Summary: New research indicates that measurable decline in brain transmission speed begins in the 30s and 40s, later than the previously assumed onset around age 25.
Source: University Medical Center Utrecht
Recent findings from University Medical Center Utrecht (UMC Utrecht) suggest that the human brain’s processing speed matures and peaks later than commonly believed. Rather than beginning to slow at about age 25, measurable slowing in transmission speed appears to emerge in the age range between 30 and 40.
These results were published in Nature Neuroscience and report direct measurements of neuronal transmission speed across a range of ages, providing new, quantitative values that can be used in neuroscience research and computational models.
Clinical technologist Dorien van Blooijs and neurologist Frans Leijten, together with colleagues at UMC Utrecht and the Mayo Clinic, examined how the speed of neural communication changes from childhood into adulthood. Their analysis draws on unique intracranial recordings that allowed precise measurement of signal latencies between brain areas.
Faster connections through development
The team found a clear developmental trajectory in transmission speed. In childhood, measured conduction speeds were around two meters per second. Those speeds approximately doubled to around four meters per second in individuals in their thirties. After this period, the data indicate a gradual deceleration. In short, neuronal communication becomes substantially faster through childhood and young adulthood and only begins to decline later than previously assumed.
Van Blooijs commented, “Our brain continues to mature for many more years than we previously thought.” The study also highlights regional differences in this maturation: association areas like the frontal lobe—important for higher-order thinking, planning and complex task performance—tend to develop later than primary motor regions involved in movement.
“This pattern was suspected from prior imaging and developmental studies, but our data provide concrete timing and speed values,” Van Blooijs added. The change in transmission speed follows a curved trajectory rather than a straight line, emphasizing gradual acceleration followed by eventual slowing.
Direct measurements from cortical stimulation
The research draws on data collected with subdural electrode grids that are sometimes implanted in patients being evaluated for epilepsy surgery. These grids typically contain between 60 and 100 electrodes placed on the cortical surface beneath the skull, allowing both stimulation and recording of localized brain responses.
“By delivering brief electrical pulses to one electrode and recording responses at others, we can map functional connections and determine response latencies,” Leijten explained. “That tells us which areas are connected and, with distance measurements, how fast signals travel between them.”
The dataset used in this study was accumulated over roughly two decades. Initially gathered to guide epilepsy surgery—identifying which areas should be preserved and which could be resected—the recordings also proved valuable as a model of healthy neural transmission when responses from unaffected tissue were analyzed.
In total, the study measured cortico-cortical evoked responses and calculated transmission speeds across association fibers and short-range U-fibers in 74 subjects, allowing for robust age-related comparisons.
Improving brain models and clinical research
Providing concrete values for transmission speed is important for several areas of neuroscience. Computational models of the human brain rely not only on knowledge of which regions connect to one another but also on accurate values for how quickly signals propagate. The numbers reported in this study make it possible to build more realistic models of neural dynamics.
Leijten noted, “With these empirical measurements, researchers can construct better simulations that improve our understanding of normal brain function and disease mechanisms.” The authors expect the findings to benefit epilepsy research directly and to inform broader investigations into developmental and degenerative brain disorders.
Open science and future directions
The study follows Open Science principles: all data from the publication have been made publicly accessible, enabling researchers worldwide to use the measurements for their own analyses and models. Making the dataset available accelerates reproducibility and opens opportunities for new discoveries based on the same empirical foundation.
Leijten emphasized the role of patients in advancing knowledge: “By participating in research, patients help drive progress that may improve treatment options for future patients.” Van Blooijs, whose work is part of her doctoral research, will defend her PhD later this year and expressed enthusiasm about the many possible follow-up studies that could use these data.
About this neuroscience research news
Author:Jerwin de Graaf
Source: University Medical Center Utrecht
Contact: Jerwin de Graaf – University Medical Center Utrecht
Image: The image is in the public domain
Original Research: Open access.
“Developmental trajectory of transmission speed in the human brain” by Dorien van Blooijs et al. Nature Neuroscience
Abstract
Developmental trajectory of transmission speed in the human brain
The structure of the human connectome develops from childhood throughout adolescence to middle age, but how these structural changes affect the speed of neuronal signaling is not well described.
In 74 subjects, we measured the latency of cortico-cortical evoked responses across association and U-fibers and calculated their corresponding transmission speeds.
Decreases in conduction delays until at least 30 years show that the speed of neuronal communication develops well into adulthood.