Unit 4: The Brain s1

Study Notes

Unit 4: The Brain

The human central nervous system forms around 2 weeks after conception.
At birth, the average human brain weighs 350 grams. By the end of the first year, it weighs 1000 grams, close to the adult weight of 1200-1400 grams.
The brain and spinal cord initially form as folds around a fluid-filled canal.
Brain development stages occur around 2-3 weeks.
The developing nervous system requires neuron production and alteration.
Neuroscientists identify these processes as: proliferation, migration, differentiation, myelination, and synaptogenesis;
Proliferation: New cell production.
Migration: Neuron movement to its final location in the brain.
Differentiation: Axon and dendrite formation, giving neurons distinctive shapes.
Myelination: Glia create insulating fatty sheaths to accelerate transmission in vertebrate axons.
Synaptogenesis: Synapse formation.
The brain and spinal cord comprise the central nervous system; they are the main organs of the nervous system.
Conscious experiences arise from neural activity in the brain.
Brain-scanning techniques offer a view into the working brain.
Brain imaging techniques allow study of internal brain workings without opening the skull.
Key brain-scanning techniques include EEG, PET, fMRI, and TMS.
The brain and spinal cord have multiple protective layers called meninges.
The outermost layer is the dura mater, a tough membrane.
Inside the dura mater is the arachnoid membrane, a web-like tissue.
The subarachnoid space contains cerebrospinal fluid and blood vessels.
The innermost layer is the delicate pia mater, adhering to brain surfaces.
The central core ("old brain") controls basic functions like eating, sleeping, and common to all vertebrates.
The hindbrain includes the medulla (responsible for breathing and heartbeat), pons (motor information transmitter/coordinator), and cerebellum (body coordination).
The pons is also involved in regulating sleep.
The reticular formation is composed of networks influencing arousal and sleep stages.

Parts of the Brain

Thalamus: Primarily relays sensory information.
Hypothalamus: Maintains homeostasis and regulates survival behaviors (eating, drinking, sexual behavior).
Cerebellum: Responsible for coordination and balance.
Brainstem: (includes midbrain, medulla, and pons) controls largely unconscious functions like heartbeat and breathing.
Cerebral Cortex: The "new brain", responsible for complex processing.
Corpus Callosum: Connects the two cerebral hemispheres.
Amygdala: Involved in processing emotions.
Hippocampus: Involved in memory.
Pituitary Gland: Regulates other endocrine glands.

Development of the Brain

The brain develops in three initial swellings (cephalon) that later form five divisions.
These divisions are telencephalon (cerebral hemispheres), diencephalon, mesencephalon (midbrain), metencephalon, and myelencephalon (medulla).