🔑 Key Definitions
Hypothalamus: Small structure below thalamus; regulates homeostasis, hormones, motivated behaviors (hunger, thirst, sex)
SCN (Suprachiasmatic Nucleus): Hypothalamic nucleus that controls circadian rhythms; the brain's "master clock"
Thalamus: Sensory relay station; all senses (except smell) pass through thalamus en route to cortex
Corpus Callosum: Large bundle of axons connecting left and right cerebral hemispheres
SCN (Suprachiasmatic Nucleus): Hypothalamic nucleus that controls circadian rhythms; the brain's "master clock"
Thalamus: Sensory relay station; all senses (except smell) pass through thalamus en route to cortex
Corpus Callosum: Large bundle of axons connecting left and right cerebral hemispheres
🧠 Hypothalamus Functions
- Homeostasis: Regulates temperature, hunger, thirst, sleep-wake cycles
- Hormone Control: Controls pituitary gland (master endocrine gland)
- SCN (Circadian Rhythms): Receives light information from retina; synchronizes biological clock
- Motivated Behaviors: Feeding, drinking, sexual behavior, aggression
📊 Thalamus & Corpus Callosum
- Thalamus: Relay for vision, hearing, touch, taste (NOT smell); filters and directs sensory input
- Specific Nuclei: Each sensory modality has dedicated thalamic nucleus
- Corpus Callosum: Enables communication between hemispheres; largest white matter tract in brain
- Commissurotomy: Surgical cutting of corpus callosum (split-brain procedure)
📊 Cerebral Cortex Structure
- Six Layers: Organized horizontally; different layers receive/send different connections
- Four Lobes: Frontal, Parietal, Temporal, Occipital
- Gyri (ridges): Folded peaks of cortex
- Sulci (grooves): Valleys between gyri; increase surface area
💡 Exam Tips
- Hypothalamus = homeostasis + hormones + motivated behaviors
- SCN in hypothalamus = master circadian clock (receives retinal input)
- Thalamus = sensory relay (all senses EXCEPT olfaction/smell)
- Corpus callosum connects hemispheres - split-brain patients have this cut
- Cortex has 6 layers (numbered I-VI from surface to white matter)
- Remember: Hypo = BELOW thalamus (hypo = under)