Spatial Representations of Depth: Do Cognitive Maps Facilitate Depth Perception?

Since the discovery of place and grid cells, the hippocampus and entorhinal cortex have become the epicentre for the cognitive map, a neural representation of an animal's local environment. Subsequent discoveries of cells which code for head direction, speed, orientation, salient landmarks, and environmental boundaries have all further contributed to our ever more complex understanding of the cognitive map and its arrangement in the brain.

Despite these discoveries, how the brain receives allocentric sensory inputs and converts them into interpretable neural signals which effect perception and behaviour is still poorly understood. Present rodent behavioural research primarily involves the use of an empty enclosure with little inclusion of the local landmarks essential for navigation that are abundant in the wild.

With recent research showing that distortions in local environmental geometry can impair navigation in rats and produce corresponding distortion of the grid cell field, understanding the relationship between the environment, physical sensation, and conscious perception in the context of spatial reasoning is of paramount importance.

This PhD project aims to combine rodent electrophysiology and human psychophysics to explore the relationship between spatial cognition and visual perception by investigating how perception is influenced by changing environmental cues. Through the use of in vivo electrophysiological recording of cells in the hippocampus and medial entorhinal cortex (MEC) during animal behavioural testing, the effect of environmental distortion and changing local landmarks on spatial reasoning ability will be investigated.

Additionally, transgenic animal lines will be used to explore the role of neurogenesis and specific structures involved in the cognitive map in neural coding for the environment, particularly the layer II output of the MEC into the dentate gyrus and hippocampus. A corresponding study of human depth perception adapted from the rodent tasks will provide translational insights into the role of visual perception and environmental continuity in human spatial cognition.