Читать книгу Concussion - Kester J Nedd DO - Страница 22
ОглавлениеUnderstanding BHET? From head to tail…
FOR JUST AS long as I have practiced medicine as a neurologist, I have been involved in the evolution of the information technology industry in health care. I have run companies involved in software development, data center operations, and connectivity between data systems. Our computer engineers and programmers would often be surprised that as a neuroscientist, I could understand the inner workings of computers and use that understanding to help troubleshoot certain dysfunctional challenges at our data center. Based on my experience in the fields of computer science and neuroscience, I have realized that computer developers and designers must have understood the inner workings of the nervous system in order to design computers. Computers at their core have a hierarchical design and function in a similar manner to the nervous system.
Except for in the movies, the one thing computers do not possess, and humans do is a higher cortical function that we call emotions. Emotions are what make us human, and they include experiences such as falling in love, expressing certain forms of judgment, sadness, happiness, pain, and suffering. To understand how computers are set up and operated, what happens when things go awry, and how to fix them, computer scientists hierarchically organize the computer system in terms of “computer dimensions.” Example of computer dimensions include terms such as software (e.g., Microsoft Word), hardware (e.g., Dell Computer Hardware system), communication (Cisco routers), operating system (e.g., Microsoft \windows 2000), processors (computer microprocessors called chips), and storage (hard drive). Neuroscientists have ironically utilized the term “dimensions” in a similar manner to help understand the complexity of the human nervous system and its operation, what happens when there is injury, and how to treat the results of such injury. The concept of the Brain Hierarchical Evaluation and Treatment (BHET) method is based on nervous system dimensions. Here are just a few dimensions to compare and contrast the human nervous system and computer systems:
Table # 8 – Brain and computer systems
| Categories | Computers dimensions | Human nervous system dimensions |
| Input | Keyboard | Sensory system (touch, sight, hearing, etc.) |
| Processors | Micro-processors | Brain systems (frontal lobe processors – executive function) |
| Output | Printer or monitor | Motor function (moving an arm or leg) |
| On–off switches | Plus, and minus switch organization | Stimulation and inhibition switches |
| Operating system | Set of organized rules and systems that give instructions | Physiologic instructions of the nervous system |
| Language system | Codified systems to communicate | Codified system – humans utilize to communicate |
| Storage system | Hard drive | Memory storage system in the temporal lobes – hippocampus |
| Power system | Power supply | Mitochondria in each cell |
| Booting system | Computer power switch | Reticular activating system (wakes up and puts the brain to sleep) |
| Reporting system | Report generation for decision making | Report generation – systems that draw conclusions to make decisions |
Simply put, the BHET protocol is a way to evaluate and treat TBI/concussion based on the hierarchical organization of the nervous system, the changes that occur in such a hierarchy following injury, and the subsequent recovery process and treatment methods. A “head to tail” approach establishes the hierarchal organization that makes us human. Symbolically, structurally, and physiologically, the tail refers to the spinal cord, the lower portion of the brain, and all of the nerves that connect to the brain and spinal cord, carrying messages to (input) and from (output) the nervous system while interacting with the outside world. The “tail” exhibits certain behavior patterns representing the most basic level of behavior that is stereotypical (one track), reactive, reflexive, not as goal-directed, and often executed without conscious thought. An example of a tail behavior is in checking the patella (knee) reflex, often performed by a neurologist tapping on the patella tendon at the knee. You might have wondered why physicians, particularly neurologists, tap you on the knee. Many may find this funny, but this action is actually a measure that tell us whether the higher centers (or the “head”) and the lower centers (or the “tail”) that they influence are connected.
The tapping of the patella tendon from the quadricep muscles produces an automatic involuntary extension of the leg that is not generally under the control of your thoughts.
Here is how the patella reflex works. When you tap the quadricep muscle tendon (patella tendon) at the knee, nerve endings in the quadricep muscle send an impulse (message) via sensory nerves to the spinal cord. Note that sensory nerves receive information from the body and the outside world and send such messages to the spinal cord and/or brain. This sensory message enters the back (dorsal) portion of the spinal cord and is picked up by another nerve cell (neuron) called the interneuron. The interneuron communicates the messages to a third nerve (neuron) at the front (anterior) portion of the spinal cord, which is a motor neuron. Motor neurons connect to muscles, and when impulses are transmitted to such muscles from the motor neuron, there is muscle contraction. In the patella reflex situation, the motor neuron connects with the quadricep muscle, which causes an automatic contraction of the quadricep muscle, resulting in the movement of the leg.
| Image # 9 – Patella Reflex (“Tail” behavior) |
This movement occurs within a second after the patella is tapped by a neurological hammer and is a good measure of the speed at which nerve impulses move through the nervous system. This kind of behavior is simple, without thought, one track, and stereotypical, meaning you will get the same response depending on how hard the knee is hit. This reflex does not really perform a function, but it is part of a broader path in the nervous system, which allows us to move in a balanced and coordinated manner when integrated with higher “head” functions. The interneuron, i.e., the second order of neurons in the three neuronal response, is connected to the higher “head” center through a system of motor nerve cells called upper motor neurons. These neurons connect to higher centers in the cerebral cortex. The connecting track to the brain is referred to as the corticospinal tract. The fascinating way we gain control at the lower levels of the motor system of our limbs comes from some interneurons that excite or stimulate muscle contraction and others that inhibit and shut down motor activities. Input from the corticospinal tracks from higher centers that connect to stimulatory interneurons promotes increased muscle activities, and input from the corticospinal tract that inhibits interneurons inhibits or reduces muscle activity or contractions. When there is damage to the higher centers such as in a TBI or concussion or a stroke, messages from the higher centers are reduced or eliminated, and the local system in the spinal cord takes over.
The corticospinal and reticulospinal tracts, when stimulated, help dampen the patella reflex by eliminating some of the nerve impulses going through. If there is a disconnection between the upper motor neurons and the lower motor neurons, then the patella reflex is not dampened, and the reflex is exaggerated. This is the major influence that the higher centers “head” have on the lower “tail.” In this case, neurologists use the patella reflex to indicate injury at higher centers. So, in the case of a stroke or brain injury where the higher centers are affected, there is limited input passed through the corticospinal tracks. This results in the patella reflex working without inhibition and, thus, causing increased or exaggerated patellar reflex. Other than in patients who are anxious, increased reflexes can mean there is some malfunction in the higher centers, starting from where the corticospinal tract connects at the level in the spinal cord and extending up into the highest centers of the brain – the cerebral cortex.
Another practical example of tail behavior is the vaso-vagal response occurring in Mario’s case when his heart automatically became bradycardic due to increased ICP. This is a kind of stereotypical response that occurs involuntarily.
By contrast, the “head” symbolically, structurally, and physiologically represents the crown of our human existence. “Head behavior” involves the most sophisticated and complex behaviors that make us human and represents what is referred to as the higher cortical functions in neuroscience. These “head behavior” functions include reasoning skills, memory, attention, perception, decision making, and emotions among other sophisticated behaviors.
The BHET method is based on our understanding of the anatomic and physiologic structure of the central and peripheral nervous system and how this structure translates into functional activities and expressions. Notably, the central nervous system comprises the brain and spinal cord. The peripheral nervous system comprises all of the nerve connections that connect the body and the outside world to the central nervous system.
