Imagine what it would be like to need to repeatedly learn the names of your friends and family, how to clean your teeth or how to use cutlery. For learning to stick, it needs to be stored in memory. Memory enables us to perform daily tasks and to remember information without having to learn it afresh every time we need to use it. To understand how learning and memory- making actually occur, it is important to understand the changes that happen in the neurons of the brain.
STUDY DESIGN DOT POINT
neural plasticity and changes to connections between neurons (including long-term potentiation and long- term depression) as the fundamental mechanisms of memory formation that leads to learning
The work of Eric Kandel and his colleagues showed the cellular basis of learning and memory formation in the aplysia (also known as the giant sea hare, or sea slug). The aplysia is ideal to study because its nervous system has only 20000 very large neurons compared to more than one billion neurons in humans. Kandel found that learning in the aplysia was demonstrated by strengthened synapses in the sensory neurons and motor neurons in response to the repeated touch of a glass rod. The greater the number of learning trials, the more readily activated its presynaptic and postsynaptic neurons became. The experiments by Kandel showed that the changes in the neurons of the aplysia lasted for several weeks. This was evidence of primitive long-term memory.
Kandel was the first to show that in long-term memory formation and in learning, individual neurons change in their structure, increase the number of synaptic connections with other neurons, and strengthen the synaptic connections between each other. Kandel’s research was done with a simple organism (aplysia), which has a brain structure that is very limited in its capacity to encode and store long-term memory. Human long-term memory formation and learning requires a highly sophisticated brain that has a large and complex cerebral cortex.
Kandel’s work built on the research findings made 60 years earlier by Donald Hebb. According the Hebb rule, memories are formed by anatomical changes to the neurons and their synapses. The stimulation of particular neurons leads to an increase in both the quantity and sensitivity of particular neuron receptors. The changes strengthen the synapse (the link between neurons) within a neuron network. The changes to the synapses also reduce the need for as much stimulation in one neuron to excite another in the future.It is only in more recent times that the Hebb rule has been able to be investigated through the use of modern research techniques. The work by Kandel with a very simple organism like the aplysia enabled future research on the neural basis of memory and learning.