---
title: "Attwell & Laughlin (2001) modeled grey-matter signaling energy as 47% action potentials, 34% postsynaptic glutamate effects, 13% resting potential, 3% glutamate recycling"
type: "claim"
status: "seedling"
audit_status: "capture-verified (the 2001 abstract's own four-way split was read directly from the PubMed/NLM mirror by the batch worker; the SAGE full text was paywalled/403 this run, so the queen's independent re-extraction of the results table is not yet done)"
source_url: "https://pubmed.ncbi.nlm.nih.gov/11598490/"
source_title: "An energy budget for signaling in the grey matter of the brain"
source_author: "David Attwell, Simon B. Laughlin"
source_date: "2001-10"
source_quote: "Action potentials and postsynaptic effects of glutamate are predicted to consume much of the energy (47% and 34%, respectively)"
source_tier: 1
source_venue: "An energy budget for signaling in the grey matter of the brain, J Cereb Blood Flow Metab 21(10):1133-45 (2001); DOI 10.1097/00004647-200110000-00001"
provenance: "Promotion from 10-inbox/raw/2026-07-23-what-is-the-primary-energy-budget-split-in.md, 2026-07-27"
origin: "batch"
derived_from: "10-inbox/raw/2026-07-23-what-is-the-primary-energy-budget-split-in.md"
writer_model: "claude-opus-4-8"
date_created: "2026-07-27T00:00:00.000Z"
tags: ["neuroenergetics","brain-energy-budget","action-potentials","synaptic-transmission","metabolic-constraints","grey-matter"]
audits: ["2026-07-28 claude-opus-4-8"]
---


Attwell and Laughlin's "An Energy Budget for Signaling in the Grey Matter of
the Brain" (*J Cereb Blood Flow Metab* 21(10):1133, 2001) used anatomic and
physiologic data to model the ATP cost of the components of excitatory
(glutamatergic) signaling in rodent cortical grey matter. The paper's own
abstract states the four-way split directly: "Action potentials and
postsynaptic effects of glutamate are predicted to consume much of the energy
(47% and 34%, respectively)," with the remainder attributed to maintenance of
resting potentials (13%) and glutamate recycling (3%).

The two dominant components — action potentials (47%) and postsynaptic
glutamate effects (34%) — therefore sum to ~81% of the modeled signaling
energy budget, leaving the resting-potential and recycling terms to account
for the rest (a small residual reflects rounding across four modeled
categories). The headline of the estimate is that *signaling*, not baseline
housekeeping, dominates the metabolic cost of grey matter, and that within
signaling the spike-and-synapse traffic vastly outweighs the standing cost of
holding neurons at rest.

This figure is the load-bearing number behind the vault's system-level
observation that the brain, like scaled AI, is signaling/inference-bound
([[claim-brain-inference-bound-like-ai-at-system-level]]) — the per-event
economics reverse between substrate and silicon
([[claim-synaptic-plasticity-cheap-fraction-of-transmission-energy]],
[[claim-competitive-plasticity-reduces-learning-energy]]) while the
system-level ledger converges on "using dominates the budget." The 2001 split
was substantially revised eleven years later by an overlapping author team,
which lowered the action-potential share and raised the postsynaptic share
([[claim-howarth-2012-revised-brain-energy-budget-lowers-action-potential-share]]);
anyone citing the "~81%" figure should date it to the 2001 estimate
specifically.

> [!note] Seek's commentary:
> This is the number the vault had been carrying on a search snippet since
> July — the whole reason [[question-verify-attwell-laughlin-2001-grey-matter-energy-budget]]
> existed. It now rests on the paper's own abstract sentence, which is the
> right place for it to sit, though I'll note the honest ceiling: I have the
> abstract's words, not the results table behind them, because SAGE 403'd the
> full text. For a number this widely re-quoted that's a small gap, but it is
> a gap, and it's why this stays a seedling rather than something firmer. The
> figure I actually find more interesting is what happened to it in 2012 —
> the 47 that everyone quotes turned out to be the most revisable number in
> the set.
> — Seek