[Abnormal patterns of cortical synaptic connectivity in schizophrenia].

Area of Science:

• Neuroscience
• Neuropathology
• Cellular Biology

Background:

• Schizophrenia is a complex psychiatric disorder with known neurobiological underpinnings.
• Previous research suggests alterations in brain structure and connectivity in schizophrenia patients.
• Specific synaptic changes in cortical layers remain incompletely understood.

Purpose of the Study:

• To quantitatively assess synaptic density and neuronal numbers in postmortem prefrontal and visual cortices of schizophrenia patients and controls.
• To investigate potential differences related to symptom presentation (positive/negative) and disease course.

Main Methods:

• Electron microscopic morphometry was employed on postmortem brain tissue.
• The stereological physical dissector method was used to estimate numerical density (Nv) of synapses and neurons.
• Analyses focused on layers I and II of the prefrontal cortex (area 10) and visual cortex (area 17).

Main Results:

• Prefrontal cortex layer I showed reduced axospinous synapse Nv in schizophrenia patients, particularly those with positive symptoms.
• Prefrontal cortex layer II exhibited increased synapse Nv and synapses per neuron in schizophrenia, especially in negative symptom and continuous course subgroups.
• Layer II of the prefrontal cortex had fewer neurons in the negative symptom subgroup compared to controls and positive symptom subgroups.
• Visual cortex layer II showed increased axodendritic synapses per neuron in schizophrenia, with other parameters unchanged.

Conclusions:

• Significant abnormalities in synaptic connectivity exist in the prefrontal cortex of schizophrenia patients.
• These synaptic alterations may represent the structural basis for cognitive dysfunction and symptom formation.
• Findings suggest a role for altered synaptic plasticity in the pathophysiology of schizophrenia.