Lab Spotlight: Mapping Decades-Long Neuronal Maturation in the Human Cortex
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Figure. Members of the Raimondo Lab, Department of Human Biology, University of Cape Town.
Meet the Raimondo Lab at the University of Cape Town
The Raimondo Lab is based in the Division of Cell Biology, Department of Human Biology, at the University of Cape Town’s medical campus in South Africa, led by Associate Professor Joseph Raimondo, Head of the Division of Cell Biology. The lab is a team of around 8–10 researchers working at the interface of cellular neuroscience, electrophysiology, and human brain tissue research.
Studying Human Cortical Circuits From Neurosurgical Tissue
A central focus of the Raimondo Lab is understanding how human cortical circuits develop and function. Through collaboration with local hospitals, the lab gains access to small pieces of human brain tissue resected during neurosurgical procedures — using the least affected portions to investigate the electrical properties and circuit organization of neurons in the developing human brain.
This work lets the lab study fundamental aspects of neuronal and circuit maturation, and build a clearer picture of the biological context in which pediatric neurological disorders arise, including focal cortical dysplasia and epilepsy.
Whole-cell patch-clamp electrophysiology in acute human and mouse brain slices
Neurosurgical tissue collaboration with hospitals in Cape Town
Organotypic mouse brain slice culture for modeling disease processes
Preserving Human Cortical Architecture for Electrophysiology
Human cortical tissue presents a specific technical challenge: it’s covered by the pia mater, a tough membrane tightly attached to the cortical surface. With conventional vibratomes, removing the pia can take significant time and risks damaging the underlying tissue.
The Compresstome made this scale of work possible: full gyral sections, sliced intact and ready for recording.
“In my previous lab we were using the vibratome, but it didn’t involve agar embedding, so the tissue sat slightly loose and was very prone to pia blocking the blade, cutting skewed slices, or even pushing the specimen off its mount. What I like about the Compresstome technique is that you hold the slice from all angles in one spot, so you can cut through neatly, and it decreases the time you need to spend removing the pia.” — Dr. Thijs Verhoog, Electrophysiology Researcher, Raimondo Lab
Human tissue slice in the lab’s recording chamber.
The Raimondo Lab uses the Compresstome to prepare acute brain slices from both mouse and human tissue. Its agarose embedding stabilizes tissue effectively enough that the lab can slice through it without extensive manipulation — particularly valuable for preserving the structural integrity of cortical gyri. Using larger specimen tubes, the lab routinely obtains full gyral sections as viable acute slices, an important advantage for electrophysiological recordings. The lab also relies on the Compresstome for mouse organotypic slice cultures, including recent work modeling neurocysticercosis, the most prevalent parasitic infection of the central nervous system and a leading cause of adult-acquired epilepsy worldwide, particularly in the Global South (read it on eLife).
Enabling Discovery: The Compresstome® in Action
A human cortical neuron captured during a live electrophysiological recording, in an acute slice prepared on the Compresstome. This is the kind of cell the Raimondo Lab studies to trace how neuronal properties change across the human lifespan.
Over eight years of Compresstome use, the Raimondo Lab has built one of the largest electrophysiological datasets of human cortical neurons in existence — recordings spanning from infancy through late adulthood. That dataset is the foundation of the lab’s latest work, now available as a preprint.
A human cortical neuron captured during a live electrophysiological recording, in an acute slice prepared on the Compresstome. This is the kind of cell the Raimondo Lab studies to trace how neuronal properties change across the human lifespan.
Research Highlight: Human Neurons Undergo Protracted Maturation Into Adulthood
In a study led by Matthijs (Thijs) Verhoog and Joseph Raimondo, the lab performed whole-cell patch-clamp recordings from surgically resected human temporal cortex, spanning subjects aged approximately 3 months to 73 years. They found that supragranular pyramidal neurons — a cell type with emerging human-specific specializations — undergo pronounced neoteny of their functional properties, with physiological maturation continuing well into adulthood.
Comparing human and mouse developmental trajectories directly, the team found human neurons mature physiologically on a timescale hundreds of times slower than mouse, and 2–6 times slower than would be predicted from anatomical brain growth differences between the species alone. A neuron subtype thought to be human-specific, with electrophysiological traits that enhance computational capacity, was found to appear only in late adolescence or early adulthood. The findings suggest that this extreme protraction of neurophysiological development is itself a fundamental evolutionary adaptation supporting humans’ extended cognitive maturation (read the preprint on bioRxiv).
Looking Ahead
The Raimondo Lab continues to expand this dataset and its investigation into how disruptions to typical circuit maturation contribute to pediatric neurological disease. By combining rare access to living human cortical tissue with controlled mouse models of disease, the lab is building a foundational picture of how human brain circuits mature — and how that process goes wrong.
A member of the Raimondo Lab preparing a specimen on the Compresstome
We’re proud the Compresstome has supported this work for the past eight years, and we look forward to seeing where it leads next.
Connect with the Raimondo Lab & Learn More About Human Cortical Tissue Research
Interested in learning more about the Raimondo Lab’s research, exploring potential collaborations, or working with human cortical tissue in your own lab?
Our scientific team would be happy to connect you with the featured researchers or discuss how Precisionary Instruments can support your experimental goals.
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