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Basal Nuclei (Ganglia) • Basal nuclei • Applied to a collection of masses of gray matter situated within each cerebral hemisphere. • They are paired and located between thalamus and white matter. • Consists of 5 pairs of nuclei: These are: • • • • • Caudate nucleus Putamen Globus pallidus Substantia nigra Subthalamic nucleus Basal Nuclei (Ganglia) • Basal nuclei • Consists of 5 pairs of nuclei: These are: • • • • • Caudate nucleus Putamen Globus pallidus Substantia nigra Subthalamic nucleus Basal Nuclei (Ganglia) • Consists of 5 pairs of nuclei: These are: • • • • • Caudate nucleus Putamen Globus pallidus Substantia nigra Subthalamic nucleus Basal Nuclei (Ganglia) Basal Nuclei (Ganglia) Basal Nuclei (Ganglia) Basal Nuclei (Ganglia) Basal Nuclei (Ganglia) Basal Nuclei (Ganglia) Caudate nucleus Globus pallidus Putamen Corpus striatum Nuclei Basales (Ganglia Basale) Caudate nucleus Putamen Striatum Cerebellum (Latin for Little Brain) Nuclei Basales (Ganglia Basale) Putamen Globus pallidus Lentiform nucleus Basal Nuclei (Ganglia) Basal Nuclei (Ganglia) Neostriatum Caudate nucleus Putamen Paleostriatum Globus pallidus Archistriatum Amygdaloid body Basal Nuclei (Ganglia) Nuclei Basales (Ganglia Basale) Basal Nuclei (Ganglia) Function of Basal Nuclei Basically the activity of basal nuclei begins by information received from sensory cortex, thalamus, substantia nigra, and red nucleus, according to thoughts of mind. • These information is integrated within corpus striatum and channeled within globus pallidus and outflow back to motor areas of cerebral cortex, and other motor areas in brain stem. • Thus the basal nuclei can control muscular movement through its effect on cerebral cortex. • So basal nuclei assist in regulation of voluntary movement and learning of motor skills. Functions of Basal Nuclei • 1- Design of plans, which convert thoughts and ideas • • into motor actions: to produce a coordinated organized purposeful movement. e.g. dressing. Determining the timing and scale of movement: to what extent the movement will be fast, and how long it will last. Storage of motor programs of familiar motor actions: e.g. signature. Functions of Nuclei Basales (Ganglia Basale) The basal ganglia are associated with a variety of functions, including : Voluntary motor control Procedural learning relating to routine behaviors or "habits" such as bruxism (gnashing of teeth), eye movements, and cognitive, emotional functions. Action selection, that is, the decision of which of several possible behaviors to execute at a given time. Basal ganglia exert an inhibitory influence on a number of motor systems, and that a release of this inhibition permits a motor system to become active. Basal Nuclei (Ganglia) Nuclei Basales (Ganglia Basale) Caudate Nucleus • Large C-shaped or comma-shaped mass of grey matter. • Lies in close relation to lateral ventricle. • It has a Head, Body, and Tail. Caudate Nucleus • Large C-shaped or comma-shaped mass of grey matter. • Lies in close relation to lateral ventricle. • It has a Head, Body, and Tail. Caudate Nucleus • Head :( Anterior) Large, & rounded and forms the lateral wall of anterior horn of lateral ventricle. • It is continuous inferiorly with putamen of lentiform Nucleus. • Body : Long &narrow continuous with head at the interventricular foramen. • It forms part of the floor of body of lateral ventricle. • Tail : Long & narrow, and lies in the roof of inferior horn of lateral ventricle. • It is connected anteriorly with Amygdaloid nucleus. Caudate Nucleus Caudate Nucleus Caudate Nucleus Connections of Corpus Striatum • Afferent Fibers ( Input): • I- Corticostriate Fibers: From all parts of cerebral cortex (mostly from sensory- motor cortex) axons pass to caudate nucleus and putamen. • Glutamate is the neurotransmitter of this fibers. • II-Thalamostriate Fibers : From intralaminar nuclei of thalamus axons pass to caudate nucleus and putamen. • III- Nigrostriate Fibers : Axons from Substantia nigra of midbrain pass to caudate nucleus and putamen. • Neurotransmitter is Dopamine. • IV_Brain stem Strial Fibers : Ascending fibers from brain stem end in caudate nucleus & putamen. • Serotonin is the neurotransmitter. • It is believed that the last 2 groups are inhibitory in function. Efferent Fibers (Output) • Striatopallidal fibers: • These fibers pass from corpus striatum (caudate nucleus & putamen) to globus pallidus. • Gamma-aminobutyric acid (GABA) is the neurotransmitter. • Striatonigral fibers: • These fibers pass from caudate nucleus & putamen to Substantia nigra. • Some fibers use GABA as a neurotransmitter, and others use substance p. Lentiform Nucleus • It is a mass of grey matter wedge-shaped or (biconvex lens). • It has 2 capsules, external capsule laterally & internal capsule medially. • Internal capsule separates between lentiform nucleus laterally & caudate nucleus and thalamus medially. • External capsule separates between lentiform nucleus and Claustrum. Lentiform Nucleus • It is divided into putamen & globus pallidus. • Putamen: Larger darker lateral portion. • Globus pallidus : Smaller, lighter medial portion. • Inferiorly putamen is continuous with the head of caudate nucleus. Lentiform Nucleus • It is divided into putamen & globus pallidus. • Putamen: Larger darker lateral portion. • Globus pallidus : Smaller, lighter medial portion. • Inferiorly putamen is continuous with the head of caudate nucleus. Basal Nuclei (Ganglia) • Substantia nigra • Located in midbrain between cerebral crus and tegmentum. • Looks dark owing to melanin pigment containing neurons.. • Consists of two parts: • Pars compacta • Pars reticularis Substantia Nigra Pedunculus cerebri Aquaductus mesencephali Pc Pr Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings • • Tr. corticospinalis Tr. corticonuclearis Substantia Nigra Cross section obtained from the level of superior colliculus Nucleus tractus mesencephalici nervi trigeminalis Strata (grisea et alba) colliculi superioris Nucleus oculomotorius accessorius Lemniscus medialis Substantia nigra, Pars compacta Nucleus ruber Fibrae parietotemporopontinae Fibrae corticonucleares Substantia nigra, Pars reticularis Fibrae frontopontinae Fila radicularia nervi oculomotorii Substantia Nigra Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Substantia Nigra • Afferents: • Most come from neostriatum. • Most of the afferent fibers terminate in SNPR, but some end in SNPC as well. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Substantia Nigra • Efferents: • Pars compacta contains dopaminergic neurons. • Efferents arising from SNPC terminate in neostriatum. Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Substantia Nigra • Efferents: • Pars reticularis’contains GABAergic neurons. • Efferents arising from • SNPR terminate in: : • Thalamus • Superior colliculus • Tegmental nucleus • Pedunculopontine nucleus Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Basal Nuclei (Ganglia) • Subthalamic nucleus • The most lower nucleus of the subthalamus. • Extents to transition zone between the tegmentum of the midbrain and subthalamus. • Located dorsolateral upper end of the SN, medial to the internal capsule, and in upper lateral part of the thalamus. Subthalamic Nucleus • Afferents • GPE • Centromedian nucleus • Parafascicular nucleus • Tegmental nucleus • Pedunculopontine nucleus Subthalamic Nucleus • Afferents • GPE • Centromedian nucleus • Parafascicular nucleus • Tegmental nucleus • Pedunculopontine nucleus Subthalamic Nucleus • Efferents • GPe and GPi • Substantia nigra Subthalamic Nucleus • Efferents • GPe and GPi • Substantia nigra Nucleus Subthalamicus Connections of Basal Nuclei (Ganglia) Nuclei Basales of Bağlantıları Connections Basal Nuclei (Ganglia) • Importants features: • Efferents from cerebral cortex to striatum are activator (use glutamate). • Neurons in the striatum are inhibitory in nature.. • Neurons in the SNr and GPm are also inhibitory in nature. • Efferents of the thalamus stimulate the cerebral cortex. Connections of Basal Nuclei (Ganglia) Direct pathway: Cortical cells project excitatory inputs onto the thalamus through the inhibitory ansa lenticularis pathway. The striatal inhibition of the SNr-GPi complex coupled with SNr-GPi inhibition of the thalamus therefore results in a net reduction of inhibition of the thalamus via the striatum. GABA GABA The SNr-GPi complex projects directly Glutamate to the striatum, which in turn projects inhibitory neurons onto the cells of the SNr-GPi complex. Glutamate Connections of Basal Nuclei (Ganglia) Direct pathway: The thalamus projects excitatory GABA GABA Glutamate glutamatergic neurons to the cortex itself. The direct pathway, therefore, results in the excitation of the motor cortex by the thalamus. Once stimulated, the cortex projects its own excitatory outputs to the brain stem and ultimately muscle fibers via the lateral corticospinal tract. The following diagram depicts the direct pathway: Glutamate Cortex (stimulates) → Striatum (inhibits) → "SNr-GPi" complex (less inhibition of thalamus) → Thalamus (stimulates) → Cortex (stimulates) → Muscles, etc. → (hyperkinetic state) Connections of Basal Nuclei (Ganglia) • Importants features: • Efferents from cerebral cortex to striatum are activator (use glutamate). • Neurons in the striatum are inhibitory in nature.. • Neurons in the GPl are also inhibitory in nature. • Neurons in the STN are activator in nature. • Efferents of the thalamus stimulate the cerebral cortex. Connections of Basal Nuclei (Ganglia) Indirect pathway: neurons in the indirect pathway project inhibitory axons onto the cells of the globus pallidus externa (GPe), which tonically inhibits the subthalamic nucleus (STN). This inhibition (by the striatum) of the inhibitory projections of the GPe, results in the net reduction of inhibition of the STN. GABA Once stimulated by the cortex, striatal GABA Glutamate Also starts from neurons in the striatum. Glutamate Connections of Basal Nuclei (Ganglia) Indirect pathway: The STN, in turn, projects excitatory thalamus and, therefore, decreased stimulation of the motor cortex by the thalamus and reduced muscle activity. The direct and indirect pathways are therefore antagonist in their functions. GABA GABA The end-result is inhibition of the Glutamate inputs to the SNr-GPi complex (which inhibits the thalamus). Glutamate Connections of Basal Nuclei (Ganglia) Indirect pathway: Following is a diagram of the indirect Glutamate GABA GABA Cortex (stimulates) → Striatum (inhibits) → GPe (less inhibition of STN) → STN (stimulates) → "SNr-GPi" complex (inhibits) → Thalamus (is stimulating less) → Cortex (is stimulating less) → Muscles, etc. → (hypokinetic state) Glutamate pathway: Connections of Basal Nuclei (Ganglia) Connections of Basal Nuclei (Ganglia) Connections of Basal Nuclei (Ganglia) A man with Parkinson's disease displaying a flexed walking posture pictured in 1892. Photo appeared in Nouvelle Iconographie de la Salpètrière, vol. 5. Connections of Basal Nuclei (Ganglia) Manifestation of Lesion of Basal Nuclei • I- Involuntary movement during rest: Chorea, athetosis, hemiballismus, and tremor. • II- Changes in muscle tone. • A- Chorea: (Dance). Lesion: in caudate N • Features: Involuntary, quick, Jerky, irregular, nonrepetitive and purposeless movement : e.g. Swift grimaces, and sudden movement of head or limb. Types: Sydenham (rheumatic fiver) more in female, Huntington’s, (hereditary), chorea Gravidarum, or chorea of contraceptive pills. Huntington’s Chorea Parkinsonism, Parkinson Disease • Lesion: Neuronal degeneration in substantia nigra leading to reduction of dopamine within corpus striatum. • Features: 1- Tremors: Pill-rolling, involuntary, rhythmic, oscillating movements. It occurs during waking time during rest, it is called static tremors. 2- Rigidity: It occurs in both flexors, and extensors, but more in flexors giving flexion attitude. It is called lead pipe rigidity. 3- Akinesia: it means lack of movement; Absence of swinging arm during walking, mask face, low- volume slow monotonous speech, and shuffling gait. Parkinsonism, Parkinson Disease Basal Ganglia Cerebellum • • • • • • • • • • • • • • • • • • • • • • • resting tremor postural instability festination rigidity masked facies bradykinesia dyskinesia torticollis chorea athetosis hemiballismus akathisia intention tremor dysmetria dysdiadochokinesia hypotonia heal to shin finger to nose rebound ataxic gait titubation nystagmus dysmetric saccades COMPARISON OF MOTOR SYSTEMS http://library.med.utah.edu/neurologicexam/html/home_exam.html Lowe r Motor Neuron Spina l Cord Uppe r Motor Neuron Corticospina l Tract Cerebellum Basal Ganglia Efferent part of monosynaptic reflex Volunta ry movement Muscle tone by inhibiting antagonists Maintains muscle fibers (trophic factors) Muscle tone Rapid coordinated alternating skilled movements that are learned Eye-head movements Facilitates intentional movements and inhib it extraneous movements Autopil ot for motor activities Normal Weakness or paralysis Fine control, espec. finger flexors Inhibitory to Lower motor neurons Weakness or paralysis Posture and Gait Balance, equili brium, orientation in space timi ng, duration, and ampli tude Voluntary movements in an automatic manor. Hyperreflexia Hyperactive deep tendon reflexes Babins ki- extensor plantar reflex Spasticity Trunca l ataxia, gait ataxia Shuffling or festinating gait, small steps, hard to turn Nystagmus, Dizziness, Masked facies, few bli nks Decomposition of movement Diffi culty turning or starting, hypo kinetic = bradykinesia Paucity of associated movements Abno rmal Areflexia Fasciculation Muscle Atrophy Flaccid paralysis Dysmetria- ataxia of arms Dysynergia Dysdiadocho kinesia- inabili ty to do rapid alternating movements Hypotonia- pendular reflexes Intention tremor Scanning speech Chorea, athetosis, hyperkinetic Rigidity ( lead-pipe ) (cogwheel), Resting tremor Soft speech BASAL GANGLIA AND CONTROL OF MOTOR FUNCTIONS Cerebral Cortex Cerebral Cortex CEREBRAL CORTEX BASAL GANGLIA Corticospinal tracts THALAMIUS Corticobulbar tracts BRAIN STEM CEREBELLUM Bulbospinal tracts SENSORY INPUT SPINAL CORD FINAL COMMON PATH BASAL GANGLIA COMPONENTS FUNCTIONAL ANATOMY BASAL GANGLIA THE BASAL GANGLIA ARE MASSES OF GREY MATTER MADE OF CELL BODIES LYING DEEP INSIDE THE WHITE MATTER OF THE CEREBRUM, AND MAKES UP PART OF THE MIDBRAIN. An upper mass is called the caudate nucleus, is separated from a lower mass, the lentiform nucleus. The lentiform nucleus consists of the putamen and the globus pallidus. Other nuclei include the substantia nigra and subthalamic nucleus. Basal Nuclei Caudate Nucleus Lenticular Nucleus Corpus Striatum Putamen Globus Pallidus Subthalamic Nucleus Substantia Nigra BASAL GANGLIA CONNECTIONS Connections for Motor Control 3 Connections to remember 1. Main input to the basal ganglia 2. Main output from the basal ganglia 3. Connections between parts of basal ganglia Basal Nuclei Caudate Nucleus Corpus Striatum Putamen Lentiform Globus Pallidus Subthalamic Nucleus Substantia Nigra MAIN INPUT TO THE BASAL GANGLIA That comes from the cerebral cortex (motor area) and projects to the NEOSTRIATUM (a term for the caudate nucleus and putamen) THE MAIN OUTPUT Is via the thalamus to the cerebral cortex (motor area) The Putamen Circuit The Caudate Circuit Basal Ganglial Pathways Loops ↑ MOTOR Direct Basal Ganglial Pathway GLU + GLU + ↓GABA - Thalamus Thalamocortical Neurons are disinhibited GPe GPi - St + DA1+ GABA SThN SNPC ↓ MOTOR Indirect Basal Ganglial Pathway GLU ↑GABA + GPe - St + GPi Thalamus GLU Subthalamic Neurons are disinhibited GLU GABA - + DA2 - - ↓GABA SThN SNPC BASAL GANGLIA FUNCTIONS • Control of movements • Planning and programming of movements • Cognition The Putamen Circuit Executes Learned Patterns of Motor Activity • Basal ganglia function in association with the corticospinal system to control complex patterns of motor activity. • Examples are: – writing of letters of the alphabet. – cutting paper with scissors, – hammering nails, – shooting a basketball through a hoop, – passing a football, – throwing a baseball, – the movements of shoveling dirt, – most aspects of vocalization, – controlled movements of the eyes – virtually any other of our skilled movements, most of them performed subconsciously. The Caudate Circuit Cognitive Control of Sequences of Motor Patterns • Cognition means the thinking processes of the brain, using both sensory input to the brain plus information already stored in memory. Thoughts are generated in the mind by a process called cognitive control of motor activity. • Example:A person seeing a lion approach and then responding instantaneously and automatically by (1) turning away from the lion, (2) beginning to run, and (3) even attempting to climb a tree. • Thus, cognitive control of motor activity determines subconsciously, and within seconds, which patterns of movement will be used together to achieve a complex goal The Caudate Circuit Change the Timing and to Scale the Intensity of Movements • Two important capabilities of the brain in controlling movement are – (1) to determine how rapidly the movement is to be performed and – (2) to control how large the movement will be. • For instance, a person may write the letter "a" slowly or rapidly. Also, he or she may write a small "a" on a piece of paper or a large "a" on a chalkboard. Regardless of the choice, the proportional characteristics of the letter remain nearly the same Movement Disorders Hyperkinetic •Hemiballismus •Huntington’s Disease •Athetosis Hypokinetic •Parkinson’s Disease •Drug Induced (Neuroleptics, MPTP) Movement Disorder Features Lesion Chorea Multiple quick, random movements, usually most prominent in the appendicular muscles Atrophy of the striatum. Huntington Chorea Athetosis Slow writhing movements,which are usually more severe in the appendicular muscles Diffuse hypermyelination of corpus striatum and thalamus Hemiballismus Wild flinging movements of half of the body Hemorrhagic destruction of contralateral subthalamic n. Hypertensive patients Parkinsonism Degenration of Substantia Nigra Pill rolling tremor of the fingers at rest, lead pipe rigidity and akinesia Parkinson’s Disease • Described by James Parkinson • Degeneration of dopaminergic nigrostriatal neurons (60-80 %). • Phenothiazines (tranquilizers drugs) . • Methyl-Phenyl-Tetrahydro-Pyridine (MPTP). The oxidant MPP+ is toxic to SN. • Five cardinal features – Tremor – Rigidity – Akinesia & Bradykinesia – Postural Changes – Speech Changes PARKINSON'S DISEASE RESTING TREMORS RIGIDITY LEAD PIPE & COG WHEEL MONOTONUS SLURRED ANARTHRIA ABSENCE OF ASSOCIATED UNCONCIOUS MOVEMENTS(SWINGING OF ARMS DURING WALKING . FACIAL EXPRESSION IS MASKED SIMIAN POSTURE SWEATING TREATMENT: L-DOPA Huntington’s Disease CORTEX Glutamate (+) PUTAMEN GABA (-) GP externa Glutamate (+) GABA (-) STN Glutamate (+) GP interna GABA (-) VA/VL THALAMUS + Huntington’s Disease • • • • • • • • Hereditory , autosomal dominant Rare onset at 30-40s as early as 20s Disease of caudate & putamen. Early, Jerky movement of hands toward end of reaching an object Later, hyperkinetic choreiform movements appear and gradually increase until they incapacitate the patient Slurred speech and incomprehensive Progressive Dementia Loss of GABA nergic neurons Hemiballismus CORTEX Glutamate (+) PUTAMEN GABA (-) GP externa Glutamate (+) GABA (-) STN Glutamate (+) GP interna GABA (-) VA/VL THALAMUS + Hemiballismus • Injury usually to subthalamic nucleus STN • Decreased inhibition (Indirect Pathway) • Characterized by uncontrolled flinging • TX: Dopamine Antagonist Left basal ganglia affect the right side of the body. Cerebral cortex UMN Pyramidal decussation LMN Basal Ganglia Thalamus