The Magnetized Man

What is dopamine?

Dopamine is a neurotransmitter. It manages motivation, motor functions, and reward-related learning in the body.  

What is a neurotransmitter? 

Neurotransmitters are molecules that send messages between neurons. Neurons are nerve cells. 

How do cells communicate with each other? 

Cells can communicate with other cells using several methods, including proteins, peptides, amino acids, dissolved gases such as carbon monoxide, and more. Neurons or neural cells communicate with each other using a combination of chemical and electrical signals. The chemical communication happens in the form of neurotransmitters like dopamine. The way that neural cells communicate electrically is a bit more complicated. In short, neurons have what’s known as an action potential. This action potential causes them to release a neurotransmitter, like dopamine, that is received by another neuron. If Neuron 1’s action potential causes an action potential in Neuron 2, that’s an excitatory input. If Neuron 1’s action potential causes no action potential in Neuron 2, that’s an inhibitory input. 

Dopamine uses G-protein-coupled receptor (GPCR) signalling. G-protein-coupled receptors are a group of membrane receptors. They receive signals in the form of proteins, peptides, light energy, and more. Right now, scientists only have a working model of how dopamine is released through GPCR signalling. 

Does every neuron create dopamine? 

Not every neuron in the brain produces and releases dopamine. The ones that do are called dopaminergic neurons, and these specialized neurons are primarily located in the ventral tegmental area (VTA) and the substantia nigra pars compacta (SNc). 

How is dopamine produced in a dopaminergic neuron? 

Dopaminergic neurons create dopamine through a two-step process using the amino acid tyrosine. In Step 1, Tyrosine Hydroxylase (TyrH) is the enzyme that turns tyrosine into L-dopa. In Step 2, the enzyme Aromatic L-Amino Acid Decarboxylase (AADC), aka Dopa Decarboxylase, turns L-dopa into dopamine. 

How much dopamine is being released into our brains, on average? 

There is no single, fixed number for how much dopamine gets released into the average person’s brain. Instead, each person has a baseline amount. When they exceed that baseline amount, they feel great. When they dip below that baseline amount, they feel not so great. 

Dopaminergic neurons typically fire in both phasic and tonic modes. They fire at about 3 to 7 Hz, when it’s tonic firing, and more rapidly at greater than 20H Hz, in phasic firing. Tonic just means that the firing happens in a continuous and sustained way while phasic means that there are transient and short bursts of firing. 

This phasic firing is what helps with learning and motivation. One way that this phasing firing gets triggered is through the activation of N-methyl-D-aspartate (NMDA) receptors. NMDA receptors are glutamate receptors and glutamate is the brain’s main excitatory neurotransmitter. When a reward is anticipated or received, this phasic firing happens. 

Reward Prediction Error (RPE): The theory behind how dopamine is released

Reward prediction error (RPE) is the difference between the reward you receive and the reward you predicted. When you get more than you predicted, this is known as a positive prediction error. When you get exactly what you predicted, you stay at baseline. When you get less than what you expected, this is known as a negative prediction error. 

What is the electromagnetic behaviour of dopamine? 

Dopamine is an electrochemically active molecule. This means that it can gain (reduction) or lose (oxidation) electrons. When a molecule like dopamine can gain or lose electrons, it can generate a measurable electrical current or signal.

It is also a monoamide neurotransmitter. This is a category of neurotransmitters that are crucial for regulating mood, movement, and other functions. These neurotransmitters contain one amino group. 

The electrochemically active nature of dopamine gives it an accessible orbital (the frontal orbital) allowing dopamine to act as an electron donor or acceptor. This makes electrochemical molecules particularly useful in bioelectronic devices and in sensors. 

There are also non-electrochemically active molecules such as glucose, lactate, and glutamate. Doctors and scientists use specialized strategies to measure non-electrochemically active molecules such as using an enzyme to turn them into detectable, electrochemically active molecules. 

What is the effect of addictive substances on the brain and dopamine production? 

Addictive substances or behaviours cause an unnatural surge in dopamine. As a result, normal, everyday things don’t feel good anymore, because you’ve become accustomed to that big surge. 

What is dopamine recycling? 

When dopamine is released into the synapse, it doesn’t just cycle around forever or get burned up by the body. Instead, they are re-taken by the neurons using the Dopamine Transporter (DAT). It prevents excess dopamine molecules from building up and helps with energy efficiency. 

What is dopamine metabolism? 

Dopamine metabolism is the process of creating, using, and then breaking down dopamine. Once dopamine is done doing its job, it’s broken down using enzymes like Monoamine Oxidase (MAO) and Catechol-O-methyltransferase (COMT). They work together with Aldehyde Dehydrogenase (ALDH) to convert dopamine into inactive metabolites such as Homovanillic Acid (HVA). 

What is the relationship between the nucleus accumbens and the ventral tegmental area (VTA) and the substantia nigra pars compacta (SNc)? 

Firstly, the ventral tegmental area (VTA) and the substantia nigra pars compacta (SNc) form a pathway called the VTA-SNc pathway. This pathway creates the core mesolimbic reward system. The SNc also connects to the Nucleus Accumbens (NAc), thereby linking reward with neural control. 

What is the Nucleus Accumbens? 

The Nucleus Accumbens (NAc) links the limbic system to the motor system.