1Nuclei basales.Nuclei basales.The extrapyramidal/basal ganglia The extrapyramidal/basal ganglia

movementmovement--regulator system.regulator system.

2Nuclei basales/Basal gangliaNuclei basales/Basal ganglia

Tha basis of the telencephalon contains structures Tha basis of the telencephalon contains structures which belong to different functional systems: corpus which belong to different functional systems: corpus amygdaloideum, claustrum, bulbus olfactorius, amygdaloideum, claustrum, bulbus olfactorius, tractus olfactorius, trigonum olfactorium, tractus olfactorius, trigonum olfactorium, tuberculum olfactorium, substantia perforata tuberculum olfactorium, substantia perforata anterior, area septalis.anterior, area septalis.

The term nuclei basales (basal ganglia) is more The term nuclei basales (basal ganglia) is more restricted. It refers to the restricted. It refers to the caudatecaudate-- and lentiform and lentiform nucleinuclei. These two large grey matter systems belong . These two large grey matter systems belong to one functional system, which is called the to one functional system, which is called the extrapyramidal motor regulation system.extrapyramidal motor regulation system.

3Nuclei basales: neuroanatomyNuclei basales: neuroanatomy

Nucleus caudatus: extends from the anterior basal Nucleus caudatus: extends from the anterior basal telencephalon, above the thalamus towards the telencephalon, above the thalamus towards the temporal pole. Between the caudate nucleus and the temporal pole. Between the caudate nucleus and the thalamus runs the stria terminalis thalamus runs the stria terminalis a pathway a pathway connecting the amygdala to the hypothalamus.connecting the amygdala to the hypothalamus.

Nucleus lentiformis: putamen. The putamen is the Nucleus lentiformis: putamen. The putamen is the external part of the lentiform nucleus, external part of the lentiform nucleus, embryologically similar to the caudate nucleus, and embryologically similar to the caudate nucleus, and the two large nuclei form the the two large nuclei form the STRIATUMSTRIATUM. The . The striatum is a large neuronal system with uniform striatum is a large neuronal system with uniform structure in the caudate and putamen.structure in the caudate and putamen.

Nucleus lentiformis: globus pallidus. The globus Nucleus lentiformis: globus pallidus. The globus pallidus is another uniform neuronal system, we call pallidus is another uniform neuronal system, we call it it PALLIDUMPALLIDUM..

The striatum and the pallidum are the two central The striatum and the pallidum are the two central structures of the extrapyramidal motor system. They structures of the extrapyramidal motor system. They are located deep inside the hemispheres.are located deep inside the hemispheres.

4Other structures which are parts of Other structures which are parts of the extrapyramidal systemthe extrapyramidal system

Substantia nigra: dopaminergic neurons which Substantia nigra: dopaminergic neurons which project to the striatum mainly.project to the striatum mainly.

Nucleus subthalamicus: located in the subthalamic Nucleus subthalamicus: located in the subthalamic region, contains excitatory neurons.region, contains excitatory neurons.

Thalamus VA and VL nuclei: the motor thalamus is Thalamus VA and VL nuclei: the motor thalamus is the final common pathway for the cerebellar and the the final common pathway for the cerebellar and the extrapyramidal system. The nuclei project to the extrapyramidal system. The nuclei project to the motormotor-- and premotor neocortex (frontal lobe).and premotor neocortex (frontal lobe).

Thalamus: some intralaminar nuclei, mainly the Thalamus: some intralaminar nuclei, mainly the centromedian nucleus.centromedian nucleus.

Tracts connecting the listed structures: ansa Tracts connecting the listed structures: ansa lenticularis, fasciculus lenticularis (these tracts are lenticularis, fasciculus lenticularis (these tracts are located in the subthalamic region).located in the subthalamic region).

5Nucleus caudatusNucleus caudatus

PutamenPutamen

Globus pallidusGlobus pallidus

ThalamusThalamus

LOBUS OCCIPITALISLOBUS OCCIPITALIS

6Striatum: nucleus caudatus (Ca) and putamen (Pu); Striatum: nucleus caudatus (Ca) and putamen (Pu); section plane is anterior to the chiasmasection plane is anterior to the chiasma

CaCa

PuPu

Corpus callosumCorpus callosum

SeptumSeptumpellucidumpellucidum

7Section plane: chiasma opticumSection plane: chiasma opticum

Chiasma Chiasma

CaCa

PuPu

SeptumSeptumpellucidumpellucidum

Globus pallidusGlobus pallidus

8Section plane posterior to the chiasmaSection plane posterior to the chiasma(optic tract is visible)(optic tract is visible)

CaCa

PuPu

CapsulaCapsulainternainterna

GlobusGlobuspalliduspallidus

TractusTractusopticusopticus

9Medium spiny neuron in striatum (transmitter: GABA) Medium spiny neuron in striatum (transmitter: GABA) projection neuronprojection neuronaxons run to the pallidum. Interneurons in striatum: acetylcholiaxons run to the pallidum. Interneurons in striatum: acetylcholine, GABAne, GABA--

and peptide (enkephalin, substance P) transmitters.and peptide (enkephalin, substance P) transmitters.

Neurons express Dopamine (D) receptors: Neurons express Dopamine (D) receptors: the Dthe D--receptors mediate transmission receptors mediate transmission

(regulate neuronal activity) and regulate the(regulate neuronal activity) and regulate themetabolism of the cells, too.metabolism of the cells, too.

10

CaCa

PuPu

Acetylcholine esterase activityAcetylcholine esterase activityin the striatum, septal area (Acb) andin the striatum, septal area (Acb) andolfactory tubercle (Tu).olfactory tubercle (Tu).The enzyme activity proves theThe enzyme activity proves thetransmitter role of acetylcholine.transmitter role of acetylcholine.Ca: nucleus caudatusCa: nucleus caudatusPu: putamenPu: putamenFrontal plane section.Frontal plane section.

11

The striatum: connectionsThe striatum: connections

ENTIRE NEOCORTEX, EXCEPT PRIMARY VISUAL AND AUDITORY AREAS ENTIRE NEOCORTEX, EXCEPT PRIMARY VISUAL AND AUDITORY AREAS

ENTIRE STRIATUM ENTIRE STRIATUM Hippocampus, amygdalaHippocampus, amygdala

Thalamus: intralaminar nucleiThalamus: intralaminar nuclei

S. NIGRAS. NIGRA(DOPAMINE)(DOPAMINE)

PALLIDUMPALLIDUM

12

Pallidum: structure and connectionsPallidum: structure and connections

The globus pallidus has a lateral and a medial The globus pallidus has a lateral and a medial section (separated by thin white matter). It is a section (separated by thin white matter). It is a homogeneous neuron system, called the homogeneous neuron system, called the pallidum.pallidum.

The pallidum contains large GABAergic neurons.The pallidum contains large GABAergic neurons.

Afferents:Afferents: from striatum (GABAergic axons), from from striatum (GABAergic axons), from nucleus subthalamicus (glutamate axons), nucleus subthalamicus (glutamate axons), substantia nigra (dopaminergic axons).substantia nigra (dopaminergic axons).

Efferents:Efferents: mainly to the thalamus (VA, VL, CM, DM), mainly to the thalamus (VA, VL, CM, DM), they are inhibitory. The pallidum also sends they are inhibitory. The pallidum also sends inhibitory axons to the subthalamic nucleus and the inhibitory axons to the subthalamic nucleus and the substantia nigra.substantia nigra.

13

The putamen and pallidum are separated in The putamen and pallidum are separated in brownbrown..Border between two parts of the GP is Border between two parts of the GP is green.green.

CaCa

PuPu

GPGP

GP: globus pallidus

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The subthalamic nucleusThe subthalamic nucleus

Located beneath the thalamus, small Located beneath the thalamus, small (pea(pea--sized).sized).

Neurons are large, multipolar cells use Neurons are large, multipolar cells use glutamate (excitatory).glutamate (excitatory).

Excitatory Excitatory afferentsafferents come from the come from the motor neocortex. Inhibitory motor neocortex. Inhibitory afferents afferents come from the pallidum.come from the pallidum.

EfferentsEfferents (strong excitation) terminate (strong excitation) terminate mainly in the pallidum.mainly in the pallidum.

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Substantia nigra (SN)Substantia nigra (SN)

Structure of the midbrain tegmentum.Structure of the midbrain tegmentum.

Contains dopaminergic (and Contains dopaminergic (and GABAergic) cells, which also contain GABAergic) cells, which also contain neuromelanin. This gives to the SN a neuromelanin. This gives to the SN a blackish tint.blackish tint.

Dopaminergic axons from the SN run to Dopaminergic axons from the SN run to the striatum (also: pallidum, amygdala).the striatum (also: pallidum, amygdala).

Afferents to the SN come mainly from Afferents to the SN come mainly from the striatum.the striatum.

16

Substantia nigraSubstantia nigra

Substantia nigra on MRI images of the living brainSubstantia nigra on MRI images of the living brain

17

Extrapyramidal motor symptomsExtrapyramidal motor symptoms

Chorea:Chorea: involuntary, fast limb movements (chorea = dance).involuntary, fast limb movements (chorea = dance).

Ballismus (hemiballismus):Ballismus (hemiballismus): sudden, largesudden, large--scale limb movements. scale limb movements. Damage to the subthalamic nucleus causes hemiballismus.Damage to the subthalamic nucleus causes hemiballismus.

Tremor:Tremor: continuous tremor is characteristic (continuous tremor is characteristic (notnot intention tremor).intention tremor).

Dystonia:Dystonia: involuntary, torsional trunk movements which force the involuntary, torsional trunk movements which force the patient in veird body positions. Movements may be painful.patient in veird body positions. Movements may be painful.

Akinesia, hypokinesia:Akinesia, hypokinesia: the movements are slowing down. Movements the movements are slowing down. Movements are rare, it is difficult for the patient to initiate a movementare rare, it is difficult for the patient to initiate a movement. It is . It is difficult for the patient to adapt the movement to the needs (e.difficult for the patient to adapt the movement to the needs (e.g.: to g.: to stop movement when asked).stop movement when asked).

Rigor:Rigor: painful increase of muscle tone.painful increase of muscle tone.

These movement disorders affect every muscle (soft palate, faciaThese movement disorders affect every muscle (soft palate, facial l muscles, masticatory muscles, laryngeal muscles, etcmuscles, masticatory muscles, laryngeal muscles, etc))

BASAL FOREBRAIN: AMYGDALOID COMPLEX

18

19

Corpus amygdaloideumCorpus amygdaloideum The amygdaloid body is located in the temporal pole, The amygdaloid body is located in the temporal pole,

beneath the cortex.beneath the cortex. It belongs to the basal telencephalon.It belongs to the basal telencephalon. Function: a structure where learning, memory, Function: a structure where learning, memory,

motivation and emotion converge. An interface between motivation and emotion converge. An interface between the diencephalon and the neocortex.the diencephalon and the neocortex.

The sensory information enters the thalamus The sensory information enters the thalamus this this sensory information gains an emotional charge in the sensory information gains an emotional charge in the amygdala (the emotional charge is the result of amygdala (the emotional charge is the result of childhood learning). The sensory information decorated childhood learning). The sensory information decorated with emotions flows towards the hypothalamus and the with emotions flows towards the hypothalamus and the striatum. In the hypothalamus this information will evoke striatum. In the hypothalamus this information will evoke autonomic reactions; in the striatum it will be added to autonomic reactions; in the striatum it will be added to the movements (motor behaviour). The amygdala builds the movements (motor behaviour). The amygdala builds up complex behavioural patterns with autonomic up complex behavioural patterns with autonomic reactions (e.g.: heart rate, blood pressure). These reactions (e.g.: heart rate, blood pressure). These reactions (if they are motor in nature) will affect striatal reactions (if they are motor in nature) will affect striatal functions, too (e.g.: agressive behaviour, depressive functions, too (e.g.: agressive behaviour, depressive behaviour).behaviour).

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Gyrus rectusGyrus rectusGyri orbitalesGyri orbitales

Bulbus, tractusBulbus, tractusolfactoriusolfactorius

Polus temporalisPolus temporalis

Phi: gyrusPhi: gyrusparahippocampalisparahippocampalisSpl: spleniumSpl: spleniumcorporis callosicorporis callosi

Mesencephalon Mesencephalon

Ventral surfaceVentral surface

Amygdala is Amygdala is located herelocated here

beneath the cortexbeneath the cortex

21

AMYAMY

CiCi

Tractus opticusTractus opticus

PutamenPutamenNucleus caudatusNucleus caudatusGlobus pallidusGlobus pallidus

ECEC

22

AMYDGALAAMYDGALACOMPLEXCOMPLEX

NUCLEINUCLEI EntorhinalEntorhinalcortexcortex

MEDIALMEDIAL

23

Amygdaloid complex:Amygdaloid complex:1. afferent connections1. afferent connections

SensorySensory-- and association neocortical and association neocortical areasareas

Olfactory systemOlfactory system

Hippocampus and entorhinal cortexHippocampus and entorhinal cortex

Intralaminar thalamic nucleiIntralaminar thalamic nuclei

24

Amygdaloid complex: Amygdaloid complex: 2. efferent connections2. efferent connections

Neocortex (feed-back projections).

Thalamus: medial nuclei (the medial thalamic nuclei are connected to the prefrontal neocortex).

Striatum.

Contralateral amygdala (through the commissura anterior).

Hypothalamus (supraoptic and tuberal regions).

ALLOCORTEX:ALLOCORTEX:1. limbic lobe 1. limbic lobe

2. olfactory brain2. olfactory brain

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AllocortexAllocortex

This term collectively describes the nonThis term collectively describes the non--neocortical areas, which are phylogenetically neocortical areas, which are phylogenetically older than the neocortex.older than the neocortex.

The allocortical areas are on the medial The allocortical areas are on the medial surface/rim of the cerebral hemisphere.surface/rim of the cerebral hemisphere.

The allocortical areas build two large The allocortical areas build two large systems: the rhinencephalon and the limbic systems: the rhinencephalon and the limbic lobe.lobe.

The rhinencephalon participates in olfactory The rhinencephalon participates in olfactory functions. The limbic lobe participates in functions. The limbic lobe participates in complex memory functions (mainly spatial complex memory functions (mainly spatial memory).memory).

ALLOCORTICAL AREAS ON THE MEDIAL SURFACE OF THE BRAINALLOCORTICAL AREAS ON THE MEDIAL SURFACE OF THE BRAIN

Green:Green: inner circle of the limbic lobe (archicortex)inner circle of the limbic lobe (archicortex)YellowYellow: outer circle of the limbic lobe (periarchicortex): outer circle of the limbic lobe (periarchicortex)Pink: Pink: septal areaseptal area

ALLOCORTICALALLOCORTICALAREAS ARE NOTAREAS ARE NOTUNIFORM: THEYUNIFORM: THEYDIFFER AS TODIFFER AS TO

THICKNESS ANDTHICKNESS ANDLAMINATIONLAMINATION

(bulbus olfactorius, paleocortex, (bulbus olfactorius, paleocortex,

archicortex, periarchicortex)archicortex, periarchicortex)..

Lobes and interlobar borders on the medial surface. C: sulcusLobes and interlobar borders on the medial surface. C: sulcuscentralis; Po: sulcus parietooccipitalis. Note, that the cingulacentralis; Po: sulcus parietooccipitalis. Note, that the cingulate gyrus andte gyrus and

the parahippocampal gyrus form an almost ringthe parahippocampal gyrus form an almost ring--like, continuous area (dotted). like, continuous area (dotted). 1: area subcallosa. These areas (except the outer parts of the c1: area subcallosa. These areas (except the outer parts of the cingulate gyrus)ingulate gyrus)

belong to the allocortex (archicortex + periarchicortex).belong to the allocortex (archicortex + periarchicortex).

The insulaThe insula

The insula is the hidden lobe of the cerebral The insula is the hidden lobe of the cerebral cortex. During the fetal development, the cortex. During the fetal development, the frontalfrontal--, parietal, parietal-- and temporal lobes grow over and temporal lobes grow over it.it.

It is not allocortex, not neocortex: mesocortex.It is not allocortex, not neocortex: mesocortex.

Its surface presents elongated gyri.Its surface presents elongated gyri.

The parts of the lobes covering it are the The parts of the lobes covering it are the opercula: frontalopercula: frontal--, parietal, parietal-- and temporal and temporal operculum.operculum.

Functionally it deals with taste, olfaction and Functionally it deals with taste, olfaction and pain sensations.pain sensations.

Dissecting the opercula, the whole extent of the insulaDissecting the opercula, the whole extent of the insulais seen (it is also seen on horizontal sections revealing is seen (it is also seen on horizontal sections revealing the basal ganglia and the thalamus).the basal ganglia and the thalamus).

The concept of the limbic systemThe concept of the limbic system(Broca, Papez)(Broca, Papez)

Cortical structures on the medial side of the Cortical structures on the medial side of the telencephalon (limbic lobe).telencephalon (limbic lobe).

Hippocampus + gyrus dentatus (limbic lobe).Hippocampus + gyrus dentatus (limbic lobe).

Fornix (tract Fornix (tract white matter).white matter).

Corpus mammillare.Corpus mammillare.

Fasciculus mammillothalamicus (tract).Fasciculus mammillothalamicus (tract).

Nuclei anteriores thalami.Nuclei anteriores thalami.

Gyrus cinguli + cingulum (tract).Gyrus cinguli + cingulum (tract).

Gyrus parahippocampalis + cortex Gyrus parahippocampalis + cortex entorhinalis. entorhinalis.

CORTICAL AREAS OF THE LIMBIC LOBE CORTICAL AREAS OF THE LIMBIC LOBE

Green:Green: inner circle of the limbic lobe (archicortex)inner circle of the limbic lobe (archicortex)Yellow:Yellow: outer circle of the limbic lobe (periarchicortex)outer circle of the limbic lobe (periarchicortex)Pink:Pink: septal areaseptal area

FunctionFunction

Animals: brain center for olfaction; helps Animals: brain center for olfaction; helps orientation in space (maps of the space in orientation in space (maps of the space in memory); memory formation (learning); memory); memory formation (learning); transfers sensory information to the transfers sensory information to the autonomic nervous system (e.g.: automic autonomic nervous system (e.g.: automic reactions in fear).reactions in fear).

Human: as above, and more Human: as above, and more regulation regulation of the expression of emotions, learning of the expression of emotions, learning social behaviour, learning of social behaviour, learning of communication and social environment; communication and social environment; in in general: memory formation is the function general: memory formation is the function of the hippocampus.of the hippocampus.

The limbic system as it appears on the medial surface of the braThe limbic system as it appears on the medial surface of the brain. C: sulcusin. C: sulcuscentralis; Po: sulcus parietooccipitalis. The cingulate and paracentralis; Po: sulcus parietooccipitalis. The cingulate and parahippocampalhippocampal

gyri form a continuous, ringgyri form a continuous, ring--like structure (dotted). 1: area subcallosa. like structure (dotted). 1: area subcallosa. These cortical areas belong to the mesocortex and to the allocorThese cortical areas belong to the mesocortex and to the allocortex. Brown:tex. Brown:

fornix, mammillothalamic fasciculus, anterior thalamic nucleus afornix, mammillothalamic fasciculus, anterior thalamic nucleus and nd thalamocortical projections to the cingulate gyrus.thalamocortical projections to the cingulate gyrus.

Gyrus rectusGyrus rectusGyri orbitalesGyri orbitales

Bulbus, tractusBulbus, tractusolfactoriusolfactorius

Polus temporalisPolus temporalis

Phi: gyrusPhi: gyrusparahippocampalisparahippocampalisSpl: spleniumSpl: spleniumcorporis callosicorporis callosi

Mesencephalon Mesencephalon

LOCALIZATION OF THELOCALIZATION OF THEENTORHINAL CORTEXENTORHINAL CORTEX

THE ENTORHINAL CORTEX IS THE INTERFACE BETWEEN THETHE ENTORHINAL CORTEX IS THE INTERFACE BETWEEN THEALLOCORTEX AND NEOCORTEX. IT IS CONNECTED TO BOTH:ALLOCORTEX AND NEOCORTEX. IT IS CONNECTED TO BOTH:THESE CONNECTIONS ARE IMPORTANT IN THE FUNCTION OFTHESE CONNECTIONS ARE IMPORTANT IN THE FUNCTION OF

THE LIMBIC SYSTEM.THE LIMBIC SYSTEM.

HIPPOCAMPAL ANATOMY:HIPPOCAMPAL ANATOMY:1.1. Pes hippocampiPes hippocampi2.2. Fimbria hippocampiFimbria hippocampi3.3. Gyrus dentatusGyrus dentatus4.4. FornixFornix5.5. Commissure of the fornix Commissure of the fornix

HippocampusHippocampus--related structures:related structures: Parahippocampal gyrusParahippocampal gyrus UncusUncus SubiculumSubiculum Entorhinal cortexEntorhinal cortex

Parahippocampal gyrusParahippocampal gyrus

Parahippocampal gyrusParahippocampal gyrus

THE HIPPOCAMPALTHE HIPPOCAMPALFORMATION:FORMATION:

AMMONAMMONS HORN ANDS HORN ANDDENTATE GYRUS,DENTATE GYRUS,

WHICH COMMUNICATE WITHWHICH COMMUNICATE WITHSYNAPSES AND FORM ASYNAPSES AND FORM A

FUNCTIONAL UNIT.FUNCTIONAL UNIT.MEC, LEC, TEC: parts of theMEC, LEC, TEC: parts of the

entorhinal cortex.entorhinal cortex.

Hippocampus:Hippocampus:

1.1. Subiculum (Sub)Subiculum (Sub)2.2. Cornu ammonis (CA)Cornu ammonis (CA)3.3. Gyrus dentatus (GD)Gyrus dentatus (GD)

4.4. Fimbria (white matter) Fimbria (white matter)

Mossy fibersMossy fibers

SchafferSchaffer--collateralscollaterals

LATERALLATERALVENTRICLEVENTRICLE

Synaptic connections of theSynaptic connections of thehippocampus and parahippocampal gyrushippocampus and parahippocampal gyrus

PHi: parahippocampalPHi: parahippocampalgyrus;gyrus;

GD: dentate gyrusGD: dentate gyrusF: fimbria of hippocampusF: fimbria of hippocampus

D,L,V,M: directionsD,L,V,M: directions

Afferents to the entorhinal cortexAfferents to the entorhinal cortex

Polysensory information from the neocortex.Polysensory information from the neocortex.

Sensory input from the olfactory brain Sensory input from the olfactory brain (tuberculum olfactorium).(tuberculum olfactorium).

Afferents from the cingulate gyrus and insula.Afferents from the cingulate gyrus and insula.

Afferents (thalamocortical fibers) from the Afferents (thalamocortical fibers) from the anterior thalamic nuclei.anterior thalamic nuclei.

Afferents from the amygdala.Afferents from the amygdala.

Raphe, VTA, locus coeruleus, MeynertRaphe, VTA, locus coeruleus, Meynert--nucleus nucleus (serotoninergic, dopaminergic, noradrenergic (serotoninergic, dopaminergic, noradrenergic and cholinergic axons).and cholinergic axons).

Efferents from the entorhinal cortexEfferents from the entorhinal cortex

Tractus perforans: gyrus dentatus, CA Tractus perforans: gyrus dentatus, CA (hippocampus)(hippocampus)

Temporoammonic pathway: subiculum, CA1 Temporoammonic pathway: subiculum, CA1 (hippocampus)(hippocampus)

Neocortex (to those areas which send Neocortex (to those areas which send afferents to it; temporal association lobe)afferents to it; temporal association lobe)

Amygdaloid complexAmygdaloid complex

StriatumStriatum

Nucleus accumbens (ventral striatum)Nucleus accumbens (ventral striatum)

Functions of the limbic lobeFunctions of the limbic lobe

The entorhinal cortex (EC) is the interface between The entorhinal cortex (EC) is the interface between neocortical areas and the hippocampus. The main neocortical areas and the hippocampus. The main projection of the EC is to the hippocampus: this tract projection of the EC is to the hippocampus: this tract excites the hippocampus very effectively.excites the hippocampus very effectively.

The hippocampus is a generator of memory (lasting The hippocampus is a generator of memory (lasting molecular changes in the neuron following a specific molecular changes in the neuron following a specific excitation pattern). The hippocampal circuit enhances excitation pattern). The hippocampal circuit enhances the entering signals by circulating it in there.the entering signals by circulating it in there.

The output of the hippocampus is towards the EC; and to The output of the hippocampus is towards the EC; and to septum + mammillary body + thalamus + cingulate cortex septum + mammillary body + thalamus + cingulate cortex (Papez(Papez--circuit). The EC and the cingulate cortex circuit). The EC and the cingulate cortex distribute the hippocampal memory signals (in form of a distribute the hippocampal memory signals (in form of a synchronized electric activity) to neocortical areas (synchronized electric activity) to neocortical areas (e.g.: e.g.: medial part of the temporal lobe). medial part of the temporal lobe).

Histology of the allocortexHistology of the allocortex

Laminated/layered cerebral cortex (neurons form Laminated/layered cerebral cortex (neurons form the laminae/layers).the laminae/layers).

Neurons: types are similar to those in the Neurons: types are similar to those in the neocortex (although less in number). neocortex (although less in number). Interneurons:Interneurons: large choice of inhibitory cells. large choice of inhibitory cells. Projection neurons:Projection neurons: pyramidal cells.pyramidal cells.

Number of layers is less compared to the sixNumber of layers is less compared to the six--layered neocortex.layered neocortex.

Transmitters are similar to neocortex.Transmitters are similar to neocortex.

Archicortex and paleocortex display different Archicortex and paleocortex display different layers and some special nerve cell types (e.g.: layers and some special nerve cell types (e.g.: mitral cells).mitral cells).

CA1CA1CA2CA2

CA3CA3

Gyrus dentatusGyrus dentatus

CA: Cornu Ammonis, AmmonCA: Cornu Ammonis, Ammons horn containing pyramidal cells.s horn containing pyramidal cells.GD: dentate gyrus containing granule cells. The white matter is GD: dentate gyrus containing granule cells. The white matter is the fimbria of thethe fimbria of the

hippocampus (F). The fimbria builds the fornix, a large tract cohippocampus (F). The fimbria builds the fornix, a large tract connecting thennecting thehippocampus to the septum and the mammillary body. The two fornhippocampus to the septum and the mammillary body. The two fornicesicesare connected with commissure: this is the hippocampal commissurare connected with commissure: this is the hippocampal commissure.e.

CA4CA4

FF

RAT BRAIN SECTION: HIPPOCAMPUSRAT BRAIN SECTION: HIPPOCAMPUS

Pyramidal cells in the human hippocampusPyramidal cells in the human hippocampus(Golgi(Golgi--impregnation)impregnation)

HIGH CONCENTRATION OF IONOTROPIC GLUTAMATE RECEPTORSHIGH CONCENTRATION OF IONOTROPIC GLUTAMATE RECEPTORSIN THE HIPPOCAMPUSIN THE HIPPOCAMPUS

Pathology of the limbic lobePathology of the limbic lobe

Memory disturbancesMemory disturbances: Wernicke: Wernicke--KorsakoffKorsakoff--syndrome in chronic alcoholics causes syndrome in chronic alcoholics causes diencephalic lesions; most frequently the diencephalic lesions; most frequently the atrophy/degeneration of the mammillary bodies. atrophy/degeneration of the mammillary bodies. The patient has a significant memory loss. This The patient has a significant memory loss. This memory disturbance is thought to originate from memory disturbance is thought to originate from the injury/degeneration of the limbic/Papezthe injury/degeneration of the limbic/Papez--circuit.circuit.

EpilepsyEpilepsy: some forms of the disease (limbic : some forms of the disease (limbic epilepsy) is maintained through the ongoing epilepsy) is maintained through the ongoing degeneration/injury of the hippocampus degeneration/injury of the hippocampus (hippocampal sclerosis).(hippocampal sclerosis).

RhinencephalonRhinencephalonOlfactory brainOlfactory brain

BULBUSBULBUS

TRACTUSTRACTUS

TRIGONUMTRIGONUM

Olfactory epitheliumOlfactory epitheliumin the nasal mucosain the nasal mucosa

Bulbus olfactoriusBulbus olfactorius(allocortex)(allocortex)

Tractus olfactoriusTractus olfactorius

Olfactory trigone &Olfactory trigone &anterior commissureanterior commissure

Afferents from the nasal cavityAfferents from the nasal cavityterminate in this layer, theyterminate in this layer, they

form the olfactory glomeruli.form the olfactory glomeruli.

This layer contains the mitralThis layer contains the mitralcells (projection neurons).cells (projection neurons).

This is the layer of the mitral This is the layer of the mitral cell axons, which form thecell axons, which form theolfactory tract. The axonsolfactory tract. The axons

project to olfactory cortices.project to olfactory cortices.

Central structures which receiveCentral structures which receiveolfactory stimuliolfactory stimuli

Olfactory tubercle (allocortex).Olfactory tubercle (allocortex).

Area piriformis (this is the anterior part Area piriformis (this is the anterior part of the temporal lobe) of the temporal lobe) the cortical area the cortical area for olfactory signals (allocortex).for olfactory signals (allocortex).

Amygdaloid nucleus.Amygdaloid nucleus.

Area entorhinalis.Area entorhinalis.

Insula.Insula.

Orbitofrontal cortex (posterior parts Orbitofrontal cortex (posterior parts --neocortex).neocortex).

OLFACTORY TUBERCLEOLFACTORY TUBERCLE

Entorhinal cx.Entorhinal cx.

AmygdalaAmygdala

Orbitofrontal cortexOrbitofrontal cortex

Neuroanatomy of painNeuroanatomy of pain

Receptors: the nociceptors are free nerve endings (mechano-, chemo- and thermo-sensitivity).

Axons: non-myelinated type IV, thin myelinated type III axons conduct the stimuli.

Primary sensory neurons: small, dark cells in the spinal-, trigeminal-, vagal ganglia. Transmitters: CGRP, substance P, somatostatin.

Central projection: spinal cord laminae I-III and the spinal trigeminal nucleus.

The thick afferent axonsThe thick afferent axonsbuild tracts and givebuild tracts and givecollateral branches to thecollateral branches to thegray matter. Thin axonsgray matter. Thin axonsenter the dorsal horn toenter the dorsal horn toform synapses. The axonform synapses. The axoncollaterals given by the collaterals given by the thick axons are responthick axons are respon--sible for spinal cordsible for spinal cordreflexes.reflexes.

Dorsal root entry into the spinal cord:Dorsal root entry into the spinal cord:thick axons medially, thin axons laterally.thick axons medially, thin axons laterally.

The spinothalamic tract in the The spinothalamic tract in the spinal cord (protopathic tract)spinal cord (protopathic tract)

Located in the anterior and lateral Located in the anterior and lateral funiculi. Pain is transmitted mainly in the funiculi. Pain is transmitted mainly in the lateral part.lateral part.

KahlerKahlers law and segregation of different s law and segregation of different sensations. The axons forming the tract sensations. The axons forming the tract are crossing in the anterior white are crossing in the anterior white commissure.commissure.

Tract axons originate from spinal cells Tract axons originate from spinal cells located mainly in laminae I, II, III, IV.located mainly in laminae I, II, III, IV.

SPTH TRACTSPTH TRACTLOCALIZATIONLOCALIZATION

Neurons ofNeurons oforigin areorigin arelocated inlocated in

the dorsal hornthe dorsal horn

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Tract crossing in theTract crossing in theanterior white commissureanterior white commissure

Trigeminal lemniscus in the brain Trigeminal lemniscus in the brain stem contains nociceptive axonsstem contains nociceptive axons

The trigeminal lemniscus (trigeminothalamic tract) The trigeminal lemniscus (trigeminothalamic tract) originates from two sensory trigeminal nuclei: the originates from two sensory trigeminal nuclei: the main sensory nucleus and the spinal trigeminal main sensory nucleus and the spinal trigeminal nucleus. nucleus.

The spinal trigeminal nucleus is the structure where The spinal trigeminal nucleus is the structure where the cranial nerve nociceptive primary afferents the cranial nerve nociceptive primary afferents terminate.terminate.

The spinal trigeminal nucleus receives nociceptive The spinal trigeminal nucleus receives nociceptive axons from the trigeminalaxons from the trigeminal--, facial, facial--, vagus, vagus-- and and glossopharyngeal nerves.glossopharyngeal nerves.

Neurons in the spinal trigeminal nucleus give rise to Neurons in the spinal trigeminal nucleus give rise to pain tract fibers which join to the trigeminal lemniscus pain tract fibers which join to the trigeminal lemniscus and terminate in the thalamus (mainly VPM nucleus).and terminate in the thalamus (mainly VPM nucleus).

Trigeminothalamic tracts (trigeminal lemniscus) in the midbrain:Trigeminothalamic tracts (trigeminal lemniscus) in the midbrain: the dorsal tract the dorsal tract comes from the main sensory nucleus, the ventral tract from the comes from the main sensory nucleus, the ventral tract from the main sensorymain sensory--and spinal trigeminal nuclei. Fibers are crossed and uncrossed. and spinal trigeminal nuclei. Fibers are crossed and uncrossed. The tracts are The tracts are

close to the spinothalamicclose to the spinothalamic-- and medial lemnisci in the tegmentum of the midbrain.and medial lemnisci in the tegmentum of the midbrain.

MESENCEPHALON: UPPER SECTIONMESENCEPHALON: UPPER SECTION

Thalamic nuclei receiving pain tractsThalamic nuclei receiving pain tracts

VPL (ventrobasal complex):VPL (ventrobasal complex): termination of the termination of the spinothalamic tract. Thalamocortical projection to spinothalamic tract. Thalamocortical projection to the postcentral gyrus.the postcentral gyrus.

VPM (ventrobasal complex):VPM (ventrobasal complex): termination of the termination of the trigeminal lemniscus. Pain fibers of the trigeminal lemniscus. Pain fibers of the trigeminothalamic also terminate here. Projection: trigeminothalamic also terminate here. Projection: postcentral gyrus.postcentral gyrus.

Ventral posteriorVentral posterior inferior nucleusinferior nucleus: spinothalamic : spinothalamic fibers terminate here. Projection: insular cortex.fibers terminate here. Projection: insular cortex.

Small nuclei in the posterior nuclear groupSmall nuclei in the posterior nuclear group (nucleus (nucleus posterior; close to pulvinar): spinothalamic fibers posterior; close to pulvinar): spinothalamic fibers terminate here. Projection: superior parietal lobule.terminate here. Projection: superior parietal lobule.

Intralaminar nuclei:Intralaminar nuclei: they participate in pain they participate in pain transduction, but we have no exact anatomical data transduction, but we have no exact anatomical data (nuclei project to the cingulate gyrus and the (nuclei project to the cingulate gyrus and the prefrontal gyrus).prefrontal gyrus).

Localization of pain sensations in the Localization of pain sensations in the cerebral cortexcerebral cortex

Postcentral gyrus (primary somatosensory cx)Postcentral gyrus (primary somatosensory cx)

Insular cortexInsular cortex

Gyrus cinguliGyrus cinguli

Lobulus parietalis superiorLobulus parietalis superior

Secondary somatosensory cortex (behind the Secondary somatosensory cortex (behind the postcentral gyrus + superior parietal lobule)postcentral gyrus + superior parietal lobule)

Prefrontal cortexPrefrontal cortex

The cortical localization of pain is more The cortical localization of pain is more widespread, compared to other somatosensory widespread, compared to other somatosensory qualities. This reflects the vital importance of qualities. This reflects the vital importance of pain.pain.

Gyrus postcentralisGyrus postcentralis

Lobulus parietalis sup.Lobulus parietalis sup.

InsulaInsula

Gyrus cinguliGyrus cinguli

Prefrontal cortexPrefrontal cortex

Spinal cord nociception is controlled by Spinal cord nociception is controlled by descending serotonergic pathwaydescending serotonergic pathway

Role of the periaqueductal greyRole of the periaqueductal grey substancesubstance (PAG):(PAG): important important integration center of the midbrain, connected to the reticular integration center of the midbrain, connected to the reticular formation, the limbic system and the hypothalamus. The PAG is formation, the limbic system and the hypothalamus. The PAG is giving descending projections to the medullary raphe nuclei.giving descending projections to the medullary raphe nuclei.

Raphespinal tract:Raphespinal tract: tract originating from the medullary raphe tract originating from the medullary raphe and terminating in the dorsal horn of the spinal cord. The tractand terminating in the dorsal horn of the spinal cord. The tractreleases serotonin which stimulates inhibitory interneurons of releases serotonin which stimulates inhibitory interneurons of the dorsal horn the dorsal horn the inhibitory neurons inhibit primary the inhibitory neurons inhibit primary afferents and the pain transmission in the dorsal horn.afferents and the pain transmission in the dorsal horn.

This is an endogenous antiThis is an endogenous anti--pain (analgesic) mechanism. Its pain (analgesic) mechanism. Its existence is proven, but the precise mechanims of action are existence is proven, but the precise mechanims of action are not. We suppose, that ascending pain tract fibers activate the not. We suppose, that ascending pain tract fibers activate the reticular formation (RF) and from the RF the PAG will be reticular formation (RF) and from the RF the PAG will be activated activated and finally the raphespinal tract.and finally the raphespinal tract.

The raphespinal tract descends to the dorsal hornand stimulates inhibitory interneurons, which can

inhibit pain transmission. One concept of dorsal horn pain control.

DDrer: Selfrer: Self--portraitportrait. . The drawing was made in front of the mirror, and sent to his docThe drawing was made in front of the mirror, and sent to his doctor tor explaining the localization of his abdominal painexplaining the localization of his abdominal pain.. The artist points to the location of The artist points to the location of

pain.pain. Handwriting: Handwriting: "Do der"Do der gelb Fleck ist und mit dem Finger drauff deut do istgelb Fleck ist und mit dem Finger drauff deut do ist mir we."mir we."

Pain is a very importantPain is a very importantinformation signallinginformation signallingillness. In most casesillness. In most cases

we can localize pain, evenwe can localize pain, evenif it comes from the if it comes from the

internal (visceral) organs internal (visceral) organs (referred pain).(referred pain).

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THE ENDTHE END