The retrosplenial area is an area of the brain related to episodic and contextual memory, navigation or imagination of future events and scenes. Its importance lies in being a necessary part of a set of regions involved in the management of brain activity when the mind and body are at rest.
In this article, we explain what the retro-plenary area consists of., Where it is located, what are the main functions it performs and what types of disorders can occur if damage occurs in this region of the brain.
Retrosplenial area: definition and neuroanatomical location
The retrosplenial area or cortex (CRE) is an area of the brain located at the bottom of the cingulate gyrus, Extending around the splenium of the corpus callosum, a structure connecting the two cerebral hemispheres. They include Brodmann zones 29 and 30 and together with the precunary and posterior cingulate form a posterior nucleus which is sometimes referred to as the “posteromedial cortex”.
This brain region is interconnected with the posterior cingulate cortex (CCP) and has strong strong connections with the pregenual and subgenital anterior cingulate cortex. CCP and CRE are part of the brain network by default, a set of areas of the brain that are activated (up to 20% above other regions) when the mind wanders and is at rest.
Animal studies have revealed that the retrosplenial zone would have reciprocal links with these three regions: the hippocampus, the parahippocampal gyrus and certain nuclei of the thalamus. Traumatic injuries and pathologies associated with these areas of the brain are believed to be involved in many amnesic syndromes.
Other notable connections between CRE and different areas of the prefrontal cortex (particularly Brodmann areas 46, 9, 10, and 11) have also been described, providing an indirect pathway for the hippocampus to connect with the prefrontal cortex. dorsolateral, and vice versa.
Studies have determined that the retro-plenary area has an important role in spatial and episodic (or contextual) memory, navigation, imagining future events, and scene processing. This brain region would also be involved in processes involving the recognition of permanent and non-mobile environmental landmarks, as well as in spatial-type judgments.
Below we will see in more detail some of the main tasks in which the retrosplenial area is involved:
Navigation, spatial and contextual memory
Studies conducted with functional magnetic resonance imaging have shown that activity in the retro-ecclesiastical zone is modulated by a variety of processes, ranging from the production and basic understanding of speech to motivation and understanding. pain. however, its involvement in navigation and spatial memory tasks seems very clear, And most brain imaging studies confirm this.
In a recent meta-analysis, the retrosplenial area showed significant activation when retrieving autobiographical information, and more specifically in recent experiences versus remote experiences, although it appears to be activated when we remember any type of experience in which we are protagonists, regardless of whether the tone is more neutral or emotional.
On the other hand, it has also been observed that the retrosplenial zone participates in the tasks of space navigation. these included passive visualization of navigation images, mental navigation and interactive navigation in virtual reality environments.
In addition, activity was also observed when learning new and newly learned environments, as well as in very familiar environments. In fact, it seems difficult to find a navigation task or topographic memory in which this region is not activated.
Regarding virtual environments, a study using a London-based virtual reality simulation showed that activity in the retrosplenial area increased when topographic representations needed to be updated, integrated or manipulated for route planning or when new topographical information had been acquired. Therefore, it appears that the activity of this brain region varies depending on specific circumstances and priorities.
Finally, with regard to the relationship between the retrosplenial area and the processing of the scene, it has been suggested that this region could address relationships relevant to the scene, Such as that which arises from objects and their context. Several studies have shown that this zone is activated by seeing objects strongly associated with a specific context, and not the other way around (when this association is weak).
Imagination of future events
In recent years, new research has emerged in the field of memory on the basis of the following premises: first, the fact that patients with bilateral lesions of the hippocampus not only cannot remember past experiences , but also find it difficult to imagine fictitious and future experiences; and second, the discovery of the memory of past experiences activates many regions of the brain which are also activated by imagining a plausible personal future and fictitious experiences.
Another meta-analysis that included several studies on this issue confirmed that the retrosplenial area is part of a common “core network” that maintains a variety of cognitive functions. This network would support the construction of “scenes” (process of generation and mental maintenance of a complex and coherent image or event), that is why it is essential in autobiographical memory, navigation or thinking about the future.
The link between memory and navigation with the imagination of future events places this region of the brain in a crucial position for understanding these cognitive processes. A recent study with functional MRI examined brain activation during recovery from autobiographical events, movie episodes, and real-life news clips, as well as imaginary events of all three types. The results concluded that there was greater activation in the face of recovery from real events.
Injury to the retrosplenial region can produce an amnesic syndrome characterized by anterograde loss (inability to store new events) of verbal and non-verbal memories, accompanied by mild retrograde amnesia (inability to remember events that occurred before the injury) . The extent of retrograde amnesia ranges from less than a year to 10 years.
In turn, damage to the right part of the retrosplenial area it can generate a selective deficit of spatial orientation and amnesia of topographic features: The subject can recognize familiar buildings and landscapes, but loses the positional relationship between two known places. Indeed, this area can play an important role in coding new sites and their relationships.
In most cases, patients can recognize landmarks in their neighborhood, for example; but they cannot navigate familiar surroundings effectively, indicating that they are unable to understand the directional information of the signals from certain landmarks.
Damage to the retrosplenial area can also compromise learning in new environments. Subjects with damaged hippocampus also show difficulty navigating in familiar and new environments, but unlike people with lesions in the retrosplenial area, they are generally able to navigate these environments and they retain their sense of focus. orientation.
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