At rest, brain activity can be characterized not by an absence of organized activity but instead by spatially and temporally correlated patterns of activity. In this experiment, we investigated whether and to what extent resting state functional connectivity is modulated by sex hormones in women, both across the menstrual cycle and when altered by oral contraceptive pills. Sex hormones have been shown to have important effects on task-related activity, but few studies have investigated the extent to which they can influence the behavior of functional networks at rest. These hormones are dramatically altered by the use of hormonal contraception, which is used by approximately 100 million women worldwide. However, potential cognitive side effects of hormonal contraception have been given little attention. Here, we collected resting state data for naturally-cycling women (n=45) and women using combined oral contraceptive pills (n=46) and evaluated the differences in resting state activity between these two groups using Independent Components Analysis. We found that in the default mode network and in a network associated with executive control, resting state dynamics were altered both by the menstrual cycle and by oral contraceptive use. Specifically, the connectivity of the left angular gyrus, the left middle frontal gyrus, and the anterior cingulate cortex were different between groups. Because the anterior cingulate cortex and left middle frontal gyrus are important for higher-order cognitive and emotional processing, including conflict monitoring, changes in the relationship of these structures to the functional networks with which they interact may have important consequences for attention, affect, and/or emotion regulation.

Sickle cell trait (AS) confers partial protection against lethal malaria. Multiple mechanisms for this have been proposed, with a recent focus on aberrant cytoadherence of parasite-infected red blood cells (RBCs). Here we investigate the mechanistic basis of AS protection through detailed temporal mapping. We find that parasites in AS RBCs maintained at low oxygen concentrations stall at a specific stage in the middle of intracellular growth before DNA replication. We demonstrate that polymerization of sickle hemoglobin (HbS) is responsible for this growth arrest of intraerythrocytic parasites, with normal hemoglobin digestion and growth restored in the presence of carbon monoxide, a gaseous antisickling agent. Modeling of growth inhibition and sequestration revealed that HbS polymerization-induced growth inhibition following cytoadherence is the critical driver of the reduced parasite densities observed in malaria infections of individuals with AS. We conclude that the protective effect of AS derives largely from effective sequestration of infected RBCs into the hypoxic microcirculation.

The recent identification of highly superior autobiographical memory (HSAM) raised the possibility that there may be individuals who are immune to memory distortions. We measured HSAM participants' and age-and sex-matched controls' susceptibility to false memories using several research paradigms. HSAM participants and controls were both susceptible to false recognition of nonpresented critical lure words in an associative word-list task. In a misinformation task, HSAM participants showed higher overall false memory compared with that of controls for details in a photographic slideshow. HSAM participants were equally as likely as controls to mistakenly report they had seen nonexistent footage of a plane crash. Finding false memories in a superior-memory group suggests that malleable reconstructive mechanisms may be fundamental to episodic remembering. Paradoxically, HSAM individuals may retrieve abundant and accurate autobiographical memories using fallible reconstructive processes.hyperthymesia | DRM | suggestion | crashing memories R esearch on memory distortion suggests that episodic memory often involves a flawed reconstructive process (1-3). Several false-memory paradigms developed in recent decades have demonstrated this. For example, in the Deese-Roediger and McDermott (DRM) (4, 5) paradigm, people falsely remember words not actually presented in a related list of words. In the misinformation paradigm, the content of a person's memory can be changed after they are exposed to misleading postevent information (2, 6, 7). In the nonexistent news-footage paradigm (also known as the "crashing memory" paradigm), people sometimes recall witnessing footage of news events for which no footage actually exists (8, 9). People can even remember events following an imagination exercise that inflates their certainty about events that they only imagined but did not actually experience (10). Even memory for our past emotions seems to be reconstructed and prone to error (11). So far, memory distortions have been investigated in subjects who have typical memory ability [children (12), adults (7), older adults (13)], but not with people with unusually strong memory ability. Memorydistortion phenomena have been explained by theoretical models that state that memory is reconstructed from traces at retrieval (1,3,14), is not reproduced from a permanent recording (15), and is prone to errors caused by source confusion (16) and association (17, 18). These studies and theoretical models paint a picture of human memory as malleable and prone to errors.However, a small number of individuals who have recently been identified appear to be uniquely gifted in their ability to accurately remember even trivial details from their distant past (19-21). Highly superior autobiographical memory (HSAM; also known as hyperthymesia) individuals can remember the day of the week a date fell on and details of what happened that day from every day of their life since mid-childhood. For details that can be verified, HSAM individuals are correct 97% of ...