What is the Difference Between Neocortex and Cerebral Cortex

The main difference between neocortex and cerebral cortex is that neocortex is the largest part of the cerebral cortex whereas cerebral cortex is the outer layer of the cerebrum. Furthermore, neocortex is responsible for higher-order brain functions including sensory perception, cognition, generation of motor commands, spatial reasoning, and language while cerebral cortex plays a key role in memory, attention, perception, awareness, thought, language, and consciousness.

Neocortex and cerebral cortex are two outer parts of the cerebrum, which is the largest part of the brain including two, cerebral hemispheres and subcortical structures including the hippocampus, basal ganglia, and olfactory bulb.

Key Areas Covered

1. What is Neocortex
     – Definition, Structure, Function
2. What is Cerebral Cortex
     – Definition, Structure, Function
3. What are the Similarities Between Neocortex and Cerebral Cortex
     – Outline of Common Features
4. What is the Difference Between Neocortex and Cerebral Cortex
     – Comparison of Key Differences

Key Terms

Allocortex, Brain, Cerebral Cortex, Gray Matter, Horizontal Layers, Neocortex

What is Neocortex

The neocortex is the largest portion of the cerebral cortex. It is made up of gray matter and contains10 to 14 billion neurons. Moreover, it consists of six layers numbered with Roman numerals from superficial to deep. These include the layer I, which is the molecular layer with very few neurons, layer II, which is the external granular layer, layer III, which is the external pyramidal layer, layer IV, which is the internal granular layer, layer V, which is the internal pyramidal layer, and layer VI, which is the multiform, or fusiform layer. However, the shape, size, density, and the organization of nerve fibers are different in each layer.

Figure 1: Lobes of the Cerebrum

Furthermore, the neocortex in the frontal, parietal, occipital, and temporal lobes performs different functions. For example, the occipital lobe contains the primary visual cortex while the temporal lobe contains the primary auditory cortex. Also, the frontal lobe is responsible for complex language processing abilities in humans. Overall, neocortex plays a role in sleep, memory and learning processes.

What is Cerebral Cortex

The cerebral cortex is the outer layer of the cerebrum. In mammals, it is separated into two cerebral hemispheres by the longitudinal fissure. However, the corpus callosum joins the two hemispheres beneath the cortex. Moreover, the cerebral cortex is the largest site of neural integration in the central nervous system, playing a key role in memory, attention, perception, awareness, thought, language, and consciousness.

Figure 2: Cerebral Cortex

Furthermore, the two main parts of the cerebral cortex are neocortex and allocortex. Here, neocortex covers the two hemispheres while allocortex covers the hippocampus and olfactory bulb. Moreover, the allocortex is characterized by the presence of three horizontal layers. Also, there are three subtypes of allocortex: the paleocortex, the archicortex, and the periallocortex. The paleocortex occurs in the olfactory bulb, olfactory tubercle, and piriform cortex. And, the archicortex occurs in the hippocampus and dentate gyrus. On the other hand, the periallocortex occurs in the transitional zone between the neocortex and the allocortex.

Similarities Between Neocortex and Cerebral Cortex

• Neocortex and cerebral cortex are the outermost regions of the cerebrum.
• Both are 2-4 mm thick.
• Moreover, they have several layers.
• They make up the largest portion of the brain responsible for rational thinking.

Difference Between Neocortex and Cerebral Cortex

Definition

Neocortex refers to a part of the cerebral cortex concerned with sight and hearing in mammals, regarded as the most recently evolved part of the cortex while cerebral cortex refers to the outer layer of the cerebrum composed of folded grey matter and playing an important role in consciousness. Thus, this is the main difference between neocortex and cerebral cortex.

Significance

Another important difference between neocortex and cerebral cortex is that the neocortex is the largest part of the cerebral cortex while the cerebral cortex is the outer part of the cerebrum.

Types

The two types of the neocortex are the proisocortex and the true isocortex while the two parts of the cerebral cortex are the neocortex and allocortex.

Occurrence

Moreover, neocortex covers the two cerebral hemispheres while allocortex of the cerebral cortex covers the hippocampus and olfactory bulb.

Horizontal Layers

Neocortex contains six horizontal layers while allocortex of the cerebral cortex contains only three layers.

Evolution

One other difference between neocortex and cerebral cortex is that neocortex is an evolutionary more recent and advanced structure while allocortex of the cerebral cortex is a less-evolved structure.

Function

Furthermore, neocortex is responsible for higher-order brain functions including sensory perception, cognition, generation of motor commands, spatial reasoning, and language while cerebral cortex plays a key role in memory, attention, perception, awareness, thought, language, and consciousness. Hence, this is the functional difference between neocortex and cerebral cortex.

Conclusion

The neocortex is the largest part of the cerebral cortex, which covers the two cerebral hemispheres of the brain. It is characterized by the presence of six horizontal layers. Sensory perception, cognition, generation of motor commands, spatial reasoning, and language are the functions of the neocortex. The cerebral cortex is the outer cover of the brain, containing neocortex and allocortex. Allocortex is characterized by the presence of three horizontal layers. It is a less-developed structure than the neocortex. On the other hand, the cerebral cortex is responsible for memory, attention, perception, awareness, thought, language, and consciousness. Therefore, the main difference between neocortex and cerebral cortex is the structure and function.

References:

1. Swenson, Rand. “Chapter 11 – The Cerebral Cortex.” REVIEW OF CLINICAL AND FUNCTIONAL NEUROSCIENCE – SWENSON, Swenson, Available Here.

Image Courtesy:

1. “Illu cerebrum lobes” (Public Domain) via Commons Wikimedia   
2. “Brainmaps-macaque-hippocampus” By brainmaps.org (CC BY 3.0) via Commons Wikimedia