The Brain: Our Control Center Unit II

The Three Brains Hindbrain – Found at the rear base of the brain & involved in the basic processes of life. Responsible for automatic and survival functions Three Parts Medulla Pons Cerebellum

The Three Brains Midbrain – Located just above the hindbrain and relays sensory information (vision & hearing) upward. Contains the Reticular Activating System Forebrain – Located at the front of the brain and controls complex emotions, thoughts, and movements. Most highly developed portion of the brain 4 Parts Thalamus, Hypothalamus, Cerebrum, & Limbic System

Three Brains

Hindbrain Medulla – controls breathing, heart rate, swallowing, digestion – vital life functions Pons – Involved in regulating body movement, attention, sleep, alertness, and facial expressions. Cerebellum – Involved in balance and coordination. Effected by alcohol (DUI test)

Midbrain Reticular Activating System (RAS) – Stretches from the hindbrain through the midbrain into the lower part of the forebrain. The “ignition” system of the brain Coordinates basic sensory information involving attention, sleep, & arousal (heart rate/blood pressure) Damage to the RAS can result in a permanent coma. “Adapts” to sounds (ex. Sounds in the city) Alcohol reduces activity

Midbrain

Forebrain Thalamus – Relay station for sensory stimulation Sorts & sends messages from the sense organs to the cerebral cortex for interpretation. Hypothalamus – regulates vital functions – body temperature (homeostasis), storage of nutrients, motivation, and emotion Hunger, thirst, sexual behavior, caring for offspring and aggression are regulated. Controls the release of hormones from the pituitary gland.

Forebrain Cerebrum – 70% of the brain’s weight Receives sensory information Transmits voluntary (conscious) motor information Cerebral Cortex – the thinking center of the brain Wrinkled surface of the brain Involved in memory, language, emotions, complex motor functions, perception, etc. Corpus Callosum – Connects the two brain hemispheres of the cerebral cortex

Forebrain Limbic System – Located in the core of the forebrain on the inner edge of the cerebrum Involved in learning & memory, emotion, hunger, sex & aggression Two Structures: Amygdala Memory during emotional events Fear & Aggression Hippocampus Memory Formation

Brain Lobes Occipital Lobe (Back Of The Brain) Main center for visual processing Enables experiencing shapes, color, and motion. Damage can cause blindness Parietal Lobes (Top & Rear) Involved in touch sensation (integrates sensory systems) Touch, Temperature, & Pressure Damage can destroy sense of touch

Brain Lobes Temporal Lobe (Side, Behind Ears) Hearing/Auditory Area Wernicke’s Area Involves the understanding of written & spoken language Damage results in difficulty understanding written/spoken language Can speak quickly & easily but speech often makes no sense Broca’s Area Involves the production of speech Damage involves difficulty speaking Damage to areas causes “aphasia” Trouble understanding/Producing Language

Brain Lobes Frontal Lobe (behind forehead) Executive Center – Higher Mental Processes Planning, Social Skills, Emotional Control, Problem Solving & Abstract Thinking Motor Skills - Involved in the coordination of movement Define “Abstract Thinking”

Cerebral Hemispheres Corpus Callosum – Collection of nerve bundles that carries messages between the two hemispheres Each hemisphere controls the opposite side of the body. Ex. Left hemisphere controls right side of the body

Cerebral Hemispheres Lateralization – Specialization of a hemisphere in a particular function Left Hemisphere – Generally handles verbal processing, language, speech, reading & writing Right Hemisphere – Generally handles nonverbal processing, spatial relations, music, and visuals People often thought of as “right or left-brained” Misconception Primary sensory & motor areas are symmetrical. Broca’s & Wernick’s area for language in the left hemisphere. Why left hemisphere is language dominant.

“Left-Brained” Or “Right-Brained”

Split Brain Patients Patients who suffer from severe epileptic seizures have their corpus callosum severed Epileptic Seizures – Bursts of abnormal neuron firings that generally occur in one hemisphere and then spread to the other Subtle effects on brain functions Ex. Able to describe verbally an object in their left hand but not in their right hand. Which object do you think the person will be able to recognize verbally?

Accidents Phineas Gage 3.5 foot rod shot through his skull Survived but extreme personality change Shows that certain parts of the brain control certain aspects of our personality

Studying The Brain Computerized axial tomography (CAT Scan) X-rays beam around the head (3D view) Pinpoints injuries and brain deterioration

Studying The Brain Position Emission Topography (PET Scan) Can see which areas of the brain are activated when performing tasks A radioactive solution is injected into the body Shows activity vs snapshot

Studying The Brain Magnetic Resonance Imaging (MRI) Can see structures in detail, hard to see areas Magnetic fields and radio waves More powerful than CAT scan, “slice images”

Studying The Brain Electroencephalograph (EEG) Measures electrical activity of brain using small electrodes pasted to you scalp The rhythmical patterns produced are “brain waves”

Brain Lobes Frontal Lobe (behind forehead) Executive Center – Higher Mental Processes Planning, Social Skills, Emotional Control, Problem Solving & Abstract Thinking Motor Skills - Involved in the coordination of movement Correct notes for students. In the initial powerpoint Frontal Lobe was labeled as “Forebrain”.