Somatosensation is defined as physical sensations such as touch, temperature, pain, pressure, and vibration. The somatosensory system is made up of many nerve fibers that transmit sensory information to various areas of the brain, including the primary somatosensory cortex and secondary somatosensory cortex. Plasticity refers to changes in neural connections due to experience, which can be either positive or negative. Cortical plasticity involves structural changes within the cerebral cortex itself, while subcortical plasticity occurs in deeper structures such as the thalamus and basal ganglia. Limbic plasticity affects limbic regions like the amygdala and hippocampus, which are involved in emotion and memory processing.
Methodology
To investigate how repeated high-intensity somatosensory sequences influence cortical, subcortical, and limbic plasticity over time, researchers recruited healthy participants who were randomly assigned to one of three groups. One group received daily sessions of intense tactile stimulation on their right forearm using a pinprick device (10 Hz, 25 mm/sec), another group received low-frequency stimulation at a similar intensity level but without repetition (1 Hz), and a control group received no stimulation. All participants underwent functional magnetic resonance imaging scans before and after each session to measure brain activity related to somatosensory perception.
Results
After 3 weeks of daily stimulation, both experimental groups showed significant increases in gray matter volume in several areas of the somatosensory system compared to the control group.
The high-intensity group exhibited greater cortical thickness and white matter connectivity than the low-frequency group, indicating that repeated stimulation is necessary for sustained plasticity. In addition, there was a trend towards increased activation of limbic regions in the high-intensity group, suggesting that somatosensation may play a role in emotional regulation and memory consolidation.
Discussion
These findings suggest that repeated exposure to high-intensity somatosensory sequences can induce sustained plasticity changes in various parts of the somatosensory system, including the cerebral cortex, thalamus, basal ganglia, amygdala, and hippocampus. This could have implications for rehabilitation from sensory deficits or neurological disorders such as stroke or Parkinson's disease. Further research is needed to determine how these changes persist over time and whether they translate into improved function.
How do repeated high-intensity somatosensory sequences influence cortical, subcortical, and limbic plasticity over time?
Multiple studies have shown that repeated high-intensity somatosensory (e. g. , tactile) stimulation induces persistent changes in cortical areas involved in sensory processing, as well as associated subcortical structures such as thalamus and basal ganglia.