NAL: Cerebral Hemispheres

What large structures of the cerebral hemisphere are grey matter? What about white matter?

• Grey

  • Basal Ganglion (3/5)

    • Caudate

    • Putamen

    • Globus pallidus

  • Hippocampus

  • Amygdala

• White

  • Internal capsule

    • Anterior limb

    • Genu

    • Posterior limb

  • External capsule

  • Extreme capsule

Reproduce the basic picture of the insular cortex.

Reference notes for answer.

What four fibers does the anterior limb of the internal capsule have? What is this part also known as?

• Thalamus → Frontal lobe

• Lentiform nucleus → Caudate nucleus

• Cortex → Corpus striatum

• Frontal lobe → pontine nuclei

Frontal part

What four fibers does the posterior limb of the internal capsule have? What is this part also known as?

• Anterior 2/3rds = fibers of corticospinal/bulbar tract

• Sensory fibers derived from the thalamus or continuing up from the lemniscus

• Fibers of the optic radiation from the lower visual centers to the cortex of the occipital lobe

• Acoustic fibers from the lateral lemniscus and temporal lobe

• Fibers from the occipital and temporal to the pontine nuclei

Label the blanked brain

Reference notes for answer.

Reproduce the simple diagram of the internal capsule with divisions.

Reference notes for answer.

What is the rough organization of the homonculus?

Face → Hand → Arm → Leg → Foot

How does the optic radiation run? What about the auditory?

Lateral geniculate nuc → parallel and below internal capsule

Medial geniculate nuc → perpendicular and below internal capsule

What are the lateral ventricles? Furthermore, how does the caudate interact with them?

Open spaces that hold CSF

• Anterior horn

• Body

• Trigone

• Posterior horn

• Inferior horn

Caudate forms lateral wall of anterior horn and roof of inferior horn

What comprises the lentiform nucleus? What part is visible laterally? What other part of the brain is this part connected to?

Putamen and globus pallidus (medial/lateral pallidum).

Putamen (connected to caudate head)

What is the basal ganglion comprised of? What about the lentiform nucleus, neostriatum, and corpus striatum?

Basal ganglion:

• Putamen

• Globus pallidus

• Caudate

• Subthalamic nuclei

• Substantia nigra (midbrain)

Lentiform: putamen + globus pallidus

Neostriatum: putamen + caudate

Corpus striatum: putamen + GP + caudate

What two commissural fibers can you see when doing a cross section of the CNS? Which one has the majority of the fibers?

Corpus callosum (majority + superior, just below medial longitudinal fissure)

Anterior commisure (minor + inferior, at inferior medial aspect of cortex but still above amygdala)

What does the hippocampus do? How is it formed? Draw the simple diagram as well to visualize it better.

Memory formation

Continuation of cortex

Reference notes

What is the fornex? What does the hypothalamus do with this?

Bundle of fibers that leave the hippocampus and run to mamillary nuclei of the hypothalamus.

Hypothalamus connects to anterior thalamic nuclei via the mammilothalamic tract

What is the function of the fornix? Also, what lobe is it part of and what is the presentation when it is removed?

Exact function unknown

Limbic lobe

Loss of recall memory but not recognition memory

What are the commissures of the cerebral hemispheres? Remember to name each sub-part.

Corpus callosum:

• rostrum

• genu

• body

• splenium

Anterior/Posterior commissure

What are the 4 functions of the amygdala?

• Processes and interprets sensory data

• Assigns negative emotional valence

• Modulates cortical-hypothalamic flow or emotion and affective expression

• Input into autonomic, endocrine, and affective responses

How are the sensory thalamus, cortex, and amygdala connected? (Hint: two roads)

High road: sensory info → sensory thalamus → cortex (modulation of response) → amygdala

Low road: sensory info → sensory thalamus → amygdala

What is the nucleus accumbens and what can stimulating it cure?

Reward center. Deep stimulation by ultrasonic waves can remove addictive behaviors.