[NEURO]LEC_008_BASAL GANGLIA.pdf

(008) THE BASAL NUCLEI DR. ARELLANO | 11/24/2020 OUTLINE - Lesions in the Basal Ganglia or Cerebellum (e.g. Parkinsonism, I. Introduction...

(008) THE BASAL NUCLEI DR. ARELLANO | 11/24/2020 OUTLINE - Lesions in the Basal Ganglia or Cerebellum (e.g. Parkinsonism, I. Introduction Huntington’s Chorea) result in uncoordinated and disorganized A. Major Cortical and Subcortical Structures movement. involved in Movement - The basal nuclei/ganglia play an important role in the control of II. The Basal Nuclei/ Ganglia posture and voluntary movement. A. Anatomical Nuclei B. Functional Nuclei A. MAJOR CORTICAL AND SUBCORTICAL III. Neostriatum A. Caudate Nucleus STRUCTURES INVOLVED IN MOVEMENT B. Types of Neostriatal Nucleus C. Compartments of the Neostriatum IV. Paleostriatum A. Globus Pallidus B. Substantia Nigra Pars Reticulata C. Subthamalic Nucleus D. Dopamine Receptor Isoforms V. Neostriatal Input/Output A. Input a. Corticostriate Projections b. Mesencephalostriate Projections c. Thalamostriate Projections d. Other Projections B. Output VI. Basal Ganglia Pathways A. Direct Pathway B. Indirect Pathway VII. Striatal Territories A. Sensorimotor Territories Figure 1. Diagram of Major Cortical and Subcortical Neural B. Associative Territories Structures involved in movement. C. Limbic Territories VIII. Pallidal & Nigral Inputs/Outputs PATHWAYS INVOLVED: A. Inputs 1. Cerebral Cortex to Spinal Cord – Corticospinal Tract a. Striatopallidal & Striatonigral Projections b. Other Projections 2. Cerebral Cortex to Cerebellum – Cerebro-Cerebellar Pathway B. Outputs 3. Cerebral Cortex to Basal Ganglia – Cortico-Striatal Pathway a. Major Output 4. Cerebellum to Thalamus – Dentothalamic Pathway b. Minor Output 5. Basal Ganglia to Thalamus – Striatothalamic Pathway c. Side Track Output 6. Thalamus to Cerebral Cortex – Thalamocortical Pathway IX. Subthalamic Nucleus X. XI. Ventral (Limbic) Nucleus Corticostriatothalamic Loops II. THE BASAL NUCLEI/GANGLIA A. The 5 Parallel Loops XII. Basal Ganglia Function A. ANATOMICAL NUCLEI A. Motor Function 1. Caudate Nucleus B. Cognitive Function 2. Globus Pallidus XIII. Blood Supply of Basal Ganglia 3. Putamen 4. Nucleus Accumbens Septi 5. Olfactory Tubercle I. INTRODUCTION B. FUNCTIONAL NUCLEI - Neural control of movement is the product of interactions within 1. Caudate Nucleus and among a number of cortical and subcortical neural 2. Globus Pallidus structures. 3. Putamen - There are three subcortical structures: 4. Nucleus Accumbens Septi 1. Basal Ganglia – a collection of masses of grey matter 5. Olfactory Tubercle situated within each cerebral hemisphere. They are the 6. Subthalamic Nuclei corpus striatum, the amygdaloid nucleus, and the 7. Substantia Nigra claustrum 2. Cerebellum - The substantia nigra of the midbrain and the subthalamic 3. Dopaminergic Mesencephalic System nuclei of the diencephalon are functionally closely related to the - Lesions in the Motor Cortex (e.g. Stroke) result in the loss of activities of the basal nuclei movement. Legend: Black – powerpoint; Blue – books; Red – audio recording Prepared by: GROUP 8  (008) THE BASAL NUCLEI DR. ARELLANO | 11/24/2020 the Internal capsule, Into the caudate nucleus and the lentiform nucleus. B. Striatum (Dorsal Striatum and Neostriatum) – Caudate and Putamen C. Pallidum (Paleostriatum) – Globus Pallidus D. Lentiform Nucleus – Putamen and Globus Pallidus E. Ventral Striatum – Ventral parts of Caudate Nucleus and Putamen, Nucleus Accumbens Septi, Striatal part of Olfactory Tubercle. F. Extrapyramidal System - Discovered by British Neurologist Kinnier Wilson (1912) - Refers to the Basal Ganglia and an array of brainstem nuclei namely: 1. Red nucleus 2. Subthalamic nucleus 3. Substantia Nigra 4. Reticular formation Figure 2. The Basal Ganglia III. NEOSTRIATUM - Caudate Nucleus and Putamen - The Basal Ganglia is a group of interconnected nuclei located - Originated from the Telencephalon (Division of at the “basement” of the brain. It has both motor and non-motor Procencephalon) functions. - During Ontogenesis, the Caudate nucleus follows the curvature of the Telencephalic vesicle and become a C-shaped structure adjacent to the anterior horn of the lateral ventricle. A. CAUDATE NUCLEUS - Head of the caudate nucleus has a relationship to the anterior horn of the lateral ventricle. - It is the part that bulges into the lateral ventricle. - Huntington’s Chorea (Huntington Disease) o Characteristic bulge of the caudate nucleus into the lateral ventricle is lost. o Atrophy of cerebral nerve tissue and basal ganglia. - Chorea consists of rapid, irregular, involuntary, dance-like movements that flow randomly from one body region to Figure 3. Nucleus Accumbens another, including oral, facial, and appendicular muscles. It is characteristic of disorders such as Huntington disease and NUCLEUS ACCUMBENS tardive dyskinesia, but also may occur as a side effect of - Located at the base of the brain. treatment in Parkinson disease. - Structure that is part of our pleasure and reward system. - Activates our motivation and allows willpower to translate into action. - ROLES: 1. Learning and Memory 2. Laughter 3. Fear and Aggression 4. Addiction 5. Placebo effect 6. Sex 7. Food Intake DEFINITIONS AND NOMENCLATURES A. Corpus Striatum - Caudate Nucleus, Putamen, Globus Figure 4. Brain of patient with Huntington’s Disease vs. Normal Brain Pallidus. o Corpus striatum is situated lateral to the thalamus and is almost completely divided by a band of nerve fibers, Legend: Black – powerpoint; Blue – books; Red – audio recording Prepared by: GROUP 8  (008) THE BASAL NUCLEI DR. ARELLANO | 11/24/2020 B. TYPES OF NEOSTRIATAL NEURONS - divides the GP into a larger lateral & a smaller medial segment 1. ASPINY NEURONS (Non-spiny Neurons; 4%) o Intrinsic Neurons or Interneurons o Four Types: 1. Cholinergic (acetylcholine-releasing) 2. GABAergic Contains Parvalbumin Largest Population 3. Somatostatin Contains Neuropeptide-Y 4. Calretinin (calcium binding protein) Immunoreactive Neurons 2. SPINY NEURONS (96%) Figure 6. External and Internal Pallidal Lamina o Neostriatal projections or Principal Neurons of Neostriatum. B. SUBSTANCIA NIGRA PARS RETICULATA o Contain GABA (Gamma Aminobyturic Acid), Taurine, (SNpr) and Neuropeptides. - Ventral zone of the SN e.g. Substance P, Enkephalin, Neurotensin, - Has Fe+ compounds Dymoprhin, and Cholecystokinin. - Considered part of the Globus Pallidus externa (head and neck o Silent at rest and discharges when stimulated by representation) whereas the GPi (arm and leg representation) cortical inputs. - morphologically & chemically, GP & SNpr are similar - large multipolar neurons Note: Both Spiny and Aspiny Interneurons are lost in Huntington’s - NT: GABA Chorea. - = 90% of input originates from the striatum C. COMPARTMENTS OF THE NEOSTRIATUM 1. Striosomes or Patches Compartment 2. Matrix Compartment STRIOSOMES MATRIX Light Heavy Early Late Input Medial frontal cortex, Sensorimotor cortex, Limbic cortex, SNpc, Supplementary motor Ventral SNpr cortex, Association cortex, Limbic cortex, Intralaminar thalamic Figure 7. Substancia Nigra Pars Reticulata nuclei, VTA, SNpc Output SNpc SNpr, GP C. SUBTHALAMIC NUCLEUS NT GABA GABA - Cytologically homogenous Neuromodulators Neurotensin, Somatostatin, - Use Glutamate as neurotransmitter Dynorpin, Substance Enkephalins, - has the shape of a biconvex lens. The nucleus has important P Substance P connections with the corpus strlatum as a result, it is involved in Dopamine D1 D2 the control of muscle activity. Receptor Table 1. Characteristics of Striosome and Matrix Compartment. IV. PALEOSTRIATUM A. GLOBUS PALLIDUS - wedge-shaped nuclear mass located between the putamen and IC (Internal Capsule) - Lamina of fibers: External pallidal lamina - separates the GP from putamen Internal pallidal lamina Figure 8. Subthalamic Nucleus Legend: Black – powerpoint; Blue – books; Red – audio recording Prepared by: GROUP 8  (008) THE BASAL NUCLEI DR. ARELLANO | 11/24/2020 D. DOPAMINE RECEPTOR ISOFORMS C. Thalamostriate Projections - Second most prominent afferents to the striatum - D1 and D2 Receptors are found in the Striatum - Centromedian Nucleus o projects to the sensorimotor striatal territory - Parafascicular Nucleus o projects to the associative & limbic striatal territories - Other Thalamic Sources: 1. Ventral anterior nuclei (VA) 2. Ventral lateral nuclei (VL) 3. Posterior nuclei (P) - Neurotransmitter: Glutamate D. Other Projections 1. Raphe nuclei (Serotonergic) o are bilaterally symmetric cell groups in the brainstem that are located directly adjacent to the midline 2. Locus ceruleus (NA) o is located in the lateral floor of the fourth ventricle 3. External (lateral) segment of GPe Figure 5. Substantia Nigra in Parkinson’s Disease B. OUTPUT **In Normal Midbrain – Substantia Nigra is Present and Dark. **In Parkinson’s Disease – Substantia Nigra is Pale. - Projections to: 1. SNpr (Substantia nigra pars reticulata) A. D2 Receptors 2. GPe (Globus Pallidus externa) & GPi (Globus Pallidus - Mediate the anti-psychotic effects of neuroleptic drugs. interna) - Exert feedback control on dopaminergic transmission. 3. Ventral pallidum - Increased in Parkinson’s Disease. 4. SNpc (Substantia nigra pars compacta) - The neostriatal neurons belonging to the “indirect” - Neurotransmitter: GABA pathway have D2 receptors; when dopamine binds to the - Output to the GP & the SNpr is organized into direct & indirect D2 receptor, the neurons are inhibited projections A. Direct Projections B. D1 Receptors - from neostriatum to GPi & SNpr - Decreased in Parkinson’s Disease. - activation leads to a disinhibitory (facilitatory) effect on - Binding of dopamine to D1 receptors causes excitation the thalamus & an increase in motor behaviour of the striatopallidal neurons in the direct pathway. - enhanced activity result in excessive activity - (hyperkinesia) of some BG DSO (Huntington’s chorea) V. NEOSTRIATAL INPUT / OUTPUT - functionally mature in childhood A. INPUT B. Indirect Projection - from neostriatum to GPe - via STN to the GPi & SNpr A. Corticostriate Projections - activation leads to increase inhibition of the thalamus & - inputs from cerebral cortex to the striatum using direct and decreased motor activity indirect pathways - enhanced activity results to poverty of movement - Direct corticostriate Projection (hypokinesia) like in Parkinson’s Reach the neostraitum via: - functionally immature in childhood 1. internal capsule and external capsules 2. subcallosal fasciculus NT & Neuromodulators involved in Striatal Output B. Mesencephalostriate Projections To GPi To GPe To SNpr To SNpc - Origin: Substantia nigra pars compacta - Dopamine (neurotransmitter) GABA + + + + o excitatory effect on D1 striatal neurons that project to Substance P + - + - the GPi & SNpr Enkephalin - + - + o inhibitory effect on D2 striatal neurons that project to Dynorphin + - + + the GPe Neurotensin - + - + - Project to the striatum via: 1. ventral tegmental area of Tasi (area A-10) 2. retrorubral nucleus (SNpd, area A-8) Legend: Black – powerpoint; Blue – books; Red – audio recording Prepared by: GROUP 8  (008) THE BASAL NUCLEI DR. ARELLANO | 11/24/2020 VI. BASAL GANGLIA PATHWAYS VII. STRIATAL TERRITORIES 1. Sensorimotor Territories - post-commisural putamen - inputs from sensory and & motor cortical areas - project to the putamen 2. Associative Territories - caudate & pre-commissioned putamen - inputs from association cortices - project to the caudate nucleus 3. Limbic Territories - (nucleus accumbens) - input from limbic and paralimbic cortical areas - projects to the sensorimotor & limbic striatum - modulates motor response based on limbic information VIII. PALLIDAL & NIGRAL INPUTS / OUTPUTS A. INPUTS A. Striatopallidal & Striatonigral Projections - Input to GPe and GPi is from putamen and STN (Subthalamic nuclei) - Input to the SNpr is from caudate and STN Figure 8. Indirect and Direct Pathways - Input from neostriatum is GABAergic (inhibitory) - Input from STN is glutamatergic (excitatory) Direct Pathway B. Other Projections - From the cortex it will stimulate your striatum using your - From DA and Ser neurons of the brainstem glutamate and simultaneously from the substantia nigra stimulating also the striatum but using dopamine. - From striatum it will now stimulate globus pallidus and B. OUTPUTS substantia nigra using GABA which is inhibitory - From this GPi/SNr it will stimulate the thalamus still using GABA A. Major Output and - From GPi and SNpr (output nuclei) to thalamus - From thalamus it will loop back into your cortex and it is - Pallidothalamic fibers follow one of two routes: excitatory using your glutamate. 1. Traverse the IC & gather dorsal to the STN as lenticular fasciculus (H2 field of Forel) Indirect Pathway *The lenticular fasciculus (field H2 of Forel), , originates in the posteromedial portion of the medial - From the cortex it will stimulate your striatum using your segment. glutamate, it is excitatory and simultaneously from your 2. Pass around the IC (ansa lenticularis) substantia nigra going to your striatum but using dopamine and *The ansa lenticularis originates from lateral portions this is simple inhibitory. of the medial segment and loops around the posterior - From the striatum it will stimulate going to your globus pallidus limb of the internal capsule to enter the prerubral field externa and subthalamic nuclei using both GABA (field H of Forel) - From this subthalamic nuclei it will stimulate globus pallidus interna and substantia nigra pars reticulata using glutamate Note: Both routes will form the prerubral field (or H field of - From this GPi/SNr it will loop back to your thalamus using Forel) and then join the thalamic fasciculus (H1 filed of GABA and Forel) to reach the target thalamic nuclei - From thalamus it go back to your cortex using glutamate which is excitatory Target thalamic nuclei: - Include: 1. Ventral anterior (VA) a. corticothalamostriate pathway 2. Ventral lateral (VL) b. collaterals of the cortico-olivary pathway 3. Dorsomedial (DM) c. collaterals of cortico-pontine pathway 4. Intralaminal nuclei - most massive striatal afferents Neurotransmitter: GABA Legend: Black – powerpoint; Blue – books; Red – audio recording Prepared by: GROUP 8  (008) THE BASAL NUCLEI DR. ARELLANO | 11/24/2020 B. Minor Output - From GPi and SNpr (output nuclei) to the following B. Pallidosubthalamic Projection areas: o Source: GPe 1. Nucleus Tegmenti Pedunculopontis (nTPP) o GABAergic projection - Links the BG with SC (via reticulospinal tract or RST) o Role: indirect pathway that links input & output nuclei - Functions: of the basal ganglia ▪ Motor function (mesencephalic locomotor center) ▪ Arousal and sleep C. Thalamosubthalamic Projection ▪ Motivation o Source: centromedian and parafascicular nuclei ▪ Attention ▪ Learning D. Nigrosubthalamic Projection 2. Habenular Nucleus o Source: SNpc and VTA - Links BG with the limbic system o Uses DA (dopamine) pathway 3. Superior Colliculus - Links BG to the: E. Reticulosubthalamic Projection ▪ SC (via tectospinal tract or TST) o Source: dorsal nucleus of the raphe ▪ Brainstem nuclei (via the tectoreticular tract or o Uses serotonin projection TRT) - Function: head and eye movements Major outflow: to GPe and GPi and to SNpr Lesions: - Interrupting subthalamic-pallidal connection - Result to hyperkinesia of ballism - Hyperkinetic disturbances, which are characterized by increased or involuntary movement, include ballismus, chorea, and athetosis. - Ballismus is most typically seen as hemiballismus because it usually occurs on one side. It consists of uncontrolled flinging (ballistic) movements of a limb. It is most characteristically seen in the upper extremity but also may affect the lower limb. This motor disorder is most common in patients with vascular lesions localized to the contralateral subthalamic nucleus *Favorable site for deep brain stimulation (DBS) in the treatment of C. Side Track Output Parkinson’s disease - Links globus pallidus externa with STN *Input to the STN is from the frontal lobe - Neurotransmitter is GABA *output is glutamatergic (excitatory) and is fast - Basal ganglia and its neural systems is composed of: 1. Core X. VENTRAL (LIMBIC) STRIATUM ▪ Composed of striatum and its pallidal and nigral targets - Output: to ventral pallidum 2. Regulators of the core - Related to the limbic system ▪ Have two categories: - Nucleus accumbens septi has a role in mediating reward and Striatal regulators motivation Pallidonigral regulators - Involvements: a. Drug addiction IX. SUBTHALAMIC NUCLEUS b. Mental DSO (schizophrenia & Tourette syndrome) Divisions: c. 1. Sensorimotor - Schizophrenia- is a Psychiatric disorder. Symptoms include 2. Associative chronically disordered thinking, blunted affect, and emotional 3. Limbic territories withdrawal. Paranoid delusions and auditory hallucinations may also be present. Inputs from the following: - Gilles de la Tourette syndrome/Tourette syndrome- A. Corticosubthalamic Projection involuntary tic-like movements or vocalizations, sometimes with o Receives glutamatergic projections from coprolalia ▪ Primary motor area ▪ Prefontral - Tics and habit spasms are abrupt, repetitive, stereotyped, ▪ Premotor simple or complex movements that often involve muscles ▪ Supplementary motor cortices outside the distribution of the facial nerve (e.g., neck) and can o (all from the frontal lobe of the brain) be reproduced or inhibited voluntarily. They are thought to be of Legend: Black – powerpoint; Blue – books; Red – audio recording Prepared by: GROUP 8  (008) THE BASAL NUCLEI DR. ARELLANO | 11/24/2020 psychogenic origin, but their association with Gilles de la o Loops back to frontal eye field and supplementary eye Tourette syndrome suggests the possibility of basal ganglia field of cortex dysfunction. 3. Dorsolateral prefrontal loop pathway o Centered on caudate nucleus XI. CORTICOSTRIATOTHALAMOCORTICAL o Origin: LOOPS ▪ Dorsolateral prefrontal cortex ▪ Posterior parietal cortex o Projection: GPi and SNpr o Thalamic targets: ▪ Ventral Anterior nuclei ▪ DM nuclei o Loops back to the dorsolateral prefrontal cortex 4. Lateral orbitofrontal prefrontal loop pathway o Centered on caudate nucleus o Origin: ▪ Lateral orbitofrontal cortex o Projection: Globus Pallidus interna and Substantia Nigra pars reticulata o Thalamic targets: ▪ Ventral Anterior nuclei ▪ Dorsomedial nuclei o Loops back to the lateral orbitofrontal cortex 1. Information from cortex goes either to striatum, or to the pallidum, or to the thalamus. 5. Limbic Loop Pathway 2. Then the information in these centres loop back to the o Centered on ventral striatum cortex o Origin: *injury to these circuits result to selective disturbance in motor, ▪ Anterior cingulate cortex cognitive, or emotional behavior ▪ Medial orbitofrontal cortex ▪ Temporal lobe THE 5 PARALLEL LOOPS o Projection: ventral pallidum o Thalamic target: dorsomedial nucleus 1. Motor loop pathway o Loops back to anterior cingulate and medial o Centered on putamen orbitofrontal cortices o Origin: o Role: genesis of schizophrenia ▪ Primary motor ▪ Primary sensory ✓ Each of the 5 circuits has a direct and indirect pathway ▪ Somatosensory association from the striatum to the output nuclei (GPi and SNpr) ▪ Premotor ▪ Supplementary motor cortices A. Direct Pathway o Projection: Globus Pallidus and Substantia Nigra pars o Contains GABA and substance P reticulata o Connects the striatum with output nuclei o GPi projects to VL, VA, and centromedian nuclei o Activation: disinhibit thalamocortical target neurons (thalamus) o Substantia Nigra pars reticulata projects to the Ventral B. Indirect Pathway anterior of thalamus o Connects the striatum with output nuclei via relays in o Loops back to the supplementary motor, premotor, and the GPr and STN primary motor cortices o Activation: inhibit thalamocortical target neurons 2. Oculomotor loop pathway o Centered on caudate nucleus o Origin: ▪ Frontal eye field ▪ Supplementary eye field ▪ Dorsolateral prefrontal cortex ▪ Posterior parietal cortex o Projection: GPi and SNpr o Thalamic targets: ▪ VA nuclei ▪ DM nuclei Legend: Black – powerpoint; Blue – books; Red – audio recording Prepared by: GROUP 8  (008) THE BASAL NUCLEI DR. ARELLANO | 11/24/2020 XII. BASAL GANGLIA FUNCTION B. Cognitive Function - Considered central in the control of movement - Basal ganglia subserve cognitive function - Play a role in non-motor behavior, cognition, and emotion - Basal ganglia has a role in retrieval of episodic and semantic information for explicit memory and in implicit tasks that require A. MOTOR FUNCTION the initiation or modification of central motor programs - Lesions in the dorsolateral prefrontal circuit → cognitive - Automatic execution of learned motor plan and in preparation disturbances (schizophrenia, huntington’s chorea, and for movement Parkinson’s disease) - Information flow from the cortex to the basal ganglia: - Lesions in the lateral orbitofrontal circuit → obsessive 1. Command from the cortex initiates action of compulsive behavior striatal neurons - Emotion and Motivation Function 2. Nigral input provides a continuous damping o Decrease in size of the basal ganglia (Bipolar DSO) effect so that cortical commands will be focused - Spatial Neglect 3. Thalamic input informs and updates the striatum o Right-sided basal ganglia lesions of the activity in other systems concerned with o Basal ganglia connected with the superior temporal movement gyrus, which has a role in spatial neglect 4. Striatum integrates and feeds information to the globus pallidus and substantia nigra pars XIII. BLOOD SUPPLY OF BASAL GANGLIA reticulate - Basal ganglia is responsible for the automatic execution of a 1. Perforating (lenticulostriate) branches of Middle Cerebral learned motor plan Artery and Anterior Cerebral Artery - As a motor skill is learned, basal ganglia takes over the role of 2. Anterior choroidal branch of Internal Carotid Artery executing the learned strategy - Lesion to basal ganglia: result to a slower, less automatic, and less accurate cortical mechanism for motor behavior Other motor roles of BG 1. Preparation and execution of movement a. Motor loop ▪ Discharge in relation to target location in space, direction of limb movement, or muscle pattern b. Oculomotor loop ▪ Discharge in relation to visual fixation, saccadic eye movement, or passive visual stimuli ▪ Participate in the reward-based control of visual attention 2. Gating function o Gating of sensory information for motor control TEST YOURSELF o DA (inhibitory) and cortical sensorimotor (excitatory) inputs to the striatum are in 1. It is the ventral zone of the substanti nigra and has Fe+ physiologic balance compounds. o Inhibitory output of the pallidum regulates a. Substancia nigra pars reticulata (SNpr) sensorimotor access b. Neostriatum o In Parkinson’s Disease, the loss of dopamine c. Subthamalic nucleus (inhibitory) will allow cortical facilitation a free hand to stimulate the inhibitory basal ganglia 2. It is cytologically homogenous and uses glutamate as a output neurotransmitter. o Limits access of sensory information to the motor a. Substancia nigra pars reticulata (SNpr) system and decreases motor activity (hypokinesa) b. Neostriatum c. Subthamalic nucleus Huntington’s chorea - Loss of basal ganglia neurons results in a decrease in inhibitory 3. Mediate the anti-psychotic effects of neuroleptic drugs and exert output of the basal ganglia, resulting to increase in access of feedback control on dopaminergic transmission. sensory information to the motor system and increased activity a. D2 Receptors - b. D1 Receptors Legend: Black – powerpoint; Blue – books; Red – audio recording Prepared by: GROUP 8  (008) THE BASAL NUCLEI DR. ARELLANO | 11/24/2020 4. Decreased in Parkinson’s Disease and binding of dopamine this receptors causes excitation of the striatopallidal neurons in the direct pathway. a. D2 Receptors b. D1 Receptors 5. Collection of masses of grey matter situated within each cerebral hemisphere. They are the corpus striatum, the amygdaloid nucleus, and the claustrum a. basal ganglia b. cerebellum c. dopaminergic mesencephalic system Answers: A, C, A, B, A Legend: Black – powerpoint; Blue – books; Red – audio recording Prepared by: GROUP 8