The Central Nervous System consists of the Spinal Cord and the Brain




Reading Notes from the book:

Kandel, Eric; Schwartz, James; Jessell, Thomas; Siegelbaum, Steven; Hudspeth, A.J. (2012-09-27). Principles of Neural Science, Fifth Edition. McGraw-Hill. Kindle Edition. (Kindle Location 11269)


The brain consists of:

1.1  Brain Stem (midbrain, pons, medulla oblongata)

1.2  Cerebellum

1.3  Diencephalon (two major divisions: thalamus and hypothalamus).

1.4  Cerebrum (Telencephalon)

a. cerebral cortex (outer layer made of dark matter)

b. underlying white matter,

c. three deep-lying structures:

                               i. the basal ganglia (Consist of five functional subcomponents: the caudate nucleus, putamen, globus pallidus, subthalamic nucleus, and substantia nigra)

                               ii. amygdala

                               iii. hippocampal formation.



Figure 15.3 from: Kandel, Eric; Schwartz, James; Jessell, Thomas; Siegelbaum, Steven; Hudspeth, A.J. (2012-09-27). Principles of Neural Science, Fifth Edition McGraw-Hill. (Kindle Locations 11273-11275).

Brain Atlas


1.1  Brain Stem (midbrain, pons, medulla oblongata)

1.1.1 Medulla


The medulla oblongata connects the higher levels of the brain to the spinal cord, and is responsible for several functions of the autonomous nervous system, which include:


1.1.2 Pons

The pons contains nuclei that relay signals from the forebrain to the cerebellum, along with nuclei that deal primarily with sleep, respiration, swallowing, bladder control, hearing, equilibrium, taste, eye movement, facial expressions, facial sensation, and posture.[2]


Within the pons is the pneumotaxic center, a nucleus that regulates the change from inhalation to exhalation.[2]

The pons is implicated in sleep paralysis, and also plays a role in generating dreams.[citation needed]


1.1.3 Midbrain

Specifically, the midbrain consists of:


Its substantia nigra is closely associated with motor system pathways of the basal ganglia.

Dopamine produced in the substantia nigra and ventral tegmental area plays a role in motivation and habituation of species from humans to the most elementary animals such as insects. Laboratory house mice from lines that have been selectively bred for high voluntary wheel running have enlarged midbrains.[10] The midbrain helps to relay information for vision and hearing.


Damage to the dopaminergic neurons of the substantia nigra is releated to the motor problems in Parkinson's disease (Kandel et al 2012).



1.2 Cerebellum ("Little brain")

The cerebellum (Latin for "little brain") is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses,[1] but its movement-related functions are the most solidly established.


The cerebellum does not initiate movement, but it contributes to coordination, precision, and accurate timing. It receives input from sensory systems of the spinal cord and from other parts of the brain, and integrates these inputs to fine-tune motor activity.[2] Cerebellar damage produces disorders in fine movementequilibriumposture, and motor learning.[2]



1.3 Diencephalon

It is made up of four distinct components: the thalamus, the subthalamus, the hypothalamus, and the epithalamus.[1]

It is associated with the pituitary gland (hypophysis) and the pineal gland (epiphysis).

The Optic Nerve (CNII) attaches to the diencephalon.

The hypothalamus performs numerous vital functions, most of which relating directly or indirectly to the regulation of visceral activities by way of other brain regions and the autonomic nervous system.



1.3.1 Thalamus


The Thalamus is a Control Room (Chamber), a Hub of Information

Every sensory system (with the exception of the olfactory system) includes a thalamic nucleus that receives sensory signals and sends them to the associated primary cortical area.



"Thalamus" by Madhero88 - Own work by uploader, sources [1] [2] [3] [4] [5] [6] [7]. Licensed under CC BY-SA 3.0 via Commons -




The thalamus also plays an important role in regulating states of sleep and wakefulness.[11] Thalamic nuclei have strong reciprocal connections with the cerebral cortex, forming thalamo-cortico-thalamic circuits that are believed to be involved with consciousness.


The thalamus is functionally connected to the hippocampus [13] as part of the extended hippocampal system at the thalamic anterior nuclei [14] with respect to spatial memory and spatial sensory datum they are crucial for human episodic memory and rodent event memory [15][16].


Informatory link for the thalamus:



1.4 Cerebrum


1.4.1 Cerebral cortex


The cerebral cortex is the cerebrum's (brain) outer layer of neural tissue in humans and other mammals.


In large mammals the cerebral cortex is folded, giving a much greater surface area in the confined volume of the skull. A fold or ridge in the cortex is termed a gyrus (plural gyri) and a groove or fissure is termed a sulcus (plural sulci).


The cerebral cortex is gray matter, consisting mainly of cell bodies (with astrocytes being the most abundant cell type in the cortex as well as the human brain as a whole) and capillaries. It contrasts with the underlying white matter, consisting mainly of the white myelinated sheaths of neuronal axons.


Neurons in various layers connect vertically to form small microcircuits, called cortical columns.



The cerebral cortex may be classified on the basis of gross topographical conventions into four lobes:


The cerebral cortex is connected to various subcortical structures such as the thalamus and the basal ganglia, sending information to them along efferent connections and receiving information from them via afferent connections. Most sensory information is routed to the cerebral cortex via the thalamus. Olfactory information, however, passes through the olfactory bulb to the olfactory cortex (piriform cortex).



Cortical areas

The cortex is commonly described as comprising three parts: sensory, motor, and association areas.


Sensory areas

The sensory areas are the areas that receive and process information from the senses. Parts of the cortex that receive sensory inputs from the thalamus are called primary sensory areas.


The senses of vision, audition, and touch are served by the primary visual cortex, primary auditory cortex and primary somatosensory cortex respectively.


In general, the two hemispheres receive information from the opposite (contralateral) side of the body. For example the right primary somatosensory cortex receives information from the left limbs, and the right visual cortex receives information from the left visual field.


The organization of sensory maps in the cortex reflects that of the corresponding sensing organ, in what is known as a topographic mapNeighboring points in the primary visual cortex, for example, correspond to neighboring points in the retina. This topographic map is called a retinotopic map. In the same way, there exists a tonotopic map in the primary auditory cortex and a somatotopic map in the primary sensory cortex.


This last topographic map of the body onto the posterior central gyrus has been illustrated as a deformed human representation, the somatosensory homunculus, where the size of different body parts reflects the relative density of their innervation. Areas with lots of sensory innervation, such as the fingertips and the lips, require more cortical area to process finer sensation.



Motor areas

The motor areas are located in both hemispheres of the cortex. They are shaped like a pair of headphones stretching from ear to ear. The motor areas are very closely related to the control of voluntary movements, especially fine fragmented movements performed by the hand. The right half of the motor area controls the left side of the body, and vice versa.


Association areas

Association areas function to produce a meaningful perceptual experience of the world, enable us to interact effectively, and support abstract thinking and language. The parietaltemporal, and occipital lobes - all located in the posterior part of the cortex - integrate sensory information and information stored in memory. The frontal lobe or prefrontal association complex is involved in planning actions and movement, as well as abstract thought. 




1.4.2 Basal ganglia

The basal ganglia are a collection of distinct masses of gray matter lying deep in the brain not far from the junction of the thalamus.


They include:

a. The striatum composed of:
         i.    the caudate nucleus
         ii.    the putamen
b. The ventral pallidum
c. The subthalamic nucleus
d. The substantia nigra (black substance)


Source: slide 6 of presentation found at the link




Source: slide 3 of presentation found at the link