Impaired inter-hemispheric facilitatory connectivity in schizophrenia.
OBJECTIVE
To investigate the inter-hemispheric connections between the dorsal premotor cortex (dPM) and contralateral primary motor cortex (M1) in schizophrenia.


METHODS
Sixteen medicated, nine unmedicated schizophrenia patients and 20 healthy age-matched subjects were studied by twin-coil Transcranial Magnetic Stimulation. To activate distinct facilitatory and inhibitory transcallosal pathways between dPM and the contralateral M1, the intensity of dPM stimulation was adjusted to be either suprathreshold (110% of resting motor threshold) or subthreshold (80% of active motor threshold). Interstimulus intervals between conditioning stimulus and test stimulus were 6, 8 and 15 ms.


RESULTS
Schizophrenia patients had comparable efficacy of the inhibitory pathway. On the other hand, medicated patients showed less facilitation of contralateral M1 following dPM stimulation at 80% of active motor threshold, at interstimulus interval=8 ms. The individual amount of facilitation induced by dPM conditioning at 80% of active motor threshold at interstimulus interval=8 ms correlated negatively with negative symptoms.


CONCLUSIONS
Inter-hemispheric facilitatory dPM-M1 connectivity is selectively altered in schizophrenia.


CONCLUSIONS
This study produced evidence that dPM-M1 connectivity is dysfunctional and that correlates with negative symptoms. These results converge with previous studies which strongly hypothesize that inter- and intra-hemispheric connectivity disturbances may play a major role in schizophrenia.
Ribolsi
Michele
M
Clinica Psichiatrica, Dipartimento di Neuroscienze, Università Tor Vergata, Rome, Italy. Electronic address: michele.81@live.it.
Mori
Francesco
F
Clinica Neurologica, Dipartimento di Neuroscienze, Università Tor Vergata, Rome, Italy.
Magni
Valentina
V
Clinica Psichiatrica, Dipartimento di Neuroscienze, Università Tor Vergata, Rome, Italy.
Codecà
Claudia
C
Clinica Neurologica, Dipartimento di Neuroscienze, Università Tor Vergata, Rome, Italy.
Kusayanagi
Hajime
H
Clinica Neurologica, Dipartimento di Neuroscienze, Università Tor Vergata, Rome, Italy.
Monteleone
Fabrizia
F
Clinica Neurologica, Dipartimento di Neuroscienze, Università Tor Vergata, Rome, Italy.
Rubino
Ivo Alex
IA
Clinica Psichiatrica, Dipartimento di Neuroscienze, Università Tor Vergata, Rome, Italy.
Siracusano
Alberto
A
Clinica Psichiatrica, Dipartimento di Neuroscienze, Università Tor Vergata, Rome, Italy.
Bernardi
Giorgio
G
Clinica Neurologica, Dipartimento di Neuroscienze, Università Tor Vergata, Rome, Italy; Centro Europeo per la Ricerca sul Cervello (CERC)/Fondazione Santa Lucia IRCCS, Rome, Italy.
Centonze
Diego
D
Clinica Neurologica, Dipartimento di Neuroscienze, Università Tor Vergata, Rome, Italy; Centro Europeo per la Ricerca sul Cervello (CERC)/Fondazione Santa Lucia IRCCS, Rome, Italy.
Koch
Giacomo
G
Clinica Neurologica, Dipartimento di Neuroscienze, Università Tor Vergata, Rome, Italy; Centro Europeo per la Ricerca sul Cervello (CERC)/Fondazione Santa Lucia IRCCS, Rome, Italy.
D000328:Adult; D014150:Antipsychotic Agents / Q000494:pharmacology; D003337:Corpus Callosum / Q000503:physiopathology*; D003627:Data Interpretation, Statistical; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology; D009434:Neural Pathways / Q000502:physiology; D012559:Schizophrenia / Q000188:drug therapy / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
D014150:Antipsychotic Agents