Preserved time but altered numerosity processing in epileptic patients with postoperative lesion in the inferior frontal gyrus.

Previous researches have shown that the inferior frontal gyrus (IFG) is involved in time and numerosity processing. This study aimed at examining (i) interval timing and (ii) interaction between duration and numerosity processing in four drug-resistant epileptic patients with postoperative lesions in the IFG in comparison with thirteen healthy controls. The duration reproduction and discrimination tasks performed in the sub- and supra-second ranges did not reveal any significant differences between patients and controls. The duration discrimination task of stimuli varying in numerosity (DurN) and the numerosity discrimination task of stimuli varying in duration (NumD) revealed that only numerosity judgment was altered in IFG patients. A time-order effect was notably observed in the NumD task but in opposite directions for the two groups: The second patch was perceived as more numerous than the first patch in controls and conversely as less numerous in patients. Finally in the DurN task, we observed a congruency effect which was dependent on numerical distance in patients but not in controls. These converging results suggest that the IFG would be more specifically involved in numerosity than in duration processing, possibly playing a role in numerical decision.

Role of the supplementary motor area during reproduction of supra-second time intervals: An intracerebral EEG study.

The supplementary motor area (SMA) has been shown to be involved in interval timing but its precise role remains a matter of debate. The present study was aimed at examining, by means of intracerebral EEG recordings, the time course of the activity in this structure, as well as in other functionally connected cortical (frontal, cingulate, insular and temporal) areas, during a visual time reproduction task. Four patients undergoing stereo-electroencephalography (SEEG) for presurgical investigation of refractory focal epilepsy were enrolled. They were selected on the presence of depth electrodes implanted within the SMA. They were instructed to encode, keep in memory and then reproduce the duration (3, 5 and 7 s) of emotionally-neutral or negative pictures. Emotional stimuli were used with the aim of examining neural correlates of temporal distortions induced by emotion. Event-related potentials (ERPs) were analyzed during three periods: During and at the extinction of the target interval (TI) and at the beginning of the reproduction interval (RI). Electrophysiological data revealed an ERP time-locked to TI-offset whose amplitude varied monotonically with TI-duration. This effect was observed in three out of the four patients, especially within the SMA and the insula. It also involved the middle and anterior cingulate cortex, the superior, middle and inferior frontal gyri and the paracentral lobule. These effects were modulated by the prior TI-duration and predicted variations in temporal reproduction accuracy. In contrast, modulations of ERPs with TI-duration, emotion or temporal performance during the target or the reproduction interval were modest and less consistent across patients. These results demonstrate that, during reproduction of supra-second time intervals, the SMA, in concert with a fronto-insular network, is involved at the end of the target interval, and suggest a role in the duration categorization and decision making operations or alternatively in the preparedness of the timing of the future movement that will be executed during the reproduction phase.

Sensation Seeking and Adaptation in Parabonauts.

Evidence from extreme environments suggests that there are relationships between difficulties of adaptation and psychological factors such as personality. In the framework of microgravity research on humans, the aim of this exploratory study was to investigate inter-individual differences of parabonauts on the basis of quality of adaptation to the physical demands of parabolic flights. The personality characteristics of two groups of parabonauts with a different quality of adaptation (an Adaptive group, N = 7, and a Maladaptive group, N = 15) were assessed using the Sensation Seeking Scale, Brief COPE, and MSSQ-Short. Compared to the Maladaptive group, the individuals of the Adaptive group scored higher on Boredom Susceptibility (i.e., a subscale of the Sensation Seeking Scale), lower on scales of susceptibility to motion sickness (MSSQ-Short) and tended to score lower on Instrumental Support Seeking (i.e., a subscale of the Brief COPE). These results suggest that individuals of the Adaptive group are more intolerant to monotony, present an aversion to repetitive and routine activities, are less susceptible to motion sickness and less dependent on problem-focused strategies. These characteristics may have contributed to developing a certain degree of flexibility in these subjects when faced with the parabolic flight situation and thus, may have favored them. The identification of differences of personality characteristics between individuals who have expressed difficulties of adaptation from those who have adapted successfully could help to prevent the risk of maladaptation and improve the well-being of (future) commercial or occupational aerospace passengers. More generally, these results could be extended to extreme environments and professional and/or sports domains likely to involve risk taking and unusual situations.

Impact of anxiety on verbal and visuospatial working memory in patients with acute stroke without severe cognitive impairment.

BACKGROUND: Working memory is the most impaired cognitive domain in the acute phase of stroke. In a context where anxiety is highly prevalent, close attention must be paid to anxiety which could mimic mild to moderate working memory impairments. This is the first study to assess the contribution of state anxiety (the currently experienced level of anxiety) to the working memory (verbal, visuospatial) in patients with first-ever acute stroke without severe cognitive impairment. METHODS: 28 patients with first-ever acute stroke and 41 matched control subjects were exposed to a neutral condition and an anxiogenic condition in which verbal (VWM) and visuospatial working memory (VSWM) performance and state anxiety were assessed. State anxiety was assessed before the beginning of the experiment (baseline), after the neutral condition and after the anxiogenic condition. RESULTS: The mean state anxiety score was higher in patients than in controls in the neutral (z = 1.9, p<0.05) and anxiogenic (z = 2, p<0.05) conditions despite a similar level at baseline. Multiple regression analyses with a dummy variable 'group' (patients vs controls) showed that increased state anxiety in patients contributed significantly more to both reduced VWM (ß = -0.93, p<0.05) and VSWM (ß = -1, p<0.05) performance between the neutral and anxiogenic conditions compared to controls. CONCLUSIONS: In a stressful context, the contribution of state anxiety to reduced working memory performance is more pronounced in patients with acute stroke than in controls. These results are of particular relevance for clinicians assessing patients in the acute phase of stroke in which anxiety is highly prevalent.

Distortion of time interval reproduction in an epileptic patient with a focal lesion in the right anterior insular/inferior frontal cortices.

This case report on an epileptic patient suffering from a focal lesion at the junction of the right anterior insular cortex (AIC) and the adjacent inferior frontal cortex (IFC) provides the first evidence that damage to this brain region impairs temporal performance in a visual time reproduction task in which participants had to reproduce the presentation duration (3, 5 and 7s) of emotionally-neutral and -negative pictures. Strikingly, as compared to a group of healthy subjects, the AIC/IFC case considerably overestimated reproduction times despite normal variability. The effect was obtained in all duration and emotion conditions. Such a distortion in time reproduction was not observed in four other epileptic patients without insular or inferior frontal damage. Importantly, the absolute extent of temporal over-reproduction increased in proportion to the magnitude of the target durations, which concurs with the scalar property of interval timing, and points to an impairment of time-specific rather than of non temporal (such as motor) mechanisms. Our data suggest that the disability in temporal reproduction of the AIC/IFC case would result from a distorted memory representation of the encoded duration, occurring during the process of storage and/or of recovery from memory and leading to a deviation of the temporal judgment during the reproduction task. These findings support the recent proposal that the anterior insular/inferior frontal cortices would be involved in time interval representation.

Personality traits of people attracted by parabolic flight.

BACKGROUND: Studies have shown that members of expeditions in extreme environments differed on the basis of personality factors (e.g., they were highly competitive, higher on Extraversion and Conscientiousness) compared to the control population. In order to identify individuals who are likely to participate in extreme environments, the aim of the present study using parabolic flights was to compare the personality traits of voluntary participants (VP) in a weightlessness experiment with those of the general population (GP) (French norms). METHODS: The personalities of 57 voluntary participants in a parabolic flights experiment were assessed using NEO-PI-R and Trait-Anxiety. RESULTS: Our results show significant differences with the general population: (1) in Trait-Anxiety (GP = 42.25 +/- 11.44 vs. VP = 34.56 +/- 6.24) and in 3 out of 5 personality domains (Neuroticism GP = 90.04 +/- 22.68 vs. VP = 78.70 +/- 17.44, +/- 18.87 vs. VP = 123.81 +/- 15.41, and Conscientiousness GP = 109.23 +/- 22.30 vs. VP = 124.47 + 19.03); and (2) in 14 out of 30 NEO-PI-R facets. DISCUSSION: These findings indicate a specific personality profile for voluntary participants in parabolic flights and confirm that participants attracted to extreme environments differ compared to the normative population.

Paradoxical state anxiety and working memory in a patient with acute stroke.

OBJECTIVE: In view of the negative impact of anxiety on working memory, we induced anxiety in 26 patients with acute stroke and 33 healthy controls, and studied how the anxiety affected their emotional reactivity and how the reactivity affected their verbal and visuospatial working memory. We compared the overall findings with those in 1 of our patients (C.B.) who had presented with an abnormally high level of state anxiety. METHODS: We gave verbal and visuospatial 1-back tasks under both neutral and anxiogenic conditions, and we compared participants' working memory scores, self-reported levels of state anxiety, and electrodermal activity. RESULTS: When comparing performance in the neutral condition, the control and patient groups exhibited disrupted verbal working memory, which was associated with greater electrodermal activity and higher state anxiety during the anxiogenic condition. Although patient C.B. also had heightened electrodermal activity during the anxiogenic condition, she experienced a significant reduction in her state anxiety. Her verbal working memory was better during the anxiogenic than the neutral condition. CONCLUSIONS: Because of the phonological (subvocal speech) nature of verbal working memory, a higher level of anxious apprehension could explain the increase in state anxiety and the corresponding disruption of verbal working memory in our patient and control groups during the anxiogenic condition. C.B.'s lower state anxiety and selective improvement in verbal working memory during the anxiogenic condition suggest that she felt less anxious apprehension.

Effects of working memory demands on frontal slow waves in time-interval reproduction tasks in humans.

Very few studies have examined the event-related potentials associated with the retention of temporal information for later use. In the present experiment, event-related potentials were recorded during two duration reproduction tasks in which a delay was introduced between the encoding and the reproduction phases. Furthermore, working memory demands were varied during the delay (number of durations to be memorized and degree of manipulation of the durations). These variables had no significant effect on the amplitude of the contingent negative variation observed during duration encoding. By contrast, the amplitude of the slow wave recorded over middle frontal regions during the delay increased with working memory demands, which confirms the key role played by these frontal regions in the cognitive processes engaged during the retention of duration in working memory.