1. THALAMUS
Lecture 4

2. Epithalamus Habenular Nuclei:
Thought to be involved in emotional and visceral responses to odors.
Projects to septal nuclei (in thalamus):
Via stria medullaris thalami.
Projects to interpeduncular nucleus:
Via habenulointerpeduncular tract.

4. Epithalamus Pineal Body Secretes melatonin (hormone):
Regulates circadian rhythms.
Activity is modulated by light-dark cycle:
Via sympathetic inputs activated by hypothalamic suprachiasmatic nucleus.
Calcification accrues with maturity.
Lesions associated with precocious puberty.

5. Thalamus 80 percent of diencephalon Separated from hypothalamus via:
Hypothalamic sulcus (groove)
Other landmarks:
Optic recess
Infundibular recess
Pineal recess

7. Thalamus Commissures: Habenular : Above the pineal recess. Posterior:
Below the pineal recess.

8. Thalamus
Functions:
Relays all sensory information except smell to the cerebral cortex.
Provides crude awareness.
Initial autonomic response of the body to intense pain (physiologic shock).
Interpretation center for crude pain, temperature, light touch, pressure.
Plays a role in arousal and alerting.
Plays a role in complex reflex movements.

9. Thalamic Sensory Relay Nuclei
Medial geniculate body:
Auditory.
Projects to primary auditory cortex in temporal lobe.
Lateral geniculate body:
Visual.
Projects to primary visual cortex in occipital cortex.

10. Thalamic Sensory Relay Nuclei
Ventral posterior nuclei:
General sensations and taste.

11. Thalamic Motor Relay Nuclei
Ventral lateral:
Voluntary motor
Ventral anterior:
Voluntary motor and arousal
Subthalamic

12. Thalamus Reticular Nucleus
Modifies neuronal activity in the thalamus.
May be involved in:
Regulating sleep-wakefulness cycle and levels of awareness.

13. Thalamus Anterior Nucleus
Concerned with certain emotions and memory.
Receives input from:
Hippocampus
Mamillary bodies
(mamillothalamic tract).

14. Thalamus White Matter Internal capsule Stratum zonale
External medullary lamina
Internal medullary lamina