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  1. The reptilian brain is a pseudoscientific concept based on two misconceptions – the first is that there are parts of the brain that appeared in reptiles, namely the midbrain (sometimes you can find other parts in the reptilian brain, such as the cerebellum), while in fact the midbrain appears already in fish, and the second is that in humans the reptilian brain makes some behavioral decisions.

    The main functions of the midbrain are designed to perform the following role:

    * Touch functions. The load for sensory sensations is borne by the neurons of the four-holmia nuclei. They receive signals from the visual and hearing organs, the cortex of the hemispheres, the thalamus, and other brain structures via conducting pathways. They provide accommodation of vision to the degree of illumination, changing the size of the pupil; its movement and head turns in the direction of the irritating factor.
    * Wire transfers. The midbrain plays the role of a guide. Basically, the base of the legs, the core and the black substance are responsible for this function. Their nerve fibers are connected to the cortex and the underlying brain regions.
    * Integrative and motor skills. Receiving commands from sensor systems, the cores convert signals into active actions. Motor commands are given by the stem generator. They enter the spinal cord, which allows not only muscle contraction, but also the formation of body posture. A person is able to maintain balance in various positions. Reflex movements are also performed when moving the body in space, helping to adapt so as not to lose your bearings.

    There is a center in the midbrain that regulates the degree of pain. Receiving a signal from the cerebral cortex and nerve fibers, gray matter begins to produce endogenous opiates that determine the pain threshold, raising or lowering it.

    Reflex functions

    The midbrain performs its functions through reflexes. With the help of the medulla oblongata, complex movements of the eyes, head, trunk, and fingers are performed. Reflexes are divided into:

    * visual;
    * auditory;
    * sentinel (indicative, answering the question ” what is it?”).

    They also provide a redistribution of skeletal muscle tone. There are the following types of reactions::

    * Static reflexes include two groups — posotonic reflexes, which are responsible for maintaining a person's posture, and straightening reflexes, which help to return to the usual position if it has been violated. This type of reflex regulates the medulla oblongata and spinal cord, reading data from the vestibular apparatus, when the neck muscles, visual organs, and skin receptors are strained.
    * Statokinetic. Their goal is to maintain balance and orientation in space while driving. A striking example: a cat falling from a height, in any case, will land on its paws.

    The statokinetic group of reflexes is also divided into types.

    * When linear acceleration occurs, the lift reflex occurs. When a person quickly rises up, the flexor muscles are strained, and the tone of the extensor muscles increases with a decrease.
    * During angular acceleration, for example, when rotating to maintain visual orientation, nystagmus occurs in the eyes and head: they face in the opposite direction.

    All reflexes of the midbrain are considered to be innate, that is, unconditional types. The red core plays an important role in integration processes. Its nerve cells activate the muscles of the skeleton, help to maintain the usual position of the body and take a pose to perform any manipulations.

    The substantia nigra is involved in managing muscle tone and restoring normal posture. The structure is responsible for the sequence of acts of chewing and swallowing, the work of fine motor skills of the hands and eye movements depend on it. Substance involved in the work of the autonomic system: regulates the tone of blood vessels, heart rate, respiration.

    As you can see, no decisions about behavior are made here.

    The limbic brain is probably the limbic system. You can read more about it here:

    And what is the mind, I think no one will say, this is largely an intuitive concept and there are many different attempts to describe it, ranging from concepts according to which the mind is an illusion and ending with concepts of the mind as a supernatural ability bestowed by a higher power, with all the intermediate options.

    As for how many brains we have – brain is just a term, the names of many structures in the body contain the word “brain” in the name – spinal cord, bone marrow, midbrain. All parts of the brain end of the central nervous system located in the head are combined under the term “brain”. In common parlance, it is simply called the “brain”, without specifying.

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