In a recent study, researchers examine how the insular cortex (the area of the brain responsible for monitoring internal bodily systems, and the integration of different external stimuli) can affect our awareness to visual stimuli depending on our heartbeat
All of us are familiar with the saying “love is blind,” but is it in fact possible that our hearts are preventing us from seeing everything in our environment? In a recent study published in The Journal of Neuroscience, researchers have conducted a series of experiments that suggest our heartbeats interfere with our awareness of visual stimuli in our environments.
Researchers presented participants with a visual stimulus (in this case a yellow octagon), that would flash onto a screen, present in a head-mounted display. Participants were required to indicate whether the octagon was located above or below a fixed point. The timing of the stimulus presentation was determined by the participant’s heartbeat via an electrocardiogram (ECG). The stimulus was presented 80 times at the same time as a heartbeat (synchronous), and 80 times between heartbeats (asynchronous). In addition, researchers conducted functional Magnetic Resonance Imaging (fMRI) to determine how the insular cortex is affected under the two aforementioned experimental designs. The insular cortex is a part of the brain that is responsible for receiving internal and external stimuli and combining them into brain signals. It is also responsible for monitoring the internal state of the body.
The results indicate that the internal signals of the heart beating interfere with the perception of visual stimuli. When the stimulus was presented synchronously, participants required longer presentation times in order to become aware of the yellow octagon. In addition, their accuracy for octagon location was greatly reduced. The fMRIs also indicated that there was a decrease in the functioning of the insular cortex during synchronous stimulus presentation, indicating a reduction in stimulus integration in the brain.
Why does the brain reduce functioning in the insular cortex when the heart is beating? The researchers of this study believe this helps to reduce conflict in the brain. Since the insular cortex is critical for internal system monitoring, it is important that the brain is able to devote more attention to the heart versus the integration of external stimuli. Reducing brain activity for visual stimulus integration means the brain can focus on ‘listening’ to the heart—a process that is necessary for the persistence of a heartbeat, and thus life. The results of this study provide an interesting perspective into how our awareness is modified by our internal systems. Ultimately, the heart can affect our awareness of visual stimuli in our surroundings.
Written By: Nicole Pinto, HBSc