Our cerebral cortex is a complex structure , extremely developed, that allows us to perform and coordinate the different functions and actions that our organism can carry out, both on a physical and mental level and on a level of perception and action.

But this structure is not homogeneous: different brain areas specialize in different functions, with certain parts of the brain being more relevant to certain mental processes. An example of this is the dentate gyrus , of great importance in the formation of memories, which we will talk about throughout this article.

What is a dentate gyrus?

We call a dentate gyrus a convolution of the cerebral cortex located in the lower part of the temporal lobe of the brain, being part of one of the oldest phylogenetic regions speaking of the cortex (the arch cortex). It borders among other structures with the corpus callosum (although it is separated from it by the grey indian), the entorhinal cortex, the hippocampus and the cingulate gyrus.

This small brain region is part of the hippocampal formation, connecting it to the cortex, and is mainly configured by grey substance (somas and amyelinic axons). In fact, it is considered that this twist can be considered a modified and partially separate part of the hippocampus itself during neurodevelopment.

Thus this part of the cortex has an important role in terms of human memory capacity, acting as a bridge between the entorhinal cortex (which in turn is considered the bridge between the hippocampus and the rest of the cortex) and the hippocampus. This structure acts by receiving afferences from the former and sending information to the rest of the hippocampal formation, passing through the perforating pathway by means of a toothed gyrus. However, its connections with the entorhinal cortex do not allow the information to be returned through the same channel. It will be other structures that send the information back to the entorhinal cortex so that it can be distributed to other parts of the cortex.

The particularity of the dentate gyrus is that it is mainly formed by granular cells , which at their axon end are transformed into mossy fibers that make synapses exclusively with the Ammon field of the hippocampus. In addition, these cells are one of the few that can generate new neurons throughout the life cycle, in certain types of mammals (it is not yet well known if this also occurs in humans).

Functions

The functions of the dentate gyrus, as mentioned above, are largely derived from its role as a connection between entorhinal cortex and hippocampus . Thus, one of its main roles is to transmit information to the latter structure in order to process it.

The jagged turn thus has an important role in the formation of memories, based on episodic memory. It also has a great importance at the level of navigation and spatial memory, being this structure the one that allows us to distinguish between similar environments.

It also plays a role in the consolidation and recovery of memory , which merits the above-mentioned when participating in the recognition of similar sites.

Since the hippocampal formation is also part of the limbic system, it is suspected that the jagged turn also plays a role in the integration into the memories of the emotions aroused by the experience. Variations in this area have also been observed in the presence of emotional disturbances such as stress or anxiety, as well as in depression.

Neuron birth in adults

Traditionally, it has always been said that the formation of new neurons occurred only in the first years of life and that once in adulthood we had approximately the same neurons for life until they died. However, over time it has been discovered that in some mammals, although not at a generalized level, some areas of the brain continue to produce, in small quantities, new neurons throughout the entire life cycle.

One of the points where this neurogenesis has been detected is the dentate gyrus. This birth has been associated with task learning and spatial learning , which in turn seem to promote the birth of new neurons. However, studies in this regard do not show that neurogenesis generates an improvement in these capacities, and contradictory results have been found (although this could be due to the need to develop strong synapses between the new neurons). Further research is needed in this area,

It has also been observed that the environment has great importance in the formation of new neurons: stress or cholinergic lesions reduce the capacity to generate new neurons, while stimulation reduces the power. The observation of alterations in neurogenesis in this area is one of the main reasons that have led us to think about the involvement of the dentate gyrus in the management of emotions, whether this alteration of neurogenesis is a cause or a consequence.

Bibliographic references

  • Nieto-Escámez, F.A.; Moreno-Montoya, M. (2011). Neurogenesis in the dentate gyrus of the hippocampus: implications for learning and memory in the adult brain. Arch. Neuroscience, 16 (4): 193-199.
  • Andersen, P.; Morris, R.; Amaral, D.; Bliss, T. & O’Keefe, J. (2006). The hippocampus book. 1st Edition. OUP. USA.
  • Clark, D.L.; Boutros, N.N. and Mendez, M.F. (2012). The brain and behavior: neuroanatomy for psychologists. 2nd edition. The Modern Handbook. Mexico.