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Related Concept Videos

Excitatory and Inhibitory Effects of Neurotransmitters01:29

Excitatory and Inhibitory Effects of Neurotransmitters

When an action potential reaches the presynaptic axon terminal, it releases neurotransmitters from the neuron into the synaptic cleft at a chemical synapse. The released neurotransmitter can be excitatory or inhibitory. The critical criteria commonly used to determine whether a molecule is a neurotransmitter at a chemical synapse are the molecule's presence in the presynaptic neuron. Second, its release is in response to strong presynaptic depolarization. And lastly, the presence of specific...
Integration of Synaptic Events01:28

Integration of Synaptic Events

Synaptic integration mainly includes the summation of graded potentials. Graded potentials, regardless of their type, cause subtle alterations in membrane voltage, resulting in either depolarization or hyperpolarization. These incremental changes, when combined or summed, can propel the neuron toward its threshold. Consider, for example, a membrane experiencing a +15 mV shift, causing it to depolarize from -70 mV to -55 mV. In this scenario, graded potentials govern the membrane's ability to...
Chemical Synapses01:26

Chemical Synapses

Chemical synapses are specialized sites between two neurons or between a neuron and a non-neuronal cell like a muscle, glandular or sensory cell.
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
Chemical Synapses01:26

Chemical Synapses

Chemical synapses are specialized sites between two neurons or between a neuron and a non-neuronal cell like a muscle, glandular or sensory cell.
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
Long-term Potentiation01:25

Long-term Potentiation

Long-term potentiation, or LTP, is one of the ways by which synaptic plasticity—changes in the strength of chemical synapses—can occur in the brain. LTP is the process of synaptic strengthening that occurs over time between pre and postsynaptic neuronal connections. The synaptic strengthening of LTP works in opposition to the synaptic weakening of long-term depression (LTD) and together are the main mechanisms that underlie learning and memory.
Hebbian LTP
LTP can occur when presynaptic neurons...
Long-term Potentiation01:35

Long-term Potentiation

Long-term potentiation, or LTP, is one of the ways by which synaptic plasticity—changes in the strength of chemical synapses—can occur in the brain. LTP is the process of synaptic strengthening that occurs over time between pre- and postsynaptic neuronal connections. The synaptic strengthening of LTP works in opposition to the synaptic weakening of long-term depression (LTD) and together are the main mechanisms that underlie learning and memory.

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Related Experiment Video

Updated: Jun 7, 2026

Inhibitory Synapse Formation in a Co-culture Model Incorporating GABAergic Medium Spiny Neurons and HEK293 Cells Stably Expressing GABAA Receptors
07:51

Inhibitory Synapse Formation in a Co-culture Model Incorporating GABAergic Medium Spiny Neurons and HEK293 Cells Stably Expressing GABAA Receptors

Published on: November 14, 2014

Ephecting excitatory synapse development.

Matthew B Dalva1

  • 1Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, 19104, USA. dalva@mail.med.upenn.edu

Cell
|October 30, 2010
PubMed
Summary

Ephexin5, a RhoA-guanine exchange factor (GEF), controls the number of excitatory synapses neurons receive. This discovery reveals a new mechanism regulating synapse formation, crucial for brain health.

Area of Science:

  • Neuroscience
  • Molecular Biology
  • Cell Biology

Background:

  • Synaptic alterations are linked to severe neurological and psychiatric conditions.
  • Understanding synaptogenesis is critical for addressing these disorders.

Discussion:

  • Margolis et al. identify Ephexin5 as a key regulator of excitatory synapse number.
  • Ephexin5 functions as a RhoA-guanine exchange factor (GEF).

Key Insights:

  • Ephexin5 limits the quantity of excitatory synapses a neuron can form.
  • This finding introduces a novel molecular mechanism governing synaptogenesis.

Outlook:

  • Further research into Ephexin5's role could lead to new therapeutic targets.
  • Understanding this pathway may offer insights into treating synaptic dysfunction in neurological diseases.

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Presynapse Formation Assay Using Presynapse Organizer Beads and “Neuron Ball” Culture
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Presynapse Formation Assay Using Presynapse Organizer Beads and “Neuron Ball” Culture

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Quantifying Synapses: an Immunocytochemistry-based Assay to Quantify Synapse Number
18:11

Quantifying Synapses: an Immunocytochemistry-based Assay to Quantify Synapse Number

Published on: November 16, 2010

Related Experiment Videos

Last Updated: Jun 7, 2026

Inhibitory Synapse Formation in a Co-culture Model Incorporating GABAergic Medium Spiny Neurons and HEK293 Cells Stably Expressing GABAA Receptors
07:51

Inhibitory Synapse Formation in a Co-culture Model Incorporating GABAergic Medium Spiny Neurons and HEK293 Cells Stably Expressing GABAA Receptors

Published on: November 14, 2014

Presynapse Formation Assay Using Presynapse Organizer Beads and “Neuron Ball” Culture
10:17

Presynapse Formation Assay Using Presynapse Organizer Beads and “Neuron Ball” Culture

Published on: August 2, 2019

Quantifying Synapses: an Immunocytochemistry-based Assay to Quantify Synapse Number
18:11

Quantifying Synapses: an Immunocytochemistry-based Assay to Quantify Synapse Number

Published on: November 16, 2010