It's been long known in psychology that the structure and functioning of the brain affect how we experience the world, but did you know that our experiences can also affect our neural structures? This process is known as brain/neuronal plasticity. Canadian psychologist Donald Hebb theorised that as we learn, the biology of our brain changes to accommodate new information. He proposed Hebb's theory of learning and neuronal growth.
Let's take a closer look at the biological mechanisms of learning proposed by Hebb and the evidence for his theory.
- First, well will discuss Hebb's theory of learning and neuronal growth.
- We will provide a summary of Hebb's theory, Hebb's theory definition, and discuss the aims of Hebb's theory of learning.
- To conclude, we will delve into an evaluation of Hebb's theory of learning and neuronal growth.
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Hebb's theory of learning and neuronal growth
Donald Hebb's theory focuses on the biological consequences of learning and memory. The central idea of Hebb's theory is that the process of learning, which involves a repeated co-activation of neurons, results in the strengthening of the connections between neurons and allows them to communicate more efficiently.
In short, neurons that fire together, wire together. This manifests in our ability to quickly recall information that we revised or perform actions without much effort after a period of practice.
Hebb's theory definition
Hebb's theory proposes a neural mechanism for learning and memory. According to Hebb, as one neuron repeatedly excites another neuron, a synaptic knob grows at the end of its axon to improve the efficiency of transmission. Memories can be represented by a co-activation of a group of neurons.
This group is called a cell assembly. Repeated activation of a cell assembly strengthens connections between the cells forming a neural pathway. Neural pathways are long-lasting and hold representations of our memories and the things we learn.
Neural pathways are the routes of activation that involve a series of interconnected neurons. They are formed and strengthened during the process of learning.
When we first try to ride a bike, the action may require intense focus and be quite difficult. However, with practice, we become better and the action doesn't require as much conscious effort from us.
According to Hebb's theory, this improvement can be attributed to the formation of neural pathways that allow us to efficiently coordinate our movements and ride the bike.
A similar process occurs when we study.
For example, it might seem incredibly difficult to memorise the entire multiplication table, however, as you practice recalling the information for months or years the knowledge becomes easily accessible and almost automatic.
This is because neural pathways associated with the multiplication table become stronger and faster.
Aim of Hebb's theory of learning
The aim of Hebb's theory was to provide a biological basis for the formation of new memories, development of skills and memory storage. His theory attempts to explain how repetition impacts neural processes associated with memory consolidation and storage.
Hebb's theory explained
Let's look in detail at the neural mechanisms for learning proposed by Hebb.
The structure of neurons
To better understand how the connections between neurons are made we need to examine the structure of neurons. Neurones consist of a cell body (soma), an axon and dendrites.
Dendrites branch out of the cell body and receive information from other neurons. Axons are long cable-like structures that transmit signals from the neuron to other neurons. Two neurons can communicate through the synapse, a gap between an axon of one neuron and a dendrite of another.
The transmission in the synapse occurs through the release of neurotransmitters into the synapse. As axons and dendrites grow they can create synapses with other neurons.
Formation of neural pathways
The strengthening of connections between neurons can be compared to the growth of muscles, the more a muscle is used the more it strengthens and grows. Stronger muscles allow us to perform certain activities more efficiently.
Similarly, with repeated co-activation, the connections between neurons become stronger and the transmission of information between them more efficient. This strengthening of the connection between neurons was proposed to occur through neural growth, the growth of the synaptic knob at the end of the axon.
As more neurons wire together, cell assemblies are created. Cell assemblies involve groups of neurons that will co-activate in response to a stimulus. The co-activation of a cell assembly creates a temporary trace in the brain that represents a memory. This cell assembly representing a unit of memory can be referred to as an engram.
Cell assemblies can be strengthened through repeated activation, forming a neural pathway, a group of interconnected cells, activation of which represents information stored in long-term memory.
Brain plasticity
Hebb's theory supports the notion of brain plasticity.
Brain plasticity is the ability of the brain to rewire itself in order to better adapt to the environment. The early years of development are characterised by great neuroplasticity and neural growth. This process slows down as children become adults, however, adult brains are still capable of plasticity and rewiring.
Brain plasticity involves two main processes:
- Neural growth and neural pruning
The pathways and neurons that are frequently used are strengthened, while the pathways that are not used are gradually pruned or eliminated. In the adult brain, new neurons are generated mainly in the hippocampus, which is the area responsible for learning and memory.
Let's say you used to have a good memory of the multiplication table. However, after a few years of not using or practising this information, you try to remember what is 87 and you struggle to find the answer in your memory.
Since you haven't used this information in a while, the neural pathways representing this memory became weaker or got eliminated completely.
Hebb's theory psychology: Evaluation
Hebb's theory continues to be influential as it produces testable hypotheses that have been supported by behavioural and neuroscientific research. A range of practical applications can also be attributed to the theory. However, the theory has been criticised for reductionism.
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