the - Play a role in eating behaviors Amygdala Amygdala Central Nuclei Olfactory bulb Hypothalamus - Give rise to efferent fibers Orbitofrontal cortex Septal Nuclei - Receives projections from basolateral & corticomedial Cingulate gyrus Ventral Striatum nuclei Basal forebrain Nucleus basalis of Meynert - Gives rise to the Ventral Amygdalofugal Pathway Medial thalamus - Terminates in the ANS nuclei (brainstem) Hypothalamus - Involved in respiratory & CV functions Brainstem Table 5. Connections of the Amygdala Nucleus Connections Functions B. FUNCTIONS OF THE AMYGDALA Corticomedial *Afferents from Behaviors assoc. (dorsomedial) olfactory bulb & with hunger 1. Control of the ANS in relation to previous experiences olfactory cortex − Indirectly: From the amygdala to the hypothalamus *Efferents to the − Directly: From amygdala to the brainstem autonomic VM nucleus of centers hypothalamus Corticomedial nucleus projects to the hypothalamus Basolateral Reciprocally *Behaviors assoc. (Indirectly) (ventrolateral) connected to the with eating & Central nucleus projects to the brainstem (Directly) sesnsory drinking association cortical *Autonomic and areas: somatic reflex IV. BRAINSTEM CENTERS ASSOCIATED WITH LIMBIC SYSTEM *Efferents to the activity FUNCTION MD nucleus of *Behavioral 1. Hypothalamus thalamus, basal reactions to − Mediates ANS (visceral) responses that accompany the nucleus of stressful situations expression of emotions Meynert, & ventral 2. Thalamus striatum − Hippocampal formation receives afferent fibers from the Central Reciprocally Respiratory & anterior, LD LP, & intralaminar nuclei. connected to the cardiovascular 3. Habenular Nuclei visceral sensory & responses -tiny structure posterior to thalamus autonomic nuclei − Project to the: (brainstem) a. Interpeduncular & raphe nuclei (midbrain) Table 4. Nuclei of the Amygdaloid Complex b. Hypothalamus c. VTA A. AFFERENT & EFFERENT PROJECTIONS TO THE AMYGDALA d. SN Afferent Projections to the Amygdala 4. Ventral tegmental area (VTA) 1. Olfactory bulb − Modulates the processing of memory via dopaminergic 2. Orbitofrontal cortex fibers 3. Cingulate gyrus − Projects ascending dopaminergic fibers to all limbic 4. Basal forebrain structures. 5. Medial thalamus 5. Locus ceruleus 6. Hypothalamus -superior-posterior pons 7. Brainstem Page 6 of 9 [NEUROSCIENCE1A] 1.9 LIMBIC SYSTEM – Dr. Steve Arellano − Sends noradrenergic fibers 9. Mammillo-interpeduncular tract − Secretes noradrenaline or norepinephrine but small - Arises from the mammillary body & terminates in the amount. It also secretes dopamine and serotonin. interpeduncular nucleus − Projects ascending noradrenergic fibers to all limbic 10. Mammillo-tegmental tract structures. - Arises from the mammillary body & terminates in the 6. Dorsal Raphe midbrain tegmentum - locate in the medial site of the brainstem 11. Stria terminalis − Sends serotinergic fibers to the limbic system, where they - From the amygdaloid body terminates in the modulate the processing of memory hypothalamus & stria terminals 12. Stria medullaris (thalami) Structure Function - Fibers that interconnect the habenular nucleus with the Hypothalamic nuclei Control ANS responses assoc. septal nuclei & anterior hypothalamus *Mamillary nucleus with the expression of 13. Anterior commissure *Preoptic nucleus emotions - Decussating fibers transmitting olfactory information Thalamic nuclei *Process information from between the olfactory bulbs & parahippocampal gyri *Anterior hypothalamus & amygdala 14. Diagonal band of broca *Lateral dorsal *Relay information to the - Fibers from paraolfactory area, terminate in *Medial Dorsal limbic lobe periamygdaloid area (temporal lobe). Habenuclear nuclei Serve as relay center for 15. Habenulointerpenduncular tract information arising from the - Arises from the habenular nucleus & terminates in the limbic system destined for the interpeduncular nucleus (midbrain) midbrain reticular formation Ventral tegmental area (VTA) Regulates processing of Note: (midbrain) memory Locus ceruleus (midbrain) Regulates processing of BLOOD SUPPLY OF THE LIMBIC SYSTEM memory Main vessels Dorsal Raphe (midbrain) Regulates processing of - Anterior and Posterior cerebral arteries memory - Anterior choroidal artery Table 6. Brain Centers Associated with Limbic System Function Branches - arises from the Circle of Willies V. PATHWAYS OF THE LIMBIC SYSTEM 1. Alveus - Two-way bundle of myelinated axons that gather to become fimbria - Consists of thin layer of white matter that lies on the superior or ventricular surface of the hippocampus. 2. Fimbria - Extends to the sub-splenial area inferior to the corpus callosum 3. Fornix - Main output pathway of the hippocampal formation - Carries commissural fibers to the habenular nuclei 4. Perforant Pathway - Main cortical input pathway to the hippocampal formation 5. Cingulum - Transmits information that interconnects the surrounding neocortex 6. Septohippocampal tract - Carries fibers that arise from the medial septal nucleus & the nuclei of the diagonal band of Broca 7. Ventral amygdalohypothalamic tract - Main projection pathway from amygdala to the hypothalamus 8. Mammillothalamic tract (mammillary fasiculus) - Principal output pathway from the hypothalamic mammillary nucleus Page 7 of 9 [NEUROSCIENCE1A] 1.9 LIMBIC SYSTEM – Dr. Steve Arellano Test Your Knowledge e. none of the above 1. It formed a transition border intervening between the diencephalon 13. The following are layers of the dentate gyrus, except * and the telencephalon _________________________ a. molecular layer 2. A process by which knowledge is stored and is retrievable in the future b. polymorphic layer _________________________ c. granule cell layer 3. The neuroanatomical basis of emotion _________________________ d. pyramidal cell layer 4. The stimulation of this system will lead to arousal, alertness, and e. none of the above attentiveness. Destruction of this system will lead to somnolence or coma _________________________ 14. The following are components of the limbic lobe, except * 5.Inhibition of serotonin synthesis or destruction of serotonin- containing a. hippocampal formation neurons in the raphe system will lead to a sleep disorder called b. subcallosal gyrus _________________________ c. cingulate gyrus 6. The following are types of neurons in the monoaminergic system, d. parahippocampal gyri except * e. none of the above a. adrenergic neuron b. cholinergic neuron 15. A bilateral lesions in the nucleus reticularis pontis caudalis will c. serotonergic neuron result in complete elimination of what type of sleep d. dopaminergic neuron e. none of the above 16. All about apneustic center in the pons, except * a. increases the depth and duration of expiration 7. The neurons are associated with memory decline in Alzheimer's disease b. sends signals for inspiration for long and deep breaths a. nucleus accumbens c. inhibited by stretch receptors of the pulmonary b. nucleus basalis of Meynert muscles c. red nucleus d. increases tidal volume d. caudate nucleus e. none of the above e. none of the above 17. The reticular nucleus of thalamus has a role in integrating and 8. The reticular formation is a mass of neurons and nerve fibers extending gating activities of thalamic nuclei, and uses a neurotransmitter * from caudal medulla to the rostral midbrain, continuous with the zona a. acetylcholine incerta (thalamus), intralaminar and reticular nuclei (subthalamus) * True b. dopamine or False c. GABA d. glutamate 9. The following nuclei belong to the median raphe nuclear group, except e. serotonin a. raphe obscurus b. raphe magnus 18. Main output pathway of the hippocampal formation. c. superior central nuclei a. fornix d. reticulotegmental nucleus b. cingulum e. none of the above c. stria terminalis d. alveus 10. The following nuclei belong to the medial reticular nuclear group, 19. This tract carries fibers that arise from the medial septal except * nucleus and the nuclei of the diagonal band of Broca. a. nucleus reticularis gigantocellularis a. cingulum b. nucleus reticularis pontis caudalis b. septohippocampal c. cuneiform nucleus c. stria medullaris d. nucleus reticularis pontis oralis d. diagonal band of Broca e. none of the above 20. Which is not part of the Hippocampal Formation 11. The following are components of the hippocampal formation, except * a. Hippocampus Proper a. dentate gyrus b. Dentate Gyrus b. dentate nucleus c. Cingulate Gyrus c. subiculum d. none of the above d. hippocampus e. none of the above 21. A circular pathway that interconnects the major limbic structure 12. The following are structures associated with the hippocampal a. direct pathway formation, except * b. indirect pathway a. induseum griseum c. papez circuit b. entorhinal cortex d. NOTA c. fasciola cinerea d. septal area Page 8 of 9 [NEUROSCIENCE1A] 1.9 LIMBIC SYSTEM – Dr. Steve Arellano 22. Subcallosal Gyrus a. It consists of white matter, which underlies the basal surface of the rostral part of the corpus callosum. b. Curves anteriorly around the genu of the corpus callosum, as the cingulate gyrus. c. Extends posteriorly, superior to the corpus callosum, as the cingulate gyrus. d. The cingulate gyrus in turn continues as the hippocampal gyrus. 23.The axons anterior to the anterior commissure terminate at all of the choices, except?. a. Septal nuclei b. Lateral preoptic area c. Habenular nuclei d. Anterior part of the hypothalamus 24. Has the highest opiate receptor in the brain 25. Lesion in Amygdala will result to what 26. Which of the Amygdala’s 3 Divisions will give rise to efferent fiber 27. Fibers that lie between the thalamus and caudate nucleus 28. Modified True or False. Lesion in the Amygdala will not cause memory Answer Key loss 1. Limbic Lobe 2. Memory 29. Which does not belong to the group to the efferent projection to 3. Papez Circuit Amygdala: Hypothalamus, Septal Nuclei, Medial thalamus,Nucleus basalis 4. Ascending Reticular Activating System (ARAS) of Meynert, Ventral Striatum 5. Insomnia 6. B 30. Modified True or False. Ventral Amygdalofugal Pathway runs from 7. B central nucleus the brainstem 8. False 9. D 31. The following are types of neurons in the monoaminergic system, 10. C except: 11. B a. adrenergic neuron 12. E b. cholinergic neuron 13. D c. serotonergic neuron 14. B d. dopaminergic neuron 15. Paradoxical sleep e. NOTA 16. A 17. C 32. The neurons are associated with memory decline in Alzheimer’s 18.a disease 19.b a. nucleus accumbens 20. c b. nucleus basalis of Meynert 21. c c. red nucleus 22. c d. caudate nucleus 23. c e. NOTA 24. Amygdala 25. Placidity, loss of fear, aggression, rage 26. Central Nuclei 27. Stria Terminalis 28. True, but there is reduction in emotional excitability 29. Medial thalamus 30. False. It should be Amygdaloid Pathway 31. B 32. B Page 9 of 9