The
Brain
In this section we will present you with the structures of the brain
that are implicated in schizophrenia and amphetamine psychosis.
We hope you gain an understanding of these complex systems, so that you
will know more about what areas of the brain the research in this
website will focus on. This page will focus on three
systems in the brain: the basal ganglia, limbic system and
tegmentum.
Basal
Ganglia
The
basal ganglia is a
collection of subcortical (beneath the cortex) nuclei in the forebrain
(front area of the brain). The
cortex is the brain matter that makes up the outside of the brain;
cortex literally means "bark," so you can think of it as the bark of
the brain. The parts of the brain beneath the cortex are referred
to as subcortical and include the midbrain and hindbrain, as well as
structures not a part of the midbrain and hindbrain. Nuclei are groups
of neurons of similar shape.
The
major parts of
the basal ganglia consist of the caudate nucleus, the putamen and the
globus
pallidus.
The
basal ganglia is involved in the
control of
movement. The nucleus accumbens contains
neurons that are part of
the basal ganglia. Thus, this structure may play a role in the
regulation of movement, including the control of complex motor activity and
the cognitive aspects of motor control. In addition, this
structure has been found to possibly be the area that becomes
activated in situations that involve reward and punishment.
The
nucleus accumbens is a nucleus of the
basal forebrain. It
receives dopamine-secreting terminal buttons from neurons of the VTA
and is thought to be involved in reinforcement and attention.
Limbic
System
This system consists of a couple of brain
structures. First it includes several regions of one form of
cortex
called the limbic
cortex; this cortex is also known as the cingulate cortex as shown in
the picture.
Besides
the limbic cortex, the most
important parts
of
the limbic system are the hippocampus and the amygdala. The
fornix and mammilary bodies are also parts of the limbic system.
The
limbic system has been implicated in learning and memory and
emotions. The implication in emotions involves feelings and
expressions of emotions, emotional
memories and recognition of emotions in other people.
The
tegmentum consists of an area
of the midbrain. It includes the bottom end of the reticular
formation, the periaqueductal gray matter,
the red nucleus, the substantia nigra and the ventral tegmental
area.
The
reticular formation
is a large structure consisting of
many nuclei. It is also characterized by a diffuse,
interconnected network of neurons with complex dendritic and axonal
processes. The reticular formation receives sensory information
and projects axons to the cerebral
cortex, thalamus and spinal
cord.
The
periaqueductal gray matter (PAG)
is so
called because
it consists mostly of cell bodies of neurons (these appear gray as
opposed to axons which appear white) that surround an area of the brain
called the cerebral
aqueduct. The PAG has been
implicated in pain systems as well as behaviors
such as fighting and mating.
The
red nucleus contains a bundle
of
axons; this is one of the two major fiber systems that bring motor
information from the cerebral cortex and cerebellum to the spinal
cord.
The
substantia nigra contains
neurons whose axons project
to the caudate nucleus and putamen parts of the basal
ganglia, this is known as the nigrostriatal
system. The ventral tegmental area (VTA)
is a group of dopamine neurons in the midbrain whose axons form
the
mesolimbic and mesocortical systems;
this
area plays a critical role in
reward and reinforcement.
Pictures contained in the web page
courtesy of
www.mhhe.com/socscience/
intro/ibank/set1.htm
www.ablongman.com/carlson8e
