Eric Kandel

Eric Richard Kandel is an American scientist, born in Vienna (Austria) on November 7, 1929. He has stood out as a specialist in neuroscience and neurophysiology, receiving a Nobel Prize in recognition of his work. in the year 2000 due to his scientific studies of Aplysia, a species of sea snail that has neural mechanisms that function in a similar way to those of humans.

Origins and formation

Born into a family of Jewish origin, his father decided to emigrate to the United States with the whole family after the Anschluss, the occupation of Austria by the Third Reich, and the first anti-Semitic measures adopted.

In his early days in the United States he was drawn to history, earning his first degree at Harvard University with a dissertation on The attitude towards National Socialism in three German writers: Carl Auckmayer, Hans Carossa and Ernst Jünger. Under the influence of a fellow student of hers and her parents - both psychoanalysts - Kandel became interested in the biology of motivation and the conscious and unconscious processes of memory.

Eric received his MD from New York University and his subsequent training was divided between Neurophysiology and Psychiatry at Massachusetts, Harvard University and Paris. In 1965 he was appointed director of the Center for Neurobiology at Columbia University, in whose laboratory he concentrates his research on neurotransmitters.

Nobel Prize

He was awarded the Nobel Prize in Physiology or Medicine in 2000, along with Arvid Carlsson and Paul Greengard.

Scientific contributions

While elasticity implies a momentary change with a return to the original form, after the interruption of the cause that produced it, plasticity implies the permanence of the change after the interruption of the cause. Hence, neuronal plasticity implies the existence of a cause (learning) that produces a change, while the change tends to last over time (memory). Eric Kandel's scientific works are mainly linked to the study of learning and memory processes. He exposes some of them.

Three types of implicit learning

The habituation to a stimulus, the sensitization to it and classical conditioning can be studied both in animals and in isolated nerve cells.^{[citation needed]}

In Kandel's experiments, he has two types of stimulus to apply to an animal. It is a sound (harmless) and an electrical discharge (harmful), while, in the case of the neuron, the applied stimulus is called S1 and S2 to the (noxious) stimulus applied to it.^{[citation needed]}

The objective is to observe how the neuron and the animal react to a sequence of stimuli (in this case, it is exemplified by the case of the neuron):

Habituation: When the repeated sequence of an innocuous stimulus (S1, S1, S1) is applied to the neuron, both the animal and the cell stop responding to said stimulus.

Sensitization: If a sequence (S1, S2, S1) is applied, after a noxious stimulus (S2, in this case), the animal and the cell sensitized respond with somewhat more vigor to all stimuli, even innocuous ones (for example, S1).

Classical conditioning: If a sequence is applied (S1, S1S2, S1), that is, when a noxious stimulus is repeatedly accompanied by another specific innocuous stimulus (for example, S1S2), the animal and the cell respond to the next innocuous stimulus with the same intensity with which they would respond to it if it were noxious.

Some principles of learning and memory

Kandel relates some of his findings to the basic ideas about knowledge proposed by empiricism and rationalism during the 17th century. Thus, while John Locke maintained that there was no innate knowledge and that everything was due to learning, Immanuel Kant maintained that we are born with certain innate schemata.

Reality proves them both partly right. The anatomy of the neural circuit is a simple example of Kantian a priori knowledge, while changes in the strength of particular connections within that circuit reflect the influence of experience.

Among the principles discovered by Kandel et al., are the following:

1) Changes in synaptic strength underlying behavioral learning may be enough to reconfigure a neural network and its information processing capacity.

2) Coinciding with Cajal's theory, a given set of synaptic connections between two neurons can be modified in opposite directions through different forms of learning; it can be weakened or strengthened, as habituation attenuates the synapse while sensitization and classical conditioning strengthen it. Those lasting changes in the strength of synaptic connections are the cellular mechanisms that underpin learning and short-term memory. Furthermore, because the changes occur at various sites in the neural circuitry corresponding to the withdrawal reflex, memory is not stored in one particular location but is distributed throughout the circuitry.

3) It is found that in the three forms of learning the duration of short-term memory depends on the length of the period of attenuation or consolidation of the synapse.

4) The robustness or tenacity of a given chemical synapse can be altered in two different ways, depending on the nature of the neural circuit activated by learning: a mediating circuit or a modulating circuit.

Kandel writes: "One of the fundamental characteristics of memory is that it is constituted in stages. Short-term memory lasts a few minutes, while long-term memory can last many days or even longer. Behavioral experiments suggest that there is a gradual transformation of short-term memory and, moreover, that transformation is achieved through repetition. Practice implies perfection"