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Long-Term Memory

For medical students2 min readUpdated 2026-10-10

Long-term memory is a fundamental physiological process that ensures the reliable retention of acquired information over a very long period. This phenomenon is based on a highly complex intracellular cascade of biochemical and structural changes that leads to the formation of an exceptionally stable memory trace resistant to disruption even by strong external influences.

Pyramidal neuronThe key cell where intracellular processes of memory formation take place

BiochemistryTrace formation occurs via protein synthesis along the chain: DNA → RNA → Protein

Stress resistanceNot erased by electroconvulsive therapy, general anesthesia, or mechanical brain injury

ConsolidationEnsures the transition of information from a short-term form to a permanent one

Memory Consolidation Process

The formation of long-term memory traces is impossible without memory consolidation. This is a specific physiological process during which acquired information is gradually transferred from short-term and intermediate storage into permanent long-term storage. Successfully consolidated memory possesses several unique and important characteristics:

Acquires a highly stable structural form.
Remains entirely unchanged over a long period.
Is neither distorted nor erased when completely new information enters the brain.

Stages and Factors of Successful Memorization

The physiological processing of information includes several consecutive stages: encoding (memorization), immediate retention, subsequent retrieval, and, ultimately, extinction. To ensure that memory traces are successfully fixed and information is stored long-term, specific stimulating conditions are required:

Repetition. Information fixation is carried out much more effectively with repeated stimulus exposures, especially if these exposures are biologically significant for the organism.
Emotional factor. Acts as a powerful catalyst. If the stimulus has high emotional significance, the consolidation process proceeds at maximum speed, ensuring the most reliable preservation of past experience.

Cellular and Biochemical Mechanisms

Although the exact mechanisms of memory formation are not yet fully established and various theoretical approaches exist in normal physiology, key regularities are distinguished. A critical process is considered to be one in which dominant motivation actively influences the complex intracellular processes of the pyramidal neuron. The activation of these structural processes occurs according to a strictly proactive principle.

At the biochemical level, active functioning of the nerve cell's genetic apparatus is triggered. The reaction chain is as follows:

The DNA molecule is activated.
RNA is synthesized on its template.
Translation of a specific protein is initiated.

The result of this complex chain is robust synthesis of effector protein molecules. These very proteins provide all necessary structural changes both within the synapses themselves and in the neuron soma, which naturally leads to the formation of the engram—a stable memory trace.

Differences from Short-Term Memory

Fundamental physiological differences exist between long-term and short-term memory. Most importantly, long-term memory has an entirely different, qualitatively distinct mechanism of formation at the cellular level.

While the short-term form is extremely vulnerable, long-term memory possesses colossal resistance to external factors. It is neither disrupted nor erased even by severe, extreme insults to the brain that typically cause retrograde amnesia. Such critical impacts include severe traumatic brain injury, therapeutic electroconvulsive therapy, or deep medical anesthesia.

Mnemonic

To quickly memorize the stages of information processing, use the acronym ESRE: Encoding, Storage, Retrieval, Extinction (or Retention, Encoding, Retrieval, Extinction).

Frequently asked questions

How does the physiological mechanism of long-term memory formation differ from short-term memory?

The physiological mechanism of long-term memory differs by structural remodeling of synapses and activation of the genetic apparatus, whereas short-term memory is based on the circulation of nerve impulses.

Characteristic	Short-Term Memory	Long-Term Memory
Basis	Circulation (reverberation) of excitation in a closed loop	Structural changes in synapses and the neuron
Biochemical process	Generation of excitatory postsynaptic potentials	Synthesis of effector protein molecules via the scheme: DNA → RNA → Protein
Stability	Disrupted by external influences (electroconvulsive therapy)	Not impaired by extreme impacts on the brain

Which specific brain structures are responsible for the memory consolidation process?

According to sources, the following structures are directly related to memory consolidation:

Hippocampus — ensures memory consolidation, i.e., the transition of short-term memory into long-term memory; plays a paramount role in the fixation of declarative/conscious memory.
Medial / deep regions of the temporal lobes, especially the hippocampus, — critical for consolidating new information; their bilateral damage impairs the fixation process.
Limbic system and memory pathways, especially the structures of the Papez circuit: pathways from the hippocampus via the fornix to the mamillary bodies, then to the anterior thalamic nuclei and the cingulate gyrus. Damage to the Papez circuit structures is associated with impaired encoding of information and its transfer from short-term to long-term memory.

Which specific proteins and transcription factors participate in the formation of long-term memory?

Based on the provided sources, the formation of long-term memory involves not specific names of individual proteins, but rather the following molecular processes and groups of molecules:

activation of the cellular genetic apparatus via the scheme DNA → RNA → protein;
synthesis of effector protein molecules;
synthesized specific proteins integrate into synaptic membranes or alter the neuron structure;
these proteins provide structural changes in synapses and the neuron, forming the engram;
during memorization, enhanced expression of immediate-early genes is described, and at the long-term memory stage — enhanced expression of late genes.

Specific transcription factors explicitly named as participants in long-term memory formation are not specified in the sources.

Which specific neurotransmitters predominantly provide synaptic transmission during memory trace formation?

According to sources, amino acid neurotransmitters—primarily glutamatergic transmission—are directly linked to memory processes:

Amino acid neurotransmitters account for the largest number of synapses in the central nervous system, over 80% in the cerebral cortex; the main neurotransmitters of this group are glutamate and GABA.
Glutamate is the primary excitatory neurotransmitter; it is localized, among other places, in the cerebral cortex and hippocampus.
NMDA receptors belong to the glutamate system; their functions include neuronal plasticity, integrative brain activity, and memory.

For short-term memory, sources also indicate the generation of excitatory postsynaptic potentials in circuit neurons and the cessation of reverberation upon the development of an inhibitory postsynaptic potential under the influence of an inhibitory interneuron.

What is an engram?

An engram is the structural memory trace in the nervous system. It is formed through the synthesis of effector protein molecules, which induce lasting changes in the synapses and the body of the pyramidal neuron.

How do emotions affect long-term memory?

The emotional factor is one of the most crucial conditions for fixing memory traces. Upon exposure to emotionally significant stimuli, the process of information consolidation occurs most rapidly and effectively.

Is long-term memory destroyed by anesthesia or brain trauma?

No, it is not destroyed. Unlike short-term memory, long-term memory possesses high stability. Extreme impacts on the brain (anesthesia, electroconvulsive therapy, mechanical trauma) can cause retrograde amnesia, but they do not erase already consolidated traces.

Go deeper

Retrograde amnesia: causes and mechanisms of development
Specific structural changes in synapses during engram formation
The influence of dominant motivation on intracellular processes of pyramidal neurons
The role of effector protein molecules in maintaining the memory trace
Modern theories of long-term memory mechanisms