The tritocerebrum is a small subdivision of the cerebrum in the brain stem of teleost fish. It lies anterodorsal to the olfactory bulb and preoptic area of the telencephalon. It is only obvious in tetrapods since the homologous structure, the tectum, is larger in reptiles and has a tetrapod-specific role. The tritocerebrum belongs to the telencephalon.
The tritocerebrum has a unique shape in reptiles, spiny lobsters and some insects like beetles. When the tritocerebrum is fully developed, it forms the third of three paired areas on either side of the brain. Its functions include body temperature regulation and releasing hormones that signal to other parts of the body. Some scientists argue that this structure evolved because it allowed additional olfactory receptors. It increased the animal’s ability to smell. This structure may have also evolved to allow additional neurons and function in the olfactory bulbs. Its functions are not completely understood, and its importance is still debated.
Evolution of tritocerebrum
It is possible that the tritocerebrum evolved to allow more neurons to be present at this position. Increased neurons are found in the olfactory bulb and the preoptic area. This would suggest that neurons increase to facilitate the ability to smell.
The tritocerebrum is most obvious in tetrapods since it lacks reptiles, spiny lobsters, and insects such as beetles. Darwin’s finches have very large tritocerebrum, but it is possible that these birds had larger brains due to their small size. However, it is not clear how much this structure has to do with body temperature regulation and the release of hormones. In addition, it is still unclear whether the tritocerebrum is a novel structure or if it was inherited from an ancestor.
The tritocerebrum may have evolved to allow for more olfactory receptors. This could have been advantageous since fish can smell more than their mammalian relatives. However, it is not clear how this increase in smell would have contributed to survival.
A phylogenetic novel structure
It is unclear whether this structure evolved because it made room for additional olfactory receptors. The adaptive value of such a structure is unclear because it does not seem highly likely that it increased survival in the ancestral species, or that the structures evolved for such a function. The tritocerebrum could also have been inherited from an ancestor, or be a response to environmental stimulus, although this may also be due to convergent evolution with other teleosts.
Currently, there are several theories as to how the tritocerebrum could have evolved. One theory states that it resulted from the mutation of the brain stem, giving rise to a new region as its main function. However, this is not supported by studies. Another theory states that it developed because it allowed additional neurotransmitters to be present in the preoptic area and olfactory bulb, which would have been advantageous.
Tritocerebrum structure
A small subdivision of the cerebrum is found in the brain stem. It lies anterodorsally to the olfactory bulb and preoptic area of the telencephalon. The tritocerebrum belongs to the telencephalon and has a similar phylogenetic position to the olfactory bulb and preoptic area.
Tritocerebrum function
There are two main hypotheses for the function of the tritocerebrum:
1) it may have evolved to allow for more olfactory receptors. This could have been advantageous since fish can smell more than their mammalian relatives. However, it is not clear how this increase in smell would have contributed to survival.
2) It may be involved in regulating body temperature and releasing hormones that act as signals to other parts of the body.
Conclusion
It is a set of dendritic cells that develop from the dorsal interneuron population present in the brain stem. They are connected to the tectum. The most notable feature is that they respond to electric fields and receive impulses from the tectum and preoptic area induced by odours. The tritocerebrum is believed to be a small subdivision of the cerebrum found in the brain stem. It belongs to the telencephalon and has a similar phylogenetic position to the olfactory bulb and preoptic area.It is a combination of three structures: the tectum, which is a sensory structure, the tritocerebrum and the pretectal nucleus. The Tritocerebrum may have evolved to allow for more neurons to be present at this position. Increased numbers of neurons are found in the olfactory bulb, the preoptic area and the Tritocerebrum. It is not clear how this increase in neurons was adaptive, but they likely increased to facilitate the ability to smell.