Central Nervous System (CNS): Basic Facts

• Adult human brain is– 2% body weight– 20% resting oxygen– 15-20% blood flow

• Consists of neurons and glial cells– Neurons are the

information processors– Glia provide metabolic

and structural support to the neurons

• Energetic needs• Myelin• Repair• spinal fluid production

and other functions

Size of Adult Human Brain

• Range: 1000 to 2000 grams • Average male = 1,350 g• Average female = 1,200 g

• Anatole France = 1,000 g (20th century poet)

• Albert Einstein = 1,230 g• Lord Byron = 2,380 g

(Romance poet)

Neurons

• 200 cell types• 10 trillion cells in head

• 25 billion pyramidal neurons, connects to 1000s of other neurons

Gray & White Matter• 60% white matter (axons)

• 40% gray matter (cells)– 2 mph to 250 mph when myelinated

Neural Structure

Human neocortex has 6 layers, 4.5 mm at deepest point

• A pinpoint on the 2,200 square cm surface area in adults

52 Brodmann Areas (1906)based on different cell types and distributions

Forebrain = Cortex & Limbic

Bottom to TopBack to FrontRight and Left

General Functions of lobes• Occipital

– Vision

• Temporal – Auditory – Memory

• Parietal – Touch– Integration

• Frontal – Motor – Executive Function

(goal-oriented, planning, sequencing)

Central Nervous System• Fissures (large cleft)

– Lateral or Sylvan fissure– Longitudinal fissure– Central fissure or sulcus

• Sulcus (shallow cleft)• Gyrus (tissue ridge)

Types of Neuroimaging: Positron Emission Tomography (PET)

MRI examplesAnatomical MRI(T1-weighted)

Structural MRI(gray matter thickness map)

Anatomical MRI(T2-weighted)

Functional MRI(activation to music)

Diffusion Tensor MRI(white matter tracts)

Electroencephalography (EEG) – Brainwaves