TelencephalonWhite matter. Basal ganglia

Telencephalic white matterProjection fibersCorona radiata Commissural fibersCorpus callosumrostrum, genu, trunkus, splenium Commissura anteriorCommissura fornicis Association fibers Fibrae arcuatae brevesFibrae arcuatae longi

Association fibers1. Fasciculus longitudinalis superior2. Fasciculus longitudinalis inferior3. Cingulum4. Fasciculus uncinatus5. Fibrae arcuatae brevae

1. Fasciculus longitudinalis superior 3. Fasciculus uncinatus 2. Fasciculus occipitofrontalis 4. Fasciculus perpendicularis inferior occipitalisAssociation fibers (lateral aspect)

1. Cingulum 4. Fasciculus occipitofrontalis superior2. Fasciculus uncinatus 5. Fasciculus perpendicularis occipitalis3. Fasciculus longitudinalis inferiorAsociation fibers (medial aspect)

Speech areas

Commissural fibersCorpus callosum symmetrical areas of the hemispheres splenium, corpus, genu, rostrumCommissura anterior temporal lobes olfatory bulbsCommisssura posterior left and right parts of tectum & tegmentum of midbrainCommissura fornicis between both crura of fornix

Corpus callosum - forceps minor- forceps major- tapetumCommissura anterior - pars anterior- pars posteriorCommissura anterior(frontal section)

Commissural fibersCorpus callosum 3. Forceps minorCommissura anterior 4. Forceps major

Lateralisation of functions

. Dominant hemisphre - mention the stimulusB. Nondominant hemisphere - points the stimulusC. Anomia can not name stimuli on the left handD. Alexia in the left visual fieldsE. Test hybrid face -the patient answers man, but point the womanSplit brain syndrome

Projection fibers

1. Crus anteriorbetween nucl. caudatus nucl. lentiformis- stripes of grey matter2. Genu3. Crus posteriorPars thalamolentiformisbetween thalamus & nucl. lentiformisPars retrolentiformisPars sublentiformisCapsula interna

Capsula interna1. Tractus corticonuclearis2. Tractus corticospinalis3. Fibrae corticothalamicae4. Fibrae thalamocorticales5. Radiatio acustica6. Radiatio optica14. Fibrae corticorubrales

White matter (frontal section)1. Corpus callosum2. Capsula interna3. Fasciculus occipitofrontalis superior4. Fasciculus longitudinalissuperior5. Fasciculus occipitofrontalisinferior6. Cingulum7. Fasciculus uncinatus8. Fasciculus longitudinalisinferior

Basal ganglia

LocationSection through the base of hemisphere exposes a. Paired nuclear masses within the hemispheres.b. Surounded by white matter (capsula interna, capsula externa, capsula extrema)

Components of the Basal ganglia

Corpus Striatum Striatum ----- Caudate Nucleus & Putamen Pallidum ----- Globus Pallidus (GP)Substantia Nigra Pars Compacta (SNc) Pars Reticulata (SNr)Subthalamic Nucleus (STN)Ventral Striatum Ventral Pallidum Nucleus Accumbens Septi Noncholiergic part of Substantia Innominata

Basal ganglia Components

STRIATUM

Nucleus Caudatus Caput, (Corpus), Cauda Caudolenticular bridges of grey matterPutamenStriatum Ventralis: Nucleus Accumbens (Septi)

Basal ganglia Components

Striatal Compartments (Mosaic or Modular Organization)

1. Striosome (Patches) - 10-20% of total striatal mass - low acetylcholinesterase (AchE) activity - high substance P (SP), neurotensin (NT), tyrosine hydroxylase - high expression of D1 dopamine receptor - high opiate receptor

2. Matrix - high acetylcholinesterase (AchE) activity - high somatostatin (SRIF) activity - high D2 dopamine receptor

Basal Ganglia Components

Traditional Concepts of Basal Ganglia

Corpus Striatum Caudate Nucleus Lenticular Nucleus Putamen Globus Pallidus Paleostriatum PallidumCorpus Amygdaloideum Archistriatum

Neostriatum Striatum Basal Ganglia Introduction

1. Putamen2. Tail of caudate nucleus3. Caudatolenticular gray bridge4. Amygdaloid body5. thalamusLateral surface of basal ganglia

1. head of caudate nucelus2. body of caudate nucelus3. caudatolenticular gray bridge4. putamen5. tail of caudate nucleus 6. external segment of globus pallidus 7. internal segment of globus pallidus8. amygdaloid body9. nucleus accumbens septiMedial surface of basal ganglia

PutamenGlobus pallidus external segment internal segmentSubthalamic NucleusSubstantia nigra

Internal capsuleComponents ofBasal Ganglia

Input Portion STRIATUM (Caudate Nucleus and Putamen)

Output Portion 1. PALLIDUM (Globus Pallidus) 2. SNr (Substantia Nigra, Pars Reticulata)Basal Ganglia Connections

Basal ganglia Connections. Striatum (nucl. caudatus + putamen)

1. Afferent fibers. Cortex (sensimotor gyrus paracentralis)b. Thalamus nucl. centromedianum, NVL, NVAc. Substantia nigrad. Nuclei raphe2. Efferent fibersa. Pallidum [striopallidal]b. SN [strionigral]

B. Globus pallidus (pallidum) 1. Afferent fibers. Striatum (striopallidal fibers)b. Nucleus subthalamicus (fasciculus subthalamicus)c. Cerebral cortexd. Substantia nigrae. Nuclei raphe2. Efferents fibersa. Common final pathway to thalamusb. Ansa lenticularis, fasciculus lenticularis, fasciculus subthalamicusBasal ganglia Connections

Basal ganglia Connections

Basal Ganglia (Main Motor Circuit) ConnectionsSupplementaryMotor Area(SMA)PrimaryMotor Area(M I)THALAMUS(VLo, VApc, CM)STRIATUM(Putamen)PALLIDUM(GPi)pyramidal tractLMN ansalenticularis lenticularfasciculus

SMA (supplementary motor area)Basal Ganglia and Pyramidal Tract upper motor neuron UMN lower motor neuron LMNpyramidal tract BASALGANGLIA CIRCUIT

Functional roleRegulate the motor activity by intrinsic and extrisic feed-back circuitsRole in the control of movementsSuppress the motor toneSuppress the excesive and unnecessary movements

Signs in lesion of basal ganglia1. Akinesia & bradykinesia - difficulty in initiation and cessation of movement2. Rigidity of muscles3. Involutary movements (hyperkinesia) tremor, tics, balism, chorea, atetosis, distonia

Basal Ganglia Functional Consideration

Functional Consideration

1. Selection of Preprogramed (learned) motor plans Basal Gangla Circuit ---- Selection Mechanism Selection Inability -------- Akinesia and Hypokinesia Faulty Selection ----------- Hyperkinesia

2. Generation (learning) of motor programs Programming of several motor fragments into complex motor routines Cerebral Palsy ------------- Disordered motor program

SYDENHAMS CHOREA- Complication of Rheumatic Fever- Fine, disorganized , and random movements of extremities, face and tongue- Accompanied by Muscular Hypotonia- Typical exaggeration of associated movements during voluntary activity- Usually recovers spontaneously in 1 to 4 months

Clinical FeaturePrincipal Pathologic Lesion: Corpus Striatum

Clinical FeaturePrincipal Pathologic Lesion: Corpus Striatum (esp. caudate nucleus) and Cerebral Cortex- Predominantly autosomal dominantly inherited chronic fatal disease (Gene: chromosome 4)- Insidious onset: Usually 40-50- Choreic movements in onset- Frequently associated with emotional disturbances- Ultimately, grotesque gait and sever dysarthria, progressive dementia ensues.HUNTINGTONS CHOREA