Piriform Cortex: What it is and What Functions Does This Part of the Brain Have?

Although there have been notable advances in science, the human brain remains an unknown in many aspects. There are structures that are becoming known little by little, and 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 found.

Piriform cortex and olfactory system

The piriform cortex is located within a larger region, the so-called olfactory cortex The olfactory cortex is the cortical area 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 brain level is that it is the only one that does not highlight the thalamus (as it does with the other senses). In addition, 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 differentiate 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, which allows you to detect and distinguish odors with great precision However, recently it has also been linked to the storage of long-term memories.

The neural 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 from Salk University (USA) discovered that this distribution is essential for the brain to distinguish odors correctly and extremely accurately.

Neuroanatomy

At a neuroanatomical level, the piriform cortex It is part of the rhinencephalon, located in the telencephalon The telencephalon is a brain structure located on the diencephalon, it is the anterior part. This 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 crust could be an attractive target for epilepsy treatment through injury, stimulation or local delivery of medications.

Features

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

1. Odor detection

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

When aroma molecules bind to receptors in the nose, the signal is transmitted to the olfactory bulb and from there to the piriform 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 a smell and illuminates a group of neurons, each smell 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 at the end of 2017, from two German neuroscientists, Christina Strauch and Denise Manahan-Vaughan, from the Ruhr University of Bochum (Germany). Their results were published in the journal Cerebral Cortex.

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

2.1. 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 the storage of memories is activated. This plasticity did appear in the piriform cortex of rats, demonstrating that long-term memory retention occurs in this area.

To study it, they used electrical impulses in the brain, with the aim of emulating processes that trigger the encoding of an olfactory sensation that could be memorized. Through a series of protocols, in addition induced long-term effects in the hippocampus (responsible for long-term memory).

2.2. Conclusions

The neuroscientists claim that their study shows how the piriform 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 cortex a region of the frontal lobe related to the cognitive processing of decision making.