Heterosynaptic plasticity

A form of synaptic plasticity involving changes in synaptic strength at synapses not directly activated by a stimulus.

In heterosynaptic plasticity, synaptic pathways that are not specifically stimulated undergo changes (synaptic plasticity) in addition to those who are specifically stimulated.

Heterosynaptic plasticity is a type of synaptic plasticity where changes in the strength of a synapse occur at synapses that were not directly activated by the initial stimulus. This phenomenon is distinct from homosynaptic plasticity, where changes occur at the synapse that was directly stimulated.

Mechanisms

Heterosynaptic plasticity involves complex interactions between different synapses and is thought to be mediated by various mechanisms, including:

• Neurotransmitter spillover: When neurotransmitters released from an active synapse diffuse to neighboring synapses, they can activate receptors at these adjacent sites, leading to changes in synaptic strength.

• Calcium signaling: Calcium ions can diffuse within the dendritic tree of a neuron, affecting synapses that were not directly activated. This can lead to changes in synaptic efficacy through calcium-dependent signaling pathways.

• Neuromodulation: Neuromodulators such as dopamine, serotonin, and acetylcholine can influence synaptic plasticity at multiple synapses, including those not directly involved in the initial activity.

Functional significance

Heterosynaptic plasticity is believed to play a crucial role in various neural processes, including:

• Synaptic homeostasis: It helps maintain overall synaptic balance and prevents runaway excitation or inhibition by adjusting the strength of synapses that were not directly involved in recent activity.

• Memory formation: By modulating synapses that were not directly activated, heterosynaptic plasticity can contribute to the formation of associative memory networks, where the activation of one set of synapses can influence the strength of others, facilitating complex learning processes.

• Neural network development: During development, heterosynaptic plasticity can help shape the connectivity of neural circuits by strengthening or weakening synapses based on the overall activity patterns within a network.

Examples

Heterosynaptic plasticity has been observed in various brain regions, including:

• Hippocampus: In the hippocampus, heterosynaptic plasticity can occur when the activation of one pathway leads to changes in the strength of synapses in a different, non-activated pathway.

• Cerebral cortex: In cortical networks, heterosynaptic plasticity can help integrate information across different sensory modalities by adjusting synaptic strengths in response to complex patterns of activity.

Related pages

• Synaptic plasticity
• Homosynaptic plasticity
• Long-term potentiation
• Long-term depression
• Neurotransmitter
• Neuromodulation