False recognitions in short-term memory - Age-differences in neural activity.

While the knowledge on age-related differences in susceptibility to episodic false memories is extensive, little is known about this phenomenon in visual short-term memory (STM). Our previous behavioural research indicated that older adults are more confident of their erroneous STM recognitions than young adults. However, unlike in episodic memory, we did not find support for older adults' higher rate of false alarms. To further understand this specific age-difference, here we investigated its neural correlates. First, the pattern of behavioural results replicated the one from our previous experiment. Second, younger adults, when compared to older adults, exhibited higher false recognition-related activity of the visual cortex, the anterior cingulate cortex, the frontal operculum/insular cortex as well as regions within the anterior and dorsolateral prefrontal cortex. No age-differences were observed in hippocampal activity. Third, younger but not older adults presented higher activity in the anterior cingulate cortex and the frontal operculum/insular cortex for false recognitions when compared to highly confident correct rejections. Finally, frontal activity was influenced by both the individuals' performance and their metacognitive abilities. The results suggest that age-related differences in confidence of STM false recognitions may arise from age-differences in performance monitoring and uncertainty processing rather than in hippocampal-mediated binding.

Inconvenient correlation - RT-BOLD relationship for homogeneous and fast reactions.

Reaction time (RT), a widely used measure of human performance in experimental psychology, has recently been included as a regressor of interest in functional magnetic resonance imaging (fMRI) data analysis. Few studies reported RT-related brain regions, but the nature of this activity is not fully understood. We aimed at exploring this topic by implementing a simple saccadic task which evokes fast and homogeneous reactions that require only the basic neural processes. Thus, a spatial cueing paradigm was chosen and implemented in a simultaneous fMRI and eye-tracking experiment. As a result, we found a wide set of brain regions showing trial-by-trial correlations of blood-oxygenation-level-dependent (BOLD) signal with saccadic RT. These regions included medial and lateral frontal lobes, bilateral intraparietal sulci, anterior insular cortices as well as the right thalamus and medial visual cortex. Further analysis was conducted in order to verify quantitatively the impact of a "time on task" effect on task-related hemodynamic responses (HDRs). The results provide evidence that even a small difference in RTs can be linked with significant increase of HDR in task-related areas. Moreover, this increase is not linear, but rather quadratic. Our findings highlight the importance of controlling for RT in fMRI data analysis when contrasting conditions that vary in RT to avoid the misinterpretation of results.

Quo vadis, neuroergonomics?

The current paper considers a new perspective in research and designing which ergonomics is facing at present. It is related to a spectacular progress in neuroscience. Implementing both the latest research results concerning the functioning of neural systems and new non-invasive techniques of brain examination in ergonomics constitutes a serious challenge and, simultaneously, offers unprecedented opportunities for the discipline. This paper posits that assuming a neuroergonomic perspective in ergonomic research and designing leads to a new quality. Knowledge concerning neural structures and mechanisms responsible for behavioural, cognitive and emotional activity will force out the knowledge based on psychological constructs from the field of ergonomics. We are questioning the perception of neuroergonomics as a discipline which resorts to psychological constructs. We are postulating rejecting such constructs in neuroergonomic field as too general in their formulation of certain regularities and failing to ensure satisfying accuracy of measurement.

Effects of diazepam and buspirone on reaction time of saccadic eye movements.

Effects of the anxiolytic drugs diazepam and buspirone were studied on the reaction time of saccadic eye movements. The study was performed with 8 healthy volunteers in a double-blind, placebo-controlled way. The purpose was to investigate the putative drug effects on the first step of an attention shifting task: the disengagement of attention. Saccadic reaction time was measured in two conditions: the 'gap' and the 'overlap' condition. In the first condition a delay is present between the offset of a fixation spot and the onset of a target, while in the second condition the offset of the spot is overlapped by the onset of the target. Clear differences in saccadic reaction time in the expected direction were found between the two conditions, with longer reaction times of saccadic eye movements in the overlap condition. The nonsedative anxiolytic buspirone in a dose of 5 mg had no significant effects on saccadic reaction times, while clear effects of diazepam in a dose of 5 mg were established. Diazepam slowed down saccadic reaction times, reduced the number of fast saccades and facilitated the number of slow saccades. However, the effects induced by this drug were identical for the two conditions. The latter result implies that the disengagement of attention is not selectively disrupted by diazepam. Perhaps, the action of diazepam is expressed in other attention factors, such as in shifting attention or in the reengagement of attention. A slowing down of these processes by the vigilance-lowering properties of diazepam might be the cause of the prolonged latencies. The increased latencies of saccadic eye movements induced by a low dose of diazepam may have practical implications.

The effect of a change in sleep-wakefulness timing, bright light and physical exercise interventions on 24-hour patterns of performance, mood and body temperature.

Experiments consisting of baseline, bright light and physical exercise studies were carried out to compare the effect of a 9-hour delay in sleep-wakefulness timing, and the effects of bright light and physical exercise interventions on 24-hour patterns of performance, mood and body temperature were examined. Each study comprised a 24-hour constant routine at the beginning followed by 3 night shifts and 24-hour constant routine at the end. Performance on tasks differing in cognitive load, mood and body temperature was measured during each constant routine and the interventions were applied during the night shifts. The 24-hour pattern of alertness and performance on the tasks with low cognitive load in post-treatment conditions followed the change in sleep-wakefulness timing while more cognitively loaded tasks tended to show a reverse trend when compared to pre-treatment conditions. There was a phase delay around 4 hours in circadian rhythms of body temperature in post-treatment conditions.