Biology subjects

Gahnstrom, C. J.

Publications and source records attributed to Gahnstrom, C. J..

4 recordsLinked to original sources

bioRxiv2026

Global structure of new relational knowledge networks is represented in retrosplenial complex, and node-distance in hippocampus

Much of our knowledge is structured in networks, but how the brain represents such networks remains unclear. In most nested knowledge structures a subset of the nodes will be highly connected to other nodes in the network. High levels of connection can exist either locally (high degree centrality) or at a global level (high closeness/betweenness centrality). Here, we explored how the human brain represents network structure using functional magnetic resonance imaging (fMRI) and a novel learning paradigm. During training, participants learned the transition structure for travel between a set of fictious partially connected alien planets. Despite encountering only individual connections, participants choices indicated they could infer the broader network structure. Next day, they viewed each stimulus during a cover task while undergoing fMRI. Representational-similarity analysis showed that shortest-path distances within the learned graph were encoded in the posterior hippocampus and right retrosplenial complex, whereas global connectivity (closeness/ betweenness centrality) was represented in the left retrosplenial complex. These findings extend the view that brain networks associated with spatial navigation also process abstract relational knowledge using principles akin to mapping physical space. The results are also consistent with proposals that the hippocampus represents distance information and that the retrosplenial cortex acts as hub for integrating recently acquired knowledge.

neuroscience↗

bioRxiv2024

London taxi drivers leverage regional boundaries to optimise route choices and improve their navigation skill across three decades

The world is defined by boundaries. They segment our experience of time and space, and in virtual environments have been shown to impact navigational choices. Here, we test the impact of boundaries on route choices in a real-world environment (London, UK) with a group of expert navigators: licensed London taxi drivers who are required to memorise the layout of over 26,000 streets to obtain their licence. After presenting photographs of a start location and a goal location, taxi drivers were asked to either accept or reject a third target street as forming part of the direct route or not. Performance increased across the adult life-span period in this group (age: 34 to 67). Taxi drivers were faster and more accurate when the target location formed part of a street network boundary (e.g. streets on the edge of the London neighbourhood Soho). Our results are consistent with taxi drivers exploiting the graph structure of the street network to plan routes, as well as consistent with the formation of hierarchical state representations to reduce the dimensionality of the planning problem. Taken together, we show that navigational skill can improve over decades of exposure and that experts exploit regional boundaries for optimal choices, providing a scaffolding over which to form action plans.

neuroscience↗

bioRxiv2023

Individuals learning to drive solo before age 18 have superior spatial navigation ability compared with those who learn later

A challenge associated with driving vehicles can be navigating to the destination. While driving experience would seem beneficial for improving navigation skill, it remains unclear how driving experience relates to wayfinding ability. Using the mobile video game-based wayfinding task Sea Hero Quest, which is predictive of real-world navigation, we measured wayfinding ability in US-based participants (n = 694, 291 men, 403 women, mean age = 26.8 years, range = 18-52 years). We also asked travel-related self-report questions, including the age one started learning to drive, the age one started driving solo and weekly driving hours. A multivariate linear regression model found that those who started driving solo below aged 18 had significantly better wayfinding ability than those starting to drive solo aged 18 and above. Other driving-related self-report measures were not associated with wayfinding ability. Future studies should determine the directionality of the association between driving experience and wayfinding ability.

neuroscience↗

bioRxiv2023

Shorter reported sleep duration in men is associated with worse virtual spatial navigation performance

Sleep has been shown to impact navigation ability. However, it remains unclear how different sleep-related variables may be independently associated with spatial navigation performance, and as to whether gender may play a role in these associations. We used a mobile video game app, Sea Hero Quest (SHQ), to measure wayfinding ability in US-based participants. Wayfinding performance on SHQ has been shown to correlate with real-world wayfinding. Participants were asked to report their sleep duration, quality, daytime sleepiness and nap frequency and duration on a typical night (n = 737, 409 men, 328 women, mean age = 27.1 years, range = 18-59 years). A multivariate linear regression was used to identify which self-reported sleep variables were independently associated with wayfinding performance. For men, longer self-reported sleep durations were associated with better wayfinding performance. For women, no such association was found. While other self-reported sleep variables showed trends of association with wayfinding performance, none of these were significantly associated with wayfinding performance in our regression model. These findings from younger U.S.-based participants suggest that a longer self-reported sleep duration may be an important contributor to successful navigation ability in men.

neuroscience↗