Chapters 11 12 Single
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Transcript of Chapters 11 12 Single
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Diencephalon midsaggital view
in-between brain Major divisions
Epithalamus
Thalamus
Subthalamus
Hypothalamus
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Epithalamus Stria medullaris
thalami Connects septal
area (olfactory) withthe habenular nuclei
Habenular nuclei Connect to each
other by habenularcommissure
Project tointerpeduncularnucleus (midbrain)
Emotions and
behavior
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Epithalamus Pineal Gland
Endocrine Single structure
[no left/right]
Circadian rhythm Calcifies at 16yrs
Detection of mid-
line shifts via x-rays Subdural/epidural
bleeding
Hematoma tumor
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Diencephalon coronal view
Thalamus Subthalamus
Hypothalamus Third ventricle
Lateral ventricles Internal capsule
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Thalamus
inner chamber Divisions
Anterior
Medial
Lateral
Intralaminar andreticular
Midline
Posterior
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Thalamus
Myelinated fibers Internal medullar
lamina
Interconnectsthalamic nuclei
External medullarylamina
Fibersentering/leaving thethalamus
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Anterior thalamic nucleus Two nuclei
Principal anterior nucleus Anterodorsal nucleus
Reciprocal connections Mamillary bodies (hypothalamus)
Mammillothalamic tract Cingulate gyrus (cerebral cortex)
Internal capsule
Input from hippocampal formation viathe fornix
Limbic system Emotion/behavior Memory
Damage causes episodic long-term
memory loss Spares short-term memory
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Medial Thalamic Nuclei Dorsomedial nucleus
Reciprocal connections Prefrontal cortex
FEF
Via anterior thalamic peduncle Input from
Temporal lobe
Inferior thalamic peduncle
Amygdaloid nucleus
Substantia nigra
Lateral/intralaminar thalamic
nuclei (adjacent)
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Medial Thalamic Nuclei Roles:
Affective behavior Decision making/judgement Memory
Damage:
Loss of physical self-activation Apathy Indifference Poor motivation
Prefrontal leukotomy Lesion prefrontal-dorsomedial
nucleus pathway Relieves severe anxiety/psychiatric
disorders No longer in use due to
pharmaceuticals
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Lateral Thalamic Nuclei 2 subdivisions
Dorsal Lateral dorsal
Functionally part of
anterior group (limbicsystem)
Lateral posterior
Pulvinar Border with lateral
posterior is vague
One complex
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Lateral Thalamic Nuclei Pulvinar
Reciprocal connections
Lateral geniculate nucleus Parietal lobe
Temporal lobe
Occipital lobe
Inputs Pretectal area
Superior colliculus
Tecto-fugal pathway in blindsight
Roles: Visual relay center
Selective attention
Speech
Pain (lesion to treat intractablepain)
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Lateral Thalamic Nuclei
Ventral subdivision Ventral anterior
Ventral lateral
Ventral posterior
Receive direct input fromlong ascending tracts
Reprocal connections withcortex
Retrograde degeneration on
cortical lesions
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Ventral Anterior
Input Globus pallidus
Substantia nigra
Intralaminar nucleus (thalamus) Premotor/prefrontal cortex
Output (reciprocal connections)
Premotor cortex
Prefrontal cortex
FEF
Intralaminar nucleus
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Ventral Anterior
Roles:Motor relay station
Regulate movement
Control of voluntary movement
Medial part
Eye, head, neck
Lateral part Body, limb
Lesion
Relieve Parkinsons symptoms
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Ventral Lateral Nucleus
InputDeep cerebellar nuclei
Globus pallidus
Primary motor cortex
OutputPrimary motor cortex
(reciprocal)
Parietal lobe Somatosensory areas
Premotor/Supplementarymotor areas
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Ventral Lateral Nucleus
Role:
Motor relay station
Cerebellum/basalganglia/cortex
Lesions for relief ofParkinsons symptoms(tremor)
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Ventral Posterior Nucleus 2 divisions
Ventral posterior medial (VPM) Ventral posterior lateral (VPL)
Inputs Medial lemniscus
VPL
Spinothalamic VPL
Trigeminal lemniscus (taste) VPM
Primary somatosensory cortex VPM & VPL
Output
Primary somatosensory cortex(reciprocal) Parietal operculum (taste)
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Intralaminar Nuclei
InputsReticular FormationCerebellum
Spinothalamic tract Pain
Trigeminal
lemniscus Pain
Globus pallidus
Cerebral cortex
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Intralaminar Nuclei
Outputs:
Other thalamic nuclei
No direct corticalconnections
Striatum
Roles:
Cortical arousal Motor control
Pain sensation
Poor localization Emotional quality
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Posterior Thalamic Nuclei Inputs:
Medial lemniscus
Spinothalamic
Auditory
Visual (?) Note: no cortical feedback
Outputs:
Parietal/temporal/occipitalcortices
Multimodal
Roles:
Multimodal integration
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Metathalamus Medial geniculate nucleus
(MGN) Auditory relay Inputs:
Lateral lemniscus
Inferior colliculus Primary auditory cortex
Output: Primary auditory cortex
Roles: Spectral analysis Sound pattern recognition Auditory memory Localization of sound Multimodal integration
Lateral geniculate nucleus
(LGN) Visual relay Inputs:
Optic tract
Primary visual cortex Outputs:
Primary visual cortex Optic radiations
Pulvinar Extrastriate cortex
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Thalamic Functions Sensory integration
All senses but olfaction Modality-specific sensory
relay nuclei Nonspecific nuclei
Multisensory (posteriornuclei)
Cortical lesions-> allsensory modalities lost Pain returns
aching/burning Not sharp/pricking
Motor Control Lesions relieve tremors Cerebellum/Basal
ganglia/motor areas
Consciousness/Awareness Part of reticular activating
system
Affective behavior/Executivefunction Prefrontal cortex
Memory/Emotions Hypothalamus/cingulate gyrus
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Thalamic Circuitry Projection neurons
Project to cortex
Local circuit neurons Inhibit projection cells
Inputs are excitatory Except basal ganglia (inhibitory)
Direct excitatory pathway
Indirect inhibitory pathway
Reticular nucleus Acts like local circuit neurons,
but is a separate thalamic
nucleus (modulatory)
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Subthalamus
3 main structuresSubthalamic nuclei
Inputs:
Globus pallidus Cerebral cortex
Thalamus
Reticular formation Contralateral
subthalamic nucleus
supramamillary
commisure
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Subthalamus
3 main structuresSubthalamic nuclei
Outputs:
Globus pallidus Substantia nigra
Hemiballismus
Damage Involuntary violent
hyperkinesia ofcontralateral upper &
lower extremities
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Subthalamus 3 main structures
Fields of Forel Globus pallidus &
cerebellum fibers
H field of Forel
Prerubral
H1 field of Forel Thalamic fasciculus
H2 field of Forel Lenticular fasciculus
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Subthalamus
3 main structuresZona incerta
Implicated in many
functions Locomotion,
oculomotor, arousal,attention, feeding,
sociosexual,somatosensory
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Clinical Correlates: Symptoms Sensory disturbances
Thalamic pain
Hemiparesis
Dyskinesias Disturbances of consciousness
Memory disturbances
Affective disturbances
Disoders of language
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Posterolateral Thalamic Infarct
Loss of sensationcontralateral
Paresthesia
Pins and needles
Thalamic pain
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Medial Thalamic Infarct Symptoms
Drowsiness
Akinetic mutism
Persistent vegitativestate
Appear awake
Maintain sleep/wakecycle
Do not
interact/communicate
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Lateral Thalamic Infarct
SymptomsContralateral
hemiparesis
Dysarthria Difficulty speaking
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Posterior Thalamic Infarct
SymptomsNeuropsychological
effects
Memory Aphasia
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Alien Hand Syndrome
Unwilled, uncontrollable movements of anupper limb
Failure to recognize it as your own except
by vision
Lesions of ventral posterior, ventral lateral
and dorsomedial nuclei