Developmental Topographical Disorientation (Topographagnosia)


                     Developmental Topographical Disorientation (Topographagnosia)

1.     Symptoms

Getting lost in a home where you have lived for 25 years. Being unable to find your way from the living room to the kitchen, or to find the bathroom. Forgetting where your own bed is even though you woke up only two minutes ago. Just how big must the world seem to people who get lost in their own homes? 

What about when they leave the house and venture into the outside world? They have no physical symptoms; they are not mentally deranged. They can be of any age. They can accomplish many things, just like most people. But when it comes to finding a specific place within their immediate surroundings or beyond, they are lost. Such people suffer from a disorder known as Developmental Topographical Disorientation (DTD), also known as Topographagnosia. 

DTD is an incurable condition that imposes severe constraints on a person's ability to navigate his or her own environment. The scientific community has not determined whether this rare mental disorder is genetically or environmentally acquired. People with DTD are incapable of cognitive mapping. They have no grasp of spatial relationships; they have no inner compass. Although they do not suffer from brain damage or memory malfunction, those with DTD cannot devise structured mental maps to find their way to their destinations. This is true even with regard to places they know well. 

It may seem counterintuitive that people who suffer from this disorder can draw detailed maps and distinguish among houses, schools, and restaurants. But the moment they set out to wherever they're going, confusion sets in. In a parking garage, they easily get lost because things appear the same wherever they look. Parking stalls, signs, cars, turns – all look like mirror images of each other. Some DTD sufferers can lose their way on streets that they have walked or driven on for years because they don't recognize the landmarks. Some of these people cannot find their own homes or schools. Simply going from one place to another is a major undertaking.

One woman who shared her personal experience with DTD on YouTube said she was able to remember specific places, but not their location in relation to one another. (Karina, 2012). She could remember a particular place, followed by another, without being able to connect them to each other and reach her destination. She could not remember the sizes of different places within a mall. For example, she would know that there was a Macy's inside the mall, but her mental map could not tell her where. All she knew was that Macy's was an entity distinct from the mall.

The woman's disorientation became even more acute when she tried to find businesses that seemed ubiquitous, such as Starbucks, Target, and CVS. When she saw the same store brand over and over on a given day, she could not remember which ones she had actually been to. Her mental map got sliced and diced into individual pieces that bore no relationship whatsoever to one another. She could not remember which specific store was next to which other store, and she was lucky to remember the names of even a few stores in any given mall. She also had a hard time getting into and out of parking lots because they all looked the same to her (discussed above). When going to school, she simply followed behind the morning crowd because she knew the crowd was going to the same school. She found it difficult to concentrate in the classroom; instead of focusing on the teacher, she was focused on learning about what seemed to be a new environment even though she had been there before. (Karina, 2012).

2.     Associated Brain Areas

A DTD patient's inability to find his or her way within the environment is usually caused by lesions to different cerebral regions involved in the attentional, perceptual or memory functions that are called upon during navigation. Research by Laria, Bogod, Fox, & Barton (2009) involved the first case of a DTD patient who lacked any structural lesions and whose sensory and intellectual functions were intact. Tests in both real and virtual environments revealed that the patient suffered from selective impairment in forming a mental representation of the environment, i.e.,a cognitive map. A functional magnetic resonance imaging (fMRI) study showed a lack of activation in the hippocampal complex and the retrosplenial cortex while the patient was forming a cognitive map. 

Although the lack of neural activity usually results in a negative finding that generally has low interpretative value, the authors concluded that the findings in this case could prove useful. First, in a group of healthy control subjects performing the same task, activity within the hippocampal complex and retrosplenial cortex was detected in each individual participant. Second, it was found that within the same regions (showing lack of neural activity while forming a cognitive map of the environment), increased neural activity was detected while the patient was performing a different navigation task. This is the first case reported in the literature showing that topographical disorientation may occur as a developmental defect causing a lifelong disorder affecting daily activities.  (Laria, Bogod, Fox, & Barton, 2009).

In the brain, the hippocampus makes maps and the prefrontal cortex makes plans. (Javadi et al.,2017).  The more these two interact, the more an individual’s cognitive mapping ability improves. The less these two areas interact, cognitive mapping suffers. The role of the hippocampus and related neuronal structures like the retrosplenial cortex are similar in that these regions are important for visual cues. Visual cues might be something as simple as a picture drawn on a white board to remind someone about doing the task. The point is, increased mental recognition of something from the sensory systems -- primarily the visual -- evoke hippocampal and pre-frontal communications. Increased communications lead to increased cognitive mapping, thus slowing down the progress of DTD. There are changes in neurons and neuroplasticity whenever people learn to navigate around their environment. This relies on increased synaptic communication between sets of neurons, where the plasticity occurs. 

3.     Lessons

In the modern world, technology is changing the environment in which we live. Human beings invented the GPS, and so the brain that was designed by natural selection to move us around our environment -- to create these cognitive maps -- is not being used to the same extent. A lot of our cognitive abilities have actually suffered because of technology like GPS. 

It has been found that DTD sufferers do not have any cognitive impairment other than the inability to find their way from one place to another. They don't seem to form a cognitive map and therefore cannot navigate around their environment, yet their other cognitive abilities are intact. If you can't tell one house from another, a house from a church, or a church from a store, you will have problems following a cognitive map. The people with DTD have normal cognitive abilities, normal attention spans, and the ability to recognize differences between houses, churches, and stores. That’s not the basis of their impairment. Their impairment is that they cannot form the relationship between those things in their minds.

Development topographic orientation is a disorder that illustrates how the human brain works both with and without brain damage. DTD enables us to understand how a smart individual with an inactive hippocampus and prefrontal cortex could do well in almost all endeavors except for getting to a specific destination. This tells us that brain areas are very specific with their functions. It works like a string of Christmas lights where, if one light does not work or is dimmer than the rest, the rest of the lights are not affected. Relating this to an individual with DTD, life is still generally normal except when it comes to finding one’s way to a specific destination. 

REFERENCES

 

Iaria, G., Bogod, N., Fox, C., & Barton, J. (2009). Developmental topographical disorientation:

     Case one. Neuropsychologia, 47 (1), 30-40. doi.org/10.1016/j.neuropsychologia.2008.08.021

 

Javadi, A-H, Emo, B., Howard, L., Zisch, F., Yu, Y., Knight, R., Silva, J., Spiers, H. (2017).

     Hippocampal and prefrontal processing of network topology to simulate the future. Nature

     Communications, 8,doi:10.1038/ncomms14652

 

Karina. (2012, June). Introduction to Topographagnosia. Retrieved from 

     https://www.youtube.com/watch?v=Mx2WQFqkTzQ

 

Kim, J., Aminoff, E., Kastner, S., & Behrmann, M. (2015). A neural basis for developmental

     topographic disorientation. Journal of Neuroscience, 35 (37), 12954-12969.

     doi.org/10.1523/JNEUROSCI.0640-15.2015

 

 

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