Subcortical Structures and Their Functions

Subcortical Structures

Brain regions below the cerebral cortex.

Gray Matter

Contains cell bodies processing information. (thalamus, hypothalamus, limbic system, basal ganglia)

White Matter

Axonal fibers communicating between brain areas.

Diencephalon

Region between brainstem and cortical white matter, composed mostly of thalamus, hypothalamus, & various small glands

Thalamus

Major relay station for sensory information, largest structure in diencephalon, motor info from cortex to body (emotion, memory, autonomic)

Massa Intermedia

connects both halves of the thalamus

lateral geniculate nucleus

a place in the thalamus that receives impulses from the optic nerve (vision)

medial geniculate nucleus

the part of the thalamus that relays auditory signals to the temporal cortex and receives input from the auditory cortex

anterior nucleus

visceral info from hypothalamus (emotion, memory, and learning)

ventral posterior leminscus

relay for the medial lemniscus and spinothalamic tracts

ventral posterior medial

relay for the
trigeminal system

Hypothalamus

Regulates homeostasis and autonomic functions. (body growth homeostasis, metabolism, temperature, reproduction)

Amygdala

Processes emotions, especially fear and threat, high emotional valence experiences

Hippocampus

Key for memory consolidation and learning. (associative, spatial, consolidation of episodic memory)

Limbic System

Network involved in emotion and memory. (frontal lobe outputs)

parts of the limbic system

hippocampus, amygdala, hypothalamus, olfactory cortex, mammilary bodies, anterior thalamus, cingulate gyrus

Papez Circuit

Pathway for episodic memory processing. (entorhinal cortex=indexing) (cerebral cortex=storage)

Basal Ganglia

Nuclei regulating smooth muscle activity. (composed of striatum and lenticular nuclei)

basal ganglia motor function

regulates duration of action, decides importance of action, terminates action

Direct Pathway

Facilitates movement by activating motor areas. (GO command)

Indirect Pathway

Inhibits movement by suppressing motor areas. (STOP pathway)

Glutamate

Excitatory neurotransmitter in motor control.

GABA

Inhibitory neurotransmitter in motor control.

Dopamine

excites direct pathway and inhibits indirect pathway

Association Fibers

Connect areas within the same hemisphere.

Commissural Fibers

Connect corresponding areas across hemispheres.

Projection Fibers

Connect the cerebrum to lower brain areas.

Corticospinal Tract

motor pathway to spinal nerves

corticobulbar tract

motor pathway to cranial nerves

Spinothalamic Tract

Sensory pathway ascending from spinal nerves.

Fornix

Association fibers connecting hippocampus to mammillary bodies.

Corpus Callosum

Major commissural fiber connecting hemispheres.

Internal Capsule

Projection fibers connecting thalamus and brainstem.