2 Neuroanatomy
Johanna Boyd and Katherine Wood
Learning Objectives
- Recognize areas of the brain.
- Apply terminology such as dorsal, ventral, anterior, posterior, sagittal, mid-sagittal, lateral, medial, horizontal, coronal, and axial.
- Understand how each person’s brain is unique.
- Understand variables that might affect a person’s brain.
- Understand how some mental illnesses can affect brain structures.
- Understand why it is incorrect to assume the size and shape of the cortex has influence on an individual’s personality.
The Body’s Nervous Systems
The human body is governed by the nervous system, which controls complicated processes such as movement, thought, and memory. The two main nervous systems in your body are the peripheral nervous system (PNS) and the central nervous system (CNS). Your brain and spinal cord make up your CNS. Your brain uses your nerves to send messages to the rest of the body. The PNS feeds information from your senses into your brain using nerves that travel throughout the entire body. The PNS contains the autonomic and somatic nervous systems.
Neuroanatomy flash cards
Brain Development
The development of the brain starts within the third week of conception, making the health of a fetus one of the most vital moments in the creation of a human. Disorders brought on from genetics, disorders within the maternal body, and external factors can all have an impact on the manner of development. Girard et al. (2003) list risk factors associated with fetal brain damage:
- Those of toxic origin such as carbon monoxide poisoning, fetal alcohol syndrome, cocaine exposure.
- Maternal/fetal coagulation disorders such as thrombocytopenia, alloimmunization.
- Maternal hypoxia such as trauma, sepsis, stroke, hemorrhage, cardiac arrest.
- Mechanic conditions such as placenta praevia, placental abruption, umbilical cord accident.
- Twin pregnancies such as monochorionic twin pregnancy with twin-to-twin transfusion syndrome (TTTS), bichorionic twin pregnancy with death of a co-twin.
- Chorioamnionitis (an infection of the amniotic fluid) and prolonged rupture of membranes (PROM), alone or in combination.
MRI is commonly used to discern complications that have results during the development of the fetus.
Moffat et al. (2015) highlight the importance of development further. During the development of the brain, nerve cells move from their origin to where they will forever remain, deeming it a highly important process: “Neuronal positioning is a fundamental process during brain development. Abnormalities in this process cause several types of brain malformations and are linked to neurodevelopmental disorders such as autism, intellectual disability, epilepsy, and schizophrenia”.
Individual Differences in the Brain
Aside from major differences, such as agenesis of the corpus callosum, each person has small differences in their brain depending on gender, genetics, and individual life experiences. For starters: Raznahan and Disteche (2021) found there is a weight difference between male and female brains, deducting that the male brain weighs around 10% more than the female brain in adulthood. Not only that, but Raznahan and Disteche (2021) found that brain weight difference between sexes was apparent even as young as toddlerhood, and it persisted through the life span. Furthermore, they claim that females have greater volume in the prefrontal cortex, orbitofrontal cortex, superior temporal cortex, lateral parietal cortex, and insula and males have heavier ventral temporal and occipital regions. This highlights how sex alone can have an impact on brain anatomy.
Differences in brain structures have been argued to effect personality traits for years, but that is not the case. Karabian et al. (2019) found that there are few statistically significant relationships between the shape of a brain structure and the personality, intelligence, opinion, and character of the individual (among others). The authors found that associations between the thickness of grey matter and personality traits were rare, and when they were found, they did not replicate. This article concludes that there is no standard map to connect behaviour to areas in the brain, as there are too many variables. Although there are certain areas attributed to certain traits, such as the amygdala to emotions, and certain grey matter structures to impulsivity (Pan, et. al, 2021), it does not mean that you are able to pinpoint an individual’s personality type by looking their brain scans.
References
Girard, N., Gire, C., Sigaudy, S., Porcu, G., d’Ercole, C., Figarella-Branger, D., Raybaud, C., & Confort-Gouny, S. (2003). MR imaging of acquired Fetal Brain Disorders. Child’s Nervous System, 19(7-8), 490–500. https://doi.org/10.1007/s00381-003-0761-x
Kharabian Masouleh, S., Eickhoff, S. B., Hoffstaedter, F., & Genon, S. (2019). Empirical examination of the replicability of associations between brain structure and psychological variables. ELife, 8. https://doi.org/10.7554/elife.43464
Moffat, J. J., Ka, M., Jung, E.-M., & Kim, W.-Y. (2015). Genes and brain malformations associated with abnormal neuron positioning. Molecular Brain, 8(1). https://doi.org/10.1186/s13041-015-0164-4
Pan, N., Wang, S., Zhao, Y., Lai, H., Qin, K., Li, J., Biswal, B. B., Sweeney, J. A., & Gong, Q. (2021). Brain gray matter structures associated with trait impulsivity: A systematic review and voxel‐based meta‐analysis. Human Brain Mapping, 42(7), 2214–2235. https://doi.org/10.1002/hbm.25361
Raznahan, A., & Disteche, C. M. (2021). X-chromosome regulation and sex differences in brain anatomy. Neuroscience & Biobehavioral Reviews, 120, 28–47. https://doi.org/10.1016/j.neubiorev.2020.10.024
