The Beginning of Neuropsychology

By: Rachel Teo & Zane Lim

According to the American Psychological Association, neuropsychology is the study of how the brain and nervous system affects behavior and cognition. In humans, with the average size of two clenched fist, the brain is central to the functioning of our body. When damage occurs to certain regions, detrimental effects can be seen on our essential functioning, such as spoken language, perception, object and face recognition, movement, and memory (Ackerman, 1992).

Spoken language

Damage to areas of the brain that controls language resulting from physical trauma, tumor, or neurodegenerative disorders may lead to impairment of language expression (Broca’s aphasia) and comprehension (Wernicke’s aphasia) (Begum, 2023).

Perception & Object Recognition

Agnosia, an inability to make use of our senses to discern and engage in object and facial identification. Deficits experienced by individuals depend on the brain regions that are damaged. For example, damaging the temporal lobe results in an inability to distinguish the difference between sounds, smell, or taste while damaging the occipital lobe may result in an inability to identify objects, places, and faces (National Institute of Neurological Disorders and Stroke, 2023). In addition, damage to the occipito-temporal lobe results in prosopagnosia, also known as facial blindness, characterized by an inability to recognise faces (Cohen et al., 2019).

Figure 1 (Bartolomeo, 2022)

Movement

Apraxia, the dysfunction to the cerebral hemisphere of the brain, in particular the parietal lobe can result in the loss of ability to execute movements and gestures despite having the physical ability to perform them. According to a review by Park (2017), there are three main types of apraxia, ideomotor, ideational and limb-kinetic apraxia. Individuals with ideomotor apraxia are able to understand instructions but find it hard to carry out physical movements necessary to complete the task. Individuals with ideational apraxia have difficulties planning and executing a task despite being able to identify the tools required (Park, 2017). Individuals with limb-kinetic apraxia are unable to execute coordinated hand movements, resulting in awkward movements (Foki et al., 2016 as cited from Park, 2017).

Figure 2: (Huang, 2023)

Phineas Gage

One of the most prominent cases of an individual surviving brain damage is Phineas Gage. With an iron tamping rod piercing through his left cheek, behind his eye and into the left frontal region of his brain due to a workplace incident, Gage miraculously survived (Evans, 2023). However, his personality changed drastically following this incident. The once hardworking and looked upon Gage became disdainful and easily irritated. Despite the change in his personality, there were no neurological deficits observed in Gage. This observation propelled neurologist David Ferrier to investigate the functions controlled by the prefrontal lobe in an experiment involving the removal of prefrontal lobes in monkeys (Schwarcz, 2018). Through his experiment, he found out that ablation or damage to the prefrontal lobe alters a person’s behavior and personality significantly, yet does not cause any dysfunction in one’s motor, sensory or perceptual abilities (O’Driscoll & Leach, 1998). Ferrier subsequently presented his findings in a lecture in 1878 while postulating the idea that experiments conducted using animal models could provide valuable information in the diagnosis and treatment of neurological patients (García-Molina, 2010).

Figure 3.1 and 3.2 (Collett, 2021 and Damasio et al., 1994 cited from Evans, 2023)

Animal models play a huge role in psychology. Besides using primates in neuropsychology research, non-primates such as rats and mice were often used as well. Moreover, studies conducted using animal models have contributed a huge part to the knowledge we learn in psychology today (Capitanio, 2017). When it comes to the development of numerous therapeutic approaches that are currently used on humans, most originated from animal experiments that were conducted more than 50 years ago. An example would be the development of deep brain stimulation (DBS), a surgical intervention for individuals with movement disorders such as Parkinson’s. DBS started off with testing done on non-primate models before being introduced to humans and thereby producing successful results (Homberg et al., 2021). Furthermore, in animal research, researchers have greater and more precise control in terms of potential confounding factors such as living environments and experimental conditions which allows them to get a better understanding on various fundamental processes. Most importantly, animal research allows us to generate answers to questions (e.g., How the activity of the amygdala relates to brain functioning?) that are impossible to study in humans (Grayson et al., 2016, as cited in Capitanio, 2017). Hence, animal research could be considered the key factor that made clinical trials possible.

References

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