3.4 - Structure of the Brain

• Hindbrain

  • A stalk on which the rest of the brain sits
  • Coordinates info coming into and out of the spinal cord
  • Controls the most basic functions of life
• Structures of the hindbrain

  1. The medulla
  2. The reticular formation
  3. The cerebellum
  4. The pons
• Medulla


  An extension of the spinal cord into the skull, coordinates heart rate, circulation, and respiration
• Reticular formation


  Small cluster of neurons that regulates sleep, wakefulness, and level of arousal
• Cerebellum


  A larger structure of the hindbrain, controls fine motor skills
• Pons


  A bridge that relays info from the cerebellum to the rest of the brain
• Midbrain

  • Sits on top of the hindbrain
  • Central location of neurotransmitters related to arousal, mood, and motivation
• Structures of the midbrain

  1. The tectum
  2. The tegmentum
• Tectum


  Orients an organism in the environment
• Tegmentum


  Involved in movement and arousal
• Forebrain

  • Highest level of the brain (figuratively and literally)
  • Controls complex cognitive, emotional, sensory, and motor functions
• Sections of the forebrain

  1. The cerebral cortex
  2. The subcortical structures
• Cerebral cortex

  • Outermost layer of the brain, visible to the naked eye
  • Split into two hemispheres
• Subcortical structures

  • Areas of the forebrain housed under the cerebral cortex, near the brain's centre
  • All play a big role in relaying info throughout the brain
  • Perform specific tasks that allow us to think, feel, and behave as humans
• Different subcortical structures

  1. Thalamus
  2. Hypothalamus
  3. Hippocampus
  4. Amygdala
  5. Basal ganglia
  6. Endocrine system
• Thalamus


  Relays and filters info from the senses and transmits them to the cerebral cortex (except for smell)
• Hypothalamus


  Regulates body temperature, hunger, thirst, and sexual behaviour
• Hippocampus


  Creates new memories and integrates them into existing networks of knowledge, allowing them to be stored indefinitely
• Amygdala


  Central in many emotional processes, but particularly the forming of emotional memories
• Basal ganglia


  Directs intentional movements, and play a role in reward processing
• Striatum


  Part of the basal ganglia, controls posture and movement
• Nucleus accumbens


  Part of the striatum, is linked to various kinds of reward processing
• Endocrine system


  Network of glands that produce and secrete hormones in the bloodstream, influences a variety of basic functions
• Thyroid


  Regulates body temperature and heart rate
• Adrenals


  Regulate stress responses
• Pancreas


  Controls digestion
• Pineal


  Secretes melatonin and influences the sleep-wake cycle
• Pituitary gland


  "Master gland" of the endocrine system, releases hormones to direct the functions of other glands
• Ovaries


  Sexual glands for females, produce mainly estrogen
• Testes


  Sexual glands for males, produce mainly testosterone
• Cerebral cortex


  Highest level of the brain, responsible for the most complex aspects of perception, emotion, movement, and thought
• Organizations of the cerebral cortex

  1. The separation of the cortex into two hemispheres
  2. The functions of each hemisphere
  3. The role of specific cortical areas
• Organization of the cerebral cortex by hemispheres

  • Left and right hemispheres are nearly symmetrical in appearance and function
  • Hemispheres have contralateral control (control over the opposite side of the body)
  • Connected by commissures, which make communication between each hemisphere possible
• Corpus callosum


  The largest commissure, allows info from each hemisphere to be registered in the other almost instantaneously
• Organization of the cerebral cortex by function

  • Each hemisphere is divided into four lobes:
  • Occipital lobe
  • Parietal lobe
  • Temporal lobe
  • Frontal lobe
• Occipital lobe


  Located at the back of the cortex, processes visual information
• Parietal lobe

  • Located in front of the occipital lobe, processes info about touch
  • Contains the somatosensory cortex, where sensitive skin areas take up larger portions of the area
  • Somatosensory cortex homunculus
• Temporal lobe

  • On the lower side of each hemisphere, responsible for hearing and language
  • Primary auditory cortex receives sensory info from the ears based on sound waves
  • Secondary auditory cortex processes info into meaningful units (words, sentences)
• Frontal lobe

  • Behind the forehead, has specialized areas for movement, abstract thinking, planning, memory, and judgement
  • Includes the motor cortex, initiates voluntary movements
  • In short, this lobe is what allows us to think, imagine, plan, and anticipate
• Organization of the cerebral cortex by cortical areas

  • Hierarchy of processing stages, from primary areas to association areas
  • Mirror neuron system