Central Nervous System (CNS): the brain and spinal cord - Enables our humanity: thinking, feeling, and acting - BRAIN AND SPINAL CORD Spinal cord delivers information from the Peripheral Nervous System to the brain Ascending neural tracts send up sensory information Descending neural tracts send back motor-control information Neural pathways control our reflexes, which are our automatic responses to stimuli Reflex: composed of a single sensory neuron and a single motor neuron which communicate through an interneuron - EXAMPLE: knee-jerk response Pain reflex: when your fingers touch a flame, neural activity excited by the heat travels through sensory neurons to interneurons in your spinal cord, which activates motor neurons to the muscles in your arm. Your hand jerks from the candle's flames before the brain receives and responds to the information - NEURAL NETWORKS Interconnected neural cells clustered into work groups. With experience, networks can learn, as feedback strengthens or inhibits connections that produce certain results. Computer simulations of neural networks show analogous learning Receives information, interprets it, and decides response - EXAMPLE: when you look at an object, our eyes receive slightly differing images of an object from our two eyes, computes their difference, and infers how far away the object must be - Neurons network with nearby neurons to have short, fast connections
