As I passed through a small unfamiliar sludge on my way back on a trail in New Hampshire, I realized that I was lost. Surrounded by a dense thicket, I searched tirelessly for familiarity. The familiar broken trunk I saw on my way, the familiar unique arrangement of 4 trees, the familiar rock with pink mushrooms under it from where I was supposed to take a right on the curve. After a long half-hour of wandering in different directions, I had even lost the sense of where I had come from. I could feel heartbeats in my throat growing stronger, muscle knots in my stomach growing tighter, and streams of sweat on my forehead growing bigger. I imagined all the worst-case scenarios. And the most frustrating feeling of all? I had been there 10 times and still, I was lost in the wilderness!
Now, imagine experiencing this panic every day, even in extremely familiar environments like your hometown. Individuals who experience such an extreme sense of disorientation and always feel lost are diagnosed with Developmental Topographical Disorientation. These individuals show an inability to generate a “cognitive map” – the brain’s GPS.
What is a cognitive map?
A cognitive map is a mental representation of relationships between different landmarks in a space as big as a city and as small as our bedroom, even when they are not in our sight. For example, as I write this, I know that Starbucks is about a mile away from the park to its north. To successfully navigate anywhere, our brain constantly updates our location with respect to the landmarks in this cognitive map by tracking the direction we face and the distance we have moved. We all use this cognitive map every day. How is it that we can walk 10 steps and take a left turn in our house while blindfolded and still be able to tell the location we are in? Through our cognitive map!
Some like the Inuits of Northern Canada or the Puluwat sailors in the Polynesian islands, renowned to sail for about 800 km without using modern navigation tools, can achieve feats of navigation by fine-tuning the cognitive map through years of apprenticeship. Back in the New Hampshire woods, not only had my phone’s GPS failed, but my brain’s GPS had erred! This was because, for all the past times on that trail, I had not developed an enriching cognitive map. Hence, I could only remember the landmarks, but could not picture where they were with respect to me. And now I wonder why.
The two strategies of navigating: Place strategy and Response strategy
Although the cognitive map or “place” strategy is extremely important, it may not always be necessary to accurately navigate. Merely recalling the sequence of steps – akin to a phone’s GPS – can help us reach our destinations. For example: turn right (response) at Starbucks (stimulus), or in my case in the woods, walk straight along the broken trunk. This navigational strategy is called a “stimulus-response” or simply, “response” strategy. Response strategy unconsciously puts us on autopilot mode and is the reason why we accidentally end up in a room in our house and forget the intention.
Though one may unconsciously favor a response or a place strategy, we can shift between different strategies depending on the task demands. For example, I started out as a place navigator enroute to my new lab in Montreal. I took copious notes of the landmarks, made errors, derived the optimal route to my lab, and was often mentally exhausted. Now, as a response navigator, I just need a handful of sequences of landmarks to take correct turns, and I can learn French while I commute. This ability of our brain to shift between these two navigational strategies has evolved to free up precious neural resources to undertake new challenges. But if we forget the sequence of turns, or if the road beyond the Starbucks is blocked, we are lost unless we have access to our cognitive map!
Competition between the brain regions involved in the two navigational strategies. Do we have a winner?
The two navigational strategies are controlled by communication and competition between two brain regions: the caudate nucleus (for response strategy) and the hippocampus (for place strategy). Activities that engage these regions can increase their function and size thanks to brain plasticity – just as our muscles buff up when we lift weights. If we use it, we preserve it, else we lose it.
Research has shown that overuse of digital GPS (e.g., Google Maps) or a response navigation strategy, and engaging in instant-reward activities such as first-person video games, uses and thus increases the size of the caudate nucleus, and decreases the size of the hippocampus given the competition between them. The hippocampus is important to give us a sense of orientation, form associations between things, emotions, and landmarks, and to form episodic memory (i.e., the memory of our life events). Its shrinkage may pose a future risk of numerous psychiatric illnesses and Alzheimer’s disease. Luckily, activities that engage the hippocampus may safeguard it from shrinking.
Alarmingly, in today’s world of GPS, we often unconsciously fall on caudate nucleus-based autopilot mode. So, the question arises: Is there any advantage of using one navigational strategy over another and if so, how could we leverage it?
Building better cognitive maps
A well-cited study compares the hippocampi between London cab drivers and London bus drivers. Cab drivers had bigger hippocampi than bus drivers because bus drivers follow the same route every day (i.e., they use a response strategy). But to drive a taut black London cabbie, one must pass a test of “the Knowledge” of landmarks on 25,000 streets to be able to generate novel routes to any nook in London without the GPS (i.e., they use a place strategy). Hence, researchers are already developing training programs to stimulate cognitive map generation and consciously engage the hippocampus of individuals with Alzheimer’s disease or Developmental Topographical Disorientation to restore the skill of forming cognitive maps.
The good news is that we can train ourselves to be better navigators with practice. The next time you think of relegating that skill from the brain to under your fingertips on a phone’s GPS, slide that device inside your pocket! Instead, be attentive to the landmarks and the relationships between them while you walk down to the cafe. Observe where the bank is in relation to the cafe and a park on the way. Imagine the route to your destination and try exploring alternate routes to the same place! Build that cognitive map!
The response strategy only led me to an impasse in the woods of New Hampshire. Thankfully, a group of hikers showed me where I was, the distance left, and the direction I was facing. And my hippocampus started firing again!
Ekstrom, A. D., Spiers, H. J., Bohbot, V. D., & Rosenbaum, R. S. (2018). Human spatial navigation. Princeton University Press.