New findings on the heterogeneity of human brain cells

Neurons in the cerebral cortex form subtypes that differ in function and connectivity

 

Researchers from Charité – Universitätsmedizin Berlin have new findings to report on the heterogeneity and connectivity of neurons in the human cerebral cortex. Here, Dr. Henrike Planert, first author of the study, and senior author Dr. Yangfan Peng answer questions about the research findings.


What was the research question or scientific inquiry behind your study?

Excitatory neurons make up the majority of neurons in the brain's outer layer (or cortex). We know quite a bit about these cells from studies in rodents. However, little was known about how diverse they are in the human brain and how they communicate with each other. We wanted to understand how the neurons differ from one another in terms of their electrical activity properties and appearance, and whether these differences affect their connections (synapses). In short, we wanted to know if we could describe subtypes and if those would be associated with how the brain processes information.

How did you approach the topic?

Using brain tissue from patients undergoing neurosurgery (with their consent), we measured electrical properties of nearby nerve cells and tested for connections between them. To do this, we activated one cell at a time and recorded the electrical response from up to nine other cells. The cells were then reconstructed under a microscope, which allowed us to compare anatomical features (for example, the size of the cell body or the length of the cells' branches).

What did you discover?

The results revealed a great diversity among nerve cells and their synapses. Based on these differences, we describe four subtypes distinguished by their electrical properties. We also found that the subtypes communicate with each other in different ways, much like specialized team members. For example, one subtype appears optimized for gathering information based on its anatomy and connections, while another excels at distributing incoming information to other nerve cells.

Was there anything that surprised you?

The cellular and synaptic diversity within a single cell type is greater than we expected. This pattern holds true across different individuals. This diversity can be functionally important: studies suggest that greater diversity can enhance information processing.

What’s your takeaway?

Nerve cells in the human brain's cortex differ from each other more than expected – likely more so than in mice. They form subtypes that communicate with each other in specific ways. Such complexity provides advantages for processing information. Based on this better understanding of the properties and interactions of nerve cells, disease-related changes and their effects on brain function can also be studied.

 

Contact

Dr. Henrike Planert  & Dr. Yangfang Peng
Institute of Neurophysiology
Charité – Universitätsmedizin Berlin


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