Toothed rotation: what it is and what functions it performs in the brain
Our cerebral cortex is a complex structure , extremely developed, which allows us to perform and coordinate the different functions and actions that our body can carry out, both physically and mentally and both at the level of perception and action.
But this structure is not homogeneous: different brain areas specialize in different functions, being certain parts of the brain 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.
- Related article: "Parts of the human brain (and functions)"
What is the dentate gyrus?
We call dentate gyrus to a convolution of the cerebral cortex located in the lower part of the temporal lobe of the encephalon, being part of one of the oldest regions phylogenetically speaking of the cortex (the arquicorteza). It is limited among other structures with the corpus callosum (although it is separated from it thanks to the gray indusium), the entorhinal cortex, the hippocampus and the cingulum gyrus.
This small brain region is part of the hippocampal formation, connecting it with the cortex, and is mainly formed by gray matter (unmyelinated axons and soma). In fact, it is considered that this turnaround it can be considered a modified part and partially separated from the hippocampus itself during neurodevelopment.
So this part of the cortex has an important role in regard to the memory capacity of human beings, acting as a bridge between entorhinal cortex (which in turn is considered a bridge between the hippocampus and the rest of the cortex) and the hippocampus. This structure acts receives afferences from the first and sends information to the rest of the hippocampal formation, passing through the dentate gyrus the perforating way. However, its connections with the entorhinal cortex do not allow the return of information 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 dentate gyrus has the peculiarity of being mainly formed by granular cells , which in their axonal terminations end up transforming into mossy fibers that synapse exclusively with the field of Amón 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 still not well known if it also occurs in humans).
The functions of the dentate gyrus, as we mentioned above, derive largely from its role as a connection between entorhinal cortex and hippocampus . Thus, one of its main roles is to transmit information to this last structure in order to process it.
The dentate gyrus 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, this structure being what allows us to distinguish between similar environments.
He also exercises a role in the consolidation and recovery of memory , something that deserves the above mentioned when participating in the recognition of similar sites.
As the hippocampal formation is also part of the limbic system, it is suspected that the dentate gyrus also plays a role in the integration in the memories of the emotions aroused by the experience. Also, the existence of variations in this area has been observed in the presence of emotional disturbances such as stress or anxiety, as well as in depression.
- Related article: "Types of memory: how memory stores the human brain?"
The birth of neurons 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 numbers, new neurons throughout the life cycle.
One of the points in which this neurogenesis has been detected is the dentate gyrus. Said 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 end up showing that neurogenesis generates an improvement in these abilities, finding contradictory results (although this could be due to the need to develop strong synapses between the new neurons). More research is needed in this area,
It has also been observed that the environment is of great importance in the formation of new neurons: stress or cholinergic lesions decrease the ability to generate new neurons, while the stimulation potency. The observation of alterations in neurogenesis in this area is one of the main reasons that led us to think about the involvement of the dentate gyrus in the management of emotions, whether this alteration of the cause or consequence neurogenesis.
- 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. Neurocien., 16 (4): 193-199.
- Andersen, P .; Morris, R .; Amaral, D .; Bliss, T. & O'Keefe, J. (2006). The hippocampus book. 1st Edition. OUP USES.
- Clark, D.L .; Boutros, N.N. and Méndez, M.F. (2012). The brain and behavior: neuroanatomy for psychologists. 2nd edition. The Modern Manual. Mexico.