Coordinating with the “Inner GPS”

Abstract

The 2014 Nobel Prize for Physiology or Medicine was awarded for the discoveries that have elucidated the components of the internal positioning system that is centered on the hippocampus and entorhinal cortex. Here I provide a less than objective discussion of the importance of these accomplishments to systems neuroscience. By identifying positioning components like place, direction, distance, borders and the like, the field is given the opportunity to have a shot at piecing together how these components are integrated into the synthetic positioning sense. We are also given what is in my view, the most experimentally accessible and therefore potentially understandable, cognitive representation. Lest we feel too confident in the completeness of our understanding, and to inspire redoubled curiosity, I briefly describe a preliminary observation from our work with the psychosis-inducing drug phencyclidine (PCP). While PCP does not disturb where individual place cells fire, it dramatically discoordinates how these cells discharge together in time. Trying to understand how the positioning component cells are coordinated to provide useful knowledge is an exciting and tenable problem to be working on.

Normal CA1 place fields but discoordinated network discharge in a Fmr1-null mouse model of fragile X syndrome

“…Indeed, like others (Bakker et al, 1994;Bhattacharya et al, 2012;Brennan et al, 2006;D'Hooge et al, 1997;Zhao et al, 2005), the most reliable cognitive deficits we have previously detected in Fmr1-null mice is cognitive inflexibility; impaired ability to update learned avoidance of a shock zone when the location of shock changed (Radwan et al, 2016). If one interprets the hippocampus place code as a dedicated code (see (Fenton, 2015a), then these findings directly contradict predictions from disruption hypotheses: place cell cognitive information processing appears normal despite abnormal experience-dependent synaptic function.…”

Late Roman Villas and Cognitive Science

“…Thompson and Varela write that 'what the organism senses is a function of how it moves, and how it moves is a function of what it senses' (Thompson and Varela 2001: 424;Jelić et al 2016: 481). The neurological mechanism behind our sense of the location of our moving body in space (proprioception), was discovered by Edvard Moser, May-Britt Moser, and John O'Keefe, who won the Nobel Prize in Medicine for their work in 2014 (Fenton 2015). The brain's internal navigation system, dubbed a 'human GPS', involves nerve cells in the brain called place cells and grid cells that are activated with movement, and location is tracked by neurons firing in the shape of a hexagonal grid -creating a kind of miniature representation of the terrestrial spatial world.…”

Epilepsy as a Network Disorder (2): What can we learn from other network disorders such as dementia and schizophrenia, and what are the implications for translational research?

“…To illustrate these concepts in experimental work with relevance to schizophrenia, consider the use of phencyclidine (PCP), a drug that induces psychosis in humans. Using hippocampal area CA1 place cells as a model system, we find that systemic administration of PCP impairs cognitive control in spatial behaviors, but does not change the spatial tuning of the neurons – under PCP, place cells maintain the same firing rates and place fields as before PCP [76, 77]. Yet PCP significantly discoordinates how the cells discharge together in time, increasing errors and uncertainty when the rat’s location is decoded against the pre-PCP ensemble discharge in the place cell population.…”