The Neurovisceral Integration Model: The Brain-heart Connection

About 150 years ago, Claude Bernard made a connection between the brain and the heart. The scientist proposed that the prefrontal cerebral cortex had a regulatory function on the activity of the subcortical circuits related to the motivated response. Years later, Thayer and Lane (2000) called this connection the.

In this way, this model would establish a network of neural structures related to physiological, cognitive and emotional regulation. This network is called the Central Autonomic Network (CAN). Thus, this network is part of an internal regulatory system. Through it, the brain can control visceromotor, neuroendocrine and behavioral responses, all of which are necessary for adaptive behavior.

This central autonomic network that we were talking about innervates the heart through the sympathetic and parasympathetic nervous systems. This interaction is considered the source of the heart rate variability (VTC).

The neurovisceral integration model and heart rate variability

It so happens that VTC is, therefore, the result of the interactions of the autonomic nervous system (ANS) and the intrinsic mechanism of the functioning of the heart. The activity of the ANS is based on the balance between the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS).

Activation of the SNS produces an increase in heart rate through slow, low-frequency impulses. It is also responsible for changes in heart rate due to physical and mental stress. On the other hand, the PNS slows the heart rate by high-frequency vagal electrical impulses.

In this way, the intrinsic cardiac mechanisms and the joint activity of the sympathetic and parasympathetic (vagus) nerves act on the sinoatrial node.

For us to understand, for practical purposes, VTC is defined as the variation in the rate of the heart beat during a defined interval of time. The most common way to measure it is from the electrocardiogram (ECG).

Recently, research on this model proposes that there is a relationship between SNP-mediated VTC and cardiac indices of attention and emotion.

This is how recent researchers make this connection between the brain and the heart. Various studies have shown a reduced VTC in some pathologies characterized by inadequate emotional regulation. 

Physiological regulation

In this way, the neurovisceral integration model proposes an association between the regulation of certain systems with vagal function and VTC. Thus, certain risk factors for having cardiovascular diseases or suffering a heart attack would be related to a decrease in the function of the vagus nerve.

Biological risk factors

• Hypertension.
• Diabetes.
• Cholesterol.

Lifestyle-related risk factors

• Smoke.
• Physical inactivity.
• Overweight.

Unchangeable risk factors

• Age.
• History of cardiovascular disease.

Other risk factors

• Inflammation.
• Psychosocial factors.

Emotional regulation

According to the neurovisceral integration model, TCV is also related to emotional regulation. Emotions reflect the state of adjustment of each person to adaptation to vital changes in their environment.

Thus, it has recently been discovered that individuals with higher levels of VTC at rest, compared to those with lower levels of rest, produce more context-appropriate emotional responses through emotion-modulated startle responses.

Furthermore, the increase in HRV associated with emotional regulation is accompanied by concomitant changes in cerebral blood flow in areas identified as important in emotional regulation and inhibitory processes.

Cognitive regulation

Finally, research has tried to determine the relationships between VTC and cognitive regulation. Thus, many of the tasks we perform on a daily basis involve cognitive processes. Some of them are:

• Work memory.
• Mental flexibility.
• Sustained attention.

In addition, research has determined after some studies that, the higher the VTC, the better executive functions of performance at all levels. This constitutes really valuable information for the understanding of our psyche in particular and our body in general.