The Nervous System

And Brain Organization

Central Nervous System

• Consists of the brain and spinal cord

• The brain is the central “computer” of the nervous system

• The spinal cord is the “cable” that is used to communicate to the rest of the body

Peripheral Nervous System

• All the parts of the nervous system outside of the brain and spinal cord

• Two major divisions

– Somatic system – the muscles and sense organs (voluntary behavior)

– Autonomic system – the internal organs and glands (involuntary behavior)

Autonomic Nervous System

• Two divisions

– Sympathetic branch – arouses the body• Prepares the body for fight or flight

– Parasympathetic branch – quiets the body or brings it back to normal

Nervous System

Central Nervous System

Peripheral Nervous System

Brain Spinal Cord

Autonomic System

Somatic System

Sympathetic System

Parasympathetic System

Brain Organization

• Cerebrum – two large hemispheres that cover the upper part of the brain

• Cerebral cortex – the outer layer of the cerebrum– made up of wrinkled gray matter that contains

nerve cell bodies

Brain Organization cont’d…

• Cerebral hemispheres – right and left halves of the cerebrum

• Corpus callosum – bundle of fibers connecting the hemispheres– Cut in a ‘split-brain’ operation

• Spatial neglect – when a person pays no attention to the left side of visual space after damage to the right hemisphere

Lobes of the Cerebral Cortex

• Lobes – areas on the cortex defined by major fissures or functions

• Occipital lobe – vision

• Parietal lobe – bodily sensations (touch, temperature, pressure)

Lobes of the Cerebral Cortex

• Temporal lobes – language (on the left only) and hearing

• Frontal lobes – motor control, speech, abstract thought

• Association cortex – all areas of the cerebral cortex not primarily sensory or motor in function – complex skills like language, memory, recognition, and problem solving

Frontallobe

Temporallobe

Parietal lobe

Occipitallobe

Cerebellum

Association Cortex

• Broca’s area – language area – grammar and pronunciation – left frontal lobe

• Aphasia – speech disturbance related to brain damage

• Wernicke’s area – language comprehension – left temporal lobe

• Agnosia – inability to identify seen objects

Subcortex

• Subcortex - all brain structures below the cerebral hemispheres

• Divided into three parts – Brainstem (or hindbrain)– Midbrain– Forebrain

The Brainstem

• Also known as the hindbrain

• Lowest portions of the brain

• Contains the cerebellum, medulla and pons

• Cerebellum – controls posture, muscle tone and coordination – stores memories related to skills and habits

• Medulla – connects brain to spinal cord – controls vital life functions such as heart rate, breathing, swallowing, etc.

• Pons – bridge between medulla and other structures – influences sleep and arousal

The Midbrain

• Small region, located above spinal cord, but below the forebrain

• Coordinates simple muscle movements with sensory information

• Reticular formation – network of fibers and cell bodies throughout the hindbrain – associated with attention, alertness and some reflexes

The Forebrain

• Contains the thalamus and hypothalamus

• Thalamus – located on top of brain stem – relays sensory information to the cerebral cortex

• Hypothalamus – controls metabolic functions including body temp, libido, hunger, thirst, and the endocrine system

HypothalamusPituitary

The Limbic System

• Contains hypothalamus, parts of the thalamus, amygdala, and hippocampus

• Large role in producing emotion and motivated behavior

• Amygdala – associated with fear responses

• Hippocampus – associated with storing memories (lies in the temporal lobe)

Temporallobe

Hippocampus

Amygdala