The human brain is a complex and fascinating organ. Each cerebral hemisphere is composed of several lobes.

And in the upper parietal lobe, hidden between layers of nerve fibers, we can find the pre-wedge, a region unique in its characteristics and in the functions attributed to it as the main center of brain coordination, as well as for participating in the processes of self-awareness.

In this article we explain what the pre-wedge is, what its structure is and where it is located, what its main functions are and what role it plays in the development of Alzheimer’s disease.

Pre-wedge: definition, structure and location

The pre-cuneus is a region located in the upper parietal lobe, hidden in the longitudinal fissure of the brain , between both hemispheres. It is bordered at the front by the marginal branch of the cingulate sulcus, at the rear by the parietooccipital sulcus and, below, by the subparietal sulcus.

The precuña has also sometimes been described as the medial area of the upper parietal cortex. In cytoarchitectural terms, corresponds to Brodmann’s area 7 , a subdivision of the parietal region of the crust.

It also has a complex columnar cortical organization and is one of the brain regions that takes the longest to complete its myelinization (process by which axons are coated with myelin to, among other things, improve the speed of transmission of nerve impulses). Its morphology shows individual variations, both in shape and in longitudinal size.

Likewise, the precuña has numerous neural connections ; at cortical level, it connects with sensorimotor areas, with areas linked to executive functions, memory and motor planning, and with the primary visual cortex; and at subcortical level, it has important connections with thalamic nuclei and the brain stem.

The precuña is a structure that has developed more in humans than in animals, since at an evolutionary level there has been a considerable increase in the size (in shape and surface area) of the parietal and frontal lobes of the human cerebral cortex with respect to the rest of the animal kingdom, with what this implies with respect to the development of higher cognitive functions. It is, therefore, a structure that has aroused great interest in the neuroscientific community , despite being anatomically so “elusive” (because of its location).


The precuña is one of the main areas of regulation and integration of our brain , and acts as a kind of conductor through which many of the signals necessary for this organ to function as an integrated whole pass.

The following are the different functions attributed to the pre-wedge:

Autobiographical information (episodic memory)

The pre-wedge works in connection with the left prefrontal cortex, which is involved in processes related to episodic memory and autobiographical memories. In this sense, it participates in aspects such as attention, recovery of episodic memory, working memory or processes of conscious perception.

1. Visuospatial processing

Another key function in which it has been suggested that the pre-wedge is involved is visuospatial processing; this area would participate in spatial attention management, when there are movements and also when images are generated .

It is also thought to deal with motor coordination in split-care processes; that is, when attention needs to be shifted to different places or spatial locations (e.g., when writing a text or drawing a picture). In addition, the pre-wedge would be activated, along with the premotor cortex, in mental operations that require visuospatial processing.

2. Self-awareness

Several investigations have linked the precuña with processes in which the conscience of oneself intervenes; in this sense, this brain region would have a relevant role in the integration of the perception of ourselves, in a network of spatial, temporal and social relations. The precuña would be in charge of generating that sensation of continuity between brain, body and environment.

In studies with functional images it has been observed that this brain structure analyzes and interprets the “intention” of others with respect to ourselves ; that is, it would act as a mechanism for analyzing the judgments of others that require an adequate interpretation in order to act accordingly (e.g. with empathy).

3. Conscious perception

In addition to having a relevant role in self-awareness processes, it has been suggested that the precuña could be, together with the posterior cingulate cortex, relevant for the processing and conscious perception of information .

It has been observed that during wakefulness the metabolism of brain glucose increases significantly, contrary to what happens when under the influence of anesthesia. In addition, during slow wave sleep and rapid eye movement sleep or REM sleep, the pre-wedge would be practically deactivated.

On the other hand, it is believed that the cognitive functions related to this brain region could contribute to integrate the internal information (coming from the brain and our organism) with the environmental or external information; in this way, the pre-wedge would have an essential role in the processes that generate the conscience and the mind in general.

4. Integrating core

More and more studies support the role of the precuña as the integrating centre of neural networks of the brain, due to its high centrality in the cortical network of this organ and its numerous and powerful connections with prefrontal areas in charge of executive functions such as planning, supervision and decision making.

The pre-wedding in Alzheimer’s disease

Early Alzheimer’s disease starts with metabolic problems in the area of the medial parietal lobes . It seems that the enlargement of these brain regions is what confers certain vulnerability to the subsequent neurodegeneration suffered by these patients.

Several studies have suggested that there may be a relationship between pre-marriage and the development of this serious disease. As we have mentioned before, precuña has evolved differently in humans than in animals: the main difference with respect to the rest of primates, for example, is that this structure presents particularly high metabolic levels.

It seems that the pre wedge has higher metabolic expenditure levels than would correspond to its size , which is also the case with its thermal values. The curious thing is that Alzheimer’s starts with metabolic problems right in the deep medial parietal area, where the pre-wedge is located. And one characteristic of Alzheimer’s is the phosphorylation of tau proteins, which occurs in mammals that hibernate in response to temperature changes.

What neuroscientists suggest is that a pathology as frequent and characteristic of humans as Alzheimer’s would be associated with areas of the brain that possess a specific morphology also in humans. And what they question is whether the increase in complexity of these brain areas could also have led to an increase in biological complexity which, secondarily, could lead to an increase in the metabolic load, oxidative stress and cellular problems that predispose a person to Alzheimer’s disease.

However, research continues on the possible link between precuña and other similar structures and the development of this and other neurodegenerative diseases, with the aim of finding new drugs and therapeutic targets that will cure or at least slow down their progress.

Bibliographic references:

  • Cavanna, A.E., & Trimble, M.R. (2006). The precuneus: a review of its functional anatomy and behavioural correlates. Brain, 129(3), pp. 564 – 583.

  • Miners, J.S., Palmer, J.C., & Love, S. (2016). Pathophysiology of Hypoperfusion of the Precuneus in Early Alzheimer’s Disease. Brain Pathology, 26(4), pp. 533 – 541.