Neurovisceral Integration Model
150 years ago, Claude Bernard hypothesized the connection between heart and brain. The French physiologist identified in the prefrontal cerebral cortex a regulatory function on the activity of the subcortical circuits related to the motivated response. Many years later, in 2000, Thayer and Lane called this connection the neurovisceral integration model.
This model describes the network of neural structures that controls physiological, cognitive and emotional functions, called the Central Autonomic Network (CAN). This network, therefore, is part of an internal regulation system. Through this system, the brain can control the visceromotor, neuroendocrine and behavioral responses necessary for adaptive behavior.
The central autonomic network innervates the heart through the sympathetic and parasympathetic system. This interaction is considered the origin of heart rate variability (VFC).
The neurovisceral integration model and heart rate variability
VFC is the result of interactions between the autonomic nervous system (ANS) and the intrinsic functioning mechanism of the heart. The activity of the ANS is based on the balance between the sympathetic nervous system (SNS) and the parasympathetic nervous system.
Activating the SNS causes an increase in heart rate by slow, low-frequency pulses. It is also responsible for changes in heart rate under the stimulus of physical and mental stress. The parasympathetic nervous system, on the other hand, lowers the heart rate by means of high-frequency vagal electrical impulses.
In this way, the intrinsic mechanisms of the heart and the joint activity of the sympathetic and parasympathetic (vagus) nerves act on the sinoatrial node.
VFC is therefore defined as the change in heart rate over a defined time interval. The most common method of measuring it is the electrocardiogram.
Recent studies on this model suggest the existence of a relationship between VFC (mediated by the parasympathetic nervous system) and heart rate linked to attention and emotions.
This is how researchers recently established the connection between the brain and the heart. Various studies have shown a reduction in VFC in some pathologies characterized by inadequate emotional regulation.
Physiological regulation according to the neurovisceral integration model
The neurovisceral integration model proposes an association between the regulation of certain systems by means of vagal tone and VFC. In this way, some risk factors for cardiovascular disease or heart attack would be related to a reduced function of the vagus nerve.
Physical risk factors
- Hypertension
- Diabetes
- High cholesterol
Lifestyle-related risk factors
- Smoke
- Sedentary lifestyle
- Overweight
Non-modifiable risk factors
- Age
- Clinical history of cardiovascular diseases
Other risk factors
- Inflammation
- Psychosocial factors
Emotional regulation
According to the neurovisceral integration model, VFC is also linked to emotional regulation. Emotions reflect the level of adaptation of each of us to the significant changes taking place in our environment.
It has recently been discovered, for example, that individuals with higher levels of VFC at rest produce emotional responses that are more context-appropriate thanks to a series of emotion-modulated reflex responses.
In addition, the increase in VFC associated with emotional regulation is accompanied by concomitant changes in the blood supply to the brain in areas identified as important for emotional regulation and inhibitory processes.
Cognitive regulation
Finally, we tried to determine the relationship between VFC and cognitive regulation. Much of the activities we normally perform are in fact related to cognitive processes. These include:
- Working memory
- Mental flexibility
- Sustained attention
Science has found that the higher the level of VFC, the better the performance of executive functions at each level. This is very valuable information for understanding our psyche in particular, and the body in general.
