Pyriform cortex: what is it and what are the functions of this part of the brain?

This part of the brain is involved in odor recognition and memory.

Although there have been remarkable advances in science, the human brain remains an unknown in many respects. There are structures that are gradually becoming known, and one of them is the pyrrhine cortex. one of them is the piriform cortex..

The piriform cortex is part of the olfactory cortex, and in addition to detecting and differentiating odors, it has recently been discovered that it is also responsible for storing long-term memories. Let's learn about its anatomy, its functions and the latest findings.

Piriform cortex and olfactory system.

The piriform cortex is located within a larger region, the so-called olfactory cortex.. The olfactory cortex is the area of the cortex in the forebrain and receives direct input from the olfactory bulb. Thus, the piriform cortex is the main region of the olfactory cortex.

The olfactory cortex is the only part of the vertebrate forebrain that receives direct sensory input. Another characteristic of the olfactory system at the cerebral level is that it is the only one that does not relieve the thalamus (as is the case with the other senses). Moreover, it is ipsilateral (each hemisphere receives information from the nostril on the same side).

On the other hand, the olfactory system is one of the first sensory systems to be one of the first sensory systems to differentiate and become functional during and become functional during fetal life.

Characteristics

Humans share the piriform cortex with mammals, amphibians and reptiles.

The piriform cortex is a part of the brain where the sense of smell is located. can detect and distinguish odors with high precision.. Recently, however, it has also been linked to the storage of long-term memories.

The neuronal distribution of this part of the nervous system is apparently random and "chaotic", and until recently it was not known exactly why. However, a team of scientists at Salk University (USA) discovered that such a distribution is essential for the brain to distinguish odors correctly and extremely accurately.

Neuroanatomy

At the neuroanatomical level, the piriform cortex is part of the rhinencephalon, located in the telencephalon.. The telencephalon is a brain structure located above the diencephalon, it is the anterior part. It is the largest area of the brain and represents the highest level of somatic and vegetative integration.

The piriform cortex is part of Brodmann's area 27. It has been suggested that this cortex could be an attractive target for the treatment of epilepsy by lesion, stimulation or local drug delivery.by injury, stimulation or local drug delivery.

Functions

The most important functions of the piriform cortex are twofold: it functions as an olfactory system and participates as a kind of "archive" where long-term memories are stored.

Detection of odors

As we have already seen, the piriform cortex is part of the olfactory cortex. But how does it detect odors?

When odor molecules bind to the receptors in the nose, the signal is transmitted to the bulb of the nose, the signal is transmitted to the olfactory bulb and from there to the pyriform cortex.. The researchers discovered that each of the neurons in the olfactory bulb is connected to almost all of the neurons in the piriform cortex.

On the other hand, they found that instead of there being a single receptor that detects an odor and lights up a group of neurons, each odor has a kind of "fingerprint" that is based more on the strength of the connections.

2. Long-term memory

Another discovery of the piriform cortex came in late 2017 from two German neuroscientists, Christina Strauch and Denise Manahan-Vaughan of Ruhr-University Bochum (Germany). Their results were published in the journal Cerebral Cortex.

Strauch and Manahan-Vaughan found that the piriform cortex, which is responsible for detecting odors, is also involved in the storage of memories. the storage of memories. Specifically, it is involved in retaining memories in long-term memory.

Experimental methodology

These scientists analyzed whether the piriform cortex of rats was capable of expressing synaptic plasticity, a phenomenon that appears when neurons communicate with each other and memory storage is activated. Such plasticity did appear in the piriform cortex of rats, demonstrating that long-term memory retention occurs in this area.

To study this, they used electrical impulses in the brain to emulate processes that would trigger the encoding of an olfactory sensation that could be memorized. Through a series of protocols, they also induced long-term effects in the brain. induced long-term effects in the hippocampus (responsible for long-term memory). (responsible for long-term memory).

2.2. Conclusions

The neuroscientists state that their study shows how the pyriform cortex can serve as a storage space for long-term memories, although it is also true that to carry it out, it needs "instructions" from the orbitofrontal cortexa region of the frontal lobe related to the cognitive processing of decision making.

Bibliographical references:

• Carlson, N.R. (2005). Physiology of behavior. Madrid: Pearson Educación.
• Guyton, A.C. (1994). Anatomy and physiology of the nervous system. Basic neuroscience. Madrid: Editorial Médica Panamericana.
• Laufs, H. et al. (2011). Converging PET and fMRI evidence for a common area involved in human focal epilepsies. Neurology, 77(9), 904-910.
• Strauch & Manahan-Vaughan. (2018). In the Piriform Cortex, the Primary Impetus for Information Encoding through Synaptic Plasticity Is Provided by Descending Rather than Ascending Olfactory Inputs. Cereb Cortex, 28(2), 764-776.