Japanese Scientists Recreate Human Neural Circuits Using Lab-Grown Brain Models

A research team in Japan developed laboratory-grown models of human brain circuits to study interactions between the thalamus and cortex. The findings provide a new method for examining the formation and function of neural networks relevant to neurological and psychiatric research.

The project was led by Professor Fumitaka Osakada and graduate student Masatoshi Nishimura at Nagoya University. Using induced pluripotent stem cells, the team produced assembloids—miniature brain models—capable of simulating connections between major brain regions.

Within these assembloids, axons from the thalamus extended toward the cortex, while cortical axons reached back toward the thalamus. These extensions resulted in the formation of synaptic connections, replicating key aspects of human brain circuit development in vitro.

The study observed that cortical regions linked to the thalamus displayed more advanced gene expression patterns than those in standalone cortical organoids. This suggests that direct connections between these regions may influence the maturation of cortical tissue in the model.

What the numbers show

• The study was published on November 17, 2025
• Research involved assembloids derived from human induced pluripotent stem cells
• Synchronized neural activity was observed in PT and CT neurons, but not in IT neurons

Neural activity in the assembloid models traveled from the thalamus to the cortex in wave-like patterns. This activity generated synchronized signals across different cortical networks, reflecting organized communication between these brain regions.

Synchronized patterns were specifically detected in pyramidal tract (PT) and corticothalamic (CT) cortical excitatory neurons. In contrast, intratelencephalic (IT) neurons did not exhibit this synchronized activity in the experiments.

The research builds on earlier studies in rodents that identified the thalamus as a key organizer of cortical circuits. By applying these findings to human-derived models, the team created a platform that may help investigate the mechanisms underlying various brain disorders.

The experimental platform may support future studies on the development and function of human neural circuits.

* This article is based on publicly available information at the time of writing.