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kennethreitz
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Publish the Obsidian vault's Knowledge folder as /knowledge (881 notes, 67 folders), with a Knowledge item in the nav and footer. - scripts/import_knowledge.py regenerates data/knowledge from the vault: slugged paths, folder notes as index pages, wikilinks resolved to site links (or plain text), callouts, highlights, and Dataview tables rendered statically. Personal notes are withheld via an exclusion list plus a privacy guard. - tuftecms/core/knowledge.py builds a concept index from note titles and aliases. First mentions on ordinary pages link to their Knowledge note (capped, never in headings, code, links, or sidenotes); Knowledge pages list related notes and where they're mentioned across the site; other pages get a Related Knowledge block. - Knowledge URLs join sitemap.xml (so the sweep test covers them), never displace existing legacy slugs, list alphabetically, and mermaid diagrams render client-side only on pages that have them.
35 lines
4.4 KiB
Markdown
35 lines
4.4 KiB
Markdown
---
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description: The accelerator — the yes that makes learning possible and, unchecked,
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burns the wire it travels.
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source: obsidian-knowledge
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---
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# Glutamate
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> *The accelerator — the yes that makes learning possible and, unchecked, burns the wire it travels.*
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---
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## Overview
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**Glutamate** is the brain's dominant **excitatory** neurotransmitter, the messenger behind roughly half of all synapses and the counterweight to GABA's brake. Its job is to push neurons toward firing, and because nearly every fast excitatory signal in the cortex is glutamatergic, it is less a specialist than the raw currency of neural activity. That ubiquity is also its danger: too much glutamate is **excitotoxic**, flooding cells with calcium until they die, which is part of the damage in stroke and neurodegeneration. Excitation, like inhibition, has to be metered. The health of a brain lives in the **excitation-inhibition balance** — glutamate and GABA held in tension, accelerator and brake — and the two are chemically intimate: GABA is manufactured *from* glutamate in a single enzymatic step, the accelerator's molecule converted into its own restraint.
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## What It Does and How Learning Happens
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Glutamate signals through several receptor types. The **AMPA receptor** carries the fast, workaday excitation of ordinary transmission — open the channel, sodium enters, the neuron leans toward firing. The **NMDA receptor** is the special one, and glutamate's most consequential trick runs through it: **long-term potentiation (LTP)**, the cellular basis of learning and memory. The NMDA receptor opens only when the receiving neuron is already depolarized *and* glutamate is present, because at rest a magnesium ion plugs the channel and only clears when the cell is sufficiently excited. So it fires solely when two events coincide. That coincidence-detection is Hebbian learning made molecular — neurons that fire together wire together — and its downstream effect is often to recruit more AMPA receptors to the synapse, physically strengthening it. Repeated activation potentiates the connection, and a strengthened synapse is, quite literally, a memory laid down in the connective weight between cells. Every skill practiced and every fact retained is glutamate having rewired the map, which is why glutamate is the workhorse molecule behind [Neuroplasticity](/knowledge/neuroscience/neuroplasticity) and why the [Hippocampus](/knowledge/neuroscience/hippocampus) — the brain's memory indexer — is so densely glutamatergic.
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## The Glutamate Hypothesis of Psychosis
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Against the older dopamine story, the **glutamate hypothesis** proposes that Psychosis arises partly from **NMDA-receptor hypofunction** — too little glutamatergic signaling through that specific channel, particularly onto the inhibitory interneurons that normally restrain cortical excitation, so that disinhibition ripples downstream and even distorts Dopamine signaling elsewhere. The strongest evidence is pharmacological: **ketamine** and PCP block the NMDA receptor, and in doing so reliably produce dissociation, perceptual distortion, and symptoms strikingly like schizophrenia, including the negative and cognitive symptoms that dopamine drugs barely touch. The same blockade, at lower doses, gives ketamine its rapid antidepressant effect — thought to work by triggering a burst of synaptic plasticity rather than by any simple lift in a single chemical — a reminder that these systems resist tidy stories. For Kenneth, whose experience of Psychosis the dopamine model only partly explains, the glutamate account is a second lens on the same territory, and the two hypotheses are converging: dopamine and glutamate dysregulation increasingly look like two readings of one disordered circuit rather than rival theories.
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## Related
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- Neurotransmitters — the messenger family glutamate belongs to
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- GABA — its inhibitory opposite, the other half of the balance
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- Dopamine — the older model of psychosis this account complements
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- [Neuroplasticity](/knowledge/neuroscience/neuroplasticity) — the rewiring LTP makes possible
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- [Hippocampus](/knowledge/neuroscience/hippocampus) — the glutamate-dense seat of memory formation
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- [The Brain](/knowledge/neuroscience/the-brain) — the organ this excitatory traffic runs through
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- Psychosis — the state NMDA hypofunction may help produce
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- [Consciousness](/knowledge/ai/consciousness) — what learning and plasticity ultimately shape
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