Limits...
P300 amplitude is insensitive to working memory load in schizophrenia.

Gaspar PA, Ruiz S, Zamorano F, Altayó M, Pérez C, Bosman CA, Aboitiz F - BMC Psychiatry (2011)

Bottom Line: A significant between group difference in P300 amplitude was evidenced only at the low WM load condition (1 -back), being smaller in SZs.SZ subjects display a lower than normal P300 amplitude, which does not vary as a function of memory load.These results are consistent with a general impairment in WM capacity in these patients.

View Article: PubMed Central - HTML - PubMed

Affiliation: Clínica Psiquiátrica Universitaria, Hospital Clínico de la Universidad de Chile, Santiago, Chile. pgaspar@neuro.med.uchile.cl

ABSTRACT

Background: Working memory (WM) tasks usually elicit a P300 ERP component, whose amplitude decreases with increasing WM load. So far, this effect has not been studied in schizophrenics (SZs), a group that is considered to have an aberrant brain connectivity and impairments in WM capacity. The aim of this study was to determine the dependency of the P300 component on WM load in a sample of SZ subjects.

Methods: We recorded 26 subjects (13 SZ patients and their matched controls) with an 80-channel electroencephalogram. Subjects performed an N-back task, a WM paradigm that manipulates the number of items to be stored in memory.

Results: In healthy subjects, P300 amplitude was highest in the low WM load condition, and lowest in both the attentional control condition and the high WM load condition. In contrast, SZs evidenced low P300 amplitude in all conditions. A significant between group difference in P300 amplitude was evidenced only at the low WM load condition (1 -back), being smaller in SZs.

Conclusions: SZ subjects display a lower than normal P300 amplitude, which does not vary as a function of memory load. These results are consistent with a general impairment in WM capacity in these patients.

Show MeSH
Grand averages and topographical distribution of the evoked P300 potentials elicited by 1- and 2- back tasks in the CM-ROI. The third column represents the subtraction of the P300 amplitudes at 1- and 2- back conditions for HS and SZ group. The differences were significant for controls (p <0.05), but not for SZ group (p > 0.05). Color bar indicates amplitude (uV).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3049741&req=5

Figure 3: Grand averages and topographical distribution of the evoked P300 potentials elicited by 1- and 2- back tasks in the CM-ROI. The third column represents the subtraction of the P300 amplitudes at 1- and 2- back conditions for HS and SZ group. The differences were significant for controls (p <0.05), but not for SZ group (p > 0.05). Color bar indicates amplitude (uV).

Mentions: Within-group analyses: The control group showed a significant decrease of P300 peak amplitude from 1- to 2-back (p = 0.018, Mann- Whitney test) and from 0- to 2- back condition (p = 0.023, Mann-Whitney test). On the contrary, SZ patients did not show a significant difference in P300 peak amplitude among any condition studied (from 0- to 1- back, p value = 0,56; 0- to 2- back p value = 0,34; and 1- to 2- back p value = 0,086). Besides, we did not find significant differences in P300 latency between 1- and 2- back tasks inside each group (Table 2 and figure 3).


P300 amplitude is insensitive to working memory load in schizophrenia.

Gaspar PA, Ruiz S, Zamorano F, Altayó M, Pérez C, Bosman CA, Aboitiz F - BMC Psychiatry (2011)

Grand averages and topographical distribution of the evoked P300 potentials elicited by 1- and 2- back tasks in the CM-ROI. The third column represents the subtraction of the P300 amplitudes at 1- and 2- back conditions for HS and SZ group. The differences were significant for controls (p <0.05), but not for SZ group (p > 0.05). Color bar indicates amplitude (uV).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3049741&req=5

Figure 3: Grand averages and topographical distribution of the evoked P300 potentials elicited by 1- and 2- back tasks in the CM-ROI. The third column represents the subtraction of the P300 amplitudes at 1- and 2- back conditions for HS and SZ group. The differences were significant for controls (p <0.05), but not for SZ group (p > 0.05). Color bar indicates amplitude (uV).
Mentions: Within-group analyses: The control group showed a significant decrease of P300 peak amplitude from 1- to 2-back (p = 0.018, Mann- Whitney test) and from 0- to 2- back condition (p = 0.023, Mann-Whitney test). On the contrary, SZ patients did not show a significant difference in P300 peak amplitude among any condition studied (from 0- to 1- back, p value = 0,56; 0- to 2- back p value = 0,34; and 1- to 2- back p value = 0,086). Besides, we did not find significant differences in P300 latency between 1- and 2- back tasks inside each group (Table 2 and figure 3).

Bottom Line: A significant between group difference in P300 amplitude was evidenced only at the low WM load condition (1 -back), being smaller in SZs.SZ subjects display a lower than normal P300 amplitude, which does not vary as a function of memory load.These results are consistent with a general impairment in WM capacity in these patients.

View Article: PubMed Central - HTML - PubMed

Affiliation: Clínica Psiquiátrica Universitaria, Hospital Clínico de la Universidad de Chile, Santiago, Chile. pgaspar@neuro.med.uchile.cl

ABSTRACT

Background: Working memory (WM) tasks usually elicit a P300 ERP component, whose amplitude decreases with increasing WM load. So far, this effect has not been studied in schizophrenics (SZs), a group that is considered to have an aberrant brain connectivity and impairments in WM capacity. The aim of this study was to determine the dependency of the P300 component on WM load in a sample of SZ subjects.

Methods: We recorded 26 subjects (13 SZ patients and their matched controls) with an 80-channel electroencephalogram. Subjects performed an N-back task, a WM paradigm that manipulates the number of items to be stored in memory.

Results: In healthy subjects, P300 amplitude was highest in the low WM load condition, and lowest in both the attentional control condition and the high WM load condition. In contrast, SZs evidenced low P300 amplitude in all conditions. A significant between group difference in P300 amplitude was evidenced only at the low WM load condition (1 -back), being smaller in SZs.

Conclusions: SZ subjects display a lower than normal P300 amplitude, which does not vary as a function of memory load. These results are consistent with a general impairment in WM capacity in these patients.

Show MeSH