Brain

• The Brain


  Receives, localises & interprets sensory input, Generates the motor output (somatic & autonomic) that controls the activities of muscles & glands, Is responsible for our emotions, behaviours, and personality, Performs intellectual (cognitive) functions, Stores memories

  
• Composition of the Brain

  Interneurons & neuroglia organised into areas of gray matter & white matter, Gray matter primarily contains cell bodies of interneurons organised into nuclei, White matter primarily contains myelinated axons of interneurons organised into tracts, Requires a constant supply of oxygen and glucose
• Major Parts of the Brain

  • Cerebrum
  • Cerebellum
  • Diencephalon (thalamus, hypothalamus, epithalamus)
  • Brain stem (midbrain, pons, medulla oblongata)
  • Spinal Cord

  
• Cerebrum


  • Largest part of the brain, Divided into two cerebral hemispheres by the longitudinal fissure, Separated from the cerebellum by the transverse fissure

  
• Gyrus and Sulcus


  Gyrus (ridge) and sulcus (shallow groove) cover the surface of the cerebrum, Increases the surface area of the cerebrum = more neurons
• Lobes of the Cerebral Hemisphere

  • Frontal
  • Parietal
  • Temporal
  • Occipital
  • Insula

  
• Regions of the Cerebral Hemisphere

  • Cerebral cortex (gray matter)
  • Cerebral white matter
  • Basal nuclei

  
• Cerebral Cortex


  • Contains nuclei that receive, localise and interpret sensory input, control voluntary skeletal muscle movements, perform intellectual and language functions, store memories, control our emotions, behaviours and determine personality

  
• Functional Areas of the Cerebral Cortex

  • Motor areas
  • Sensory areas
  • Association areas

  
• Motor Areas


  Control voluntary skeletal muscle movements
• Sensory Areas


  Receive and localise sensory input, Allow us to consciously perceive sensations
• Association Areas


  Interpret sensory input to make sense of the information, Plan and coordinate motor responses, Perform intellectual functions, store memories & determine behaviours and personality
• The cerebral cortex receives sensory input from, and sends motor output to, the opposite (contralateral) side of the body

  
• Motor Areas of the Cerebral Cortex

  • Primary motor cortex (precentral gyrus)
  • Premotor cortex
  • Frontal eye field
  • Broca's area

  
• Primary Motor Cortex


  Generates the somatic motor output that stimulates voluntary skeletal muscle movements
• Specific areas of the primary motor cortex are devoted to controlling specific body parts, with the amount of cortex devoted to a body part proportional to the complexity of its movements
• Motor Association Areas


  • Frontal eye field
  • Broca's area
  • Premotor cortex
• Frontal Eye Field


  Controls voluntary eye movements
• Broca's Area


  Controls the muscles involved in the production of speech, Usually located in the left hemisphere (left frontal lobe) only
• Premotor Cortex


  Controls learned, skilled motor activities of a complex nature, e.g., typing, tying a bow
• Sensory Areas of the Cerebral Cortex

  • Primary somatosensory cortex
  • Somatosensory association area
  • Visual cortex
  • Visual association area
  • Auditory cortex
  • Auditory association area
  • Gustatory cortex
  • Visceral cortex
  • Vestibular cortex

  
• Primary Somatosensory Cortex


  Receives general sensory information, Perceives sensations of touch, pain, vibration, pressure, temperature & proprioception

  
• The amount of sensory cortex devoted to a particular body part depends on the number of receptors it has
• Somatosensory Association Area


  Receives general sensory input from the primary somatosensory cortex, Interprets general sensory input and compares it to stored memories of past sensory experiences so that you can recognise an object by touch alone
• Visual Cortex


  Receives visual input detected by photoreceptors
• Visual Association Area


  Interprets visual input, Allows us to recognise what we see, Stores memories of past visual images
• Auditory Cortex


  Receives sound input detected by the hair cells in the ear to produce & locate sounds

  
• Auditory Association Area


  Interprets auditory input, Allows us to recognise sounds, Stores memories of past sounds

  
• Other Special Sensory Areas

  • Vestibular (equilibrium) cortex
  • Visceral cortex
  • Gustatory cortex
  • Olfactory cortex
• Wernicke's Area


  Comprehends written and spoken language, Usually located in the left temporal lobe (left hemisphere) only
• Prefrontal Cortex


  Responsible for our intellect, complex learning abilities (cognition), personality and behaviour

  
• Cerebral Cortex Areas and Functions

  • Primary motor cortex - Generates somatic motor output for voluntary movements
  • Premotor cortex - Controls skilled, complex motor activities
  • Frontal Eye Field - Controls voluntary eye movements
  • Broca's Area - Controls speech production
  • Wernicke's Area - Comprehends written & spoken language
  • Prefrontal cortex - Responsible for intellect, cognition, personality & behaviour
  • Primary somatosensory cortex - Receives & localises general sensory input
  • Somatosensory association area - Interprets general sensory input
  • Special sensory areas - Receive special sensory input
  • Special sensory association areas - Interpret special sensory input

  
• Cerebral White Matter


  The communication "railway" of the brain, Composed of myelinated axons organised into commissural, association and projection tracts

  
• Prefrontal cortex


  Responsible for intellect, cognition, personality & behaviour
• Frontal lobe


  Responsible for intellect, cognition, personality & behaviour

  
• Review 1. Cerebral Cortex

  
• Primary somatosensory cortex


  • Located in parietal lobe (postcentral gyrus)
  • Receives and localises general sensory input
  • Perceives sensations of touch, temperature, pressure, vibration, pain & proprioception

  
• Somatosensory association area


  • Located in parietal lobe
  • Interprets general sensory input to recognise objects by touch alone
• Special sensory areas


  • Located in occipital & temporal lobes & insula
  • Receive special sensory input
• Special sensory association areas

  • Located in occipital & temporal lobes & insula
  • Interpret special sensory input to give meaning to sensations