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Published on: September 8, 2021
Impaired inter-hemispheric facilitatory connectivity in schizophrenia
Michele Ribolsi1, Francesco Mori2, Valentina Magni1
1Clinica Psichiatrica, Dipartimento di Neuroscienze, Università Tor Vergata, Rome, Italy.
Summary
Inter-hemispheric connections between the dorsal premotor cortex (dPM) and primary motor cortex (M1) are altered in schizophrenia. Specifically, facilitatory pathways are reduced, correlating with negative symptoms.
Area of Science:
- Neuroscience
- Psychiatry
- Brain Connectivity
Background:
- Schizophrenia is associated with widespread disruptions in brain connectivity.
- Understanding inter-hemispheric communication is crucial for elucidating schizophrenia's pathophysiology.
Purpose of the Study:
- To investigate inter-hemispheric connections between the dorsal premotor cortex (dPM) and contralateral primary motor cortex (M1) in schizophrenia patients.
- To determine if these connections differ between medicated, unmedicated patients, and healthy controls.
Main Methods:
- Twin-coil Transcranial Magnetic Stimulation (TMS) was used on 16 medicated, 9 unmedicated schizophrenia patients, and 20 healthy controls.
- TMS assessed facilitatory and inhibitory transcallosal pathways between dPM and contralateral M1 using suprathreshold and subthreshold stimulation.
- Interstimulus intervals of 6, 8, and 15 ms were employed.
Main Results:
- The inhibitory dPM-M1 pathway efficacy was comparable across groups.
- Medicated schizophrenia patients exhibited reduced facilitation in the contralateral M1 following dPM stimulation at specific parameters (subthreshold, 8 ms ISI).
- This reduced facilitation negatively correlated with the severity of negative symptoms in patients.
Conclusions:
- Inter-hemispheric facilitatory dPM-M1 connectivity is selectively altered in schizophrenia.
- dPM-M1 connectivity is dysfunctional in schizophrenia and linked to negative symptoms.
- Findings support the hypothesis that disturbed inter- and intra-hemispheric connectivity plays a significant role in schizophrenia.
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