International Journal of Psychophysiology 48 (2003) 11–24
0167-8760/03/$ - see front matter ᮊ 2003 Elsevier Science B.V. All rights reserved.
Induced oscillations and the distributed cortical sources during the
Wisconsin card sorting test performance in schizophrenic patients:
new clues to neural connectivity
J.A. Gonzalez-Hernandez *, I. Cedeno , C. Pita-Alcorta , L. Galan , E. Aubert ,
a,b, a,b c d d
´´ ˜ ´
Department of Clinical Neurophysiology, ‘Hermanos Ameijeiras’ Hospital, Havana, Cuba
Department of Psychiatry, ‘Hermanos Ameijeiras’ Hospital, Havana, Cuba
Department of Psychiatry, ‘Manuel Fajardo’ Hospital, Havana, Cuba
Cuban Neuroscience Center, Havana, Cuba
Received 6 September 2001; received in revised form 12 November 2002; accepted 19 November 2002
Prefrontal dysfunction has been associated with schizophrenia. Activation during Wisconsin card sorting test
(WCST) is a common approach used in functional neuroimaging to address this failure. Equally, current knowledge
states that oscillations are basic forms of cells-assembly communications during mental activity. Promising results
were revealed in a previous study assessing healthy subjects, WCST and oscillations. However, those previous studies
failed to meet the functional integration of the network during the WCST in schizophrenics, based on the induced
oscillations and their distributed cortical sources. In this research, we utilized the brain electrical tomography
(variable-resolution brain electromagnetic tomography) technique to accomplish this goal. Task specific delta, theta,
alpha and beta-2 oscillations were induced and simultaneously synchronized over large extensions of cortex,
encompassing prefrontal, temporal and posterior regions as in healthy subjects. Every frequency had a well-defined
network involving a variable number of areas and sharing some of them. Oscillations at 11.5, 5.0 and 30 Hz seem to
reflect an abnormal increase or decrease, being located at supplementary motor area (SMA), left occipitotemporal
region (OT), and right frontotemporal subregions (RFT), respectively. Three cortical areas appeared to be critical,
that may lead to difficulties either in coordinatingysequencing the inputyoutput of the prefrontal networks—SMA,
and retention of information in memory—RFT, both preceded or paralleled by a deficient visual information
ᮊ 2003 Elsevier Science B.V. All rights reserved.
Keywords: Synchronization; Associative visual cortex; Supplementary motor cortex; Frontotemporal cortex; VARETA
*Corresponding author. Departmento de Neurofisiologia (Seccion X) Hospital Hermanos Ameijeiras, San Lazaro 701, Habana
3, Codigo Postal 10300, Cuba.
E-mail addresses: email@example.com (J.A. Gonzalez-Hernandez), firstname.lastname@example.org (J.A. Gonzalez-Hernandez).