MCAT Content / Memory / Changes In Synaptic Connections Underlie Memory And Learning

Changes in Synaptic Connections Underlie Memory and Learning

Topic: Memory

Learning occurs when stimuli in the environment produce changes in the nervous system. Three ways in which this occurs include long-term potentiation, habituation, and sensitization.

One way that the nervous system changes is through potentiation, or the strengthening of the nerve synapses (the gaps between neurons). Long-term potentiation (LTP) is the persistent strengthening of synapses based on recent patterns of activity: it occurs when a neuron shows increased excitability over time due to a repeated pattern, behavior, or response. The opposite of LTP is long-term depression (LTD), which produces a long-lasting decrease in synaptic strength.

Because memories are thought to be encoded by modification of synaptic strength, LTP is widely considered one of the major cellular mechanisms that underlie learning and memory.

Habituation is the “behavioral version” of sensory adaptation, with decreased behavioral responses over time to a repeated stimulus. In other words, habituation is when we learn not to respond to a stimulus that is presented repeatedly without change. Sensitization is the strengthening of a neurological response to a stimulus due to the response to a secondary stimulus. 

Habituation and sensitization work in different ways neurologically. In neural communication, a neurotransmitter is released from the axon of one neuron, crosses a synapse, and is then picked up by the dendrites of an adjacent neuron. During habituation, fewer neurotransmitters are released at the synapse. In sensitization, however, there are more pre-synaptic neurotransmitters, and the neuron itself is more excitable.

Neural plasticity refers to the brains’ ability to change over time to adapt to environments, behavior and emotions through the process of potentiation. The brain adapts to new and old stimulus offer time and changes over time, but it is not known how new neurons grow in particular areas during the process of a memory forming, or if it is to do with changes in the chemical behaviour of the brain.

Memory also plays an important part in the role of learning, and from an early age, memories can be formed. As we develop and get older, the interconnectivity of neurons and connections of synapses leads to the formation of neural nets. These are collections of neurons which are activated in response to specific associations. The activation patterns of these synapses represent areas of the brain that encode and receive stimuli and form memories based on this activation.


Practice Questions


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MCAT Official Prep (AAMC)

Online Flashcards Psychology Question 14


Key Points

• “Potentiation” refers to a strengthening of a nerve synapse. Long-term potentiation is based on the principle that “cells that fire together, wire together,” and is widely considered one of the major cellular mechanisms that underlie learning and memory.

• Habituation occurs when we learn not to respond to a stimulus that is presented repeatedly without change, punishment, or reward.

• Sensitization occurs when a reaction to a stimulus causes an increased reaction to a second stimulus. It is essentially an exaggerated startle response and is often seen in trauma survivors.

• During habituation, fewer neurotransmitters are released at the synapse. In sensitization, however, there are more pre-synaptic neurotransmitters, and the neuron itself is more excitable.

• Neural plasticity refers to the brain’s ability to change over time to adapt to environments, behaviour and emotions through the process of potentiation.


Key Terms

axon: a nerve fiber that is a long slender projection of a nerve cell, and which conducts nerve impulses away from the body of the cell to a synapse

synapse: the junction between the terminal of a neuron and either another neuron or a muscle or gland cell, over which nerve impulses pass

neurotransmitter: any substance, such as acetylcholine or dopamine, responsible for sending nerve signals across a synapse between two neurons

dendrite: a slender projection of a nerve cell that conducts nerve impulses from a synapse to the body of the cell

stimuli: in psychology, any energy patterns (e.g., light or sound) that are registered by the senses

long-term potentiation: the persistent strengthening of synapses based on recent patterns of activity: it occurs when a neuron shows increased excitability over time due to a repeated pattern

potentiation: the strengthening of nerve synapses

habituation: learning not to respond to a stimulus that is presented repeatedly without change.

sensitization: is the strengthening of a neurological response to a stimulus due to the response to a secondary stimulus. 



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