28-02-2013, 05:13 AM
(This post was last modified: 28-02-2013, 05:46 AM by Adele Edisen.)
Would you-all like to know about a Nobel Prize winner in Physiology/Medicine, J.C. Eccles, 1963, whose hypothesis on synaptic inhibition in the mammalian nervous system was based on the supposition that certain identifiable interneurons existed in the spinal cord, despite neuroanatomists insistence that these neurons, called Golgi Type II interneurons, only exist in the retina of the eye, the cerebral cortex and cerebellum? Santiago Ramon y Cajal, who won a Nobel Prize in 1906 with Camillio Golgi, said they were extremely rare in the spinal cord, and in A Textbook of Neurohistology by Fawcett and Bloom, 1995, the authors do not mention their presence in the spinal cord. David P.C. Lloyd of Rockefeller Institute for Medical Research, and later Rockefeller University University, who discovered direct synaptic inhibition in the myotatic reflex system of the cord in 1941, never accepted Eccles' hyothesis which reversed Eccles own original hypothesis of electrical transmission to a chemical mode for excitation and inhibition. Ralph W. Gerard, M.D., Ph.D., Professor of Physiology at the University of Chicago, and President of the American Physiological Society, did not accept the existence of an interneuron-mediated inhibitory pathway either. The insertion of the Golgi Type II interneuron and the chemical hypothesis was made by Eccles because he did not know the neuroanatomy of the spinal cord nor had he evefr measured the intramedullary (within the cord) conduction delays of the sensory input to the point of synapic contact with motoneurons and intramedullary motoneuron output to the outside.
The central delay from the time of entry into the spinal cord to its exit from the cord in the cat is 0.8 milliseconds in the myotatic relex system; 0.5millisecond of that is due to excitatory and inhibitory sensory input within the cord, and about 0.3 milliseconds is due to electrical conduction over the dendrites, cell body, and axon of the motoneurons. These times would be longer in humans because of the larger distances to be traveled. In the cat, the central delay is due entirely to conduction time, and there is no 'synaptic delay' of 0.3-0.5 milliseconds at the synapse in the reflex system, as is being taught in physiology textbooks for fifty years or so, despite published evidence contradicting the Eccles' hypothesis.
Here is a modern problem which is being perpetrated in the scientific community largely due to research grants from pharmaceutical companies eager to sell drug products which can increase or decrease the excitability of neurons, and there are plenty of those. Yet none of them are accurately known to be involved by excitatory or inhibitory sensory endings at their synaptic boutons. Some amino acids are known as acting in a depressing or stimulating action, but the mechanisms are unknown. There are chemicals involved in the sympathetic and parasympathetic portions of our nervous system which are under hormonal control, but nervous transmission in the somatic part of the mammalian system is basically electrical conduction in nature and hence much more rapid in response, as needed in movements of the body.
An example of the myotatic reflex is the "knee-jerk" reaction when the tendon at the knee is tapped with a rubber hammer, causing a reflex extension of the knee joint by contraction of the quadriceps muscle that lies over the thigh. This is where the quadriceps muscle (the agonist) responds to a stretch, the myotatic reflex.. The sensory nerve carries this infomation to its motoneurons and at the same time a branch from the nerve goes directly to the hamstring muscle motroneurons (antagonist muscles) at the back of the thigh to prevent them from being stimulated to react.
Why is it important to study inhibition? Well, excitation and inhibition are the two basic processes by which the nervous system carries on its functions - from consciousness, hormonal control, digestion, maintaining body temperature, hearing, smelling, seeing, touching, feeling, moving, thinking, inmagining, dreaming, reading, et cetera and et cetera....
I know this is a lot of technical information to get all at once, but if a lay person can understand it, wouldn't you think an expert in the neurosciences could understand it as well? The entire field of neurophysiology has been remiss in their work, having studied only the last five years iof published works and told their graduate students to do the same. The Scientific Method works, if it is allowed to do so.
Just an example.
Adele
The central delay from the time of entry into the spinal cord to its exit from the cord in the cat is 0.8 milliseconds in the myotatic relex system; 0.5millisecond of that is due to excitatory and inhibitory sensory input within the cord, and about 0.3 milliseconds is due to electrical conduction over the dendrites, cell body, and axon of the motoneurons. These times would be longer in humans because of the larger distances to be traveled. In the cat, the central delay is due entirely to conduction time, and there is no 'synaptic delay' of 0.3-0.5 milliseconds at the synapse in the reflex system, as is being taught in physiology textbooks for fifty years or so, despite published evidence contradicting the Eccles' hypothesis.
Here is a modern problem which is being perpetrated in the scientific community largely due to research grants from pharmaceutical companies eager to sell drug products which can increase or decrease the excitability of neurons, and there are plenty of those. Yet none of them are accurately known to be involved by excitatory or inhibitory sensory endings at their synaptic boutons. Some amino acids are known as acting in a depressing or stimulating action, but the mechanisms are unknown. There are chemicals involved in the sympathetic and parasympathetic portions of our nervous system which are under hormonal control, but nervous transmission in the somatic part of the mammalian system is basically electrical conduction in nature and hence much more rapid in response, as needed in movements of the body.
An example of the myotatic reflex is the "knee-jerk" reaction when the tendon at the knee is tapped with a rubber hammer, causing a reflex extension of the knee joint by contraction of the quadriceps muscle that lies over the thigh. This is where the quadriceps muscle (the agonist) responds to a stretch, the myotatic reflex.. The sensory nerve carries this infomation to its motoneurons and at the same time a branch from the nerve goes directly to the hamstring muscle motroneurons (antagonist muscles) at the back of the thigh to prevent them from being stimulated to react.
Why is it important to study inhibition? Well, excitation and inhibition are the two basic processes by which the nervous system carries on its functions - from consciousness, hormonal control, digestion, maintaining body temperature, hearing, smelling, seeing, touching, feeling, moving, thinking, inmagining, dreaming, reading, et cetera and et cetera....
I know this is a lot of technical information to get all at once, but if a lay person can understand it, wouldn't you think an expert in the neurosciences could understand it as well? The entire field of neurophysiology has been remiss in their work, having studied only the last five years iof published works and told their graduate students to do the same. The Scientific Method works, if it is allowed to do so.
Just an example.
Adele