Find below a great essay detailing the importance of the brain, as a runner-up of the Anatomy Blog Competition for the most significant anatomical discovery, written by Patricia Sim.
Whether it takes the form of macrostructures or microstructures, the study of the human form has experienced revolutionary changes throughout history. Human anatomy was first pioneered by Hippocrates II in Ancient Greece (1), who emphasised the importance of the spine and nervous system in controlling body physiology in 400 B.C.E. (2). The exploration of human anatomy continued through Western Europe, where physician Professor Mondino de Liuzzi conducted the first human dissection, revolutionising the accuracy of anatomical structures and functions. These changes have made it possible for people to thoroughly research human anatomy, leading to significant discoveries. One such example is the brain, which is both humankind’s most devoted ally and greatest adversary. It is a powerful and unpredictable organ that can aid in worldwide knowledge.
The brain is a complex organ that performs a wide range of tasks. Different parts of the brain are responsible for controlling various mental and physiological processes, including memory and motor movements. Embryologically, the brain consists of the forebrain, midbrain, and hindbrain. The forebrain, further divided into the diencephalon and telencephalon, handles sensory data, memory, and language in addition to controlling motor functions. On the other hand, the auditory, visual, and motor processes are controlled by the midbrain, which connects the forebrain and the hindbrain. The metencephalon and myelencephalon of the hindbrain help to regulate autonomic functions and coordinate locomotion.
Some of the most severe mental illnesses and disorders have therapies based on the anatomy of the brain. The World Health Organization states that depression is a prevalent mental disorder that greatly increases the overall burden of disease worldwide (3). Currently, the diagnosis of Major Depressive Disorder (MMD) is made primarily on behavioural evaluations and self-reports which can potentially contain bias. Neuroimaging research, however, might offer more conclusive proof of this. For instance, earlier diffusion tensor imaging (DTI) investigations found abnormal brain activity in the putamen (4), prefrontal cortex (5), temporal gray (6), occipital lobe (5), and caudate (5). In neural circuits linking the cortical and subcortical areas, some of these structures may also serve as dominant brain hubs, which are regions of highly interconnected brain networks (7). One of the main causes of MDD may be a deficiency in these neural circuits (8). As a result, having an anatomical understanding of these would aid researchers in developing new treatments that target these specific areas in the future.
As a component of neuroanatomy, a major function of the brain is localisation. This is a process whereby the site of injuries can be mapped onto the region innervated by a single spinal nerve (in the body) or by a cranial nerve (in the face) based on the clinical manifestation of the injury itself. This region is called a dermatome. By conducting a relatively straightforward test for dysfunction in the injured area, doctors are able to trace the nerve back and identify the source of the injury. For instance, the trigeminal nerve (CN V1), which has an olfactory role, innervates the lateral aspect of the forehead. As a result, if a patient with head trauma complains of abnormal smell, they can be tested by identifying odors. If the result is abnormal, the problem can be attributed to the olfactory nerve. In some cases, especially injuries involving the spinal nerves (9), tracing the nerve may not be as straightforward. When more than one pathway is impacted, physicians must look at where the pathways intersect and make additional clinical inferences to aid in the diagnosis. Having said this, due to the comparatively simple neuroanatomical structure, lesions in the cranial region are more easily localized than lesions in the spinal region. Clinically, lesions in cranial regions may present in various ways; for example, cortex lesions may manifest as sensorimotor issues e.g. paralysis or cognitive issues such as memory deficits. Therefore, understanding the anatomy of the brain as well as other areas of the nervous system such as the spinal cord and nerves would help doctors perform neurological examinations and identify the source of lesions.
Understanding the anatomy of the brain is essential because it can be applied to various fields, such as child developmental psychology and artificial intelligence. For instance, parents may want to be cautious and protect their kids from negative experiences, for example, violence, in order to avoid traumatic brain changes. This phenomenon is referred to as neuroplasticity – the ability of the brain to restructure neuronal networks. It is a field that is rapidly gaining prominence. It studies how the nervous system, and the brain in particular, can adapt and change its structure in reaction to stimuli. Research has shown that the early years of brain development are sensitive to environmental changes, and experiences that occur during this time have a lasting impact on the structure and function of the brain through changes in DNA structure and chromatin function, which in turn affect the likelihood of developing mental disorders later in life (10). In addition, the brain-derived neurotrophic factor (BDNF), which is connected to synaptic plasticity, is of special interest. According to research (10), experiencing childhood adversity causes changes in volume and structure in particular brain regions, most notably the hippocampus (which is in charge of learning and recollection) and the amygdala (which is in charge of emotions). In later years, these modifications have an impact on a child’s mental and social growth. The connection between plasticity and brain morpho-physiology is one area that requires a lot of research, so it will be interesting to see how this field develops over the coming years.
All discoveries in anatomy throughout the ages have been quite significant; historical ones laid the groundwork for modern-day medicine, which continue to expand today. How these developments are used in the fields of research and healthcare with the intention of improving human health is what counts the most.
References
1. Malomo AO, Idowu OE, Osuagwu FC. Lessons from history: Human anatomy, from the origin to the Renaissance. Int. J. Morphol. 2006;24(1): 99-104.
2. Habbal O. The Science of Anatomy: A historical timeline. Sultan Qaboos Univ Med J. 2017;17(1):e18-e22. doi:10.18295/squmj.2016.17.01.004
3. World Health Organization. Depression [Internet]. https://www.who.int/news-room/fact-sheets/detail/depression [Accessed 26th February 2023].
4. Zhong X, Pu W, Yao S. Functional alterations of fronto-limbic circuit and default mode network systems in first-episode, drug- naive patients with major depressive disorder: a meta-analysis of resting-state fMRI data. J Affect Disord. 2016;206:280-286.
5. Huang M, Lu S, Yu L, et al. Altered fractional amplitude of low frequency fluctuation associated with cognitive dysfunction in first-episode drug-naive major depressive disorder patients. BMC Psychiatry. 2017;17:11.
6. Shen Z, Jiang L, Yang S, et al. Identify changes of brain regional homogeneity in early and later adult onset patients with first episode depression using resting-state fMRI. PLoS ONE. 2017;12:e0184712.
7. van den Heuvel MP, Sporns O. Rich-club organization of the human connectome. J Neurosci. 2011;31:15775-15786.
8. Zhang FF, Peng W, Sweeney JA, Jia ZY, Gong QY. Brain structure alterations in depression: Psychoradiological evidence. CNS Neurosci Ther. 2018; 24: 994– 1003. https://doi.org/10.1111/cns.12835
9. Masdeu JC. Localization. In: Aminoff M., Daroff R. (eds.) Encyclopedia of the Neurological Sciences. Second edition. Academic Press; 2014. p.913-915.
10. Miguel PM, Pereira LO, Silveira PP, Meaney MJ. Early environmental influences on the development of children's brain structure and function. Dev Med Child Neurol, 2019;61: 1127-1133. https://doi.org/10.1111/dmcn.14182