NEUROLOGICAL AND GENETIC BASES OF

BEHAVIOR

Chapter 3

Learning Objectives:-Identify major divisions and subdivision for the human nervous system-Identify the parts of the neuron and describe the basic process of neutron transmission-Differentiate between the structures and function of the various parts of the central nervous system.

Neurons

Specialized cells in the nervous system that send and receive information throughout the body.

Spinal Cord

A bundle of nerves that connects the brain to the rest of the body.

It is protected by bony spinal column and surrounded by cerebrospinal fluid.

Types of Neurons

Sensory Neuron: Pick up stimuli inside the body or in the world and send INPUT SIGNALS to the brain.

Motor Neuron: Send signals in the opposite direction, sending OUTPUT SIGNALS from the brain to glands, muscles, and organs.

Interneurons: Connect neurons to one another, connects the input sensory neurons to the output motor neurons.

Structure of a Neuron

Have three basic parts -Central part is the SOMA-Dendrites -Axon

Central part is the SOMA

Which is Latin word for body

This cell body contains nucleus or control center for the neuron.

Attached to the Soma are branchlike extensions, know as Dendrites.

DENDRITES

The Greek word meaning “trees”

Dendrites receive information from other neurons and bring it to the soma.

After organizing the this information, the soma transmits it to a tube like extension called a axon.

Axon

Greek word meaning “Axle”

The axon carries the information down it’s tube in the form of an electrochemical impulse.

Axon can range in length from 1/32 of an inch to more than 3 feet.

Myelin Sheath

This coating that coats the tube like structure speeds up the passing of information.

This is slowly destroyed in people who have (MS) multiple sclerosis.

When loss of the Myelin Sheath the brain is unable to efficiently communicate with the body's muscles. Cause’s loss of muscle control.

Terminal Buttons

At the end of each axon are branches with knoblike tips.

This come close but do not touch, the dendrites of other neurons.

This space in-between is called SYNAPSE in Greek meaning “to clasp”.

Neuron Activity

The Nervous System

Central Nervous system (CNS) Brain and Spinal Cord

Peripheral Nervous system (PNS) All the nerves located outside the brain and spinal

cord. Has 2 major divisions the Somatic Nervous system

and Automatic Nervous System.

Somatic Nervous System

A division of the peripheral nervous system that sends commands to voluntary skeletal muscles and the skin.

Messages received from the muscles and skin provide you with a sense of touch, the sense of position in the surroundings, and perception of temperature and pain.

Autonomic Nervous System

The division of the peripheral nervous system that controls movement of involuntary, no skeletal muscles.

This includes the heart, lungs, and stomach muscles.

Has two separate branches Sympathetic Nervous System: Fight or Flight Parasympathetic Nervous System: Calm Down

The Endocrine System

A network of glands that manufactures and secretes hormones directly into bloodstream.

Hormones: chemical messengers, carried by the bloodstream, that regulate or stimulate the body.

The endocrine system is interconnected with, but not part of the nervous system

Glands and Hormones in the endocrine system

Gland Hormone Effects

Pituitary Gland Growth Hormone Growth (especially bones)

Thyroid Gland Thyroxin Metabolic processes

Adrenal Gland Epinephrine/norepinephrine

Increase metabolic activities and blood glucose

Gonads Testosterone , estrogen and progesterone

Testosterone-Growth of muscles, bone and hair Estrogen and Progesterone- Regulation of menstruation and reproductive cycles

THE BRAIN

Ways to Study the Brain

EEG (Electrocephalograph): A brain-imaging technique that records “waves” of electrical activity in the brain.

CAT scan (Computerized axial tomograph): A brain imaging technique that combines thousands of x-ray brain photographs to construct a picture of the brain.

MRI (Magnetic resonance Imaging): A brain-imaging technique that produces three-dimensional images of the brain’s soft tissues.

PET Scan (Positron emission tomography):A brain-imaging technique that measures the average neural activity in the different brain regions over a few seconds

FMRI (Functional Magnetic Resonance Imagining):A brain-imaging technique that measures the average neural activity in different brain regions over a few seconds.

HINDBRAIN MIDBRAIN

FOREBRAIN

The Three Major Brain Regions

Hindbrain

The part of the brain found at the rear or base of the skull that controls the most biological needs.

Pons: Is concerned with sleep and arousal. (Located above the medulla)

Cerebellum: Regulation and coordination of body movements, also plays a role in learning. (Sits behind the medulla and pons.)

Medulla Oblongata: Controls involuntary reflexes such as: breathing, heart rate, swallowingsneezing and digestion.

Midbrain

The part of the brain above the hindbrain that plays a role in attention, stimulation, and consciousness.

Combines sensory information and sends it to other brain regions.

Reticular Formation: Involved in the regulation and maintenance of consciousness and sleep. When you are startled by a loud noise, your heightened arousal is due to reticular formation

The Forebrain

The part of the brain above the midbrain that controls emotional reactions, thought processes, movement, sensory information, and body temperature.

Hypothalamus: Provides homeostasis, maintaining a constant internal body state. Regulates eating, drinking and sexual behavior. Controls the release of hormones from the pituitary gland.

Limbic system: In the core of the forebrain is a series of interrelated doughnut shaped neural structures called Limbic system. Amygdala: Controls fear and aggression. Hippocampus: Important in memory formation.

Thalamus: The brain’s sensory relay station. It sorts and sends messages from the eyes, ears, tongue, and skin to other parts of the brain

Cerebral Hemispheres

Corpus Callosum: is a thick band of more than 200 million white nerve fibers that transmit information between the two hemispheres.

Our brain is cross-wired.Right controls left, left controls right.

Which one are you?

Half a brain?

Partner upEach person can only use one side of his/her

body (one right the other left)On your own try to completing a task using only

the one side of your body (example: tying a shoe)Now work together (one person is right the

other left)

How would it be to have only one hemisphere of your brain?

Brain Plasticity

Plasticity: The brains ability to change (for better or worse) Language Development

Clinical periods: During these times, particular experiences must occur for development to proceed normally. Genie’s story

Knowing what you know now about the brain, do you think

someone could live a normal life without one of their

hemispheres?

Lobes of the brain

Occipital Lobe- Visual Regions, allow us to experience shapes, color, and motion.

Parental Lobe- Touch and sensation, how you experience you and the space around you.

Temporal Lobe- hearing and language, helps us understand words and sentences.

Frontal Lobe- coordination of movement and higher mental processes. Such as abstract thinking.