Myelin is a lipid-rich (fatty) substance that surrounds nerve cell axons (the nervous system’s “wires”) to insulate them and increase the rate at which electrical impulses (called action potentials) are passed along the axon.
The myelinated axon can be likened to an electrical wire (the axon) with insulating material (myelin) around it.
However, unlike the plastic covering on an electrical wire, myelin does not form a single long sheath over the entire length of the axon.
Glioma is a type of tumor that starts in the glial cells of the brain or the spine.
Gliomas comprise about 30 percent of all brain tumors and central nervous system tumours, and 80 percent of all malignant brain tumours.
Treatment for brain gliomas depends on the location, the cell type, and the grade of malignancy.
Often, treatment is a combined approach, using surgery, radiation therapy, and chemotherapy.
Amygdala is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain’s cerebrum in complex vertebrates, including humans.
Shown to perform a primary role in the processing of memory, decision-making and emotional responses (including fear, anxiety, and aggression), the amygdalae are considered part of the limbic system.
Glutamatergic neurons in the basolateral amygdala send projections to the nucleus accumbens shell and core.
Activation of these projections drive motivational salience.
Hippocampus is a major component of the brain of humans and other vertebrates.
Humans and other mammals have two hippocampi, one in each side of the brain.
The hippocampus is part of the limbic system, and plays important roles in the consolidation of information from short-term memory to long-term memory, and in spatial memory that enables navigation.
The hippocampus is located in the allocortex, with neural projections into the neocortex in humans, as well as primates.
Gray & White Matter
Grey matter is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capillaries. The colour difference arises mainly from the whiteness of myelin.
White matter refers to areas of the central nervous system that are mainly made up of myelinated axons, also called tracts. White matter is named for its relatively light appearance resulting from the lipid content of myelin.
Glia are non-neuronal cells in the central nervous system (brain and spinal cord) and the peripheral nervous system that do not produce electrical impulses.
They maintain homeostasis, form myelin in the peripheral nervous system, and provide support and protection for neurons.
In the central nervous system, glial cells include oligodendrocytes, astrocytes, ependymal cells, and microglia, and in the peripheral nervous system glial cells include Schwann cells and satellite cells.
Cerebrum is the largest part of the brain containing the cerebral cortex (of the two cerebral hemispheres), as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb.
In the human brain, the cerebrum is the uppermost region of the central nervous system.
The cerebrum develops prenatally from the forebrain (prosencephalon).
In mammals, the dorsal telencephalon, or pallium, develops into the cerebral cortex, and the ventral telencephalon, or subpallium, becomes the basal ganglia. With the assistance of the cerebellum, the cerebrum controls all voluntary actions in the human body.
Prefrontal cortex is the cerebral cortex which covers the front part of the frontal lobe.
Many authors have indicated an integral link between a person’s will to live, personality, and the functions of the prefrontal cortex.
This brain region has been implicated in executive functions, such as planning, decision making, short-term memory, personality expression, moderating social behavior and controlling certain aspects of speech and language.
The frontal cortex supports concrete rule learning.
Occipital lobe is the visual processing center of the mammalian brain containing most of the anatomical region of the visual cortex.
The occipital lobe is divided into several functional visual areas.
Each visual area contains a full map of the visual world.
Although there are no anatomical markers distinguishing these areas (except for the prominent striations in the striate cortex), physiologists have used electrode recordings to divide the cortex into different functional regions.
Temporal lobe is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain.
The temporal lobe is involved in processing sensory input into derived meanings for the appropriate retention of visual memory, language comprehension, and emotion association.
Temporal refers to the head’s temples.
Parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus.
The parietal lobe integrates sensory information among various modalities, including spatial sense and navigation (proprioception), the main sensory receptive area for the sense of touch in the somatosensory cortex which is just posterior to the central sulcus in the postcentral gyrus, and the dorsal stream of the visual system.
Several areas of the parietal lobe are important in language processing.
Brodmann area is a region of the cerebral cortex, in the human or other primate brain, defined by its cytoarchitecture, or histological structure and organization of cells.
Many of the areas Brodmann defined based solely on their neuronal organization have since been correlated closely to diverse cortical functions.
For example, Brodmann areas 3, 1 and 2 are the primary somatosensory cortex; area 4 is the primary motor cortex; area 17 is the primary visual cortex; and areas 41 and 42 correspond closely to primary auditory cortex.
Cerebral cortex is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals.
The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consisting of allocortex.
The cerebral cortex is the largest site of neural integration in the central nervous system. It plays a key role in attention, perception, awareness, thought, memory, language, and consciousness.
Neural circuit is a population of neurons interconnected by synapses to carry out a specific function when activated.
Neural circuits interconnect to one another to form large scale brain networks.
Sometimes neural circuitries can become pathological and cause problems such as in Parkinson’s disease when the basal ganglia are involved.