Chapter 3 Section 2: The Brain: Our Control Center

Frontal Lobe of the Brain Involved in motor function, problem solving, spontaneity, memory, language, initiation, judgement, impulse control, and social and sexual behavior.

Temporal Lobe Involved in high-level auditory processing such as hearing.

Brainstem Controls the flow of messages between the brain and the rest of the body, and it also controls basic body functions such as breathing, swallowing, heart rate, blood pressure, consciousness, and whether one is awake or sleep.

Parietal Lobe Involves sensation and perception and integrating sensory input. Integrates sensory information to form a single perception (cognition)

Occipital Lobe The visual processing center.

Cerebellum Receives information from the sensory systems, the spinal cord, and other parts of the brain and then regulates motor movements.

Every person is unique in part because of the capacity for learning and thought made possible by the human brain.

In ancient times it was widely believed that the body was inhabited by souls or demons. This, the ancients reasoned, made people different from animals and attributed psychological thought to it.

The ancient Egyptians believed that a little person dwelled within the skull and regulated behavior.

The Greek philosopher Aristotle thought that the soul had set up living quarters in the heart.

B.F. Skinner (1987) noted that the English language still reflects the belief in the heart as the seat of will, thought, hunger, and joy.

Today, however, we recognize that the mind, or consciousness, dwells within the brain.

Parts of the Brain The brain is divided into three sections. 1. hindbrain 2. midbrain 3. forebrain

The hindbrain is the lower portion of the brain and is involved in many vital functions such as heart rate, respiration, and balance.

The midbrain includes areas that are involved in vision and hearing.

The forebrain, the front area of the brain, is involved in complex functions such as thought and emotion.

The Hindbrain Medulla – involved in vital functions such as heart rate, blood pressure, and breathing.

Pons – located in front of the medulla and is involved in regulating body movement, attention, sleep, and alertness.

Cerebellum – looks like the larger part of the brain, under which it rests, but it is much smaller. It is involved in balance and coordination.

The Midbrain Located between the hindbrain and the forebrain. Involved in vision and hearing.

Reticular activating system Begins in the hindbrain and rises through the midbrain into the lower part of the forebrain. Important for attention, sleep, and arousal.

Stimulation of the reticular activating system makes us alert. If affects arousal by increasing heart rate and blood pressure, and it increases brain activity.

Sudden, loud noises stimulate the reticular activating system and can awaken a sleeping person.

The Forebrain Contains four major areas Thalamus Hypothalamus Limbic system Cerebrum The forebrain is the part of the brain that makes it possible for humans to engage in complex thinking processes.

Thalamus Serves as a relay station for sensory stimulation. Most of the messages coming from the sense organs go through the thalamus on the way to the higher levels of the brain (those areas responsible for mental processes such as thinking and reasoning).

Hypothalamus Lies below the thalamus Very tiny, but it is extremely important. Involved in many aspects of behavior and physiological (normal functions of living organisms and their parts) functions. Vital to the regulation of body temperature, the storage of nutrients, and various aspects of motivation and emotion. Also involved in hunger, thirst, sexual behavior, caring for offspring, and aggression.

Disturbances within the hypothalamus can lead to unusual drinking and eating behaviors. Among lower animals, stimulation of parts of the hypothalamus triggers behaviors such as fighting, mating, or nest building.

Limbic System Forms a fringe along the inner edge of the cerebrum. Involved in learning and memory Emotion Hunger Sex Aggression If damaged, people can recall old memories, but not create new memories.

Cerebrum Only in human beings does the cerebrum make up such a large part of the brain. Accounts for 70 percent of the weight of the brain. Wrinkled with ridges and valleys The surface is the cerebral cortex Outer layer of the brain

The cerebral cortex is the part that makes us uniquely human, the part that thinks. Also concerned with memory, language, emotions, complex motor functions, and perception.

The Cerebral Cortex: What Makes Us Unique Composed of two sides – a left side and a right side. Each side is called a hemisphere. The structure that connects the two hemispheres is called the corpus callosum. Information received by one side of the body is transmitted to the opposite hemisphere of the brain.

If you touch something with your left hand, that information is sent to the right side of your brain. The corpus callosum aids in getting information from one side of the brain to the other.

Frontal lobe- behind the forehead Each hemisphere of the cerebral cortex is divided into four parts, or lobes. Frontal lobe- behind the forehead Parietal lobe- lies to the top and rear of the head Temporal lobe- lies to the side, just below the ears Occipital lobe- located at the back of the head

Senses and Motor Behavior Occipital lobe contains the primary visual area of the cerebral cortex. When light strikes the eyes, neurons in the occipital lobe fire, enabling us to see.

Hearing, or auditory, area of the cortex lies in the temporal lobe. Sounds are relayed from the ears to the thalamus to the auditory area.

Messages received from the skin sense are projected to the sensory cortex in the parietal lobe.

When we clap our hands or wiggle our toes, different parts of the frontal lobe are stimulated.

Association Areas Association areas- serve mainly to shape information into something meaningful on which we can act. Example: Neurons in the occipital lobe fire when we view vertical lines and others fire when we see horizonal lines. Activity in the association areas then integrates the information into a meaningful image. Other association areas make possible such complex psychological functions as thought and language.

Language Abilities For nearly all right-handed people, language functions are based in the left hemisphere. Language functions are also based in the left hemisphere of about two out of three left-handed people. Only a small percentage of people have language functions based in the right hemisphere.

Two key language areas: 1. Broca’s area 2. Wernicke’s area Damage to either area is likely to cause an aphasia, a difficulty with specific aspects of understanding or producing language.

Wernicke’s area Located in the temporal lobe Pieces together sounds and sights Difficult to understand speech if damaged May be able to speak if damaged, but speech is often meaningless

Broca’s area Located in the frontal lobe near the motor cortex that controls the area of the face used for speaking. If damaged, people speak slowly and laboriously, using simple sentences. Comprehension is good, but my speak only key words. Example: “The three bananas are lying on the table.” “Bananas lie table.”

Left Versus Right Hemispheres The same hemisphere that contains most language functions also is usually more involved in logic, problem solving, and mathematical computation. The nonlanguage hemisphere is more concerned with imagination, art, feelings, and spatial relations. Logical people are left brained. Creative people are right brained.

Corpus callosum, which connects the two hemispheres, is cut. Split-brain operations Corpus callosum, which connects the two hemispheres, is cut. Used to help people with serious neural disorders such as epilepsy. People with epilepsy experience seizures (bursts of abnormal neuron firing that generally occur in one hemisphere and then spread to the other. Cutting the corpus callosum can reduce seizures from spreading.

Methods of Studying the Brain Much of the early studies came from studies of people with brain injuries.

Accidents Which particular area is damaged may have a greater effect than the amount of the damage.

Electrical Stimulation of the Brain Jose Delgado (1960s) Used electrical stimulation of the brain to show how an animal could be make to change behavioral patterns. Researchers implanted an electrode into a bull’s brain. The brain was stimulated and the bull dramatically stopped this charge and circled to the right.

James Olds and Peter Milner Used rats with electrodes implanted in their brains. Rats pressed a lever, the electrodes stimulated a portion of the hypothalamus. Rats found it pleasurable and pressed the button up to 100 times a minute. Part of the hypothalamus where the electrodes were implanted thus became known as the “pleasure center.”

The Electroencephalogram (EEG) Records the electrical activity of the brain. Electrodes attach to the scalp and detect small amounts of electrical activity called brain waves. Certain brain wave patterns are associated with feelings of relation and with sleep. Used to help locate tumors.

Scans Computerized axial tomography (CAT) scans A moving ring passes X-ray beams around and through the head. Density of the brain tissue determines how much radiation is absorbed. Computers measure the amounts of radiation and piece together a thee- dimensional view of the brain.

Magnetic Resonance Imaging (MRI) A person lies in a very powerful magnetic field. Radio waves cause parts of the brain to give off extra energy. Energy is measured from multiple angles and translated by a computer into a visual image.

Positron emission tomography (PET) Show activity of the brain rather than a snapshot of the brain at a given time. Person is injected with radioactive sugar. As is reaches the brain, more is used where brain activity is greater.