PSY 240 1st Edition Lecture 5PSY 240: Developmental PsychologyBiology and Behavior – Brain and Body DevelopmentThe Neuronneuron: a nerve cell (basic unit of nervous system)-avg. human brain ~100 billion neuronsglial cell: 10x as many glial cells:-fill gaps between neurons-aid neural communication-care & upkeep of neurons3 types of neurons:1. sensory neurons: receive signals from senses2. motor neurons: send signals to muscles3. interneurons: connect sensory & motor3 functions of a neuron:1. receive signals from other neurons or senses2. “process” signals3. send signals to other neurons, muscles, organs“Neurotransmission”Structure of a NeuronThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Structure of a neuroncell body: central part of neuron, contains nucleus (regulates cell functioning)dendrites: branches that receive messages from other neuronsaxon: long, cable-like extension delivers messages to other neuronsmyelin sheath: layer of fatty tissue that insulates axon and speeds up neurotransmissionmultiple sclerosis: deterioration of myelin slowed communication with muscles, impaired sensation in limbsterminal buttons: structures at ends of axon terminal branches-release chemicals into the space between neurons, to be picked up by dendrites of nextneuronsFrom Neuron to Neuron:~100 billion neurons average 10,000 connections to other neurons (hundreds of trillions of connections)Brain Developmentneurogenesis: creation of new neurons (mitosis)-mostly prenatal (18 weeks after conception) 250,000/minute at peak!-neural migration “arborization”-myelination (brainstem cortex) (birth young adulthood)synaptogenesis: formation of neural connections (across synapses)-more than 1 million/secondsynaptic pruning: elimination of unused connections-remember apoptosis? (genetically death cells, purposely)-(100,000 synapses/minute at peak)-ages 1-10, adolescenceThe Braincerebral cortex: convoluted pinkish gray surface of he brain (1/8 inch thick: 30 billion neurons & 300 trillion synaptic connections most high-level mental processes  ex. Learning, memory, decision making, personality, thinking, sensation, consciousness etc.cerebral hemispheres: cortex is divided into two halves -hemispheres control side of body (ex. Right arm and leg controlled by left hemisphere, and viceversa)corpus callosum: large band of neural fibers (more than 200 million) that connects left & right hemispheres-can transfer more than 1 billion bits of information per secondOur Divided brains: Hemispheric specializationLeft brain: written language, spoken language, number skills, reasoning (analytical & verbal)Right brain: insight, art awareness, imagination/creativity, music awareness (intuitive & perceptual)-cerebral cortex divided into lobes:1. frontal lobe: planning, memory search, sophisticated motor control, reasoning, emotion regulation, decisions, morality, personality, producing language, and so many other high-level functions-the frontal love is what makes us uniquely human.-motor cortex: section of the frontal lobe (controls fine movements and is organized by body part2. parietal lobe: sense of toucha. integrates sensory information  spatial location, navigationi. -arithmetic, numbers- sensory cortex: section of the parietal lobeo registers touch on the body 3. temporal lobe: hearing (understanding language)4. occipital lobe: vision- -separate areas for shape, color, motion, etc. Experiences & Brain Developmentplasticity: brain’s ability to modify itself-happens in all people, to some extent-often most evident in brain reorganization following damage-ex. Brain most plastic in childhood, easier to recover from brain damage-make adjacent fingers more sensitive!-sensory cortex for blind person’s braille finger expands as sense of touch takes over occipital lobeexperience-expectant development: “use it or lose it”-brain expects events to happen, anticipates-Ex. Expect eyes to encounter light-if not eye development, but not occipital lobe development-can lead to vulnerability- cataracts: if removed early in childhood fairly normal visual development-if removed late visual declineexperience-dependent development: reaction to experiences-Ex. Right-handed violinists (motor cortex for finger control more developed in right hemisphere than left)-smart phones increased neural sensitivity in fingertipsPhysical DevelopmentPhysical growth: spurts in first 2 years, early adolescence-sexes equal until ~10-12, then 2 years faster in women-full female height: 15 ½-full male height: 17 ½-cephalocaudal development-2 months old: head= 50% of body length-adulthood: 10%-infants: large head & eyes, small mouth & nose, fat cheeks-ex. Makes babies seem cute, more likely to be taken care of-ex. Attraction positively correlated with amount of female reproductive