Diencephalon & Cerebrum

Where is the diencephalon located?

Between the brainstem and cerebrum

What are the 4 components of the diencephalon?

Thalamus, Subthalamus, Epithalamus, Hypothalamus

What is the thalamus?

Largest part of the diencephalon; paired gray matter masses connected by interthalamic adhesion

Main function of the thalamus?

Sensory relay station → sends sensory info to the cerebral cortex

Exception to thalamic relay?

Smell (olfaction)

Function of medial geniculate nucleus?

Auditory processing

Function of lateral geniculate nucleus?

Visual processing

Extra role of thalamus?

Filters sensory information before reaching cortex

Location of subthalamus?

Inferior to thalamus

Structure of subthalamus?

Mainly white matter tracts + subthalamic nuclei

Function of subthalamic nuclei?

Motor control

Location of epithalamus?

Posterior and superior to thalamus

Components of epithalamus?

Habenula + Pineal gland

Function of habenula?

Motivational and emotional control; links reward-based behavior

Clinical relevance of habenula?

Linked to depression, addiction, schizophrenia

Function of pineal gland?

Secretes melatonin

Role of melatonin?

Regulates sleep–wake cycle (↑ in darkness, ↓ with light)

Additional role of pineal gland?

May influence puberty timing

Location of hypothalamus?

Most inferior & anterior part of diencephalon

What connects hypothalamus to pituitary gland?

Infundibulum

Key role of hypothalamus?

Link between nervous and endocrine systems

Functions of hypothalamus?

• Homeostasis

• Hunger & thirst

• Temperature regulation

• Heart rate & BP

• Emotions & mood

• Sex drive

Why do emotions affect hunger/thirst?

Hypothalamic nuclei are closely packed → cross-influence

Example of hypothalamus function from lecture?

Smells triggering emotional/visceral responses (e.g., comfort, nausea)

What is the cerebrum?

Largest part of the brain; responsible for higher thinking

Functions of cerebrum?

• Conscious thought

• Memory

• Sensory interpretation

• Motor contro

3 main parts of cerebrum?

1. Cerebral cortex (outer gray matter)

2. Basal nuclei (deep gray matter)

3. Cerebral medulla (white matter

What are gyri?

Raised ridges

What are sulci?

Shallow grooves

What are fissures?

Deep grooves (e.g., longitudinal fissure)

Precentral gyrus function?

Primary motor cortex

Postcentral gyrus function?

Primary somatosensory cortex

Frontal lobe function?

Motor function, mood, aggression

Parietal lobe function?

Touch, pressure, general sensory processing

Occipital lobe function?

Vision

Temporal lobe function?

Hearing, smell, memory

Insula (“5th lobe”) function?

Taste, emotion, self-awareness

Function of white matter?

Connects different brain regions via axons

Association fibers?

Connect areas within same hemisphere

Commissural fibers?

Connect both hemispheres (corpus callosum)

Projection fibers?

Connect cerebrum to brainstem/spinal cord (internal capsule)

Thalamus = ?

Sensory relay station

Hypothalamus = ?

Homeostasis + endocrine control

Pineal gland = ?

Melatonin + sleep

Cerebrum = ?

Higher thinking & conscious processing