The Nervous System And Brain Organization Central Nervous

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 Brain Peripheral Nervous System Spinal Cord Autonomic System Sympathetic System Somatic 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

Parietal lobe Frontal lobe Occipital lobe Temporal lobe 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

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)