Summary: New research uncovered that the phases of a heartbeat significantly influence brain and motor system excitability.
The study utilized transcranial magnetic stimulation (TMS) on 37 healthy volunteers to observe changes in cortical and corticospinal excitability across the cardiac cycle. They found heightened excitability during the systolic phase, when blood vessels are distended.
This discovery could revolutionize treatments for depression and stroke by aligning them with the cardiac cycle for enhanced effectiveness.
Brain and motor system excitability varies with the cardiac cycle, being higher during the systolic phase.
The study used TMS to stimulate nerve cells in synchronization with heartbeats, revealing a significant brain-heart connection.
These findings offer potential for fine-tuning treatments like TMS for depression and stroke recovery, based on cardiac activity.
Optimal windows exist for action and perception during the 0.8 seconds of a heartbeat, according to research published November 28th in the open access journal PLOS Biology.
The sequence of contraction and relaxation is linked to changes in the motor system and its ability to respond to stimulation, and this could have implications for treatments for depression and stroke that excite nerve cells.
The ways in which we perceive and engage with the world are influenced by internal bodily processes such as heartbeats, respiration and digestion. Cardiac activity can influence auditory and visual perception, and touch and sensory perceptions have been shown to be impaired during the systolic phase of the cardiac cycle when blood vessels are briefly distended.
Esra Al of the Max Planck Institute for Human Cognitive and Brain Sciences, Germany, and colleagues, wanted to understand whether there were changes in cortical and corticospinal excitability — the ability to respond to stimuli — across the cardiac cycle. 37 healthy human volunteers aged between 18 and 40 years received a series of transcranial magnetic stimulation (TMS) pulses — non-invasive short magnetic pulses that stimulate nerve cells — above the right side of the brain.
Motor and cortical responses as well as heartbeats were measured during the pulses and the authors found that higher excitability was recorded during the systolic phase. These simultaneous recordings of brain activity, heart activity, and muscle activity, suggest the timing of heartbeats and their neural processing are linked to changes in the excitability of the motor system.
TMS is used in treatments for depression and recovery after stroke. The research raises questions about whether these could be fine-tuned to improve results, as well as contributing to a greater understanding of brain-body interactions in health and in disease.
The authors add, “Intriguingly, this study uncovers a remarkable connection between the human heart and brain, revealing distinct time windows tailored for action and perception.”
About this neuroscience research news
Author: Claire Turner Source: PLOS Contact: Claire Turner – PLOS Image: The image is credited to Neuroscience News
Cardiac activity impacts cortical motor excitability
Human cognition and action can be influenced by internal bodily processes such as heartbeats. For instance, somatosensory perception is impaired both during the systolic phase of the cardiac cycle and when heartbeats evoke stronger cortical responses.
Here, we test whether these cardiac effects originate from overall changes in cortical excitability.
Cortical and corticospinal excitability were assessed using electroencephalographic and electromyographic responses to transcranial magnetic stimulation while concurrently monitoring cardiac activity with electrocardiography.
Cortical and corticospinal excitability were found to be highest during systole and following stronger neural responses to heartbeats. Furthermore, in a motor task, hand–muscle activity and the associated desynchronization of sensorimotor oscillations were stronger during systole.
These results suggest that systolic cardiac signals have a facilitatory effect on motor excitability—in contrast to sensory attenuation that was previously reported for somatosensory perception. Thus, it is possible that distinct time windows exist across the cardiac cycle, optimizing either perception or action.