Combining a new CO2 laser wave guide with transoral robotic surgery: a feasibility study on four patients with malignant tumors

We present a series of patients treated by transoral robotic surgery (TORS) using a new CO₂ laser wave guide (CO₂ LWG) (Lumenis, Santa Clara, CA). Patients older than 18?years, with malignant pharyngo-laryngeal tumors were enrolled in this prospective study after signing an informed consent. Four patients were enrolled in the study. The mean age was 56?years. One patient had a T1 base of tongue tumor, two patients had supraglottic tumors (T1, T2), and one had a T1 palatine tonsil tumor. All the procedures could be performed using a Maryland forceps, a 0° endoscope and a CO₂ LWG introduced via the robotic arm introducer. The laser parameters were: superpulse or continuous mode, 7–15?W, continuous delivery. The average set-up time was 30?min. The average surgical time was 94?min. No complications were noted due to the intraoperative use of the robot or the CO₂ LWG. One laser fiber was used for each of the surgeries. The mean coagulation depth was 200?μm (range 100–300). The mean hospital stay was 6?days. The CO₂ LWG is a reliable tool for TORS. It allowed more than 1?h of work without any trouble.     

Decisional space determines saccadic reaction times in healthy observers and acquired prosopagnosia

Determining the familiarity and identity of a face have been considered as independent processes. Covert face recognition in cases of acquired prosopagnosia, as well as rapid detection of familiarity have been taken to support this view. We tested P.S. a well-described case of acquired prosopagnosia, and two healthy controls (her sister and daughter) in two saccadic reaction time (SRT) experiments. Stimuli depicted their family members and well-matched unfamiliar distractors in the context of binary gender, or familiarity decisions. Observers’ minimum SRTs were estimated with Bayesian approaches. For gender decisions, P.S. and her daughter achieved sufficient performance, but displayed different SRT distributions. For familiarity decisions, her daughter exhibited above chance level performance and minimum SRTs corresponding to those reported previously in healthy observers, while P.S. performed at chance. These findings extend previous observations, indicating that decisional space determines performance in both the intact and impaired face processing system.     

Repeated Social Stress Increases Reward Salience and Impairs Encoding of Prediction by Rat Locus Coeruleus Neurons

Stress is implicated in psychopathology characterized by cognitive dysfunction. Cognitive responses to stress are regulated by the locus coeruleus–norepinephrine (LC–NE) system. As social stress is a prevalent human stressor, this study determined the impact of repeated social stress on the relationship between LC neuronal activity and behavior during the performance of cognitive tasks. Social stress-exposed rats performed better at intradimensional set shifting (IDS) and made fewer perseverative errors during reversal learning (REV). LC neurons of control rats were task responsive, being activated after the choice and before reward. Social stress shifted LC neuronal activity from being task responsive to being reward responsive during IDS and REV. LC neurons of stressed rats were activated by reward and tonically inhibited by reward omission with incorrect choices. In contrast, LC neurons of stress-naive rats were only tonically inhibited by reward omission. Reward-related LC activation in stressed rats was unrelated to predictability because it did not habituate as learning progressed. The findings suggest that social stress history increases reward salience and impairs processes that compute predictability for LC neurons. These effects of social stress on LC neuronal activity could facilitate learning as indicated by improved performance in stressed rats. However, the ability of social stress history to enhance responses to behavioral outcomes may have a role in the association between stress and addictive behaviors. In addition, magnified fluctuations in LC activity in response to opposing behavioral consequences may underlie volatile changes in emotional arousal that characterize post-traumatic stress disorder.In response to acute stressors, neural systems that regulate the hypothalamic–pituitary–adrenal axis, autonomic function, behavior, and cognition are engaged in a coordinated manner to cope with the stressor and promote survival. Persistent or repeated activation of these stress systems as a result of chronic or repeated stress, or inappropriate activation of the systems in the absence of stress, is maladaptive and results in pathology (Chrousos and Gold, 1992; de Kloet et al, 2005; McEwen, 1998). Such maladaptive stress responses are thought to underlie symptoms such as hyperarousal, inappropriate fear, and attentional and cognitive dysfunctions that characterize certain psychiatric disorders (Gold and Chrousos, 2002). Interestingly, although many studies report impairment of cognitive processes by stressors, there are also reports of enhancement and these differences may depend on the specific stressor and the cognitive endpoint (Bondi et al, 2008; Butts et al, 2013; Graybeal et al, 2011; Lapiz-Bluhm et al, 2009; Thai et al, 2013). These differences underscore the complexity of effects of stress on neural circuits that regulate cognitive functions.The locus coeruleus–norepinephrine (LC–NE) system is a stress-response system that has been implicated in cognitive responses to stress and in stress-related psychopathology (Southwick et al, 1999; Valentino and Van Bockstaele, 2008; Wong et al, 2000). LC neurons are spontaneously active and their discharge rate is positively correlated to behavioral indices of arousal (Aston-Jones and Bloom, 1981b; Foote et al, 1980). Salient stimuli elicit a phasic activation of LC neurons that precedes orientation to the stimulus and this has implicated the system in attention (Aston-Jones and Bloom, 1981a; Berridge and Waterhouse, 2003; Foote et al, 1980). LC neuronal recordings in animals performing operant tasks indicate that phasic LC discharge is associated with focused attention and staying ‘on-task'', whereas high-tonic LC discharge is associated with labile attention and task disengagement (Aston-Jones and Cohen, 2005; Bouret and Sara, 2005; Sara, 2009). It has been suggested that this high-tonic mode of LC discharge facilitates cognitive flexibility (Aston-Jones and Cohen, 2005). Acute stressors and exposure to the stress-related peptide, corticotropin-releasing factor (CRF) bias LC activity towards a high-tonic state that may be adaptive in a dynamic environment with life-threatening challenges (Curtis et al, 2012; Valentino and Foote, 1987; Valentino and Wehby, 1988). Notably, certain doses of CRF improve extradimensional set-shifting performance during an attentional set-shifting task (AST), an endpoint of cognitive flexibility (Snyder et al, 2012). In contrast to the activating effects of acute stressors on LC neuronal activity, repeated social stress produces an enduring inhibition of rat LC discharge that is apparent several days after the last stressor (Chaijale et al, 2013). These findings are relevant to humans given that social stress is one of the most common human stressors. A similar enduring inhibition of LC activity occurs in rats exposed to a model of post-traumatic stress disorder that involves the administration of three consecutive stressors (George et al, 2013). It is unknown how this state of LC inhibition impacts on cognition.As cognitive dysfunction is thought to be one of the maladaptive consequences of repeated stress and the LC–NE system has been implicated in cognitive aspects of the stress response, the present study investigated the long-term effects of repeated social stress on LC activity recorded during the performance of an AST that assesses simple discrimination (SD), compound discrimination (CD), intradimensional set shifting (IDS), reversal learning (REV), and extradimensional set shifting. The results provided evidence that repeated social stress changes the relationship between LC neuronal activity and task performance, and renders LC neurons responsive to reward regardless of its predictability.     

Associations between adolescent cannabis use and young-adult functioning in three longitudinal twin studies

Observational studies have linked cannabis use to an array of negative outcomes, including psychiatric symptoms, cognitive impairment, and educational and occupational underachievement. These associations are particularly strong when cannabis use occurs in adolescence. Nevertheless, causality remains unclear. The purpose of the present study was thus to examine associations between prospectively assessed adolescent cannabis use and young-adult outcomes (psychiatric, cognitive, and socioeconomic) in three longitudinal studies of twins (n = 3,762). Twins reporting greater cumulative cannabis use in adolescence reported higher levels of psychopathology as well as poorer socioeconomic outcomes in young adulthood. However, cannabis use remained associated only with socioeconomic outcomes (i.e., educational attainment, occupational status, and income) in monozygotic-cotwin control analyses, which account fully for shared genetic and environmental confounding. Follow-up analyses examining associations between twin differences in adolescent cannabis use and longitudinal change in academic functioning during the middle- and high-school years provided a possible mechanism for these associations, indicating that greater cannabis use during this period was associated with decreases in grade point average and academic motivation as well as increases in academic problem behavior and school disciplinary problems. Our findings thus suggest that cannabis use in adolescence has potentially causal, deleterious effects on adolescent academic functioning and young-adult socioeconomic outcomes despite little evidence suggesting a strong, causal influence on adult mental health or cognitive ability.

The legality of cannabis in the United States is changing rapidly. A total of 16 states and the District of Columbia have legalized recreational cannabis use, and the majority now allow medical marijuana. Although research is still in its infancy, studies have generally concluded that legalization is associated with increased rates of use, frequent use, and cannabis-use disorders among adults (1–4) but with stable or even decreasing use among adolescents (3–5). Despite these findings, many individuals and institutions have cited concerns regarding the effects of cannabis on minors whose access may increase with the legalization of adult use, with medical authorities such as the American Academy of Pediatrics and US Surgeon General putting out statements warning against potential dangers (6, 7).Concerns regarding adolescent cannabis use are supported by three streams of research. First, large-scale observational studies have shown that adolescent use is associated with many negative outcomes, including mental health problems (8–11), misuse of alcohol and other drugs (8, 11, 12), cognitive impairment (13–16), reduced socioeconomic attainment (11, 17), and unemployment (18, 19). Most studies find these associations become increasingly likely the earlier cannabis use is initiated. Second, neuroimaging studies have reported associations between chronic cannabis use and long-term changes in brain activity in areas responsible for reward and emotion processing (e.g., ventral striatum and amygdala), which some have hypothesized may contribute to compulsive behavior and greater negative emotionality among users (20). Third, studies from the animal literature routinely report cannabis-induced alterations in molecular, neural, and behavioral assays, with one recent review summarizing these findings as “clearly indicat[ing] that adolescent-onset exposure to cannabinoids can catalyze molecular processes that lead to persistent functional deficits in adulthood, deficits that are not found to follow adult-onset exposure” (21).