Cerebral Cortex

Cerebral Cortex

Cerebral Cortex - The outermost layer of the brain containing gray matter. Responsible for many "higher-order" functions like language and information processing.

Layers of the Cerebrum• Gray Matter

– Outer layer of the brain

– Composed of neuron cell bodies (site of nucleus)

– Includes regions of the brain involved in muscle control, sensory perceptions, like seeing and hearing, memory, emotions, speech and critical thinking/problem solving

Cell Body of Neuron

Layers of the Cerebrum• White Matter

– Contains mainly long, myelinated axons– Involved in the relay of sensory information

from the rest of the body to the cerebral cortex

Axon of Neuron

Myelin = fatty outer covering of axons.

Allows for faster transmission of message.

Limbic System

• set of evolutionary primitive brain structures

• involved in emotions and motivations, like the ones related to survival– fear, anger, sexual

behavior

• also involved in feeling of pleasure– eating and sex

Limbic System Structures• Amygdala – linked to both fear

responses and pleasure. Anxiety, autism, depression, post-traumatic stress disorder, and phobias are linked to abnormal functioning

• Hippocampus – sends memories out to the appropriate part of the brain for long-term storage and retrieves them when needed.– damage to hippocampus can

cause an inability to form new memories

Amygdala shrinks by more than 30% in males upon castration – minimizes pleasure

Diencephalon – “Interbrain”

• Sits on top of the brain stem

• Enclosed by the cerebral hemispheres; well-hidden brain region

• Made of three parts– Thalamus Thalamus

– Hypothalamus Hypothalamus

– Epithalamus Epithalamus

Thalamus• The relay station for sensory

impulses (switchboard)

• Transfers impulses to the correct part of the cerebrum for interpretation

• All incoming impulses get sorted here first and identified as pleasant or non-pleasant

Hypothalamus• Under the thalamus

• Controls organs by maintaining homeostasis

• Important autonomic nervous system center

– Helps regulate body temperature

– Controls water balance

– Regulates metabolism

The pituitary gland is attached to the hypothalamus. It releases hormones

which affect growth, sexual development, metabolism and

reproduction.

Epithalamus

• Helps to regulate the sleep/wake cycle by releasing hormones like melatonin from pineal gland

• Controls some parts of emotions and mood

Epithalamus

Brain Stem• Attaches to the spinal cord;

primitive “rat brain”• Controls automatic

behaviors necessary for survival (breathing)

• Parts of the brain stem each about an inch long

– Midbrain

– Pons

– Medulla oblongata

Brainstem• Midbrain = Smallest region of

the brain which relays auditory and visual information.

– Also controls eye movements, like blinking

• Pons = “bridge” of the brainstem. Controls Breathing.

• Medulla Oblongata = The lowest part of the brain stem– Merges into the spinal cord– Contains important control centers

• Heart rate control• Blood pressure regulation• Breathing• Swallowing• Vomiting

Cerebellum• contains ~70% of all the brain's

neurons; yet is only 10% of the volume of the brain!

• contributes to precise timing of skeletal muscle activity (i.e. walking, running or standing on your hands)

• controls our balance and equilibrium

• Doesn’t function well under influence of alcohol

• Works like ‘auto pilot’ – monitors body position and amount of tension in body parts

Cerebellum and other brain parts

Dura Mater: outermost meninges; tough and thick. Can restrict movement of the brain within the skull. Protects the brain from movements that may stretch and break brain blood vessels.

Meninges = three connective tissue membranes covering and protecting brain

Central Nervous System Disorders• Meningitis = inflammation of

meninges. Serious threat since bacteria or viruses can spread to brain.

• Concussion = injury is slight; dizzy, see stars, or lose consciousness briefly but no permanent damage.

• Stroke = blood circulation to a brain area is blocked from ruptured blood vessel or blood clot.

More Brain Disorders

• Hemorrhage = bleeding from ruptured blood vessels.

• Aneurysm = dilation, bulging or ballooning out of part of the wall of a vein or artery in the brain

– Can get larger over a lifetime

– Pushes on brain regions causing symptoms like blurred vision, stutter, etc.

– Can hemorrhage

What brain structures can you see?