Brain Structure and Function

• Lateralization of brain function


  The view that distinct brain regions perform certain functions
• It is believed that different brain areas are responsible for controlling language, formulating memories, and making movements
• If a certain area of the brain becomes damaged


  The function associated with that area will also be affected
• Areas of the Cortex

  • Primary Motor Cortex
  • Broca's Area
  • Prefrontal Area
  • Broca's Area
  • Auditory Cortex
  • Wernicke's Area
  • Visual Cortex
• Primary Motor Cortex is responsible for the voluntary movement of skeletal muscles
• Divisions of the brain

  • Hindbrain
  • Midbrain
  • Forebrain
• Hindbrain


  Located at the base of the brain near the back of the skull
• The hindbrain controls vital activities over which we have no conscious control such as breathing, coordinating voluntary muscle movements, and reflex actions
• Components of the hindbrain

  • Cerebellum
  • Medulla
• Cerebellum


  • Receives information from sensory systems, spinal cords, and other parts of the brain
  • Regulates posture, balance, and coordinates fine muscle movements
  • Affected by alcohol consumption
• Medulla


  • Controls vital functions like heart rate, breathing, digestion, and swallowing
  • Damage to the medulla can lead to being put on life support to regulate breathing and heart function
  • If damage is severe, the person may be pronounced brain dead
• Midbrain


  • Sits on top of the hindbrain under the cerebral hemispheres
  • Acts like the brain's sensory switchboard passing information between the spinal cord and forebrain
  • Receives messages from senses (except smell) and sends them to higher brain regions
• Components of the midbrain

  • Reticular formation
• Reticular formation


  • A network of nerves running through the midbrain from the forebrain to the hindbrain
  • Screens incoming information to allow higher brain centers to attend to important information
  • Plays a role in controlling sleeping, alertness, and arousal level
• The reticular activating system (RAS) has both ascending and descending pathways to regulate arousal level and muscle tone
• When the RAS is low


  We go to sleep
• Forebrain


  • Most highly developed and largest part of the brain
  • Plays a major role in thinking, feeling, and behavior
  • Consists of various structures including hypothalamus, thalamus, cerebral cortex
• Thalamus


  • Filters information from all senses (except smell) and passes it to the appropriate part of the brain for processing
  • Acts as a relay system
  • Plays a role in regulating arousal level
• Damage to the thalamus can result in reduced sense of touch, visual or hearing impairment
• Hypothalamus


  Regulates the release of hormones controlling body temperature, biological clock, sex drive, thirst, and hunger needs
• Cerebrum


  • Lies above and in front of the cerebellum
  • Consists of an outer layer called the cerebral cortex
  • Has two hemispheres separated by a deep groove
• Cerebral cortex


  • Located over and around most of the other brain structures
  • Left and right hemispheres are almost symmetrical
  • Joined by the corpus callosum which allows messages to be sent between hemispheres
• Broca's Area


  Responsible for the command of language and speech
• Prefrontal Area


  Responsible for problem solving, decision making, and complex thinking
• Auditory Cortex


  Receives auditory information (pitch, tone, sound quality)
• Visual Cortex


  Complex processing of visual information
• Wernicke's Area


  Responsible for the interpretation of language/speech
• EEG does not use imaging techniques
• CAT scan produces still pictures
• MRI uses strong magnetic field and radio frequency pulses to produce 3D images
• MRI measures activity in the brain based on oxygen consumption by neurons
• PET scans provide dynamic imaging of brain activity
• PET scans use a glucose solution to record brain energy consumption
• PET scans show brain areas activated during specific activities like reading, speaking, thinking
• Sensory and motor functions are found in virtually the same place in each hemisphere
• The two hemispheres are joined by the corpus callosum
• Corpus callosum


  A thick band of fibers which lets messages be sent from one hemisphere to the other
• The left hemisphere gets sensory information from the right side of the body


  Controls the right side
• The right hemisphere receives sensory information from the left side of the body


  Controls the left side
• If the corpus callosum is cut, the two hemispheres could not communicate together