Download Chapter 6

Chapter 6 Diencephalon
 Chris Rorden
University of South Carolina
Arnold School of Public Health
Department of Communication
Sciences and Disorders
University of South Carolina
1
Diencephalon – Gross Anatomy

1.
2.
3.
4.
Four Parts
Thalamus
Epithalamus
Subthalamus
Hypothalamus
2
Midsagittal Brain Section
Corpus Callosum
Thalamus
Pons
3
Functions
 Thalamus: Integrator
and gateway for
information
 Subthalamus: Important
in motor control
 Hypothalamus:
Mediates endocrine and
metabolic states
 Epithalamus: Diurnal &
automatic body
functions (diurnal
functions refer to
regulation of sleep and
wakefulness, body
temperature, and
metabolic rate)
4
Thalamus
 Channels sensory information
 pain, taste, temperature, audition,
vision
 Integrates sensorimotor
information
 From Basal Ganglia, Cerebellum,
and Cortex
 Regulates function of association
cortex and cortically mediated
speech, language, and cognitive
functions.
5
Thalamus - neighbors
6
Thalamic Structure
 Three levels of Nuclei
1. Medial
2. Lateral
3. Ventral
 Many Nuclei or receiving groups of neurons on
thalamus at each level
7
Thalamus: Anterior Nucleus
 Related to Limbic Brain and contributes to direction of
–
–
–
–
digestive
respiratory
urogenital
endocrine functions
A
Anterior nucleus
P
8
Reticular Nucleus
Located between external
medullary lamina and
internal capsule
Receives and projects
within thalamus
Integrates and regulates
thalamic activity
Only thalamic nuclei
that does not have
cortical outputs
A
P
Reticular nucleus
9
Intralaminar Nuclei
 Complex in core of internal
medullary lamina
 Afferent Connection
– Globus Pallidus, Vestibular N.,
Superior colliculus, brainstem
reticular formation, Cortex,
Brainstem, Cerebellum
 Efferent Connection
– Basal Ganglia and Cortical Areas
 Modulates Excitability of
association cortex
10
Medial Nuclear Complex
 Dorsomedial Nuclei:
– Afferent connections from
prefrontal cortex, hippocampus,
centromedianum nucleus,
hypothalamus
– Efferent projections to prefrontal
and orbitofrontal cortex and limbic
structures
– Integrates emotion, thought, and
judgment
– Destruction lowers threshold for
rage
– May play a role in Korsakoff's
syndrome
Dorsomedial nuclei
A
P
Intralaminar nuclei
11
Medial Nuclear Complex
Midline N. Complex
– Afferent Connections from brainstem reticular
formation
– Efferent Connections to Cingulate gyrus and
hypothalamus
– Important in visceral functions
12
Lateral Nuclear Complex
Dorsolateral N.
– Contributes to visceral sensory integration
– Lateral Posterior N.
– Multisensory Receiving Area
Pulvinar
– Connects visual areas with association cortex
– Important in language formation, language
processing, lexical properties, reading writing
– Injury can lead to spatial neglect
13
Thalamic Anatomy
Pulvinar
Midline nuclear
Complex
Lateral posterior
nucleus
Dorsolateral nucleus
14
Ventral Nuclear Complex
Ventral Anterior N.
– Premotor cortex and skilled movements
Voluntary movements
Ventrolateral N.
– Contributes to voluntary motor tasks
Ventral Posterior N.
– Sensation from Body and Face
15
Thalamic Anatomy
Ventral Anterior N
Ventrolateral N
Ventral posterior N
16
Geniculate Bodies
Lateral Geniculate N
– Relay center for Vision
Medial Geniculate N
– Relay center for Audition
17
Epithalamus
Pineal Gland
– Cone shaped endocrine (release hormones)
structure
– Inhibitory influence over gonadal function (sex
function)
– Diurnal rhythms
Habenular Nucleus
– Serves autonomic function and emotional drives
18
Subthalamus
Subthalamic Nuclei
– Motor functions
– Hemiballism (motor disorder: involuntary violent
movements, persists only during wakefulness)
Zona Incerta
– Visuomotor Coordinator
19
Thalamic Anatomy
Coronal Slice
Subthalamus
20
Cognitive Functions of Thalamus
 Involved in language and speech functions
 Types of subcortical aphasia include a thalamic
based aphasia (left dominant thalamus)
 Word Fluency Problems
 Neurogenic stuttering from surgeries in thalamus
 Thalamic Syndrome
– Gross detection of sensations at thalamic level
– Thalamic pathologies can result in very strong
misinterpretations of sensation
21
Hypothalamus
Hypothalamus
– Near Optic chiasm and
Mammillary Bodies
– Hypophysis (Pituitary gland)
Hormones regulates body
temp, water and food
intake, metabolism, sexual
behavior, anger,
aggression.
E.G. Thyroid Stimulating
Hormone
22