Difference Between Telencephalon and Diencephalon

The key difference between telencephalon and diencephalon is that telencephalon is the anterior part of the brain, which is also called the cerebrum, while diencephalon is the part of the brain that is placed between the telencephalon and the midbrain.

The brain consists of cerebrum, cerebellum and medulla oblongata. The cerebrum, also known as telencephalon, belongs to the anterior part of the brain. It is the largest part of the brain. Moreover, it is the uppermost region of the brain. Diencephalon is a part of the forebrain located between telencephalon and midbrain. It is important to understand the functionality of the telencephalon and the diencephalon that forms the anterior brain.

CONTENTS

1. Overview and Key Difference
2. What is Telencephalon 
3. What is Diencephalon
4. Similarities Between Telencephalon and Diencephalon
5. Side by Side Comparison – Telencephalon vs Diencephalon in Tabular Form
6. Summary

What is Telencephalon?

Telencephalon is also known as the cerebrum. It is the largest part of the brain and roughly constitutes about 85% of the total weight of the brain. The telencephalon consists of the cerebral hemisphere: left and right cerebral hemispheres. The cerebellum is situated below the telencephalon.

The telencephalon develops during the 5^th week of embryonic development. It develops from the neural tube, where the extreme end of the neural tube develops into the telencephalon. During the development of the telencephalon, the development of sulci and gyri takes place. Moreover, the cerebral cortex starts appearing, creating a boundary to the telencephalon. The cortex surrounding the telencephalon consists of the prefrontal cortex, motor cortex, somatosensory cortex and occipital cortex. It also consists of subcortical structures.

The functions of the telencephalon vary widely. It is the main component of the brain that deals with most of the brain activity. Apart from coordinating brain activity, it is also important for sensory recognition, olfaction, language and speech, learning and memory.

What is Diencephalon?

Diencephalon forms a part of the forebrain. It is situated between the telencephalon and the midbrain. It consists of a variety of structures within. They are the thalamus, and hypothalamus including the posterior pituitary, epithalamus, subthalamus and pineal body. In addition, the optic nerve is also attached at the diencephalon. And, it is the main nerve that is involved in giving sight, with the help of the rod cells and the cone cells in the retina. The diencephalon forms during the 3^rd week of embryonic development. The diencephalon also arises from the neural tube.

Diencephalon’s main function is to give rise to the anterior forebrain structures. Thus, the hypothalamus is important in maintaining homeostasis. The thalamus serves in relaying sensory and motor impulses between the spinal cord and medulla oblongata.

What are the Similarities Between Telencephalon and Diencephalon?

• • The development of both parts occurs during embryonic development.
  • Moreover, the neural tube develops, and differentiates into both structures.
  • Both are a part of the anterior brain.
  • They participate in sensory recognition and brain activity.

What is the Difference Between Telencephalon and Diencephalon?

Telencephalon is the largest part and the uppermost region of the brain. Meanwhile, diencephalon is a part of the forebrain located between telencephalon and midbrain. So, this is the key difference between telencephalon and diencephalon. Telencephalon and diencephalon development begins during embryonic development. That is; diencephalon develops during the 3^rd week while the telencephalon develops during the 5^th week.

Furthermore, depending on the structures each part consists, the functionality of both telencephalon and diencephalon also varies. Telencephalon is important for sensory recognition, olfaction, language, speech, learning and memory. Meanwhile, diencephalon is important for homeostasis, sensory recognition and visual detection. Therefore, this is another difference between telencephalon and diencephalon.

Summary – Telencephalon vs Diencephalon

Telencephalon and diencephalon form the brain anatomy in relation to the anterior part of the brain. The telencephalon is the most anterior part of the brain, and it is also called the cerebrum. Meanwhile, the diencephalon is the part between the telencephalon and the midbrain. Although both are actively involved in the transmission of sensory signals, they differ in their specific functions based on the different parts they have. Thus, it is important to understand the constituent parts of both telencephalon and diencephalon in order to understand the specific function of each.

Reference:

1. Ackerman, Sandra. “Major Structures and Functions of the Brain.” Discovering the Brain., U.S. National Library of Medicine, 1 Jan. 1992, Available here.
2. “Know Your Brain: Telencephalon.” Neuroscientifically Challenged, Neuroscientifically Challenged, 7 July 2017, Available here.

Image Courtesy:

1. “Lobes of the brain NL” By Henry Vandyke Carter – This is a retouched picture, which means that it has been digitally altered from its original version. Modifications: vectorization (CorelDraw) Modifications made by Mysid (Public Domain) via Commons Wikimedia
2. “Illu diencephalon” (Public Domain) via Commons Wikimedia