The missing link in neuroscience – Can we decipher behavior by studying neurons?

“If the human brain was so simple that we could understand it, we would be so simple that we couldn’t” 

Writer: Chrysi Anastasaki
Editor: Ebani Dhawan
Artist: Rebecca Shutt


The golden age of neuroscience reveals exciting discoveries while we take tantalizing glimpses into neurons and cerebral structures. The human brain weighs approximately three pounds, yet it is made up of 86 billion neurons that communicate to form connections called synapses. Neuroscience facilitates the study of the neuronal activity to provide previously inaccessible knowledge about the structure and function of the brain.

For instance, in functional magnetic resonance imaging (fMRI), the BOLD signal (Blood Oxygenation Level-Dependent) is a technique used to measure cerebral blood flow (the higher the flow, the higher the activation) in order to delineate regional functions. Simultaneously, the encephalogram (EEG) can extract electrical neural impulses correlated with an event (event-related potentials or ERPs), which requires cognitive processing, such as decision making. 

The constellation of information collated from diverse techniques serves the purpose of understanding how neurons transmit information and how, for example, a cerebral area participates in X function or brain injury affects Y function, etc. In addition, scientists have observed the concept of neuroplasticity, which describes the dynamic effort of the brain to form new connections as a result of new experiences. Behavioural changes have been linked with the ability of the brain to adapt to novel information. For example, when humans learn a new skill, plastic changes occur in the neuronal structure that reflect this learning procedure.

We are interested in neuroscience because we believe that the high-resolution images or the neuronal signaling reflect our behaviour. The latter has been studied long before the rapid expansion of neuroscience, when scientists relied on observations and measurements of  accomplished tasks to infer outcomes. 

Occasionally, behavioural data are not seen as ‘compelling’ enough compared to neurophysiological or neuroimaging data. However, this can be a distraction from the unsolved problems that are associated with the use of these techniques. One of the common issues is the reverse-inference error. For example, several studies have traditionally associated the amygdala with the feeling of fear. Does that mean that whenever humans have an overactive amygdala they experience fear? Different studies have actually revealed that events such as viewing pictures of doughnuts when someone is hungry, might also contribute to this region’s activation. 

Another predicament is the group-to-individual inference meaning that, if neuroimaging data reveal a trend for a population, then a random person with the same characteristic(s) (e.g. frontal lobe lesions) belongs to the same category. This presumption does not account for the bio-variability (genetics, culture, medical examination) of human living.  It is possible for a person to be different from the rest, thus, they cannot be substantially matched with the settled description. The list of issues goes on, but misinterpretations can turn speculations into facts or errors into acceptable beliefs. This leads to the determination that neuroscience can give precise (e.g. how much of our brains we use) and concise (e.g. exceptional mathematical ability linked to the left brain, while artistic inclination to the right brain) answers about complex topics. 

However, it is important to understand that each field of study has its weaknesses and strengths. We are not in a position to discuss neuroscience as we discuss Newton’s laws or Relativity. Neuroscience tests theories by using multiple methods and reports observations, which can be used to answer diverse questions ranging from medicine to psychology or philosophy. Sometimes, these questions are answered confidently, while others scientists are left with nebulous data and more confusion. 

Furthermore, neuroscience has not claimed -yet- the ability to locate where thoughts come from. Hence, it would be a misuse of its potential to take the liberty and assume countless possibilities driven by the fascination to learn about the brain. The quest for ‘popular’ answers can neglect the purpose of estimation, which is a rough calculation of the value of an observation that does not fathom a hundred percent certainty. 

All in all, we might need to redefine our expectations of neuroscience. This begins with the opportunity to be informed, not only about ‘cool neuroscience facts’, but also about the limitations of studies and how to critically appraise results. Perhaps, the bridge between neurons and behaviour is the acknowledgement of the finite. This humble realization honors the potential without ‘disrespecting’ its boundaries.  Future prospects will continue to expand this complex discipline until we disentangle how ‘the molecular machines within behaving organisms’ shape the way we are. Stay tuned! 

References

  1. https://www.theatlantic.com/science/archive/2017/02/how-brain-scientists-forgot-that-brains-have-owners/517599/
  2. http://jaapl.org/content/45/3/278#sec-6
  3. https://doi.org/10.1016/j.neuron.2018.04.024
  4. https://www.mdmag.com/peers-perspectives/einstein-brain/current-limitations-in-neuroscience
  5. http://jonlieffmd.com/blog/the-limits-of-current-neuroscience
  6. https://www.the-scientist.com/news-opinion/linking-neurons-to-behaviors-37753

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