Excitatory & Inhibitory Neurotransmitters (HL IB Psychology)

Neurotransmitters – Excitatory & Inhibitory Synapses

What are excitatory synapses?

• During the process of neurotransmission small sacs called vesicles containing the neurotransmitter are released into the synapse to the post-synaptic neuron where cells containing receptors may trigger a change in the cells

• The change which occurs in the post-synaptic neuron will be either excitatory or inhibitory depending on the type of neurotransmitter involved

• If the neurotransmitter causes an electrical signal to be transmitted down the cell they are known as excitatory neurotransmitters

• Excitatory neurotransmitters increase the likelihood that the neuron will fire an action potential

• Glutamate is a key excitatory neurotransmitter which has numerous functions including gut and digestive health, memory, learning and strengthening the immune system

• Too much glutamate in the brain can lead to some neurodegenerative diseases such as Alzheimer's and Huntington’s disease

• Artificial food additives such as monosodium glutamate (MSG) may contribute to specific psychiatric illnesses such as psychosis, anxiety and depression

Looks tasty…but watch those MSG levels!

What are inhibitory synapses?

• During the process of neurotransmission small sacs called vesicles containing the neurotransmitter are released into the synapse to the post-synaptic neuron where cells containing receptors may trigger a change in the cells

• The change which occurs in the post-synaptic neuron will be either excitatory or inhibitory depending on the type of neurotransmitter involved

• If the neurotransmitter blocks an electrical signal, preventing it from being transmitted down the cell, it is known as an inhibitory neurotransmitter

• Inhibitory neurotransmitters decrease the likelihood that the neuron will fire an action potential

• Gamma-aminobutyric acid (GABA) is a key inhibitory neurotransmitter which has numerous functions including relieving anxiety, aiding concentration, improving sleep

• Practising yoga, meditation and relaxation exercises have been linked to increased levels of GABA

Which studies focus on agonists & antagonists?

• Kraal et al. (2020) - a review article which explored research into a link between low-MSG diet and improved pain symptoms and better mental health   

• Streeter et al. (2010) investigated whether changes in mood, anxiety, and GABA levels are linked to yoga practice

Kraal and Streeter’s studies are available as separate Key Studies – just navigate the Brain and Behaviour section of this topic to find them.

Yoga – good for the body, good for the mind too….