No abstract

Background-Stress is an important factor in the development and maintenance of anxiety disorders. Stress also potentiates anxiety-like response in animals, but empirical evidence for a similar effect in humans is still lacking.

Chronic treatment with selective serotonin reuptake inhibitors (SSRIs) alleviates both anxiety symptoms and associated physiologic disturbances in anxious patients. However, limited research considers the degree to which chronic SSRI treatment influences anxiety in healthy individuals. This study examined the effect of 2-week citalopram treatment on two threat responses: short-and long-durationpotentiated startle. Prior work suggests that these two responses provide neurally and functionally distinct models of fear and anxiety, respectively, in rodents. Healthy volunteers (n ¼ 53) received either placebo or citalopram (20 mg per day) for 2 weeks under doubleblind conditions. They were each tested twice, before and after treatment. Participants were exposed to three conditions, including one in which predictable aversive shocks were signaled by a cue, a second in which unpredictable shocks were anticipated, and a third in which no shocks were administered. Aversive states were indexed by acoustic startle. Phasic fear-potentiated startle to the threat cue, as well as sustained startle potentiation to the experimental context in the predictable and unpredictable conditions, were investigated. Citalopram affected neither baseline startle nor short-duration fear-potentiated startle to discrete threat cues. However, citalopram reduced long-duration startle potentiation in the predictable conditions. These results are consistent with the hypothesis that short-and long-duration aversive states are mediated by distinct neural systems. They suggest that citalopram alleviates symptoms of anticipatory anxiety, not fear, by acting on mechanisms underlying long-duration aversive states.

CESM was comparable to MRI in assessing residual malignancy after completion of NST.

Theories of animal defensive behavior postulate that imminent, predictable threat elicits highly focused attention toward the threat source, whereas remote, unpredictable threat elicits distributed attention to the overall environment. We used threat of shock combined with measurement of prepulse inhibition of the startle reflex to test these claims in humans. Twenty-seven participants experienced periods of threat and safety. Threat and safe periods were short or long, with the short threat periods conveying relatively predictable, imminent shocks and the long threat periods conveying unpredictable shocks. Startle reflexes were elicited with equal numbers of acoustic probes presented alone, preceded by a tactile prepulse, or preceded by an auditory prepulse. We observed enhanced tactile relative to auditory prepulse inhibition during short threat periods only. This finding supports the notion that imminent threat, but not remote threat, elicits attention focused toward the relevant modality, potentially reflecting preparatory activity to minimize the impact of the noxious stimulus.Whether aversive stimuli are predictable or unpredictable in time is a critical determinant of how an organism will adaptively respond to, and what neural structures will be activated by, threatening conditions. Studying rodents, Walker and Davis (1997) have distinguished between phasic fear, which is mediated by the amygdala in response to cues predicting imminent noxious stimulation, and sustained anxiety, which is mediated by the bed nucleus of the stria terminalis (see Davis, 1998Davis, , 2006. Along these lines, abundant evidence suggests that humans can be instructed or conditioned to fear discrete cues that predict aversive stimuli (e.g., shock) and to show anticipatory anxiety when aversive stimuli are presented unpredictably (i.e., without a discrete warning cue; Grillon, Ameli, Woods, Merikangas, & Davis, 1991;Grillon, Baas, Lissek, Smith, & Milstein, 2004). Recent studies of humans have demonstrated that these responses or states are dissociable pharmacologically Grillon, Cordova, Morgan, Charney, & Davis, 2004). In the present study, we intended to elaborate the distinction between fear and anxiety by demonstrating differences in cognitive processes under conditions of predictable versus unpredictable shock. In particular, we examined how attention is allocated under short (10 s) periods with relatively predictable timing of shock delivery and long (60 s) periods with more unpredictable timing of shock delivery.The concept of threat imminence has figured prominently in theories of animal defensive behaviors (Blanchard & Blanchard, 1989;Fanselow, 1994;Gray & McNaughton, 2000) and (Lang, Bradley, & Cuthbert, 1997;Öhman, Hamm, & Hugdahl, 2000). One common theme is that when potential threat exists but is not imminent, attention is heightened, but not necessarily directed toward specific aspects of the environment (Blanchard & Blanchard, 1989;Fanselow, 1994). An organism may show cautious approach and be highly sensit...

Establishing a diagnosis of Alzheimer dementia can be challenging, particularly early in the course of the disease. However, with disease-modifying therapies on the horizon, it is becoming increasingly important to achieve the correct diagnosis as soon as possible. In challenging presentations of dementia, such as patients with clinically atypical features or early-age onset of mild cognitive impairment, amyloid PET is a valuable tool in determining the diagnosis of Alzheimer dementia. Furthermore, preliminary data show that amyloid PET findings alter clinical management in patients who meet the appropriate use criteria. There are currently three U.S. Food and Drug Administration (FDA)-approved fluorine 18 ( 18 F)-labeled radiopharmaceuticals that allow in vivo detection of cerebral amyloid deposition, which is a hallmark pathologic feature of Alzheimer dementia. Knowledge of the common imaging features among these three 18 F-labeled radiopharmaceuticals in the normal and abnormal brain will enable the radiologist to more accurately interpret amyloid PET studies. As in other subspecialties of radiology, imaging signs in amyloid PET are helpful to distinguish if a region is normal or abnormal. This article reviews appropriate use criteria for amyloid PET, introduces the properties of the radiopharmaceuticals, explains the algorithmic approach to interpretation with examples of normal and abnormal amyloid PET scans with MRI correlation, and provides an atlas of regional amyloid PET signs and common artifacts. © RSNA, 2018 •

Tomosynthesis-guided VAB is a feasible method to sample ADs that are occult at 2D mammography and ultrasound. Tomosynthesis-guided VAB is a minimally invasive method that detected a significant number of carcinomas, most of which were grade 1 cancers. Further studies are needed.

MR imaging is a highly sensitive and specific test in the evaluation of patients younger than 50 years with acute RLQ pain that uses a rapid imaging protocol performed without intravenous or oral contrast material.