PSYC 304

#separator:tab #html:true "Metaphors and the brain in antiquity ""Two schools of thoughts: Doctors who thought brain is the source of intelligence, philosophers who thought the heart was the source of intelliegence Egypt: Head traumas cause unusual behaviour, mummification of perserving the heart and throwing out the brain Greek -Hippocrates: Brain: emotion, intellect -Aristotle: heart: Intelligence, Brain= AC just to cool down everything Romans -Galen: dissected animals and started seeing that the brain is different parts, discovered the cerebrum is soft so it has to do with memories, and the cerebellum is tough so it has to do with motor control. Ventricles has holes and fluid blood pumps around body to control things. Humours: throughts travel through fluid " "18th century metaphors about the brain ""- were finally able to disect humans after death which led to better findings of the brain. -Galens knowledge lost in latin west but translated to arabic -Hydraulics: Push fluids through tube to activate. Vesalius, Descartes: Maybe we are biological automaton... but u cant go against the church. Humans + Soul where ??? Pinial gland Materialism in science: where most neuroscientists stand, everything is matter and energy which can be easily observed AKA cause and effect (thougths, love, etc are PHYSICAL, if we do not folow this what is the point. Birth of white/ grey matter, anatomical maps (ventrivcles), gyri and sulci " "19th century metaphors ""Wires/electricity: Galvani and du-ois reymond. Maybe the brain has this.. measuring the voltage in the brain NOT WIRES THO: dorsal (damage these and animals cant receive sensory input)/ ventral (damage these and the animal loses motor control) results of bell and magendie -Localization of function: Flourens (damages cerebellum and movement), gall (phrenology), Broca's metaphor: brain is like electrical -> imperfect... only targets one direction " "Two major biological insights in 19th century ""Evolution: Darwin, animal models -Selected for something  - we all have origins Cellular theory: Shwann  -Base unit of like is a single cell " "Golgi vs Roman y cajal ""-late 19th, early 20th c. - golgi's stain: Silver nitrite, only 10% of neurons take up the stain, started to see individual neuron - golgi:reticular theory: sees neurons are touching, and they are all contonous and travel together through a net/ mesh. Signals travel back and forth (which is not the case) -Roman y cajal drawings:  Uses golgis stains and draws them sees that there are a lot of varieties of types of cells depending on the region, and that there are diff patterns and wiring --> doctrine: Base unit is a single neuron, not all are the same. There is an input and an output, they come close and there is a small gap (synapse), NOT continous -R y C was right cux electron microscope proved him right. " "20th century ""-when modern neurosceince was born  -- structual MRI, brainbow mouse, two photon microscopy " "todays metaphor: the computer ""-Binary hcosed because of neurons (input and output) -Computers REPRESENT information; brains CONSTRUCT information. " "What exactly is neuroscience? ""What it means to be you - The study of the nervous system - the goal: learn how the NS functions and how it relates to the mind " "Human brain facts ""-2-3% of our body weight ~ 3 lbs - consumes 20% of your energy -slightly larger in men than women (proves that size does not mean intelligence) -huge individual variation -composed of neurons, glia (""glue""), stem blood cells, blood vessels -<100 billion neurons, more than half of which are in your CEREBELLUM - Consistency of soft tofu - convoluted (wrinkled): no special function, just to fit more brain  -cells are not replaced: most cells at 1 yrs old. " "Is there adult neurogenesis ""-long history of controversy -Limitations to studying this in humans because you have to take a slice of the brain -Only one subregion -if it plays a role it is hard to say what it is -Yes evidence till 13, but after 17 there is no more " "What are some patters of how the brain looks in different animals? ""-More convolutions -frontal lobe gets bigger - forebrain gets bigger " "What are some exceptions to the patters of animal brains  ""-Dolphins have a much bigger brain than humans, while parrots have a smaller one... but both have high language use and intelligence compared to other animals " "does size count in brains? ""-No!!! - Usually the biggest animal means a bigger brain, but that does not mean smarter -brain mass to body ratio --> humans have a disproprtionately bigger brain to body ratio - Still does not give us a mechanism " "Brain cell density ""-Being dense per unit of volume= intelligence as a species -dense brain in a better measurement than size -# of neurons counts -doesnt have to be big neurons -intelligence also correlates with sophistication of cellular connections (wiring) -being dense isnt an insult. Dense means smart ohohohho " "Matter ""-Gray matter: Cell body, small unmyelinated neurons -White matter: Fatty substance on it, myelin sheath wraps around axons -> White has to do with axons -> Coming from or going to gray matter, point a--> B " "What are the different types of staining? (EXPLAIN AND REMEMBER NAMES) ""For both: only way to show full neuron is golgi stain -Nissl-stained (cressyl violet) gray matter -->GRAY matter, binds to cell body ONLY, wont show branches of the neuron -Fiber stained of whotematter: Staining insulating glia cells --> Bind to protein, myelin, darker=WHITE matter, wont show whole cell " "two basic cell types ""1. Neurons -Communicate on axon and carries info supa fast (action potential) -SIgnal is DIRECTED, targeted system. 2. Glia -Support cells, foundational in development -Myelin is created by glia " "The neuron ""<img src=""Neuron.gif"">- Many types but similar design -Dendrite--> soman--> axon--> terminals Input----flow of signal----> output " "Pyramidal neurons ""-Information for the cerebral cortex -looks like a pyramid <img src=""pyramidal neuron.png""> " "Skellate neuron ""-Sends info to the subcortical regions <img src=""skellate neuron.png""> " "Purkinje ""-Sends info to the cerebellum -a BUNCH of dendritic trees <img src=""Purkinje neuron.png""> " "two basic types of neurons (just name) ""-Projection neurons -Interneurons " "Projection neurons  ""-Have a charecteristic shapes -have supa long axons that project to a different BRAIN REGION (e.g. spinal cord) -big signals -can build an axon as long as it needs to be <img src=""projection neuron.png""> " "Interneurons ""-At the synapse -generally star shaped -have short axons that project INTERNALLY (not diff brain regions, SAME brain region) -unmyelinated because axon is SHORT --> does not need to myelnate because it does not have to be a fast signal - modify signal --->usually inhibitory in nature (not just about blocking signal) in order to create synchornisity, timing (like a dance, means careful timing and pattern of neurons, fast degree of neurons firing) - eeg measures this -when ur asleep interneurons blocks signals so you dont hear thinds <img src=""interneuron.png""> " "What are the diff types of glial cells (only names for now) ""MACROGLIA -Astrocytes -Schwann Cell -Oligodendrocyte MICROGLIA -only one type, is small. " "Microglia ""First: there is a blood-brain barrier that keeps the brain isolated because the body has a lot of viruses that if they get in the brain can be vert severe, so it is blocked off ---> immune system cannot protect brain BUT!!! microglia can -Covered in receptors -trying to find evidence of a virus in the brain --> if found they become ""prime"" state and they move super fast to catch it ----> once caught they inflate supa big and engulf the virus and digest it to get rid of it. <img src=""Microglia.webp""> " "Oligodendrocyte ""-Wraps around several axons -in CNS -IN THE BRAIN CUZ CNS -Myelinated glia <img src=""Oligodendrocyte_illustration.png""> " "Schwann cell ""-outside of brain -wrap around entire cell ON axon -in PNS NOT brain -ONE axon -form the myelin sheath on axons outside the brain -MYELINATED GLIA <img src=""schwann cell.webp""> " "Astrocytes ""-most abundant CNS glial cell -lots of roles -glial scars- when brain is damaged. -ASTRO (star) -""feet"" wrapped around blood - they are half of blood-brain barrier*** -All nutrion and other things will be mediated by it -Maintain environment in brain so that other cells do their jobs ---> very supportive cells. -Specifically in synapse <img src=""astrocyte.webp""> " "Glial networks (astrocytes) ""DONT WORK ALONE! -Specialized proteins -->Gap junctions: A's are covered in this, they come together and stick together which creates a continous passage way (a hole/pore) from the insde of one A to the inside of the next A --> Like golgi talked about: forms a reticulum.. proves that he wasnt COMPLETELY wrong just like mostly wrong -What do the holes do? --->each cell  is connected ot all the other cells, so they flow pretty smoothly. (e.g: if there is a lot of K that is not supposed to be there will flow into some A's and it will keep flowing and buffer it out to make it even, rapid. -calcium is a signalling molecule -There are some cases that they are connected to gap junctions, almost always INTERNUERONS*** " "The tripartite synapse ""-not a convo of just presynaptic (axon terminal) and post synaptic (dendrites) --> ofc axon reselases chemicals (neurotransmitters, float through synapse and bind to receptors) --> Astrocytes play a role in this too, they ENGULF the synapse to create a controlled environment, they also release chemical messages ---->NOT called neurotransmitters because they do not come from neurons, they are called: GLIAL transmitters -------> they also RECEIVE chemical signals from neurons, they are covered in receptors -glutuamte receptors they are only partially activated, so how do they become fully actived? --> there is another molecule (where is come from?... idk) <img src=""The-tripartite-synapse-Many-synapses-are-juxtaposed-with-an-astrocyte-process-in.png""> " "the central dogma of molecular biology ""DNA is a way of coding for RNA, RNA determines what protein  DNA--TRANSCRIPTION--> RNA--TRANSLATION--> PROTEIN " "What do proteins do? ""-So much!! -Transport, cellular signalling, enzymes, hormones, etc " "Soma: nucleus: explain how transcription works ""-Every cell has the same gene, inside there is a lot of different types of DNA, cells end up being different depending on the type -how transcription occurs: there is a start and stop codes that are in a double helix pattern (aka dna), the start and stop codes tell a specialized protein (AKA RNA polymerase-Mkaes chuncks of RNA based on the genes) where to begin and where to end when they are creating anther piece of RNA. We can tell where they begin and end because of stop codes and start codes -When an RNA polymerase makes a chunk of RNA(transcription) oit makes a lot more RNA than you need for the protein, so you have a lot that are releveant and valuabe and others that are irrelevant (not really tho has other uses), so they are removed which is called SPLICING, aka mRNA--> messenger rna that codes for the protein you need " "What determines transcritption (just name the 2 mechanisms for now) ""1. transcription factors 2.Histone modification " "Transcription factors ""-This gene is only expressed if BOTH activators are present and the repressor is absent -The binding sites are activators/repressors -If there is one activator there is little transcription, and if there is 2 activators there is normal transcirption -If at any point there is a repressor transcription will not occur --->essentially it is little signaling mechanisms that will increase or decrease the likelihood of a gene being transcribed to RNA " "Histone modification ""Epigenetic (gene changes that can be related to experience) changes that change how genes are stored. --DNA is super long, so in order to pakc a lot into a small space, we wrap DNA around histones and they have a bunch of DNA wrapped arounf them --> if the DNA is wrapped very tightly around it, the RNA polymerase cannot turn it into RNA easily--> NOT easy to transcribe ---> if it is looser on the histones now the genes are more exposed and open and it is easier for the RNA polymerase to transcribe the DNA to RNA -> how tightly or loolsey coiled your DNA is will infleunce how likely your genes are expressed -WHy?? --> Methylation (DNA) can happen to cheimcal exposure, stuff that happens in your life, histone modifications, not just in their genes in generations. " "Soma (and elsewhere): ER and golgi apparatus ""How do we turn mRNA to protein! -We use a diff protein (looks like baseball glove)-RIBOSOMES, outside of the nucleus find them in the endoplasmic reteculum (fluffy stuff) around the golgi apparatus -Some protein has to be woven (ribosome) into the outside of your cell in the plasma membrane --> some of your ribosome have to produce the proteins into the intracellular fluid (floating around)---> some have to do the work of threading the protein into membrane (skin) Endoplasmic reteclumum- rough or smooth, i=either yes ribisomes or no ribosomes ---> skin inside cell and oyu can take those peices to where you need them and take them to the outside of the cell... Take them where they need to be -> Either putting the protein in the intracellular fluid or weaving it into a piece of membrane --> once in the membrane the golgi apparatus will help ship it to where it needs to go. " "Soma (and elsewhere): Mitochondria ""Neurons are a very energy intensive thing, so mitochondrias are very important Mitochondrias have their own membrane and when you look inside they have their own dna (mitochonrial DNA-> mtDNA) -> mtDNA suggests that at some points they werent an organ in yoru cell they were their own type of cell (bacteria) and our cells swallowed them and ""kept them around""- symbiotic relationship occured -they are good at producing molecule, called ATP (is our currency of our cell-> energy), when you want to store energy you turn it into ATP and when you wanna break it down you break down ATP and it releases energy you can use --> main energy we use for many of our cellular processes, need two things--> Sugar and O2 and are turned through the krebs cycle to ATP and produce C02 -mitochondria are not passed down equally, everyone receives their mtDNA through your mom, which you can follow back to find common ancestors. " "The cell membrane ""-has a uniqe design --> phospho (heads) lipid (tails) bilayer, this bilayer is good at keeping things in and out of the cell (barrier) --> because it is so effective you need specialized proteins (holes, pores, passageway) from the inside to the outside, they will allow passage from one way to another (ribosomes) " "cytoskeleton ""-three diff types: Microtubules, neurofilament, microfilament -forms a highway from cell body to axon, there are specialzied proteins that carry vessicles will walk up and down cytoskeleton  -->Kinesin: Anterograde transport (from input to output) --> Dynein: Retrograde transport (output to input) ------> with every step they consume ATP to do this walking movement (AKA main currency), " "The synapse ""-has a lot of mitochondria there are different types of post synaptic sides (not necessarily dendrites) Axosecretory: Axon terminal secretes directly into bloodstream--> HORMONES Axoaxonic: Axon terminal secretes into another axon Axodendritic: Axon terminal ends on dendrite spine Axosomatic: Axon terminal ends on soma Axosynaptic: Axon terminal ends on another axon terminal " "The dendrites ""there are presences or absences of dendritic spines Presence: SPINY neuron that has glutamate (excitatory) Abscence: Aspiny (or non spiny) neuron that has GABA (inhibitory) What are the spines for: They are a localized area that we can modify--> can change one synapse to respond a specifc thing without changing all the other synapses  --> a specifc relationship " "CNS ""brain and spinal cord " "PNS-basic ""PNS--> SNS+ ANS (autonomic) SNS--> AFFERENT AND EFFERENT  -External environment, (mostly) conscious ANS--> Afferent and efferent -Internal environment, (mostly) non-conscious --->Efferent: Sympathetic nervous system + Parasympathetic  " "Afferent VS Efferent what is it ""Afferent: Sensory, bringing IN information. It travels from the BODY to the BRAIN Efferent: Motor. It travels from the BRAIN to the BODY " "ANS efferents ""Sympathetic: Mobolize energy, be ready for an action, makes ATP in the moment Parasympathetic: Conserve energy, storing energy for the future Not always mutually exclusive/in opposition to one another  -Both target the same thing: Gut, heart, salivary glands " "Are ANS effects always generalized across the body?** ""-Unilateral sympathetic response (AKA r-r, L-L) -something specifc about how SNS responds??? idk ask prof or rewatch " "Clusters and bundles- explain ""Cell clusters:- GRAY matter Nucleus/nuclei (CNS) vs. ganglion/ganglia (PNS)--> BUT basal ganglia is a nuclei bundle of axons:- WHITE matter Tract (CNS) vs. nerve-optic, spinal (PNS) vs. fibres (all- CNS or PNS) --> REMEMBER tract is in brain + spinal cord... NERVE is away from that. " "Anatomical dimensions-look at ipad for better. ""-Always from patients POV <img src=""IMG_0132.jpeg""><img src=""IMG_0133.jpeg""> " "Spinal cord ""Intermittent projections from spinal cord -From brain--> Cervical--> Thoracic--> Lumbar--> Sacral--> Coccygeal -The cervical is the thickest region because it is collecting sensory infromation from bottom(coccygeal) --> it also slowly sends signals posterior which is why is gets thinner --> fewer motor neurons as you go lower Narrows/tapers when from cervical to coccygeal why? (above) -tappers because it is colllecting sensory infor to go post to ant and taperring Ends in cauda equina (tail) -Frays of nerves where neurons need projecting, few axons. Grey/white matter divisions (Grey is inner H) -This is opposite to how the brain is (grey would be outside on brain) Dorsal/ventral organization -Dorsal: sensory information, picks stuff from skin, BUT the signals arent coming from your hand because damage there would be impossible to heal, so it is in DORSAL ROOT ganglion -Ventral: Motor, in gray matter SPinal cord damage: Loss of function related to segment damage, why? ---Higher up means worse damage because you are cutting efferent signals ---In CNS axons will not grow back in adulthood " "How we looked at the brain divisions before (3) ""-Appear early in development -Termed the forebrain, midbrain and hindbrain -However, we have grown to have huge forebrains, so it is now not the best to map out the brain " "5 Major divisions of the brain (just name for now) ""Telencephalon(cerebral) Diencephalon Mesencephalon(midbrain) Metencephalon Myelencephalon (medulla) -THE M's go in alphabetical order*** " "myelencephalon (AKA medulla) ""Adjacent to spinal cord -Lots of tracts (axons-> efferent and afferent, white matter) -Involuntary control of life-sustaining functions-> lots of nuclei that are super important --->Diaphram, heart, early reflexes -Doctors are reluctant to perform surgery here because of that, damages here are often fatal <img src=""IMG_0134.jpeg""> " "The reticular formation ""-Brain stem (mid and hind) AKA the reticular activating system -> LOOK like net or mesh (golgi bruh) ~100 nuclei- big collection Runs from Myelencephalon to mesencephalon -Critical for arousal, wakefeulness, attention, sleep --> NOT for consiousness -Damage tot his regions causes major disruptions to life and/or can be fatal <img src=""IMG_0135.jpeg""> " "Metencephalon ""-Again, lots of tracts, comprised of multiple regions -Also houses reticular formation -There is a ventral side and a dorsal side <img src=""IMG_0136.jpeg""> " "Metencephalon--> VENTRAL side ""The pons: Large white-matter buldge, continuing from spinal cord/medulla Damage? --> Stroke: Muscle weakness, motor control, numbness, sensory and motor <img src=""IMG_0137.jpeg""> " "Metencephalon: DORSAL side ""The cerebellum: 10% of brain volume, >50% of neurons -> very dense, because there is a lot of neurons Critical for motor coordination, more: Comparator of what you meant to do and what you actually do Damage? -Only if in damage in adult life is it noticeable to the person: Gait, impacts coordination, not automatic or efforless-> trying to correct movement <img src=""IMG_0138.jpeg""> " "Mesencephalon (midbrain) ""-Comprised of a roof (Tectum) and a floor (tegmentum) <img src=""IMG_0139.jpeg""> " "Mesencephalon: tectum ""Comprised of two pairs of bumps (colliculi) -the BP of your brain -Superior colliculi: Vision with respect to eye movement ---> visual motor system, salient (bright, flashy, moving), can surpress it but it is outside of conscious control -inferior colliculi: audition with respect to head/body orientation- something comes into your POV or something catches your attention -Outside of conscious access Damage: Paurinauds syndrom: problem mocing eyes? idk/ <img src=""IMG_0140.jpeg""> " "Mesencephalon: Tegmentum ""-Contains part of reticular formation -more fibres -Periacqueductal grey- PAG, amygala -Dopamine producing regions --> 2 nuclei <ul><li>Sustantia nigra</li><li>Ventral tegmental area (VTA)</li></ul><div>---> These have to do with movement, or motivation</div><div>Red nucleus: instincs, crawling, swinging arm, not motor regions</div><div>pattern of function for these: movement, evolutionary important movement</div><div>Damage:</div><div>Parkinsons, drug addiction (VTA)</div> <img src=""IMG_0141.jpeg""> " "Diencephalon ""NOTE: WHERE THE TURN OF ANTERIOR AND POSTERIOR OCCURS- because before on spinal cord the top (anterior) and the tail (posterior) and now it is NOSE(anterior) and the back of the brain (posterior)  ---> we use to refer to anterior as ventral and posterior and dorsal before the switch occurs in this area of the brain! -comprised of two structures: the thalamus and hypothalamus <img src=""IMG_0142.jpeg""> " "Diencephalon : thalamus ""Many nuclei: inputs from sensory systems, cerebellum, basal ganglia, also has motor neurons --ALMOST all afferent at the thalamus before onward to the cortex, except for smell where it goes to the cortex before the thalamus why--> maybe because chemosensation -Often called relay center for sensory info--> We do not need a relay center unless it is doing some sort of other job ---> true, but receives almost as much from cortex as it sends to cortex-> from thalamus to the cortex tons of axons, but the sensory cortex sends back about an equal number out outputs to the thalamus creating a loop that goes from the thalamus to the cortex from the cortex to the thalamus Corticothalamic loops: ----> the idea is that it is a reverberation where A activates B and B activates A over and over again. You also have spirals where you have signals that go from the thalamus to a cortical region then from there to the neighboring part of the thalamus to a neighboring.. etc making a loop that varies in region (btwn cortex and thalamus) -->  critical for processing in awarness, the way that things move from priamary sensory cortex, to secondary, etc.. they also mught be prolly related to concious experiences, remember-present. damage: Vision, hearing large: DOC, AKA brain death where you have sleeping and waking state but there is no obviour awareness <img src=""IMG_0143.jpeg""> "

PSYC 304

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