Neuroscience ● Neurons send and receive information throughout the body in the form of electrochemical signals ● AW ● Soma (cell body) ○ Stores nucleus of the cell ● 2 types of fibers connected ● Dendrites (pick up) ○ pick up incoming messages from other neuron/stimulation ● Axons (away) ○ carry messages to another neuron or muscle/gland ○ axon terminals ■ where neurotransmitters are stored ● Myelin sheath ○ layer of fatty cells wrapped around axon to insulate ■ insulation speeds up communication ■ EX) Multiple Sclerosis→ destruction of myelin sheath ● slows down communication to muscles ● Glial cells ○ Cells in the nervous system that support, nourish, and protect neurons. The Neural Impulse ● Cell membrane is a semipermeable boundary – ion concentration inside and outside the cell creates all-or-none action potential ○ every neuron is covered by semipermeable membrane ■ semipermeable→ some chemicals can pass, some not ○ electronic chemicals inside and outside neuron ■ nothing happening ● inside has - charge, outside has + charge ■ disruption ● semipermeable membrane breaks down ● + ions rush in ■ certain threshold reached leads to firing of neuron ■ quick burst surges down axon→ neuron fires ● action potential ○ all or none response ■ neuron either fires or doesn’t ■ EX) can’t sort of fire gun ● Synaptic vesicles release neurotransmitters into synapse. Find receptor sites in a lock-and-key fashion. ○ synaptic cleft ■ space between axon terminal of 1 neuron and dendrite of another ○ neurotransmitters released into synapse and bind to specialized receptor sites on dendrites ■ neurotransmitters relay signal by binding to receptor sites ○ lock and key fashion ■ certain neurotransmitters fit into certain receptor sites ○ neurotransmitters go back up into synapse ■ either broken down ■ or reabsorbed into axon terminal for later use (reuptake) ■ process takes milliseconds! ● EX) $1 drop (easy to catch it when you drop it yourself than someone else dropping it ○ Brain sends both messages simultaneously ■ Eyes register $ dropped (sensory neurons) ■ Hands get signal to catch (motor neurons) ■ Too much of a neurotransmitter?→ some drugs block receptor sites or block creation of neurotransmitter to reduce activity ■ Too little of neurotransmitter?→ drug to block process of reuptake ● When you block reuptake it forces neurotransmitter to stay in synapse longer Neurotransmitters ● Many neurotransmitters play different roles and overlap/interact. ● Some neurotransmitters will excite next neuron ○ (making it more likely to fire) ● Other neurotransmitters are inhibitory ○ make next neuron less likely to fire - making it more negative) ● Acetylcholine ○ ○ Enables muscle action, learning, & memory Muscle action ■ Blockage would cause paralysis ■ EX) botulism (found in contaminated food) ● blocks acetylcholine, resulting in paralysis ■ Botox blocks acetylcholine receptors ● paralyzes (relaxes) facial muscles ● treats severe migraines and tic disorders to relax neck ● Prevents sweating (actors use to not sweat) ■ Increase would cause violent muscle spasms ■ EX) spider bites - causing increase of acetylcholine ● Can result in violent muscle spasms ○ ● Linked to learning and memory ■ Alzheimers ● Not enough acetylcholine ● Brain doesn’t produce enough acetylcholine ● Medication raises acetylcholine levels ○ slows progression of disease (if diagnosed early enough) GABA (brain’s brake pedal) ○ Inhibits other neurons from firing ○ Some epileptic seizures can be caused by low levels of GABA ○ Low levels of GABA linked to anxiety ■ Anxiety meds can increase GABA ○ Low levels can also lead to insomnia ● Serotonin ○ Regulation of sleep, eating, pain, aggressive behavior, primarily mood ○ Often called mood molecule ○ undersupply of serotonin ■ Depression patients have undersupply ■ Anxiety and eating disorders, migraines ○ People trying to quit smoking (how?) ○ Prozac (SSRI= selective serotonin reuptake inhibitor) ■ Antidepressant ■ blocks reuptake of serotonin ● If you don’t have enough you want to increase what you have forcing serotonin to stay active for a longer time ■ forces serotonin to remain active ● Dopamine ○ Influences movement learning attention and emotion ○ Control of voluntary movement ■ EX) parkinson’s disease ● Undersupply of dopamine ● Caused by death of neurons that produce dopamine ● Take drug L-Dopa ○ chemical that passes through BBB & converts itself into dopamine ○ actual dopamine won’t work with blood-brain barrier ○ Pleasure enhancing neurotransmitter (feel good) ○ Oversupply of dopamine can lead to schizophrenia ■ delusions and false beliefs ■ medications (antipsychotics) block activity of dopamine ● ● ● ● ● ● ● ○ Medications can lead to opposite symptoms ■ Parkinson’s patients can start having schizophrenic symptoms ● Due to increase of increase of dopamine ■ Schizophrenics can develop Parkinson’s like disorders for life ■ Proper medication/balance needed to alleviate symptoms Oxytocin ○ (hormone of love and bonding) ■ Released when you orgasm ■ Related to relationship of parents and children ● Mother gives birth oxytocin is released ○ Mothers w/ high levels of oxytocin during pregnancy have more attachment actions ○ Father given synthetic oxytocin will tend to bond child ● Strangers given oxytocin are more likely to help a stranger than those ● Giving autistic children oxytocin can help read emotions of other people Glutamate ○ A major excitatory neurotransmitter; involved in memory ○ Oversupply ■ Can overstimulate the brain causing migraines or seizures ● Why people avoid MSG (monosodium glutamate) in food Norepinephrine ○ Helps control alertness and arousal ○ Undersupply can depress mood Agonist - A molecule that increases a neurotransmitter's action Antagonist - a molecule that inhibits or blocks a neurotransmitter's action Neurotransmitters can lead to addictions ○ Cigarettes and drugs lead to surge of dopamine (pleasure enhancing feel good) ■ Continuous raising of dopamine levels ■ Cigarettes are addictive not only because of nicotine but also rush of dopamine ■ Addictions are caused by habitual usage and nicotine in cigarettes ○ Smokers are half as likely to developing parkinson’s than nonsmokers ■ Parkinsons caused by low dopamine levels, smoking raises dopamine ○ Also likely to cause schizophrenia ■ Increase of dopamine Morphine and heroin fit into body’s natural endorphin receptor sites ○ Endorphins are linked to pain killer and pleasure ■ “Morphine within” - natural opiate-like neurotransmitter linked to pain control and pleasure ■ Ex) getting injured and not feeling pain for a few moments after injury ● Body releases natural painkillers upon injury ○ Repeated use (opiate drugs) tricks body into thinking enough endorphins are being produced ■ So body slows down endorphin production ● Addict needs drugs to feel normal ● Reason why withdrawal is so painful ○ Natural endorphins not being produced ● Cocaine blocks reuptake of dopamine ○ ○ ○ ○ ○ keeps dopamine active for longer cocaine users experience schizophrenic like symptoms can lead to drug induced schizophrenia Rush of cocaine will then deplete brain’s of dopamine and serotonin and norepinephrine ■ That’s why lows after getting high are linked to depression ● Ecstasy (eats holes in brain) ○ ○ causes surge in serotonin - increases mood ○ damages serotonin receptors ■ linked to depression and parkinson’s disease ■ EX) study with monkey ● damaged dopamine neurons ○ parkinson’s like symptoms ● Caffeine blocks adenosine receptors ○ adenosine makes people sleepy ○ increases adrenaline and dopamine levels ● Some neurotransmitters linked to craving for carbohydrates ● Stress leads to cortisol production ○ Cortisol regulates neuropeptide - turns on/off body’s craving The Nervous System ● ● ● Nervous system - the body’s speedy electrochemical communication network, consisting of all the nerve cells of the peripheral and CNS Central nervous system (CNS) ○ The brain and spinal cord Peripheral nervous system ○ The sensory and motor neurons that connect the CNS to the rest of the body ○ Somatic nervous system ■ The division of PNS that controls the body’s skeletal muscles. Also called skeletal nervous system ○ Autonomic nervous system ■ Part of the PNS that controls the glands and the muscles of the internal organs ● Sympathetic (arousing) ○ Involved in fight or flight ● ● ● ● ● ● ● ● ● Parasympathetic (calms) Nerves ○ Bundles axons that form neural cables connecting the central nervous system with muscles, glands, and sense organs Sensory (afferent) neurons ○ Carry information from receptors to the brain and spinal cord Motor (efferent) neurons ○ Carry outgoing info from the brain and spinal cord to the muscles and glands Interneurons ○ Neurons within the brain and spinal cord; communicate internally and process information between the sensory inputs and motor outputs The Endocrine System The body’s “slow” chemical communication system Hormones ○ Chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues Adrenal glands ○ A pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress Pituitary gland ○ The endocrine system’s most influential gland. ○ Under the influence of the hypothalamus the pituitary regulates growth and controls other endocrine glands The Brain ● Tools for studying the brain ○ Electrical recordings – EEG (electrodes on brain) ■ Records waves of electrical activity in brain ● Shapes and patterns vary on activity ■ Somewhat limiting ○ Brain-imaging techniques – CAT, MRI, PET ■ CAT scan ● Takes pictures of the brain ■ MRI scan ● picture of the brain with magnetic field ○ more detailed, and clearer pictures ● MRI of any body part ■ fMRI ● Take moving picture of brain while it’s actually working ● FunctionalMRI ■ PET scan ● Can tell which part of the brain is active when engaging in certain activities ● It also measures brain activity ● It is basically an x-ray of the brain ○ Experimental interventions – lesions, electrical stimulation ■ lesions ● Surgically destroy part of the brain for research ● Mainly done animals for the sake of research not on humans ● Done in humans for epilepsy and other illnesses (medical reasons why it maybe necessary) ● Patients sometimes must be awake during brain surgery ○ Ex: tumor is on part of ability to speak only way to know if they don’t touch that part is if that part of the brain is working ○ Slowly woken back up, sedated but awake ○ no pain receptors in brain ■ EX) Hannibal scene where hannibal removes part of another guy’s brain ■ ■ Electrical stimulation ● small amount of electrical stimulation in brain applied ○ patient can report reactions ○ Example, if the electrical stimulation is applied to the part of the brain responsible for hand motion, the patient undergoing surgery will move his/her hand involuntarily. ● done to make sure important parts of brain aren’t damaged ● Man played guitar during own brain surgery to make sure motor skills weren’t being damaged ○ Clinical case studies ■ Phineas Gage ● Rod went through frontal lobe and completely destroyed it Lowest portions of the brain are the oldest structures; highest portions are the newest structures. The newest part of the brain is the cerebral cortex. ● Cerebellum ○ ○ “Little brain” at rear of brain stem Functions include processing sensory input, coordinating movement output and balance, and enabling nonverbal learning and memory ● Brainstem (oldest part of the brain) A damage in the part of the brain can lead to death (depending on which part is damaged) ○ Medulla – swallowing, breathing, heart rate. Most vital functions ■ no survival without the medulla ● EX) superman actor (Christopher reed) injured his medulla, couldn’t breathe on his own ■ Pons ● Sits above medulla ● Regulates helps coordinate movements and control sleep ○ Reticular formation – controls sleep, arousal, attention. ■ active during sleep, produces visual images while asleep ○ Thalamus – “sensory relay station.” ■ senses go through thalamus first, then appropriate cortex ■ It directs all the traffic between your senses and cortex. Everything that hits your senses, except for smell, goes through the thalamus. ● Limbic system (newer than brainstem) ○ Limbus means border ■ Between brainstem and newest brain area ○ emotion, motivation, memory ○ fully developed in mammals ○ helps in suppression of instinctive behavior (hunger and sex drive) ○ Amygdala – “aggression center” ■ Linked to aggression and fear; linked to emotions ■ stimulation could cause extreme anger/violent behavior ● EX) UT school shooting, killer had brain tumor stimulating his amygdala ■ damage to amygdala could lead to lack of fear and anger ● not be able to recognize those emotions in a person’s face ● Ex) woman with amygdala lesions ○ Gun pointed in face experienced no fear ○ Hippocampus – plays a role in forming new memories ■ NOT where memories are stored ● memories stored everywhere, not in a particular spot in your brain ■ H.M. (27 years old) – case study that gave us more info about the hippocampus ● had severe seizures ○ epileptic seizures ■ electric activity all over brain ● seizures originated around his hippocampus ○ doctors removed his hippocampus ○ survived surgery, couldn’t form new memories anterograde amnesia (can’t form new memories) ■ feels stuck in permanent memories ■ knew he was aging ■ EX) Memento, 50 first dates ● character 10 second Tom ○ Alcohol affects the hippocampus ○ Hypothalamus – emotion, basic drives, reward center ■ stimulation leads to strong feelings of pleasure ■ discovered on accident ● electrode in rat’s brain ● rat’s continuously pressed lever to stimulate hypothalamus at the expense of other vital behaviors like eating and drinking ■ In humans it’s pleasurable (not orgasmic) ■ linked to addiction and drug use ● Cerebral Cortex (outermost surface structure of brain) (newest part of brain) ○ highest level functions: thoughts, vision, language ○ It is wrinkled because it saves space and it is a more compact arrangement of the brain ○ left and right hemispheres ■ Each hemisphere is divided into four lobes ● Frontal, parietal, occipital, temporal ○ Association areas - areas of cerebral cortex not involved in primary motor functions or sensory functions; involved in higher mental functions like learning, remembering, thinking and speaking ○ Contralateral – opposite side ■ ○ Ex) right hemisphere controls left side of brain Frontal lobe ■ Involved in speaking and muscle movements and in making plans and judgments ■ Motor cortex ● processing motor behavior ● more intricate movements have more parts dedicated to them (they occupy a larger surface area of the brain). E.g the face (facial expression), the hands etc. ■ Prefrontal cortex ● Part Phineas gage had damaged ● controls logic, control, judgments (moral judgments even) ○ know difference between right and wrong ■ can’t follow through ● extensive alcohol abuse can permanently damage brain ■ Broca’s area – language production ● ability to speak ● damage can lead to loss of ability to speak= aphasia ○ Temporal Lobe ■ Auditory cortex ● stimulation could lead to hearing things ● damage could cause deafness ■ Wernicke’s area – language comprehension ● ability to understand language ● damage can lead to lack of understanding of language ○ they can speak but not understand what they’re saying ■ speak nonsense ○ Parietal Lobe ■ Sensory cortex ● stimulation can lead to feeling sensations ● fingers and faces are extremely sensitive ● can’t tell difference between 1 and 3 fingers on certain parts. E.g Face vs back ○ Occipital Lobe ■ Visual cortex ● stimulation can lead to seeing things. Random lights and random images. Nothing to complex like seeing your childhood home or significant other ● damage could lead to blindness Hemispheric Specialization ● Contralateral - opposite side ● Left hemisphere vs. Right hemisphere ○ Each hemisphere controls opposite side of body ○ each hemisphere is specialized in different abilities and functions ■ left hemisphere ● verbal abilities ○ reading, writing, speaking ○ language hemisphere ● trauma ○ could be greatly upsetting (internal trauma not always ○ Aware of trauma ○ ex) losing ability to speak ■ right hemisphere ● nonverbal abilities ○ emotions, spacial thinking, imagery, facial recognition ● trauma isn’t as debilitating, more subtle ○ Unaware of it-even positive affect ■ For right handed people, 96% of people have language in the left hemisphere ■ left handed females have the best prognosis ○ Anesthetizing - It is possible to put one hemisphere to sleep ■ Anesthetizing left hemisphere can lead to crying ■ Anesthetizing right hemisphere can lead to laughter, and positive feelings ● Aphasias – severe language impairment (damage to Left Hemisphere) ○ Left hemisphere damage ○ Any form of a language impairment ■ Broca’s aphasia – damage to the Broca’s area ● Can’t speak ■ Wernicke’s aphasia – damage to Wernicke’s area ● Can’t understand language ● So they can speak but they don’t understand what they are saying ○ Can be very specific aphasia depending on area damaged NB: Damage here is not limited to just physical damages. ● Agnosia – object recognition/spatial disorientation (Damage to Right Hemisphere) ○ Right hemisphere damage ○ Visual Agnosia ■ Unable to recognize things - unable to understand what they’re looking at ■ Inability to recognize something based on vision ■ No problem with sight just problems with pattern recognition ● Ex) Man thinks glasses are bicycle ○ Prosopagnosia (“face blindness”) ■ Inability to recognize faces ● Examples ○ Dr. P - Man who mistook his wife for a Hat ■ Thought his wife’s face was a hat. When he touched her he knew it was a human face, but his issues were with vision. ■ Saw faces where there weren’t any ● patted parking meters because he thought they were children ○ Another man couldn’t recognize what a glove was until he put it on ■ Most extreme cases, can’t recognize themselves or loved ones ■ Can be congenital - not as nearly as severe ○ Left side neglect ■ Right side damage ■ Inability to focus attention to anything on the left hand side ● Disruption of spatial awareness ● They can see just fine but they aren’t just able to focus their attention on the left side ● The left side doesn’t exist ○ Ex) shaving right side of face, only applying makeup on right side ● Deny ownership of left side of body ○ Wheelchair woman ■ Only ate right hand side of spaghetti ■ Had to do a 360 degree turn to eat other half ■ can’t acknowledge what she doesn’t believe exists ■ show’d woman the left side for experiment and had to discontinue because she was so disturbed ■ equivalent of showing us the other dimension ○ Grey’s Anatomy episode lol? The Split Brain ● Severing corpus callosum eliminates communication between the hemispheres ● ○ corpus callosum ■ thick bundle of nerve fibers that send signals between the two hemispheres ■ some individuals need their corpus callosum severed ● For epileptic seizures ○ cutting corpus callosum can prevent seizures from spreading to whole brain by trapping electrical activity in one hemisphere and reduce severity ○ Traps information as well as seizures in only one hemisphere ● Right periphery goes to left hemisphere vise versa ○ Split brain patients ■ Flash image to right visual field (left hemisphere) ● they can verbalize what they saw ■ Flash image to in left visual field (right hemisphere) ● they cannot verbalize what they saw ● they can draw the image, but only with the left hand, even though they don’t know what they’re drawing ■ Like having two different minds working separately ● each half of the brain does only what is communicated it to it, because there’s no communication between hemispheres Neural Plasticity Some parts of the brain can regain functionality due to neural plasticity ● Neural plasticity – brain’s ability to change in response to experience ○ Experiment: 2 groups of rats raised in cages ■ impoverished vs enriched ● rats raised in enriched environment had larger neurons and more synaptic connections than impoverished rats ● Enriched rats - more developed brain ○ Growth of synaptic connections ■ More synaptic branching in wernicke’s area in more educated people ■ String players have parts of brain more developed neurons skills for finger dexterity ■ Deaf people’s auditory cortex (which they don’t make use of) of brain is rewired to accommodate for more connections to help in visual (enhanced ability to read lips, etc.) processes ■ Blind people- visual cortex will rewire for hearing and touch. It doesn’t stay unused. ■ “Your lose one sense and others become sharper”. ○ Plasticity is adaptive ■ Phantom pain ● lose a limb and claim to still feel sensations of pain in area of body that was lost ○ because part of brain responsible for sensory cortex is still devoted to that body part despite limb not being there ● Lose left hand ○ Part of brain devoted to left hand other parts will take over ● part of cortex rewires to take over other part ○ Ex) guy lost his foot, foot sensors are near genital sensors, so he has much larger part of brain devoted to genital sensors now ○ feels orgasms in his nonexistent foot/orgasms feel better. ● Hemispherectomies – removal of the left or right half of the brain (last resort) ○ removal of entire hemisphere ■ Doesn’t leave them completely disabled ■ Ex) removal of left hemisphere from child’s brain would lead to loss of language skills and paralyzation of right side of body ● BUT (with therapy) right hemisphere will start to adapt and take over language and right side movement ○ Human brain isn’t fully developed until the age of 25 ○ More plasticity at a younger age ■ Younger hemispherectomy happens better recovery will be ○ Empty hemisphere fills with cerebral spinal fluid ○ Some things never recover
