Neurological Mechanisms of Schizophrenia, OCD, and REM Sleep

Schizophrenia: Positive Symptoms

  • Biological Mechanism: The underlying neurological cause for positive symptoms in schizophrenia is an overabundance of dopamine. Specifically, there is "too much dopamine" located in the Mesolimbic pathway.

  • Manifestations and Rationales:

    • Hallucinations: This occurs because the brain interprets signals that aren't actually there.
    • Delusions: These are form of distorted reality where abnormal dopamine levels cause the brain to develop an incorrect interpretation of reality.
    • Disorganized Thinking: This symptom manifests because neural communication within the brain becomes chaotic, leading to a breakdown in logical thought processes.

  • Memory Aid: A simplified way to distinguish these is titled "Easy Memory":

    • Positive symptoms represent the brain "adding" things to experience.
    • Examples of items the brain adds include Hallucinations and Delusions.

Schizophrenia: Negative Symptoms

  • Biological Mechanism: In contrast to positive symptoms, negative symptoms are driven by a deficiency of dopamine. This involves having "too little dopamine" located within the Mesocortical pathway.

  • Manifestations:

    • Flat Affect: A reduction in the range and intensity of emotional expression.
    • Alogia: Characterized by "little speech," or a poverty of speech.
    • Poor Motivation: A lack of drive to initiate or complete tasks.
    • Social Withdrawal: Avoiding social interaction or preference for isolation.

  • Memory Aid:

    • Negative symptoms represent the brain "losing" capacities or behaviors that are normally present.

Obsessive-Compulsive Disorder (OCD)

  • Biological Mechanism: OCD is associated with a hyperactive neural circuit.

  • Circuit Components: The primary structure identified in this hyperactive circuit is the Orbitofrontal cortex.

Phantom Limb Pain

  • Symptom Description: Patients experience sensations in a limb that is no longer part of the body. These sensations include:

    • Cramping.
    • Electric pain.
    • Itching.

  • Biological Rationale/Mechanism: The pain in the missing limb occurs because the brain—not the limb itself—is the organ producing the pain signal.

REM Sleep (Rapid Eye Movement)

  • Mechanism of Activation:

    • The process begins when the brainstem activates the cortex.
    • As a result, the brain becomes very active during this sleep stage.
    • The activity level is significant enough that the EEG (electroencephalogram) pattern resembles wakefulness.

  • Physiological Inhibition:

    • Simultaneous to the activation of the cortex, the brainstem inhibits the spinal motor neurons.
    • The result of this inhibition is that the muscles cannot move, creating a state of temporary paralysis during sleep.

  • Primary Manifestation:

    • The most notable manifestation of this heightened brain activity and physical immobility is Dreaming.