By Sofia Oural
Of all the vital life processes, the birth of ideas and thought stands as one of the most mysterious yet less acknowledged ones. Although the science behind brain cell communication is well understood, processes are not greatly comprehended due to their extreme complexity. Diving into the world of neural circuits, synaptic transmissions, and information processing can sound overwhelming, but it is time to explain the biology behind human thought.
Our journey begins with sensory inputs. Whether it be visual (a nice painting), auditory (your favourite song), tactile (that one fuzzy blanket you love), or any other external stimuli that catches your attention, specialized cells called sensory receptors are ready to receive the message. They transform physical stimuli into electrical signals, and the quest to the brain officially begins. These electrical signals travel along sensory neurons until they reach the central nervous system.
The nerve cell, or neuron, is the key player in this entire process. It has three main components: the dendrites (thin fibres that extend from the cell in a branch-like fashion to receive information from other neurons), the cell body (which carries out most of the neuron’s basic cellular functions), and the axon (long, thin fibre that carries nerve impulses to other neurons). These cells may be small, but they are certainly mighty. Nerve signals often travel long distances in the body. For example, if you accidentally touch a boiling teapot, the sensory information has to travel from the tip of your finger all the way to the brain. And from there, the nerve signals have to travel back to the arm muscles to make them contract and draw back the hand. To that, we may add the level of complexity implied by the fact that you thought out the words “ow that is hot!” and can come to the logical conclusion that if you had left your hand there you could have burned yourself. Countless neurons can be involved in such a system, which means the body needs to have a sophisticated communication system to rapidly send signals through cells. The solution is actually two solutions: first, within the nerve cells themselves, electrical signals are transmitted along the cell membrane. Secondly, for communication between cells, the electrical signals are usually converted into chemical signals that small neurotransmitters can transfer from cell to cell. Neurotransmitters are chemicals released by the neuron sending the signal (presynaptic neuron), which binds to receptors on the surface of the receiving (postsynaptic) neuron. There are some neurotransmitters which are more common and therefore, better known:
- Dopamine: the “reward neurotransmitter”. Dopamine contributes to the reinforcement of behaviours, cementing neural pathways associated with pleasurable experiences and creating a neurochemical environment that encourages creative thinking and innovation
- Serotonin: well-known for its role in mood regulation, optimal levels of serotonin enhance cognitive flexibility and innovative thinking. Extensive research on the effects of serotonin concludes that it is proof of the link between emotional states and the formation of specific ideas.
- Glutamate: the most abundant neurotransmitter. Glutamatergic transmission facilitates changes in synaptic strength (the efficiency of the propagation of signals from one cell to another) which are essential for the production of new information
Neurotransmitters come in about 100 different kinds and can reach several postsynaptic neurons at once, typically to either ligand-gated receptors or second messenger receptors. Neurotransmitters binding to ligand-gated channel receptors cause a channel to open which allows for the movement of ions (charged atoms) across the cell membrane of one neuron and towards the other. The channels can be excitatory or inhibitory depending on how likely it is that this transmission will encourage further transmission of the message to a third neuron. Moreover, second messenger-linked receptors are designed to help pass signals from the cell’s exterior to its interior. This process is much slower as it involves a complex process of chemical reactions that can, once again, prove to be excitatory or inhibiting, which will determine how much further the message will travel.
A series of neurons carrying an impulse from one to the other is occasionally referred to as neurons “firing”. The stimuli we are exposed to in our daily lives lead to a pattern of neuron firing, which results in a thought process. If the stimulus repeats itself, the continuous patterns of neuronal firing reinforce the circuit. This is why we have the same feelings in similar situations: we say the same things all the time —like saying “good morning!” to the doorperson every day, and react in predictable patterns —that one movie that makes us cry every time or the song that is an instant mood booster. And what is more, humans can perform neuroplasticity. This means the nervous system can change its activity (the patterns of neuronal firing) in response to internal or external provocation of learning and experience, which will eventually lead to a new behaviour.
The role of memory in idea generation
Which neurons fire after which is not a random process, and academic interpretations of idea generation have long assumed that new ideas do not develop out of nowhere but rely on meaningful variations of available knowledge. These views have been supported by behavioural research showing that critical thinking relies on both semantic memory (general knowledge accumulated throughout our lives) as well as episodic memory (specific past events and experiences). But memory retrieval alone, of course, cannot lead to new ideas. The generation of new ideas is assumed to further rely on executive processes, which is the kind of selective attention that typically acts while the brain is trying to coordinate many things at once and therefore directs subsequent processing to achieve a goal. These executive processes guide the strategic search, selection and integration of relevant knowledge and are needed to guide mental simulations and assess outcomes.
But what brain processes are specific to the generation of a genuinely new representation? Several functional Magnetic Resonance Imaging (fMRI) studies on creative cognition have contrasted the generation of creative and common object uses. For example: how may one use a hat? Analyses of the response behaviour revealed that original ideas are not always newly created on the spot but are occasionally recalled from memory. From this research, we can conclude that most people tend to start by remembering uses before shifting towards the generation of brand-new concepts. Recalled uses can vary substantially in their originality, ranging from prototypical uses —using the hat as a head covering— to more original uses that people have occasionally witnessed in the past —using the hat to collect donations, or as a frisbee. Importantly, these recalled ideas differed in the kind of memory they were drawn from: prevalent ideas are likely recalled from semantic memory, whereas original object uses are more likely obtained from searches of episodic memory, which contains more autobiographical details.
When we perceive any kind of sensory stimulus, it will be cross-referenced to most of our available memory to find patterns and set the foundation for new associations, depending on the task at hand. The human brain is also remarkable at finding patterns and relationships, which means neural circuits responsible for associative thinking will draw from other knowledge to put together what may at first appear as unrelated concepts but will then become the seeds for an original idea.
The formation of ideas is a complex and multifaceted process. From our senses to our memories from childhood, all the way through synapsis and neurotransmitters thinking is no easy task. Neurobiologists do not have all the answers, and there is still much to learn about the most mysterious process of them all. This article is certainly a simplification of the absolute miracle that is our ability to think, but exploring the intricacies of neural pathways can help us better understand what fuels imagination, creativity, and innovation. By continuing this research, this understanding may be used to further unlock the potential of the human mind. However, the journey of discovery is far from over, and the mystery behind ideas remains an elusive goal in neuroscience.
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Astra Stem 
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