McGill Researchers Map 38 Neuropeptide Receptors Across the Human Brain, Revealing How Ancient Signaling Molecules Shaped Higher Cognition
A Nature Neuroscience study from the Montreal Neurological Institute constructs the first whole-brain atlas of 14 neuropeptide families, uncovering a cortical-subcortical gradient and evidence that neuropeptide refinement coincided with the evolutionary emergence of the neocortex.
Overview
Researchers at McGill University’s Montreal Neurological Institute have constructed the first comprehensive atlas of neuropeptide receptor expression across the entire human brain, mapping 38 receptors spanning 14 neuropeptide families. The study, published in Nature Neuroscience on March 17, 2026, reveals that neuropeptide systems are organized along a pronounced cortical-subcortical gradient and that their evolutionary refinement tracks closely with the emergence of the mammalian neocortex and higher cognitive function.
The work was led by Eric G. Ceballos, Asa Farahani, Zhen-Qi Liu, Filip Milisav, Justine Y. Hansen, Alain Dagher, and Bratislav Misic, all based at McGill’s Neuro.
What We Know
Neuropeptides are small protein-like molecules that neurons use to communicate with each other. Unlike fast-acting neurotransmitters such as glutamate or GABA, neuropeptides modulate brain activity over longer timescales, influencing mood, appetite, pain perception, and social behavior. Despite their importance, no prior study had systematically mapped neuropeptide receptor distribution across the whole human brain at this resolution.
Using gene transcription data as a proxy for receptor protein expression, the McGill team reconstructed a topographical atlas covering both cortical and subcortical structures. The atlas encompasses receptors for well-known neuropeptide families including neuropeptide Y, corticotropin-releasing hormone, oxytocin, and opioid peptides, according to the study.
The most striking finding is that most neuropeptide receptors are preferentially expressed either in the cortex or in subcortical regions, establishing a clear anatomical gradient. This cortical-subcortical divide aligns with known divisions in the hypothalamus and maps onto distinct functional domains. Meta-analytical decoding of the neuropeptide receptor maps reveals a functional spectrum: cortically enriched neuropeptides tend to be associated with sensory and cognitive processing, while subcortically enriched systems are linked to reward, homeostasis, and bodily functions, as described in PubMed records of the study.
At the molecular level, the researchers found that neuropeptides preferentially colocalize with metabotropic — that is, slower-acting — neurotransmitter signaling molecules rather than ionotropic ones. This suggests a system-wide correspondence between molecular mechanisms that operate on similar timescales, reinforcing the view that neuropeptides function as modulators that tune rather than drive neural circuits.
The team also examined the atlas through an evolutionary lens. Comparative analysis across species found evidence of extended positive selection for neuropeptide genes in early mammals. The timing of this selection pressure coincides with the expansion of the neocortex, the brain region most associated with abstract reasoning, language, and complex social behavior. The finding suggests that the refinement of neuropeptide signaling was not merely a passive consequence of brain growth but may have been a contributing factor in the evolution of higher cognitive abilities, according to the preprint version of the study.
Why It Matters
Neuropeptide receptors are overwhelmingly G protein-coupled receptors, the single largest family of drug targets in modern pharmacology. By providing a detailed spatial map of where each receptor is expressed, the atlas offers a framework for understanding how neuropeptide dysfunction contributes to psychiatric and neurological conditions including depression, anxiety disorders, autism spectrum disorders, and neurodegeneration.
The cortical-subcortical gradient identified in the study could help explain why certain neuropeptide-targeting drugs have broad or unexpected side effects: a compound designed to modulate a reward-related neuropeptide in subcortical structures might inadvertently affect cognitive processing in cortical areas where the same receptor is expressed at lower levels.
What We Don’t Know
The atlas relies on transcriptomic data — measurements of gene activity — as a proxy for actual receptor protein levels. While gene transcription is a reasonable indicator, post-translational modifications, receptor trafficking, and local degradation rates mean that mRNA abundance does not always correspond directly to functional protein expression at the cell surface.
The study maps receptor distribution at a regional level but does not resolve which specific cell types within each region express which receptors. Single-cell resolution mapping, while technically demanding at the whole-brain scale, would be necessary to determine whether neuropeptide receptors are concentrated on excitatory neurons, inhibitory interneurons, or glial cells in each region.
It also remains unclear how neuropeptide receptor expression changes dynamically — in response to stress, circadian rhythms, aging, or disease states. The atlas provides a static reference framework, and longitudinal studies will be needed to understand how the neuropeptide landscape shifts under different conditions.