Neuroscience: Brain Signaling, Synapses, and Neural Circuits
The brain is a network of billions of neurons.
Each neuron sends and receives electrical signals.
These signals travel along the axon.
They then reach the axon terminal.
When a signal arrives, calcium enters the terminal.
This triggers the release of neurotransmitters.
Neurotransmitters cross the synaptic cleft.
They bind to receptors on the next neuron.
The binding opens ion channels.
Ions flow in or out of the cell.
This creates a postsynaptic potential.
If the potential is strong enough, a new signal fires.
Synapses are the junctions between neurons.
They can be excitatory or inhibitory.
Excitatory synapses encourage firing.
Inhibitory synapses dampen activity.
Synaptic strength can change.
This process is called plasticity.
Repeated use can strengthen a synapse.
Unused connections may weaken over time.
Neural circuits link many neurons together.
A circuit can process a specific piece of information.
Sensory input enters the circuit first.
Processing then moves to higher‑order areas.
Feedback loops are common in circuits.
They help regulate activity.
For example, a motor command is sent.
Sensation from the movement returns to the circuit.
The brain balances excitation and inhibition.
This balance keeps activity stable.
Too much excitation can cause seizures.
Too much inhibition can impair function.
Neurotransmitters also act as modulators.
They can fine‑tune circuit activity.
Dopamine, for instance, influences reward.
Serotonin affects mood and sleep.
Overall, brain signaling relies on electrical impulses.
Synapses translate those impulses into chemical messages.
Neural circuits organize the flow of information.
Together, they enable perception, thought, and action.
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