Human Tech Tree

Life

Neuroscience & Psychology

51 points from the earliest roots to the research frontier: 35 researched, 3 current research, 7 unsolved and 6 that become possible once they are solved. State of knowledge: October 2026.

Open the interactive tree →

Antiquity3000 BC – 500 AD

  • Brain as seat of thought~400 BCResearchedGreek physicians concluded that thought, feeling and sensation come from the brain, not the heart.

Middle Ages & Renaissance500 – 1700

  • Willis maps the brain1664ResearchedThomas Willis's Cerebri Anatome (1664) described the brain's blood supply and tied brain parts to functions, founding what became neurology.

Industrial Age1700 – 1900

  • Nerves run on electricity1791ResearchedLuigi Galvani showed that frog muscles twitch under electrical stimulation, so nerve signals are electrical.
  • Brain localization (Broca)1861ResearchedDamage to specific brain areas causes specific losses, such as speech, so functions have addresses.
  • Golgi's silver stain1873ResearchedCamillo Golgi's 'black reaction' stained a few whole nerve cells completely, making their branching shapes visible for the first time.
  • Psychology as a science1879ResearchedWilhelm Wundt opened the first psychology laboratory and made the mind a subject of experiments.
  • Neuron doctrine1888ResearchedThe nervous system consists of separate nerve cells that communicate across tiny gaps.

Machine Age1900 – 1945

  • Freud, Pavlov, behaviorism1900ResearchedEarly theories explained behavior through unconscious conflicts or through learned reflexes.
  • First intelligence test1905ResearchedAlfred Binet and Théodore Simon built a test in 1905 to find French schoolchildren who needed extra help, starting psychological testing.
  • Alzheimer's disease described1906ResearchedAlois Alzheimer reported in 1906 a woman whose memory loss came with plaques and tangles in her brain, defining the disease later named after him.
  • Chemical nerve signalling1921ResearchedOtto Loewi's frog-heart experiment (1921) proved that nerve cells signal with chemical messengers.
  • EEG1924ResearchedElectrodes on the scalp record the brain's electrical rhythms in a living person.
  • Penfield's brain map1937ResearchedWilder Penfield stimulated the exposed brains of awake patients and mapped which strip of cortex moves or feels each body part: the 'homunculus'.
  • Operant conditioning1938ResearchedB. F. Skinner showed in 1938 that behaviour is shaped by its consequences: rewards make a repeat more likely, punishments less likely.

Atomic & Space Age1945 – 1990

  • Hebbian learning1949ResearchedDonald Hebb proposed in 1949 that connections strengthen between cells that fire together: the first theory of how learning is wired.
  • How nerve cells fire1952ResearchedHodgkin and Huxley's equations explained how ion flows create the nerve impulse.
  • Psychiatric drugs1952ResearchedChlorpromazine, lithium and later antidepressants showed that chemistry can treat mental illness.
  • Patient H.M. and memory1953ResearchedAfter brain surgery in 1953 Henry Molaison could not form new memories, showing that the hippocampus is the gateway to memory.
  • REM sleep discovered1953ResearchedAserinsky and Kleitman found in 1953 that sleep cycles through stages, including rapid-eye-movement sleep, when most vivid dreams occur.
  • Cognitive revolution1956ResearchedThe mind came to be studied as an information-processing system, ending the dominance of behaviorism.
  • Visual cortex cells1959ResearchedHubel and Wiesel found in 1959 that cells in the visual cortex respond to oriented edges, building images step by step.
  • Split-brain studies1961ResearchedAfter surgeons cut the link between a patient's brain halves in 1961, Sperry and Gazzaniga showed that each half can perceive and act without the…
  • Cognitive behavioural therapy1963ResearchedAaron Beck's work on depression in the 1960s led to a short, structured talking therapy that targets distorted thoughts and has strong trial evidence.
  • L-DOPA for Parkinson's1967ResearchedCarlsson found brain dopamine in 1957 and Hornykiewicz its loss in Parkinson's in 1960; high-dose L-DOPA from 1967 was the first effective treatment.
  • Place and grid cells1971ResearchedJohn O'Keefe found in 1971 that single hippocampal cells fire at particular places; the Mosers added grid cells in 2005, a brain 'GPS' (Nobel 2014).
  • Long-term potentiation1973ResearchedBliss and Lømo showed in 1973 that brief intense activity strengthens synapses for hours or days: a cellular trace of memory.
  • Magnetic brain stimulation1985ResearchedAnthony Barker's 1985 device used a magnetic pulse to make the motor cortex fire through the skull, painlessly; it is now a treatment for depression.
  • Worm connectome1986ResearchedJohn White, Sydney Brenner and colleagues traced all 302 neurons of the roundworm C. elegans and their connections from electron micrographs in 1986.
  • Neuroprostheses and DBS1987ResearchedImplants that stimulate nerves or brain tissue, such as cochlear implants and deep brain stimulation, treat disease.

Digital Age1990 – 2015

  • Large-scale neural recording1990–2017ResearchedWatching thousands of neurons at once: two-photon imaging, calcium sensors and Neuropixels probes record brain activity cell by cell.
  • Functional MRI1992ResearchedMRI can show which brain regions become active during thought, without surgery or radiation.
  • Dopamine and reward prediction1997ResearchedSchultz, Dayan and Montague (1997) showed that dopamine neurons signal errors in predicted rewards, like the error term of temporal-difference…
  • First implanted BCIs2004ResearchedA paralyzed man controlled a computer cursor by thought through an electrode array in his brain.
  • Optogenetics2005ResearchedGenes for light-sensitive proteins let scientists switch chosen neurons on or off with light.

Present2015 – Oct 2026

  • Alzheimer's antibody drugs2023ResearchedLecanemab (2023) and donanemab (2024) clear amyloid plaques and modestly slow early Alzheimer's decline on trial scales; whether this matters…
  • Brain-computer interfaces2023Current researchImplants decode movement and speech intentions from the brain, giving paralyzed people back communication.
  • Brain wiring maps2024Current researchElectron-microscope and AI pipelines have mapped every neuron and synapse of whole fly brains.
  • Psychedelic therapy trials2025Current researchPsilocybin and MDMA, given with therapy, show promising effects in trials but have not yet been approved by the FDA.

Research Frontier · Todayunsolved as of Oct 2026

  • Alzheimer's and brain declineopenUnsolvedDiseases such as Alzheimer's destroy brain cells, and no treatment stops or reverses the decline.
  • Causes of mental illnessopenUnsolvedWe lack biological explanations and objective tests for depression, schizophrenia and other mental disorders.
  • ConsciousnessopenUnsolvedWhy and how brain activity gives rise to subjective experience is still unexplained.
  • How memories are storedopenUnsolvedHow experiences are physically written into the brain and kept for decades is not understood.
  • Regrowing the spinal cordopenUnsolvedCut nerve fibres do not regrow in the adult spinal cord, so paralysis is usually permanent; stimulation and stem cells give partial gains.
  • Simulating a whole brainopenUnsolvedA model built from an animal's wiring diagram and cell physics that reproduces how a real brain works does not yet exist.
  • What sleep is foropenUnsolvedAnimals from jellyfish to humans sleep and too little sleep harms health, yet no one has shown for certain what sleep does for the brain.

If Solvedbecomes possible

  • Consciousness test2040s?If solvedA validated measurement tells whether a patient, an animal or an AI system has subjective experience.
  • Mechanism-based psychiatry2040s?If solvedMental disorders are diagnosed with biological tests and treated with therapies matched to each person's mechanism.
  • Restoring and protecting memory2040s?If solvedImplants and drugs rebuild lost memory and keep dementia from erasing a life's recollections.
  • Sleep medicine by mechanism2040s?If solvedOnce sleep's job is known, doctors can test what a patient's sleep fails to do and treat that cause.
  • Walking again after paralysis2040s?If solvedCombined cell, gene and stimulation therapies restore useful movement and organ control after severe spinal injury.
  • Whole-brain emulationopenIf solvedOne specific brain is scanned in full detail and its digital copy runs on a computer, reproducing that individual's behavior and memories.