THE BRAIN

Structures of the brain that are implicated in schizophrenia 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 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 ventral tegmental area (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 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.

TEGMENTUM

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.

NEURONS

 Cells in the nervous system are called neurons. The neuron is an information processing and transmitting cell that undermines all bodily functions.  It is estimated that the human brain contains over 100 billion neurons, with each neuron potentially communicating with hundreds of other neurons. This vast interconnectedness allows simple neuronal activity to translate into complex neuronal messages creating human behavior.

NEUROTRANSMISSION

The basic structure of a neuron includes a cell body (soma), dendrites, axon and axon terminal.

Neurotransmission is an electrochemical message that allows neurons to communicate information with one another neuron.

Electrochemical messages pass from the dendrites (projections from the cell body)

Through the soma or cell body

Down the axon (long extended structures)

And across the synapses (gaps between cells)

To the dendrites of the next neuron

NEUROTRANSMITTERS

Neurotransmitters are the chemical substances manufactured in the neuron that aid in the transmission of information throughout the body. They either excite or stimulate an action in the cells (excitatory) or inhibit or stop an action (inhibitory).

These neurotransmitters fit into specific receptor cells embedded in the membrane of the dendrite.

After neurotransmitters are released into the synapse and relay the message to the receptor cells, they are either transported back for later use (reuptake) or are metabolized and inactivated by enzymes, primarily monoamine oxidase

These neurotransmitters are necessary in just the right proportions to relay messages across synapses

GABA

GABA is the most common inhibitory neurotransmitter in the nervous system and is found throughout the body.  Produce calming effects and are target sites for benzodiazepines.

Glutamate

Glutamate is an excitatory neurotransmitter that is involved in learning and memory. Alterations in production may play a role in the underpinnings of neurodegenerative disorders, such as Alzheimer’s disease and schizophrenia.

Acetylcholine

Acetylcholine is responsible for muscular movement and has been shown to have a role in memory formation. It was the first neurotransmitter to be discovered, and thus is the best known.

Epinephrine and Norepinephrine

Epinephrine and norepinepherine act very similarly. They are associated with vigilance and the fight-or-flight response. Their activity revs up the sympathetic nervous system, preparing a body to face danger or run away from it.

Serotonin

Serotonin plays a role in mood, apptetite, sleep rhythms and arousal. Decreases in serotonin have been shown to correlate with clinical depression and risk for suicide.

Dopamine

Dopamine has been implicated in numerous functions within the body, including movement, attention, learning, and the reward and reinforcement. Schizophrenia and other psychotic disorders are associated with increased or dysregulation of dopamine