Global Neuroscientists Map Whole-Brain Activity During Decision-Making in Mice

Research Overview

Neuroscientists worldwide have collaborated to conduct the first comprehensive mapping of whole-brain activity in mice during decision-making processes. This landmark study utilized intracranial electrodes to simultaneously record the activity of over 500,000 neurons distributed across 95% of the rodents’ brain volume.

Key Finding: A Distributed, Coordinated Decision-Making Architecture

Analysis of the neural activity data confirmed a previously theorized model of cognitive architecture: decision-making is not governed by a single specialized brain region, but emerges as a coordinated process across multiple brain areas.

Experimental Design and Data Acquisition

To identify all regions involved in decision-making, researchers trained mice to operate a small steering wheel to align graphical stimuli on a screen. Successful central alignment of the shape triggered a sugar water reward.

Across 12 laboratories, 139 mice were studied, yielding a neural map of 620,000 neurons across 279 brain regions. A subset of 75,000 well-isolated neurons was further analyzed for detailed functional characterization.

Technical Milestones

The resulting neural map exhibits unprecedented resolution in studying brain function during cognitive processes. It represents a critical milestone in two respects:

• Specimen scope: Unlike prior studies limited to fruit flies, fish larvae, or partial brain sections of complex organisms, this work maps the entire brain of a mammalian model.

• Spatial coverage: The 95% brain volume coverage exceeds previous datasets, enabling a holistic view of decision-related neural networks.

Research Implications and Publication

The findings were published in two companion papers in Nature. While the data are not definitive, they establish a foundational framework for neuroscientific investigations of decision-making. The dataset is publicly available, facilitating reproducibility and advanced analyses of complex cognitive abilities.

Expert Commentary

Juan Lerma, a research professor at the Spanish National Research Council (not affiliated with the study), noted: “These results corroborate aspects of brain function previously inferred from limited studies. It is as if we intuited a movie’s ending without seeing it, but now the full narrative is revealed. Notably, decision-making engages far more brain areas than expected, whereas sensory processing relies on more localized regions.”

Human Brain Comparison

The human brain, with ~86 billion neurons (each forming thousands of synaptic connections), weighs ~1.4 kg but consumes ~20% of the body’s resting energy—a disproportionately high metabolic cost for its size. While supercomputers outperform the brain in numerical calculations, no machine yet matches its energy efficiency, adaptive learning, or parallel processing capacity.

This study advances neuroscience toward fully decoding human decision-making, though significant challenges remain.

Original article published in WIRED en Español and translated from Spanish.