Healthcare (Commonwealth Union) – Researchers have noted that the human brain appears to age more slowly than believed on prior occasions—and this happens in layers—at least in the part of the cerebral cortex that processes the sense of touch.
Scientists from DZNE, the University of Magdeburg, and the Hertie Institute for Clinical Brain Research at the University of Tübingen made this determination via brain scans of both younger and older adults, complemented by studies in mice. Their results, published in Nature Neuroscience, also shed light on how sensory processing changes as we age.
The cerebral cortex, just a few millimeters thick and intricately folded, typically becomes thinner over time. Professor Esther Kühn, a neuroscientist at DZNE and the Hertie Institute indicated that the thinning of the cortex is a classic sign of aging, largely due to neuron loss, which can lead to declines in certain abilities. Generally, it’s assumed that reduced brain volume equals diminished function.
She further indicated that yet they know very little about how the cortex actually ages. Considering how essential it is for daily activities; this lack of knowledge is striking. This is the reason it was investigated applying high-resolution brain imaging.
Together with the colleagues from Tübingen and Magdeburg, Kühn concentrated on the section of the cerebral cortex responsible for processing tactile information, known as the “primary somatosensory cortex. Kühn indicated that this area stretches along the top of the head on both sides, roughly a finger’s width wide, toward each ear. She indicated that this region is crucial for perceiving our own bodies and interacting with the environment and every time she picks up a key, turn a door handle, or even walk, she relies on tactile feedback to guide my movements.
Using magnetic resonance imaging (MRI), scientists achieved an exceptionally detailed map of a region in the cerebral cortex. They accomplished this by using an ultra-sensitive scanner with a magnetic field strength of seven Tesla, capable of capturing tiny brain structures no larger than a grain of sand. The study examined roughly 60 male and female participants aged 21 to 80.
“Until now, it had not been considered that the primary somatosensory cortex consists of a stack of several extremely thin layers of tissue, each with its own architecture and function. We have now found that these layers age differently. Although the cerebral cortex becomes thinner overall, some of its layers remain stable or, surprisingly, are even thicker with age. Presumably because they are particularly solicited and thus retain their functionality. We therefore see evidence for neuroplasticity, that is, adaptability, even in senior people.”
This stacked organization of the primary somatosensory cortex is also present in other regions of the human brain and even in other species. Kühn indicated that from an evolutionary standpoint, this method of processing sensory information appears to be advantageous.
Researchers noted that only the deepest cortical layers showed signs of age-related decline, appearing thinner in older participants compared to younger ones. In these lower layers, a process known as modulation occurs, in which touch signals are either amplified or diminished depending on the situation. Kühn pointed out that this is closely tied to focus and attention. She stated that for example, if she is wearing a ring, she will eventually stop feeling it even though the physical stimulus is still present. She only becomes aware of it again once she deliberately draws attention to it.
Kühn indicated that the upper and middle layers of the cerebral cortex are the ones most directly exposed to outside influences and they remain constantly active because we are always interacting with our surroundings.
She further indicated that in contrast, the deeper layers of the cortex receive less stimulation, particularly as we grow older and interprets the results as evidence that the brain tends to maintain areas that are used frequently.
