The Cortex's Inhibitory Control: Regulating Posture, Stress Response, and Muscle Tone for Human Function

This podcast episode delves into the critical role of brain inhibition, particularly by the cortex, in regulating fundamental human functions. The speaker emphasizes that the vast majority of brain cells are inhibitory, designed to prevent the system from running rampant. Four primary areas of cortical inhibition are outlined: anterior flexor muscles above T6, posterior flexor muscles below T6, the intermediolateral cell column (IML) responsible for the stress response, and the inhibition of inhibition of anterior horn cells which regulate muscle tone. These inhibitory processes are presented as essential for maintaining balance and control within the nervous system.

The discussion elaborates on how these inhibitory functions manifest in daily life and in pathological states. The inhibition of flexor muscles is highlighted as a recent evolutionary development enabling bipedalism, contrasting human posture with that of four-legged animals. Examples like infant posture, age-related postural changes, and the decorticate posture seen in stroke patients illustrate the consequences of impaired cortical inhibition. A key distinction is made between a 'strong' and 'weak' brain, with the former capable of quickly turning off the stress response and maintaining optimal posture, while the latter struggles, leading to prolonged stress states and compromised physical stability.

Practical insights are offered regarding the interconnectedness of brain function, posture, and stress. The speaker notes that stress responses disconnect the cortex, reducing inhibition and leading to defensive, flexed postures (e.g., wrestlers, boxers). Conversely, maintaining good posture can positively influence brain activity and relaxation. The mechanism of 'inhibition of inhibition' for anterior horn cells is explained as the cortex's way of determining basic muscle tone, which directly impacts reaction time and stability, particularly crucial for preventing falls in the elderly.

The broader implications of these neurological mechanisms are significant, touching upon public health and evolutionary biology. The episode underscores the importance of a well-functioning cortex for overall health, stress management, and physical safety, especially in aging populations where falls are a leading cause of injury and death. The content implicitly advocates for practices that support brain health to enhance these vital inhibitory functions, thereby improving quality of life and resilience against physical and psychological stressors.

most brain cells are inhibitory the vast majority

the four things that inhibits... number one is it inhibits anterior flexor muscles above t6... secondly it inhibits the inhibition... of anterior horn cells three it inhibits your mi ml that is your stress response fourth it inhibits secondary stimuli

this is what allows us to be upright to be biped rather than quadruple and this is one of the most recent developments in in evolution

what happens in a stroke when someone has a physical brain lesion that just kills off a whole bunch of brain cells so they lose that inhibition then that shoulder will pull in the arm will bend and the hand will flex this is called a decorticate means you could disconnect in the cortex decorticate posture

when you have a stress response then you're disconnecting the cortex and you're having less inhibition

the brain inhibits those cells [IML] so what does that mean it means that whenever you have a stress response that's going to kick in automatically to save your life... but with a high functioning cortex that can quickly turn off that stress response

the brain ultimately the cortex is what turns off that stress response... it's wired to turn it off but first the brain has to be strong and function

a minus and a minus becomes a plus essentially the brain determines the muscle tone in your body

if you have a good high muscle tone you will catch yourself very very quickly if you have a really slow really low muscle tone and a really slow reaction time your face is going to hit the floor before you know it

falls are the number one cause of injury death in people over 65