Brain Structure - Brain Theory from a Circuits and Systems Perspective - page 6

obtained not by funded research, but by pure accident. Alzheimer's disease
involves the progressive degeneration of hippocampal neurons and thus of memory
functions.
As a point of interest, Alzheimer's and Parkinson's diseases are involved with
degeneracy of the hippocampus. Alzheimer's is thought to be caused by a plaque,
that is, sticky proteins that fold about the neurons and eventually destroy their
function. This disease also causes neuronal loss in (cerebral) subcortical areas.
Substantia Nigra
The substantia nigra is also known as the black substance. The substantia nigra in
the midsection of the brainstem produces dopamine for the basal ganglia and frontal
lobes. Extensive cell demise in the substantia nigra results in Parkinson's disease,
which usually results in the gradual loss of conscious regulation of movement.
Thalamus
The thalamus is like a relay station in sorting the senses, except the sense of smell. It
has two golf ball-sized structures deep within the cerebral hemispheres. It is also
involved in cognitive functions.
Hypothalamus
The hypothalamus is smaller, marble sized, and is below the thalamus; it is involved
in body regulatory functions such as body temperature, blood circulation, hunger
and thirst, sleep, sexual arousal, hormonal secretion, and defensive responses.
Sometimes it is called the brain's brain; it is in the center behind our eyes.
Olfactory Bulb
The olfactory bulb is the initial odor-processing region. Roughly 30 differing
molecules are involved in approximately 10,000 different odors. Seven primary
odors in ordinary terms would be peppermint, roses, nail polish, musk, camphor,
vinegar, and rotten eggs. Many animals have a more powerful sense of smell than
humans. The olfactory bulb plays a role in the recall of emotional memories.
However, for some reason, we cannot recall the odor of an imagined object as
easily as we can recall its shape and color.