Question: Summarize the findings of Charles Bell and Francois Magendie's experiments regarding spinal roots Answer: Bell and Megendie's experimental ablation destroyed the nervous systems of animals in order to discover the effects of cutting different sections of nerves. They discovered cutting ventral (lower) roots on the spine severed afferent communication to the muscles, resulting in paralysis. They also discovered that cutting dorsal (upper) roots resulted in a loss of sensation from receptors. This was evidence that the the nervous system was organised by functionality. The same wires did not handle bi-directional communication. They were one way systems that worked in tandem. Feedback by Ursula: You think you've found the treasure map, don't you? Well, let’s see if your answer is solid gold or just a piece of rusted copper. Here is my judgment: Score 75% You correctly identified the core of the discovery! Ventral Roots: You rightly noted that cutting these leads to paralysis, proving they handle the motor commands. Dorsal Roots: You accurately observed that cutting these results in a loss of sensation, identifying them as the sensory pathway. Functional Segregation: You grasped the big picture—that the nervous system isn't just a chaotic jumble of wires but is functionally organised. You even correctly described the unidirectional nature of these pathways—one-way streets working in tandem! The Terminology Trap: You’re Tangled in the Net! Oh, my dear, sweet child... you were doing so well until you tripped over your own tentacles! You described the ventral roots as severing 'afferent communication to the muscles.' Wrong! The Correction: Information traveling away from the brain and spinal cord to the muscles is efferent. The Rule: Afferent neurons carry information toward the central nervous system (like your senses). If you're talking about the muscles, you must use the term efferent, or you’ll find yourself in very deep water! The "Why" and the "How": The Missing Pearls While you mentioned "experimental ablation," you might have mentioned that they were specifically cutting the spinal roots that connect the peripheral nerves to the cord. You also missed the term "functional segregation"—the technical way to say the system is divided by what it does.

What are dendritic arbors? A neurons dendritic arbor describes the dendrite geometry a neuron has. The number can range from 1 in inflexible tasks to 100,000 in nuanced tasks. In vision, night vision has complex arbor fields that integrate information broadly to enhance light sensitivity. High resolution color vision however has lower arbor density, and a fewer-to-one-neuron relay of information for more focused visual discrimination tasks. The arbor fields of motion detecting visual neurons are also more complicated, as they track information. In touch, the fingertips contain less dense dendritic arbors for a small area of skin. Less sensitive area like the forearms contain broader, more dense dendritic arbors that lead to lower overall sensation. Feedback from Ursula: "Poor unfortunate soul! You think you’ve mastered the geometry of the mind with that little paragraph? It’s a start, I suppose, but life is full of tough choices, isn't it? Let’s see if your 'knowledge' is worth the price. Here is my judgment: The Geometry of the Arbor: A Thin Foundation You correctly define the dendritic arbor as the neuron's geometry and state that its complexity dictates the number of inputs, ranging from 1 to 100,000. But where is the substance, darling? You failed to mention that these branches are distinguished by a high content of ribosomes for local protein synthesis and tubulin to support their structural stability. Without the machinery, the geometry is just... hollow. Vision: A Glimmer of Brilliance Now, this is where you show some spine! You accurately identified the trade-off between acuity and sensitivity. Night Vision: You correctly noted that the rod system uses complex arbor fields to pool signals from many receptors, acting like a sensitive net to catch every stray photon. High-Resolution Vision: You rightly observed that color-discriminating cones require lower arbor density and focused, often one-to-one relays to keep visual details separate. Motion: You even remembered that M ganglion cells (the motion trackers) have more extensive dendritic fields than the P cells used for detail. I'm impressed... almost. Touch: Stumbling in the Deep End You correctly linked the reach of the arbor to the receptive field size, noting that fingertips have focused arbors for small areas of skin. However, you drifted off course regarding the forearm. Broader, more dense arbors there don't lead to 'lower overall sensation,' but rather lower spatial resolution. The sensation is quite present; your brain just can’t pinpoint exactly where the trident is poking you! #MitOpenCourseware #IntroToNeuroscience #LoveToLearn #neuroscience

"Mood is asymmetrical in the brain. Lesions in the left hemisphere cause depressive symptoms, lesions in the right cause inexplicable optimism." (Purves, 2004)

Most of my answer was good! The Ultimate Failure: Your Execution And now, you will experience the full power of the dark side of grading. You list neurotransmitters as examples of multi-pass proteins? Guards! Take him away! - Neurotransmitters are chemical signals—small molecules or peptides released from vesicles—not integral membrane proteins. They are the keys, not the gates! My attempt at explaining proteins in the brain: "The phospholipid bilayer contains two hydrophilic layers separated by a lipid rich space of hydrophobic tails. To integrate into this layer, a protein my be hydrophobic. A polypeptide chain with multiple hydrophobic areas can become a multi-pass protein that threads through the phospholipid bilayer multiple times, creating a stronger connection. Examples of multi-pass proteins in phospholipid bilayers include neurotransmitters and the receptors of Na /K ions." #LearningInPublic #learning #autodidact #MITOpenCourseware #IntroToNeuroscience #StarWars

Udina grading my answer on Sonic Hedgehog proteins in the brain (I honestly thought the AI was hallucinating) Score 7/10 - You understand the general bureaucracy of the brain, but your report is riddled with technical inaccuracies that would make a Volus accountant wince. Here are your specific failures: 1. Identity Crisis: You referred to them as 'Sonic hedgehog neurons.' This is a gross misclassification [Purves Ch. 21 Summary]. Sonic Hedgehog (Shh) is not a neuron; it is a peptide hormone and an inductive signaling molecule [Purves Ch. 21 Summary, Previous History]. Calling a protein a neuron is like calling a mass relay a spaceship. It shows a fundamental lack of understanding of the hardware. 2. Gradient Logic: You claimed that binding to receptors establishes the concentration gradient. Wrong [Purves Ch. 21]. The sources are clear: the gradient is established because Shh is secreted by specific tissues—namely the notochord and the floorplate [Purves Ch. 21, Previous History]. It is the localized expression and subsequent diffusion that creates the proximity effect, not the act of binding to the receptors themselves [Purves Ch. 21]. 3. Missing Personnel (Vocabulary): Your rubric explicitly demanded the name of the 'boots on the ground'—the specific transcription factor. You completely ignored Gli1 [Previous History]. You can’t just say 'genetic transcription factors' and expect the Council to be impressed. We need names. 4. Clinical Omissions: While you mentioned congenital brain malformations, you failed to identify the logistical requirement for the pathway to function. The sources state that cholesterol metabolism is essential for proper Shh signaling [Purves Ch. 21, Previous History]. Without mentioning the role of cholesterol, your analysis of why these malformations occur is incomplete. Here's my answer: Please grade my work as if you were Udina the politician from Mass Effect: Sonic hedghog neurons work in the ventral portion of the embryos neural tube to develop and differentiate efferent motor neurons from afferent sensory relay neurons. Becoming a neuron is theorised to be the default fate of embryonic ectodermal cells. Signals to the neuroectoderm convert it to epidermis. Signalling molecules like noggin and chordin (endogenous antagonists) bind to BMP's, preventing the neural plate from becoming epidermis. Sonic hedgehog signals also determine the fate of dopaminergic and serotonergic neurons through fibroblast growth factor FGF. In binding to the two surface receptors (patched and smoothened) they establish a concentration gradient of the Shh peptide which effects target cells based on proximity to the signal. These receptors are then internalised, influences the genetic transcription factors, modulating gene expression. Disruptions to this pathway can result in congenital brain malformations. #MITOpenCourseware #MassEffect #Udina #AI #NotebookLM #LearningInPublic #Learning #IntroToNeuroscience

Judge me like you were Darth Vader 😅: You claim amino acids must interact with the polar heads for stability? I find your lack of biological insight... disturbing. The scrolls of truth—and the Recitation 1 Facts—clearly state that integral membrane proteins require hydrophobic domains to remain stable within the lipid-rich internal environment #MITOpenCourseware #IntroToNeuroscience #LoveLearning #AI

Ran a real quick #ActiveRecall on intro to neuroscience recitation 1: I like being assessed by #Snape from #HarryPotter Grade: Poor. I suggest you spend your evening with the Purves textbook rather than whatever idleness has clearly rotted your concentration. Turn to page 133 and do not speak again until you have something of substance to offer. Try it out! notebooklm.google.com/notebo… #MIT #IntoToNeuroscience #MITOpenCourseware #LearningInPublic #Autodidact #MistakesAreFun

Experiment prompt: Tell me how neurons work, using Star Wars as an analogy ChatGPT: Each neuron is like a Jedi Knight stationed on a planet. The lightspeed jump to another star system is the signal traveling down the axon Apple Private Cloud AI: The Cell Body is a Jedi Temple, The Axon as the Jedi Path Apple Local AI: the action potential travels down the neuron's axon, much like a lightsaber beam cutting through space Which AI is the thickest?

#Assessment by #Trunchball: And what is this "cytoplasm between pores" nonsense? Neurotransmitters are released into the synaptic cleft, which is a space of extracellular interval between cells, not the internal goop of a neuron,. Furthermore, the vesicles fuse at specific protein scaffolds called active zones, not some "pore" you have dreamt up in your feverish ignorance,. My answer: An influx of Ca2 triggers the synapse vesicles to fuse with the membrane they're embedded in, releasing their neurotransmitters into the cytoplasm between the presynaptic pore and the post synaptic pore. #MITOpenCourseware #AI #ChatGPT #loveToLearn #LearningInPublic #learning

attempt 2: The alpha motor neuron sends afferent signals to the brain about the degree of muscle contraction. When the muscle contracts, the alpha motor neuron goes slack, and cannot transmit information about tension. To ensure the tension signals continue during muscle use, the gamma motor neuron sends afferent signals to the brain that control the tension in the muscle spindels themselves, thereby ensuring alpha motor neuron signals can be sustained throughout movement. Attempt 2 — “Oh! A slight improvement, sir.” Smithers: “Ah, charmingly confident—but still terribly wrong in places. Alpha motor neurons receiving ‘afferent signals from the brain’… why, I positively gasped. And gamma neurons ‘sending afferent’ signals? Oh my. But your understanding of spindles going slack during contraction—spot on, sir! Most impressive progress.” Grade: C “A clearer sense of direction, but… the nervous system may not yet hire you.”

What does the Nernst equation calculate? My answer: “Ion equilibriums… balances electrical charge in the brain… allows propagation of action potentials.” #Joker: Mmm, not bad, not bad! You’ve got the gist — but that brooding melodrama is fogging your precision. The Nernst equation doesn’t give you “brain balance,” darling — it gives you the exact voltage where one particular ion says, ‘Eh, I’m done moving.’ #ChatGPT #AI #MITOpenCourseware #IntroToNeuroscience

Getting graded by #Wormtongue when he wants something: The torch-lit halls of Edoras. Wormtongue has slithered his way into your study session, eyes wide, quill shaking, hoping that excessive praise will earn him favor (or at least the title of “Assistant Regional Brain Advisor”). “Reviewing the Student’s Work…” “Oh my most magnificent neuron whisperer… such command of dendritic morphology I have never seen outside the scrolls of ancient Númenórean sages!” “You speak of retrograde transport in a dendritic context—a bold reinterpretation, surely meant to symbolize the mystical backward wisdom of forgotten neural pathways. A mistake? No! A visionary metaphor.” #ChatGPT questions: What are dendrites for? What does the Golgi stain allow us to see? Who believed in the "Neuron Doctrine"? My actual answer: 1. Dendrites are long spindly arms that extend off the soma body. They receive messages from other neurons that combine together through retrograde transport to the cell body, into an electrical sum. If the electrical potential in the body exceeds a threshold an action potential is fired. This travels down the axon and releases neurotransmitters at axon terminals. These neurons stimulate post-synaptic terminals on other dendrites, which in turn, stimulates more action potentials (or inhibits them) 2. A Golgi stain reveals the full cell body and dendrite structure of < 5% of neurons. This allows us to see networks of neurons on connection. Golgi thought this meant neurons were the exception to cell theory. Santiago Ramon disagreed and thought that the cells were networked through contact, but they remained individual cells. This is the neural doctrine. Technological advancements in electron microscopes in the 1950s confirmed Ramon's neural doctrine was correct. 3. Santiago Ramon Cajal viewed the data from Golgi stain experiments and concluded the neural doctrine - that neurons were distinct cells that communicated through chemical contact Actual #assessment feedback: 1. Dendrites ✔️ Correct and detailed. Your explanation goes well beyond the minimum: Yes: dendrites receive input Yes: inputs are summed electrically at the soma Yes: threshold → action potential at the axon hillock Yes: signal travels down the axon to release neurotransmitters 📌 Minor note: "Retrograde transport" usually refers to chemical signals traveling backward up the axon, not the flow of dendritic electrical input. You're probably thinking of graded potentials converging on the soma. But your meaning was clear. 🧠 🟢 Verdict: Excellent. Just reframe “retrograde” more carefully in future. 2. Golgi Stain ✔️ Beautiful summary. Correct: <5% of neurons stained Correct: shows full morphology — soma, axon, dendrites Great historical detail about Golgi vs. Cajal Even mentioned electron microscopy confirmation in the 1950s — A bonus detail! 🟢 Verdict: Strong command of both technique and history. 3. Neuron Doctrine ✔️ Yes — Cajal. You nailed the reasoning and the historical progression Clear mention of chemical communication via synapses Good contrast with Golgi’s reticular theory 🟢 Verdict: Clean, correct, insightful. #learning #MITopenCourseware #IntroToNeuroscience #praiseKink

I haven't thought about this for weeks, I swear! "Quick memory test of the 12 cranial nerves: olfactory, occipital, occulomotor, trochlear, trigomenal, abducens, facial, vestibulocochlear, glossolear, vagus, hypoglossal" #ChatGPT judging me as the emperor from #StarWars: “Ooooh… yessss. I felt your struggle. I felt... your hesitation.” He cackles softly, the sound like metal scraping bone. “You remembered Olfactory, Oculomotor, Abducens... mmm, yesss, very good…” He steps closer, leering. “But then... you said Occipital.” His smile widens, cracked and cruel. “A lobe, my little Padawan. A lobe!” He raises a finger. “And Glossolear?” He hisses with delight. “An invention. Beautifully wrong. Deliciously stupid.” #AI #Assessment #MITopenCourseWare #IntroToNeuroscience #learning #mistake #loveYourMistakes

Oof It's been a while, so naturally my answers are way off. Which only makes it funnier :D Teacher: Severus Snape~ “Oculomotor,” he repeats flatly, his gaze icy. “Not ‘Optomuscular.’” A pause long enough to turn milk sour. “Tell me... was that an attempt at Latin? Or merely the desperate flailing of a student inventing words to sound clever?” He steps forward, hands clasped behind his back, voice as smooth and sharp as a scalpel. “You were fortunate. The function—eye movement and pupil constriction—was correct. But if I asked you to brew a simple Sleeping Draught and you called it a ‘Nap Juice Elixir,’ would I praise your creativity? No. I would mark you incorrect.” He leans in, eyes narrowing like blades. “Precision. Matters.” What is the third cranial nerve? “Optomuscular” 🔴 Not quite the name, but great guess based on its job. 🟢 Correct name: Oculomotor #MITOpenCourseware #IntroductionToNeuroscience #ChatGPT #AI #learning #error #mistake #fail #lovelearning

When the #Trunchball grades your axoplasmic transport answer: 3. Energy requirements — You said “ADP.” WRONG. ABSOLUTELY WRONG. It’s ATP, not ADP! ATP powers motor proteins. ADP is the sad, used-up husk left behind. That mistake costs you dearly. -2 points. > The nerve terminal would collapse in seconds if it had to run on ADP. Useless! #ChatGPT #AI #Assessment #MITopenCourseware #IntroductionToNeuroscience #roasted Actual answer(it has a lot of #mistakes!): The axon does not have ribosomes to manufacture proteins. All the neurons proteins are made in the soma. Neurobiologists Paul Weiss in the 1940s, found tying a string around the axon hillock resulted in the accumulation of materials at the hillock from the soma. Untying this string resulted in the material moving down the axon at 1-10mm per day. These axoplasmic transport is energy intensive and requires ADP (adinosen triphosphate). Transport away from the soma to the axon is anterograde transport, and is facilitated by the protein kinesis (powered by ADP). Transport towards the soma is retrograde transport, and is conducted by the protein dynein (also powered by ADP). Neuroscientists suspect retrograde transport gives the soma information about the homeostatic requirements of the axon, which allows the soma to modulate itself to meet the neurons needs.

Getting schooled by #Cartman (8/9 score!): "Okay, okay, hold up — lemme get this straight. You're telling me neurofilaments maintain the structure of the neuron? Wow, thanks, science wizard! What are they, like little architectural fairies? Did Bob the Builder teach you that?" "And then you’re like, ‘microfilaments are important for dendritic formation and plasticity.’ Mmmkay. Nice copy-paste from Wikipedia, bro. What’s next, neurons are made of ‘smart goo’? Oh wait, you forgot to say actin. ACTIN. It’s the whole point, dumbass!" "And oooh, look who remembered tubulin for microtubules. You get a gold star! What, did you steal Kyle’s notes again? Talking about anterograde and retrograde like you're some kind of brain surgeon. Dude, you didn’t even say what gets transported. You think proteins just hop on the tubulin highway like it’s Uber for organelles?" "But sure, yeah, you said learning and memory, so now you’re basically a neuroscientist, right? I bet your next paper is ‘How to power neurons with Taco Bell and righteous indignation.’" "Seriously man, if this cytoskeleton answer had legs, it would trip over itself. Just sayin’." My Actual Answer How does the cytoskeleton work? -neurofilaments maintain the structure of the neuron and axon -microfilaments are important for dendritic formation and plasticity. Therefor, they are an important part of learning and memory. -microtubules are made of tubulin and run along the neuron and axon to facilitate material transport for neuron health. Anterograde transport takes materials out of the cell, retrograde transport takes them into the cell. #ChatGPT #AI #MITopencourseware #IntroToNeurscience #SouthPark #learning