THE FUNCTIONS OF THE FUNCTIONS OF THE NERVOUS THE NERVOUS

SYSTEMSYSTEM

The Central Nervous System: lower cortex The Central Nervous System: lower cortex to brain stem.to brain stem.

The cerebral cortexThe cerebral cortex

• Frontal lobe• Parietal

lobe• Occiptial

lobe• Temporal

lobe

THE temporal lobeTHE temporal lobe

• Temporal lobes – Separated from the frontal and

parietal lobe by the lateral fissure

• Three important areas:– Auditory projection area, – visual and auditory association

areas– Additional language area:

Wernicke’s Area.

THE auditory or THE auditory or temporal cortextemporal cortex

• Auditory cortex:– receives sound information from the ears– lies on the superior (uppermost) gyrus of the temporal lobe.

• Wernicke’s area – Just posterior to the auditory cortex – Left hemisphere only– interprets language input arriving from the nearby auditory

and visual areas.– also generates spoken language through Broca’s area and

written language by the way of the motor cortex.

• Inferior temporal cortex– lower part of the lobe (as the name implies)– plays a major role in the visual identification of objects.

THE occipital cortexTHE occipital cortex

• Occipital lobes – location of the visual

cortex, – visual information is

processed.

• contains a map of visual space because adjacent receptors in the back of the eye send neurons to adjacent cells in the visual cortex.

THE Midbrain and THE Midbrain and brainstem brainstem

• Older areas of the brain

• More “animal-like” in that regulate more basic (noncognitive) functions

THE ThalamusTHE Thalamus

• Lies deep within the brain

• Located just below the lateral ventricles,

• Receives information from ALL of the sensory systems EXCEPT olfaction (smell)

• Relays info to the respective cortical projection areas.

THE hypothalamusTHE hypothalamus

• Smaller than thalamus

• Inferior to the thalamus,

• Plays a major role in controlling emotion and motivated behaviors

• Controls the 4F;s:– Feeding (eating and

drinking)– Fighting – Fleeing– F….sexual activity.

THE hypothalamusTHE hypothalamus

• Hypothalamus exerts influence largely through its control of the autonomic nervous system– Automatic system– Sympathetic: fear/flight/fight– Parasympathetic: feeding, sexual behavior

• Hypothalamus also influences the body’s hormonal environment – Controls the pituitary gland.– The pituitary is known as the master gland because it

controls other glands in the body.

THE pineal glandTHE pineal gland

• posterior to the thalamus

• participates with other structures in controlling daily rhythms or circadian rhythm in humans and animals.

• secretes melatonin, related to sleep/circadian rhythm

• controls seasonal cycles in nonhuman animals

corpus callosumcorpus callosum

• Dense band of fibers that carry information between hemispheres

• Is found a couple of inches below the brain’s surface where the longitudinal fissure ends

• Implicated in gender differences in brain function, autism and other developmental disorders

THE VentriclesTHE Ventricles

• Cavities in brain and central canal in spinal cord which form during development – Form a hollow interior of the nervous system.– filled with cerebrospinal fluid or CSF,

• CSF carries material from the blood vessels to the central nervous system

• CSF also transports waste materials in the other direction.

THE midbrain areasTHE midbrain areas

• Midbrain contains structures that have secondary roles in vision, audition and movement.– Superior colliculi: help guide eye movements

and fixation of gaze.– Inferior colliculi: help locate the direction of

sounds.

• Ventral tegmental area (VTA), which plays a role in the rewarding effects of food, sex, drugs and so on.

Corpus Striatum• Motor Habits

– Behaviors you do “without thinking”– Walking, writing, proficient or well learned

behaviors

• Located between the cortex and the thalamus

• Composed of three very large nuclei– Caudate nucleus –  Putamen–  Globus pallidus–   collectively- called the striatum

Basal Ganglia and Corpus Striatum

• Basal Ganglia–  Diffuse system of nuclei– Important for coordination of

body movement

• Substantia Nigra• One of the structures

involved in movement, projects to the basal ganglia to integrate movements.

• Parkinson's disease, Huntington's chorea both involve damage to these area

Limbic System

• Group of interconnected structures

• Amygdala:– Helps regulate states of

emotional arousal

• Hippocampus: – Plays important role in

the formation of memories

THE hindbrainTHE hindbrain

• The hindbrain is composed of – the medulla – the pons– the cerebellum– Controls most basic life functions

• The medulla – forms the lower part of the hindbrain.– Set of nuclei involved with control of essential life

processes • cardiovascular activity • respiration (breathing).

THE ponsTHE pons

• Means “bridge” in Latinˉ Bridges between upper and lower brain areas

• Serves as a major highwayˉ sensory neurons pass through the pons on way to

thalamusˉ motor neurons pass through between the cortex

and the cerebellum

• Contains centers related to sleep and arousal• Pons is also part of reticular formation.

THE reticular formationTHE reticular formation

• Collection of several nuclei • Runs through the middle of the hindbrain and the

midbrain.

• Major role in sleep and arousal

• Contributes to attention • Helps modulate aspects of motor activity

– Reflexes – muscle tone

• Implicated in disorders such as autism, narcolepsy

THE CErebellumTHE CErebellum

• One of most distinctive appearing brain structure.– Perched on the back of the brain stem– wrinkled or striped- striated tissue– divided down the middle like the cerebral hemispheres

–– Name means “little brain.”

• Critical for refining movements initiated by the motor cortex

• Controls speed, intensity and direction of movement.

• It also plays a role in motor learning, and research implicates it in other cognitive processes and in emotion.

THE CErebellumTHE CErebellum

THE spinal cordTHE spinal cord

• Finger-sized cable of neurons • Carries commands from the brain to the muscles and

organs• Carries sensory information into the brain.

• Dorsal root: Sensory– Sensory neurons enter the spinal cord through the of each

spinal nerve.

• Ventral root: Motor– The axons of the motor neurons pass out of the spinal cord

through the.

• Reflex Pathway: – sensory neurons from the dorsal side connect with motor

neurons, either directly or through an interneuron.– This pathway produces a simple, automatic movement in

response to a sensory stimulus, called a reflex.

Protecting the CENTRAL Protecting the CENTRAL NERVOUS SYSTEMNERVOUS SYSTEM

• Meninges:– Covers both the brain and spinal cord – Protective three-layered membrane called the.– The space between the meninges and the CNS is filled

with cerebrospinal fluid, – This cushions the neural tissue from the trauma of

blows and sudden movement.

• Blood-brain barrier:– Limits the passage between the bloodstream and the

brain– Provides constant protection from toxic substances – Prevents neurotransmitters from circulating in the

blood.

• The peripheral nervous system (PNS)consists of:– cranial nerves that enter and leave the

underside of the brain, – Spinal nerves that connect to the sides of the

spinal cord at each vertebra.

• The PNS can be divided into the – Somatic nervous system: voluntary behavior – Autonomic nervous system (ANS): involuntary

or automatic behavior

THE PERIPHERAL THE PERIPHERAL NERVOUS SYSTEMNERVOUS SYSTEM

THE somatic THE somatic nervous SYSTEMnervous SYSTEM

• Motor neurons that operate the skeletal muscles – – Neurons that move the body – Typically refer to voluntary muscles rather

than smooth muscle movement

• Sensory neurons – bring information into the central nervous

system from the body and the outside world.– Includes all senses

THE autonomicTHE autonomicNERVOUS SYSTEMNERVOUS SYSTEM

• Regulates general activity levels in the body

• Controls smooth muscle:– Stomach– Blood vessels– Glands– Heart – Lungs– Other vital and “automatic” organs.

• Sympathetic nervous system – activates the body in ways that help it cope with

demands, such as emotional stress and physical emergencies

– Fear/flight/fight.

• Parasympathetic nervous system – slows the activity of most organs to conserve energy, – also activates digestion to renew energy– Which one modulates sexual behavior?

– Question: can you wet your pants when you are afraid?

THE ANS has two divisionsTHE ANS has two divisions

Testing the ANS!