Stress Impairs Intentional Memory Control through Altered Theta Oscillations in Lateral Parietal Cortex.

Accumulating evidence suggests that forgetting is not necessarily a passive process but that we can, to some extent, actively control what we remember and what we forget. Although this intentional control of memory has potentially far-reaching implications, the factors that influence our capacity to intentionally control our memory are largely unknown. Here, we tested whether acute stress may disrupt the intentional control of memory and, if so, through which neural mechanism. We exposed healthy men and women to a stress (n = 27) or control (n = 26) procedure before they aimed repeatedly to retrieve some previously learned cue-target pairs and to actively suppress others. While control participants showed reduced memory for suppressed compared with baseline pairs in a subsequent memory test, this suppression-induced forgetting was completely abolished after stress. Using magnetoencephalography (MEG), we show that the reduced ability to suppress memories after stress is associated with altered theta activity in the inferior temporal cortex when the control process (retrieval or suppression) is triggered and in the lateral parietal cortex when control is exerted, with the latter being directly correlated with the stress hormone cortisol. Moreover, the suppression-induced forgetting was linked to altered connectivity between the hippocampus and right dorsolateral prefrontal cortex (PFC), which in turn was negatively correlated to stress-induced cortisol increases. These findings provide novel insights into conditions under which our capacity to actively control our memory breaks down and may have considerable implications for stress-related psychopathologies, such as posttraumatic stress disorder (PTSD), that are characterized by unwanted memories of distressing events.SIGNIFICANCE STATEMENT It is typically assumed that forgetting is a passive process that can hardly be controlled. There is, however, evidence that we may actively control, to some extent, what we remember and what we forget. This intentional memory control has considerable implications for mental disorders in which patients suffer from unwanted (e.g., traumatic) memories. Here, we demonstrate that the capacity to intentionally control our memory breaks down after stress. Using magnetoencephalography (MEG), we show that this stress-induced memory control deficit is linked to altered activity in the lateral parietal cortex and the connectivity between the hippocampus and right prefrontal cortex (PFC). These findings provide novel insights into conditions under which memory control fails and are highly relevant in the context of stress-related psychopathologies.

[A modular retraction system (VarioLift) for laparoscopy without pneumoperitoneum]. / Ein modulares Retraktionssystem (VarioLift) für die Laparoskopie ohne Pneumoperitoneum.

Because of adverse physiological effects and technical disadvantages of the pneumoperitoneum, alternative methods of abdominal wall lifting have been explored recently. Most of these systems are complicated in their system set-up and handling or the intraabdominal exposure is limited. The modular retraction system (VarioLift, AESCULAP Tuttlingen) consists of two different components, one for the abdominal wall lifting, and one for internal organ compression. Via a 2 cm mini-laparotomy two lifting parts of different size and shape are introduced into the abdominal cavity, assembled to each other and attached to an outside mechanical lifting arm which is suspended to the operating table. Using combinations of these parts, the system can be adjusted to different abdominal quadrants and the patient's individual anatomy. According to the needs of vision for internal organ compression a translucent plastic membrane can be placed for posterior organ retraction using the same access. In contrast to other systems the modular retraction system (VarioLift) allows an individual adjustment to the patient's anatomy and, if necessary, compression of internal organs. A planar suspension of the abdominal wall with a good lateral exposure and a dome-shaped suspension without tenting effects is provided. Time needed for mini-laparotomy and system set-up is only slightly longer than installation of a pneumoperitoneum.

Systems and instruments for laparoscopic surgery without pneumoperitoneum.

The insufflation of carbon dioxide into the peritoneal cavity is a routine technique of abdominal exposure in laparoscopic surgery. Because of adverse physiological effects and technical disadvantages of the pneumoperitoneum, alternative methods of abdominal wall lifting have been explored recently. Two groups of retraction systems exist: intraabdominal lifting and subcutaneous lifting of the abdominal wall. Some systems require additional pneumoperitoneum, because the extent of intraabdominal exposure is not sufficient. Other systems are working completely without gas insufflation. Two systems combine abdominal wall lifting with pressure on the internal organs. Every method allows the use of standard laparoscopic instruments, which originally were designed for a regular pneumoperitoneum. The use of a low-pressure pneumoperitoneum in combination with mechanical augmentation of the peritoneal cavity reduces physiological disadvantages of laparoscopy. But technical advantages, such as combination of laparoscopic and open techniques, can be realized only without gas insufflation. Conventional instruments have been designed to fit the ergonomical needs of isopneumic laparoscopy and to be employed with simple valveless cannulae.

[Initial experiences with the modular retraction system (VarioLift) for laparoscopic surgery without pneumoperitoneum]. / Erste Erfahrungen mit dem modularen Retraktionssystem (VarioLift) für die laparoskopische Chirurgie ohne Pneumoperitoneum.

The VarioLift system is an alternative method for abdominal wall lifting to create sufficient intra-abdominal space and adequate laparoscopic exposure to the operating field. The installation of a CO2 pneumoperitoneum is not necessary, which means that technical disadvantages, systemic and local physiological effects, or complications related to gas insufflation are not relevant when this method is used. The surgeon is allowed to combine the advantages of endoscopic surgery, such as magnified video-endoscopic visualisation, with well-known open surgical techniques to create a symbiosis of prove methods.