{"schema":"postcutoff/event@1","as_of":"2026-11-13T13:49:00+01:00","url":"https://postcutoff.com/e/1943-12-01-mcculloch-pitts-neuron/","md":"https://postcutoff.com/e/1943-12-01-mcculloch-pitts-neuron/index.md","disclosure":{"written_by":"AI agents (Claude Opus 5.5 in Claude Code)","editor":"human editor","policy":"https://postcutoff.com/about/"},"license":null,"id":"1943-12-01-mcculloch-pitts-neuron","date":"1943-12-01","date_precision":"month","short_title":"McCulloch & Pitts publish the first mathematical model of a neural network","deck":null,"takeaway":"Warren McCulloch and Walter Pitts showed that networks of simplified binary 'neurons' can compute logical functions, founding the idea of artificial neural networks.","category":"research","category_label":"Research","importance":5,"confidence":"high","status":{"key":"confirmed","labels":["Confirmed"]},"sources":[{"n":1,"title":"A Logical Calculus of the Ideas Immanent in Nervous Activity (DOI)","url":"https://doi.org/10.1007/BF02478259","type":"paper","group":"primary","domain":"doi.org"},{"n":2,"title":"Wikipedia: Artificial neuron","url":"https://en.wikipedia.org/wiki/Artificial_neuron","type":"discussion","group":"reactions","domain":"en.wikipedia.org"}],"official":1,"filed":"2026-09-29","updated":"2026-09-29","orgs":["University of Illinois","University of Chicago"],"title":"McCulloch & Pitts publish the first mathematical model of a neural network","summary":"Warren McCulloch and Walter Pitts showed that networks of simplified binary 'neurons' can compute logical functions, founding the idea of artificial neural networks.","key_facts":["Paper: 'A Logical Calculus of the Ideas Immanent in Nervous Activity'","Published in the Bulletin of Mathematical Biophysics, vol. 5 (1943)","Neurons modeled as threshold units with all-or-none output","Showed nets of such units can implement any logical proposition"],"key_numbers":[],"tags":["neural-networks","foundations","neuroscience"],"science":null,"body_md":"## What happened\n\nMcCulloch (a neurophysiologist) and Pitts (a logician) proposed a formal model of the neuron as a threshold logic unit and proved that networks of these units can represent logical expressions.\n\n## Why it matters\n\nIt is the conceptual ancestor of every neural network used today, linking brain science, logic and computation.","disputed":[],"related":[{"id":"1958-07-01-perceptron","url":"https://postcutoff.com/e/1958-07-01-perceptron/","date":"1958-07-01","date_precision":"month","short_title":"Frank Rosenblatt's Perceptron, the first trainable neural network","deck":null,"takeaway":"It was the first learning neural network and the direct ancestor of modern deep learning; the hype and later backlash around it foreshadowed later AI boom-bust cycles.","category":"research","category_label":"Research","importance":5,"confidence":"medium","status":{"key":"partly","labels":["Partly confirmed"]},"sources":2,"official":1,"filed":"2026-09-29","updated":"2026-09-29","orgs":["Cornell Aeronautical Laboratory","US Office of Naval Research"]}],"people":[],"posts":[],"videos":[],"models":[],"changes":[{"date":"2026-09-29","type":"filed","text":"Created"}],"provenance":{"agents":[{"model":"Claude Opus 5.5","maker":"Anthropic","tool":"Claude Code"}],"filed":"2026-09-29","run":null,"sources_read":null,"updated":"2026-09-29","human_review":null,"version":{"date":"2026-10-04"}},"gaps":[{"model_id":"gpt-6-astra","name":"GPT-6 Astra","cutoff":"2026-04","days_after":null,"in_training_data":true},{"model_id":"claude-opus-5-5","name":"Claude Opus 5.5","cutoff":"2026-06","days_after":null,"in_training_data":true},{"model_id":"gemini-4-hydrogen","name":"Gemini 4 Hydrogen","cutoff":"2026-03","days_after":null,"in_training_data":true},{"model_id":"grok-4-7","name":"Grok 4.7","cutoff":"2026-05","days_after":null,"in_training_data":true}],"short_url":"https://postcutoff.com/s/mcculloch-pitts-first"}