Tail behavior can be seen in the most complex forms of life but is generally suppressed by the more sophisticated head behavior. Such tail behavior can be observed in humans in the period around birth, prior to the complete development of their nervous system. Babies display primitive tail behavior that allows them to survive in the uterus. Pediatric neurologists and pediatricians spend a considerable period of their careers monitoring such tail behaviors, as the suppression of such behaviors represents the maturity of the nervous system while the retention of tail behaviors in humans can mean developmental delays or injury.
I recall my pediatric neurology professor saying that these primitive behaviors comprising tail behavior are inhibited by higher centers in the brain as these centers become mature. The failure to inhibit such tail behavior indicates a malfunction in the higher centers. The frontal lobe represents the highest center of head behaviors and functions as the command center for most of the activities that make us truly human. When the frontal lobes fail to work properly, tail behavior returns, hence the name frontal release signs. A return of tail behavior after it has been inhibited highlights a new injury to the nervous system. Primitive tail behavior seen in adults can occur after the higher cortical centers are damaged and no longer can inhibit or control lower tail centers. Individuals with an injury to the frontal lobe in the brain can see a return of the primitive frontal release signs, such as the suck reflex, grasp reflex, and rooting reflex. In TBI context, the frontal lobe is one the most common parts of the brain to be injured due to its location in the front of the head. It is subjected to many forces in, say, a motor vehicle accident and in many sporting activities.
Frontal release signs are now used in the profession to grossly assess the presence of injury in the frontal lobe and notates a disruption in the structural and physiological functioning of the brain. Injury to the frontal lobes represents some of the highest forms of brain hierarchical disorganization.
Table # 9 – Examples of “Tail” behaviors
| Reflexes | Description | Name |
| Suck reflex seen in children | This is seen when an object such as a pacifier or mothers’ breast or the nipple from a bottle used for feeding is placed in a baby’s mouth, invoking a sucking response. This reflex is a primitive reflex seen in animals to allow for the young to get food from the mother, as the animal is not yet in a position to seek out its own food. Over many years, early sucking has come to be associated with animal survival. | Frontal release sign |
| Grasp reflex | This is used to maintain balance when holding on to objects to maintain posture. Babies grab objects automatically when placed in their hands. In fact, this reflex is so powerful that an adult with their two index fingers can lift a child with the child grasping the two index fingers of the adult. | Frontal release sign |
| Rooting reflexes | Stroking the corner of the face causes the head and neck to move towards the area being stroked. | Frontal release sign |
| Babinski reflexes | This refers to the fanning of the toes when the bottom of the feet is stroked. This reflex is inhibited when a child starts to stand and walk. | Upper motor neuron sign |
Humans have achieved the highest form of power in nature due to the development of head behavior through the processes of phylogeny (how we evolve over time and generations) and ontogeny (how we evolve from conception through adulthood and to our death). This head behavior allows us to develop social order, build family units, communicate at the highest level, survive, and protect ourselves. While some tail behavior can integrate with more complicated behaviors from the higher centers, without the presence of such higher centers, our basis for being human does not exist. A patient in a comatose or vegetative state generally exhibits tail behavior only and not head behavior. A coma or vegetative state occurs when their head behavior becomes absent to the point that there is little to no control over tail behavior. Complete brain death occurs when there is no tail behavior or head behavior, starting from the level of the brain stem up to the cerebral cortex.
Pillars of the BHET methodology
THERE ARE SOME fundamental principles that form the pillars of the BHET method:
1. The multi-domain and multi-dimensional approach – brain hierarchy and function: The nervous system functions in a hierarchical manner, and the disruption of this hierarchy forms the basis of improper brain/nervous system function. Defining the hierarchical order of brain functioning forms our understanding of the following:
• The level of disorganization of the brain and its functions
• Where we are in the recovery process
• The prognosis and quality of life after injury
• How to predict outcomes and determine who will improve and not improve and to what extent
• When and how to start and stop treatment
• How to sequence, order, modify, and proceed with the best available treatment
• Helps us define the course of natural history following TBI and concussion
Due to the complexity of the human brain and its functions and to better understand the brain’s hierarchical organization, the BHET method was designed by categorically organizing the nervous system as per the following:
• Dimensions
• Sub-dimensions
• Levels
• Sub-levels
• Domains
A dimension according to the BHET method is a categorization of nervous system order that stands alone, such as brain anatomy.
A sub-dimension is the components that make up the dimension, such as gross anatomy (macro view) and histology (micro view). The gross anatomy represents what you can see with the naked eye. The histological anatomy is what you cannot see with the naked eye but can see microscopically. In this case, the anatomic dimension will have two sub-dimensions: the gross anatomic sub-dimension and the histological sub-dimension.
A domain consists of multiple dimensions that are grouped together for the purpose of establishing relationships. For example, the combination of anatomy and physiology to better understand how the brain functions will be considered one domain.
A level provides for an ordinal description in the form of “high to low,” “low to high,” “complex to simple,” or “simple to complex”. Examples of anatomic levels are the following hierarchical levels of the brain, i.e., the cerebral cortex (the highest level) vs brain stem (middle level) vs spinal cord (lowest level).
Sub-levels are the elements that comprise a level. The “head to tail” description of the title suggests that the levels of functioning on a hierarchy start from the most complex and go to the simplest, hence the title of this work.
Thinking through the concept of dimensions and domains is perhaps the most uninteresting part of this work, but it represents the core