Structure and Neuronal Pathways
In rodents, the islands of Calleja are composed of seven distinct clusters within the olfactory tubercle, with the major island creating a border between the septum, the nucleus accumbens, and the diagonal band. Some of the islands contain a "core" of neuropil, or unmyelinated axons and dendrites, filled with a large cell in some cases. Projections to and from the islands connect the structures to the piriform cortex, which is responsible for processing smell, as well as areas of the basal forebrain, a region responsible for determining an animal's level of wakefulness. The projections with the piriform cortex align with the rest of the olfactory system, the path beginning in the sensory cells of the nose and then proceeding through the olfactory bulb to regions such as the piriform cortex, olfactory tubercle, and amygdala. However, the projections to the basal forebrain structures actually originate from the smaller outer cells of the island clusters as opposed to the large cells within the "core."
The islands of Calleja receive inputs from the back of the amygdala, which processes emotional memory, as well as the septum, nucleus accumbens, and piriform cortex. The islands also receive information in the form of dopamine from the substantia nigra and ventral tegmental area, located in the midbrain of the brainstem. Information traveling from these midbrain structures is triggered in response to rewarding activities or feelings. The islands project to the back of the thalamus, a region with many responsibilities such as sensory information processing, regulation of wakefulness, and relaying information to the cerebral cortex.
Read more about this topic: Islands Of Calleja
Famous quotes containing the words structure and, structure and/or pathways:
“Each structure and institution here was so primitive that you could at once refer it to its source; but our buildings commonly suggest neither their origin nor their purpose.”
—Henry David Thoreau (1817–1862)
“There is no such thing as a language, not if a language is anything like what many philosophers and linguists have supposed. There is therefore no such thing to be learned, mastered, or born with. We must give up the idea of a clearly defined shared structure which language-users acquire and then apply to cases.”
—Donald Davidson (b. 1917)
“All pathways by His feet are worn,
His strong heart stirs the ever-beating sea;
His crown of thorns is twined with every thorn;
His cross is every tree.”
—Joseph Mary Plunkett (1887–1916)