Gated transformations from egocentric to allocentric reference frames involving retrosplenial cortex, entorhinal cortex, and hippocampus

Abstract

This paper reviews the recent experimental finding that neurons in behaving rodents show egocentric coding of the environment in a number of structures associated with the hippocampus. Many animals generating behavior on the basis of sensory input must deal with the transformation of coordinates from the egocentric position of sensory input relative to the animal, into an allocentric framework concerning the position of multiple goals and objects relative to each other in the environment. Neurons in retrosplenial cortex show egocentric coding of the position of boundaries in relation to an animal. These neuronal responses are discussed in relation to existing models of the transformation from egocentric to allocentric coordinates using gain fields and a new model proposing transformations of phase coding that differ from current models. The same type of transformations could allow hierarchical representations of complex scenes. The responses in rodents are also discussed in comparison to work on coordinate transformations in humans and non-human primates.

Hippocampal spatial view cells, place cells, and concept cells: View representations

“…When egocentric encoding is found, in rodents, for example, by "egocentric boundary cells" (Alexander et al, 2020(Alexander et al, , 2023Wang et al, 2018Wang et al, , 2020Wang et al, , 2023, the most parsimonious account of its utility is in obstacle avoidance (a running rat with poor vision using vibrissae and olfactory cues does not want to run into a boundary), for maintaining distances from other individuals as in flying flocks of birds or bats, and so forth. In conclusion, hippocampal and parahippocampal cortex spatial view cells found in primates including humans may be key to understanding the functions of the hippocampal system in memory and navigation in humans (Georges-François et al, 1999;Robertson et al, 1998;Rolls, 1999Rolls, , 2021aRolls, , 2021bRolls, , 2021cRolls, , 2023aRolls, , 2023bRolls et al, 1998;Rolls, Robertson, & Georges-François, 1997); these cells go beyond rodent place cells, and indeed they compute something different and are used in different ways.…”

“…In Section 2.2, the role of facing location in the encoding of these allocentric neurons is considered (Mao et al, 2021;Zhu et al, 2023). In Section 2.3, evidence for some egocentric encoding in the hippocampal system of rodents (Alexander et al, 2023;Wang et al, 2023) is discussed. In Section 3, the case is made that the issue of the coordinate framework for spatial representations, allocentric versus egocentric, is separate from the interesting issue of view-dependent spatial representations, which relates to which side a scene is viewed from by an observer (Wirth, 2023).…”

“…Egocentric view representations are shown by some rodent hippocampus-related neurons. For example, neurons in the retrosplenial cortex show egocentric coding of the position of boundaries in relation to the rodent (Alexander et al, 2023), and neurons in the rodent lateral entorhinal cortex represent the angular bearing of objects and boundaries in an egocentric frame of reference (Wang et al, 2023). Neurons with egocentric encoding of this type might be suitable for obstacle avoidance (rather than remembering where objects are in the world, or for allocentric navigation).…”

“…This is a commentary on issues important in understanding hippocampal function that are raised by papers in the Special Issue of Hippocampus (2023) entitled "Hippocampal system neurons encoding views in different species" (Alexander et al, 2023;…”

A place with a view: A first‐person perspective in the hippocampal memory space

“…While this is an enticing hypothesis, many recent findings indicate that there may be more similarities across species than one could expect. As reviewed in this issue (Alexander et al, 2023), visual input is represented in rodents and primates in a similar way in cortical regions projecting to the hippocampus, leading to a representation of space and visual space with respect to the self. These results show that an initial visual sampling yields similar egocentric representations, referenced to the body, in different species, which are suitable for navigation even without relying on the hippocampus (LaChance & Taube, 2023, in this issue).…”