According to the National Institute of Mental Health, approximately 1 percent of the U.S. population is diagnosed with schizophrenia. Schizophrenia has no exact known cause but is categorized as a brain disorder affecting the balance in neurotransmitter concentration of dopamine, glutamate and serotonin systems. Symptoms present in the disorder are positive, which means psychosis, or negative, which means affecting emotions and behavior. The primary areas of the brain implicated in schizophrenia are the forebrain, hindbrain and limbic system.
Forebrain
The forebrain is the topmost and largest portion of the brain and includes the cerebral hemispheres which are divided into four lobes, limbic system, thalamus, hypothalamus and corpus callosum. As a whole, the forebrain serves to control cognition (the process of thinking, knowing, learning and judging), sensory and motor function, temperature regulation, reproduction, hunger, sleep cycle and emotional expression. It is within the frontal lobe where skewed thought organization occurs, creating the delusional ideations that are a common positive symptom of schizophrenia. It is also in this lobe that overstimulation of dopamine impacts decreased glutamate and neural activity. The temporal lobe regulates hearing and object and facial recognition. When schizophrenia is present the temporal lobe process is skewed, and a result is auditory and visual hallucinations.
Hindbrain
The hindbrain includes the pons, medulla and cerebellum and serves to manage motor activity, posture, balance and circulation of blood. It is the undermost portion of the brain, and when schizophrenia is present a result of this portion of the brain being affected is shown in the negative symptoms of blunted movement and inappropriate body language signals. Additionally, in severe schizophrenia catatonic behaviors are present, characterized by rigid posture, aimless motor activity and decreased reaction to environmental cues.
The Limbic System
The limbic system is a collection of brain systems including the hippocampus and amygdala. This system is located in the innermost portion of the brain and serves to regulate emotions, memories, learning and sexual behavior. In a brain affected by schizophrenia this causes affective flattening which is considered a negative symptom of the disorder. Additionally, impairment in this portion of the brain creates disorganized behaviors preventing normal social connecting, bizarre actions and preoccupation with inappropriate sexual content.
