Retrosplenial region

Retrosplenial cortex
Medial surface of the brain with Brodmann's areas numbered.
Details
Identifiers
Latin	Regio retrosplenialis
NeuroNames	ancil-111
Anatomical terms of neuroanatomy []

The retrosplenial cortex (RSC) is a cortical area in the brain, located posteriorly (towards the back) and comprising Brodmann areas 29 and 30 .The region's name refers to its anatomical location immediately behind the splenium of the corpus callosum in primates, although in rodents it is located more towards the brain surface and is relatively larger. Its function is currently not well understood, but its location close to visual areas and also to the hippocampal spatial/memory system suggest it may have a role in mediating between perceptual and memory functions.

There is a large amount of variation in the region's size across different species. In humans it comprises roughly 0.3% of the entire cortical surface whereas in rabbits it is at least 10% and in rats it extends for more than half the cerebrum dorso-ventrally, making it one of the largest cortical regions. On the basis of its microscopic cellular structure it is divided into dysgranular (area 30) and granular (area 29) regions.

The retrosplenial cortex has dense reciprocal projections with the visual cortex, postsubiculum (also known as dorsal presubiculum) and with anterior thalamic nuclei and the hippocampus.

Neurophysiological studies of retrosplenial cortex have mainly been done in rats. In rodents, around 8.5% of neurons in the retrosplenial cortex are head direction cells while other neurons have correlates with movement parameters such as running speed, and there is also evidence of weak spatial coding. Much of the observed activity has been found to be conjunctive (reflecting more than one parameter at once). A recent study of rats running on a long linear maze found complex patterns of activity reflecting conjunctions between position on the track, position on the track within the room at large and whether the animal was turning left or right.

In humans, fMRI studies implicate the retrosplenial cortex in a wide range of cognitive functions including episodic memory, navigation, imagining future events and processing scenes more generally.Rodent studies suggest the region is important for using surrounding visual cues to carry out these tasks. Retrosplenial cortex is particularly responsive to permanent, non-moving environmental landmarks and is also implicated in using them to make spatial judgements.