Grey matter volume increases in various parts of the brain have been identified in a number of skilled groups such as musicians, mathematicians , bilinguals, jugglers, and medical students. Professional musicians with increased grey matter volume in Broca’s area(frontal lobe of the brain) were found to show enhanced judgments of line orientation and three-dimensional mental rotation ability. This was attributed to their musical sight-reading and motor sequencing expertise.
However,this expertise can come at a cost, with some musicians suffering focal dystonia, a loss of control and degradation of skilled hand movements.
Hippocampus is a complex brain structure embedded deep into temporal lobe. It has a major role in learning and memory. Studies and research has shown that the size of the Hippocampus changes with the cognitive and skill function performed by humans. The size of Hippocampus have been found to increase in size in fighter pilots and London taxi driver. While the size increases with repeated performance of complex tasks and learning, the size could also shrink due to non-usage like reliance on automation for the functions usually performed by the brain.
Loss of neurons is considered to be an irreversible process since dying cells cannot be replaced. Hippocampus is one of the unique regions in the brain where neurogenesis continues even in adult life. Though, described initially, as “too little,” neurogenesis in the brain is now thought to be functionally important. It has been seen that neurons, hence, produced integrate into the mainstream neurons. They have also, hence, shown to be functionally important. Hippocampus is now known not just to be important in learning and memory but also in:
- Spatial navigation
- Emotional behavior
- Regulation of hypothalamic functions
Use of GPS and change in Hippocampus
A study was conducted in 2018 on the use of Augmented Reality (AR) glasses with GPS navigation for prolonged use. The aim of the study was to assess possible changes in functional connectivity of hippocampus and other Brain regions involved in spatial navigation with the use of GPS guidance navigational system over 3 months.
The study found a decrease in functional coupling of the right hippocampus after 3 months of using GPS navigation. These preliminary observations support the assumption that externalization of some mental capacity (spatial navigation) to technological device has measurable neurobiological consequences.
Researchers at McGill University found was significant in terms of how spatial orientation affects the brain. After performing fMRI (functional Magnetic Resonance Imaging) scans on people using both of those strategies, the individuals that used a spatial navigation strategy had an increased activity in the hippocampus. Conversely, they found that using a GPS excessively might to lead to atrophy in the hippocampus as a person ages, and this could put them at higher risk for cognitive diseases later in life. One of these diseases might be Alzheimer’s which impairs the hippocampus and leads to problems with spatial orientation and memory. Researchers also found a greater volume of grey matter in those who used spatial navigation, and this group scored higher on standardized cognition tests than those who used the other strategy. The results of this study demonstrate that using orienteering and building cognitive maps might be better for the brain than using a GPS.
MRI analysis of London taxi Drivers & Bus Drivers
The London taxi drivers perhaps undergo the most difficult test in the world, that of memorizing 25,000 streets of London. In a study that compared data from MRI scans of the study group, the grey matter of the taxi drivers was higher as compared to the bus drivers. Furthermore, years of navigation experience correlated with hippocampal gray matter volume only in taxi drivers, with right posterior gray matter volume increasing and anterior gray matter volume decreasing with more navigation experience. In addition to structural brain differences, the neuropsychological testing revealed that taxi drivers, while performing better than bus drivers on tests relating to knowledge of London, were significantly poorer at acquiring or retrieving new visuospatial information from objects and locations. In other words, they fared poorly as compared to others at learning object-place and word-pair associations. This could suggest a broader associative deficit within visual and verbal domains. This could be due to limited capacity for further consolidation and storage in the posterior hippocampus.
The study concluded that it is not enough to focus on the positive effects of being skilled, but that there may be costs associated with expertise that also need to be identified and considered.
Changes in the Hippocampal Volume and Shape in Early-Onset Mild Cognitive Impairment
Mild cognitive impairment (MCI), especially the amnestic type of MCI, refers to an early stage of Alzheimer’s disease (AD) during which patients display cognitive impairment without apparent disabilities in their activities of daily living. Patients with MCI show memory dysfunction, and 10–20% of MCI annually progresses into Alzheimer Disease. Atrophy or degeneration of the hippocampus is one of the most sensitive biological indicators of AD, and hippocampal volumetric is the best-established structural biomarker for AD, especially for early diagnosis.
The fact is that volumetric changes have been confirmed in a number of studies of the human brain. These changes could be dues to the onset of a disease like the Alzheimer Disease or due to prolonged reliance on external technological aid which reduces the functions usually performed by the human brain. Hippocampus in particular is divided into posterior and anterior parts. Posterior being mainly responsible for spatial awareness and anterior being used for emotional response. While constant use of one faculty can result in strengthening the neural network or even increase in the brain size, there seems to be a limitation to the the growth. As seen in the London taxi drivers, the increase in posterior hippocampus affects certain functions associated with the anterior hippocampus.
There is a need to balance the functional requirements of the pilots not only from the technology aspects but also from physio-psychological point of view so that the overall cognitive functions are not compromised with. Technology and Artificial Intelligence is the future and will take over numerous functions routinely performed by humans but will they take over the cognitive functions or affect them is worth a discussion.