Acute Stress Dysregulates the LPP ERP Response to Emotional Pictures and Impairs Sustained Attention: Time-Sensitive Effects

Abstract

Stress can increase emotional vigilance at the cost of a decrease in attention towards non-emotional stimuli. However, the time-dependent effects of acute stress on emotion processing are uncertain. We tested the effects of acute stress on subsequent emotion processing up to 40 min following an acute stressor. Our measure of emotion processing was the late positive potential (LPP) component of the visual event-related potential (ERP), and our measure of non-emotional attention was the sustained attention to response task (SART). We also measured cortisol levels before and after the socially evaluated cold pressor test (SECPT) induction. We found that the effects of stress on the LPP ERP emotion measure were time sensitive. Specifically, the LPP ERP was only altered in the late time-point (30-40 min post-stress) when cortisol was at its highest level. Here, the LPP no longer discriminated between the emotional and non-emotional picture categories, most likely because neutral pictures were perceived as emotional. Moreover, compared to the non-stress condition, the stress-condition showed impaired performance on the SART. Our results support the idea that a limit in attention resources after an emotional stressor is associated with the brain incorrectly processing non-emotional stimuli as emotional and interferes with sustained attention.

Keywords: ERP; acute stress; emotion; late positive potential; sustained attention.

Figure 1

The testing procedure. The testing procedure consisted of 3 testing Blocks after stress (SECPT) or control stress induction.

Figure 2

Cortisol levels for the two conditions at four time points. There was a significant time × condition interaction (F (3, 93) = 4.22, p < 0.05, partial η² = 0.11) for cortisol with the stress condition yielding higher cortisol levels relative to the control condition in Block 3 (p < 0.05).

Figure 3

LPP ERP. The LPP ERP elicited by the IAPS in the control and stress conditions during each Block at each electrode location. In Blocks 1 and 2 (3A) and (3B), there were no differences in the LPP amplitude between the stress and the control conditions. However, in Block 3 (3C), the neutral pictures elicited a larger LPP in the stress condition relative to the control condition during Block 3. Black horizontal bar in Cz indicates the 400 ms picture exposure and the yellow horizontal bar indicates the LPP analysis latency range.

Figure 3

LPP ERP. The LPP ERP elicited by the IAPS in the control and stress conditions during each Block at each electrode location. In Blocks 1 and 2 (3A) and (3B), there were no differences in the LPP amplitude between the stress and the control conditions. However, in Block 3 (3C), the neutral pictures elicited a larger LPP in the stress condition relative to the control condition during Block 3. Black horizontal bar in Cz indicates the 400 ms picture exposure and the yellow horizontal bar indicates the LPP analysis latency range.

Figure 3

LPP ERP. The LPP ERP elicited by the IAPS in the control and stress conditions during each Block at each electrode location. In Blocks 1 and 2 (3A) and (3B), there were no differences in the LPP amplitude between the stress and the control conditions. However, in Block 3 (3C), the neutral pictures elicited a larger LPP in the stress condition relative to the control condition during Block 3. Black horizontal bar in Cz indicates the 400 ms picture exposure and the yellow horizontal bar indicates the LPP analysis latency range.

Figure 4

SART performance. There was impaired target accuracy and delayed reaction time on the SART at 15 min and 30 min following stress (black bars represent 1 standard error). Asterisks indicate a statistical difference between stress and control condition at p < 0.05.