RAMON Y CAJAL: FOUNDER OF NEUROSCIENCE

 

theme: Spanish neuroanatomist Ramon y Cajal was the founder of modern brain research i.e. neural science or 'neuroscience'. He was the first to suggest that the functions of the brain could be understood by analyzing the functional architecture of the nervous system.

"The first morphological studies of the nervous system were done by the Spanish anatomist Santiago Ramon y Cajal." (Eric R. Kandel and Robert D. Hawkins. 'The Biological Basis of Learning and Individuality Scientific American September 1992 79-86)

                               Cajal was the first to study the nerve cell or 'neuron'  At the end of the nineteenth century it was generally believed that the brain is made up of a continuous net of nerve tissue... 'reticular network' or 'syncitium'.  

    Recent findings in brain research suggest that it is possible to understand the functioning of the brain once there is sufficient explanation for the specific functions of individual nerve cells and their connections. The transformation of neural information and its storage as memory involve only nerve cells and their interconnections. The founder of modern brain research is the Spanish anatomist Santiago Ramon y Cajal who began his studies of adult and embryonic neurons about 100 years ago. (Gerald Fischbach, "Mind and Brain," Scientific American      276: 3, September 1992, 49.)

The great Spanish neuroanatomist Ramon y Cajal considered as the founder of modern brain research  was the first to analyse the functioning of the brain in terms of its architecture. When he began his studies of adult and embryonic neurons... Cajal applied Golgi's silver staining technique to the morphological study of adult and embryonic nerve tissue and observed that only some cells were stained in their entirety. As a result of his findings Cajal proposed that the nervous system is made up of neurons which are isolated cells, but each one independently living its own biological life.. with its independent biological existence...  formulated  his 'neuron doctrine' which states that the nervous system is made up of discrete units... isolated unjoined nerve cells or 'neurons' rather than a continuous net of nerve tissue syncytium linked up with hypothetical 'protoplasmic bridges' as was generally believed at the time. With the silver staining technique, Cajal observed a large variety of  nerve cells or 'neurons' - those with short axons communicating with neighbouring cells, those with long axons projecting to other regions of the brain, those with spindle shaped bodies, those with rounded shape cell bodies and those with highly branched extensions called 'dendrites'... 'dendritic branching' or 'arbors'. He described the neuron as an electrically charged or 'polarized' cell that receives signals on its short branched extensions... 'dendrites', and sends the information along its long unbranched extensions - the 'axons'.

 

 He proposed that the functions of the brain could be understood by analyzing the functional architecture of the nervous system. Applying Golgi's silver staining technique to the study of nerve tissue, he observed that only some cells are stained in their entirety. This led to his formulation of the 'neuron doctrine' which states that the brain is made up of discrete units rather than a continuous net of nerve tissue or 'syncitium' as was originally thought. He described brain cells as electrically charged or 'polarized' cells that receive signals on short branched extensions and send the information along the long unbranched extensions. With the silver staining technique, Cajal observed a large variety of nerve cells or neurons.

Cajal's 'neuron doctrine': neurons are polarized cells... Cajal integrated his knowledge of the action potential into his neuron doctrine. He recognized that the properties of the neuron could be explained in terms of the transduction, conduction and transmission of electrical signals or 'impulses'. As a polarized cell the neuron has the functions of a transducer, a conductor, and a transmitter of electrical impulses all at the same time. The neuron is a transducer because it converts or 'transduces' the stimulus energy from the outside world - the environmental stimulus energy - into electrical impulses. The neuron is a conductor because it propagates or 'conducts' the transduced signals to the cell body and then down the axon. The neuron is a transmitter, because it converts the conducted electrical signals into chemical messages and then conveys or 'transmits' them from one neuron to to a neighboring neuron. He deduced that as a polarized cell, the neuron receives signals on the dendrites and send the information along long unbranched extensions the 'axons'. He proposed that nerve impulses travel from the dendrites of a neuron to its cell body and then along the axon to the dendrites of the neighboring neuron. This flow of information would be a finite process.

 With this suggestion Cajal set the stage for a cellular analysis of the 'reflex arc'.

Nerve impulses are 'electrochemical pulses,' regions of charge reversal travelling along the nerve fiber, also known as nerve 'signals.' (Roger Penrose, The Emperor's New Mind: Concerning Computers Minds and the Laws of Physics, (N.Y. Oxford Univ. Press, 1989),) 

Neurons are connected at specialised contact points the 'synapses'   English physiologist Charles Sherrington (1861-1952) worked out the details of the reflex arc in the spinal cord of mammals  (The Integrative Action of the Nervous System, published 1906). Sherrington described the specialized contact points between connecting neurons and introduced a term derived from the Greek word meaning 'to clasp' i.e. 'synapse'.

 Since the 1940s techniques have been developed for studying individual neurons and the synapses which connect them. The new techniques have revolutionized the neurosciences and made it possible to analyze neural processes of increasing complexity.

Implications for education impact of brain research or 'neuroscience' on learning theory....

We know today that it is the diverse nature of the neurons which accounts for the brain's complexity.

'brain-based learning'

 'holistic education'

                               

References:

 Cajal The Integrative Action of the Nervous System, published 1906

 Penrose, Roger. The Emperor's New Mind: Concerning Computers Minds and the Laws of Physics N.Y. Oxford University. Press, 1989 pp. 375-392.

Gerald Fischbach, "Mind and Brain," Scientific American 276: 3, September 1992, 49.