ISSN : 1226-9654
Neural correlates of episodic memory deficits may be different in schizophrenia patients with hallucinations (SH) and patients without hallucinations (SnH). However, little is known about how specific neural correlates involved in episodic retrieval may differ between SH and SnH. We aimed to determine whether neural oscillations in SH during episodic retrieval are different from those in SnH and normal controls (NC) after navigating rooms in a virtual environment (VE). The VE was used to enhance patient motivation in episodic memory test by engaging higher cognitive involvement. Subjects experienced a navigation session and a retrieval session. Electroencephalogram (EEG) was recorded during the retrieval session, and time-frequency analyses were examined (7 NC, 7 SnH, and 7 SH). Consistent with previous reports, the results revealed that theta power was correlated with successful episodic retrieval, suggesting that the reductions of theta power may contribute to episodic memory deficits in SH and SnH. Notably, the theta power differences between the old and new conditions was positively correlated with episodic retrieval performances across SH, SnH, and NC. Other oscillatory activities (i.e., alpha and beta) may also contribute to episodic retrieval with a diversity of functional relevance across groups. Overall results showed deficits in episodic retrieval, corresponding oscillations in EEG frequency bands. The neural oscillations across different frequencies and their relationship to cognitive processes, including inhibition and attention in episodic memory, are also discussed.
When participants are asked to identify two targets in a rapid serial visual presentation (RSVP), wherein a sequence of visual stimuli was presented in rapid succession, they often fail to identify a second target if it is presented within half a second after the appearance of the first target. This deficit, called attentional blink, has been considered to reflect the capacity limitation of temporal attention. A recent study showed that attentional blink can be eliminated through the color-salient training during which a second target can be easily identified by displaying it in a salient color. The current study explored whether the color-salient training effect can occur even in RSVP with an untrained set of targets and distractors. Experiment 1, which employed letter targets and number distractors during training sessions, did not show any effect of the color-salient training, in that attentional blink did not disappear even after the training. In Experiment 2, after the color-salient training employing RSVP with number targets and letter distractors, attentional blink was eliminated not only in trained RSVP with number targets and letter distractors, but also in untrained RSVP with letter targets and number distractors. This result suggested the color-salient training effect can be transferred to another RSVP with an untrained set of targets and distractors, and it was consistent with the hypothesis that the color-salient training influences attentional control mechanisms that are related to both target selection and distractor inhibition. In addition, the results of Experiment 1 that failed to show the color-salient training effect provided clues related to conditions in which the color-salient training can work.
The present study examined whether individual differences in working memory capacity (WMC) modulate the effect of working memory load on emotional face processing. Each group of high-span and low-span was selected by virtue of participants’ WMC scores of operation span task. Working memory load (WML) was manipulated within subjects by the mental rehearsal of two (low-WML) versus six (high-WML) visual objects in delayed recognition task. A picture of negative (angry) or neutral face was presented during delay while event-related brain potentials were recorded. Behavioral results of recognition judgment showed that relative inaccuracy by negative face compared to neutral face was found only at high-WML. In case of low-WML, valence effects (enhanced N170 amplitude to negative compared to neutral face) were found on both left and right hemispheres of low-span as well as high-span. But, in case of high-WML, valence effect was found only on right hemisphere of high-span. These results suggest that working memory load reduces attentional resources for distracting negative facial expressions, but high-span of working memory can process facial expressions even under high load of working memory. Taken together, these findings demonstrate that facial expression processing is dependent on attentional resources.
In this study we examined the preferential difference of the pictorial composition and the lateralization hypothesis as the explanation. In Experiment 1, right-handed 40 participants assessed their preference of the pictures presented with 5 Likert Scale. There were three conditions of depending on location of an object, which were CENTER, RIGHT, LEFT. The result showed that CENTER was the most significantly preferred position among three conditions. Comparing LEFT with RIGHT, the latter got the higher preference scores than the former. It was supported by some previous studies. In experiment 2, we used divided visual field paradigm to examine the processing fluency and preference for the composition of word and picture. The stimuli were presented in two types, which was WORD(left)-PICTURE and the opposite composition, PICTURE(left)-WORD(right). We hypothesized that PICTURE(left)-WORD(right) condition had more processing fluency than the other one, which leads the preference for this condition. The result of the experiment supported our hypothesis. PICTURE(left)-WORD(right) was more accurately recognized and preferred to the other one. The results of two experiments implied that subjective preference depends on the location of the principle object, which means that brain lateralization affect the preference.