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Challenging the negative learning bias hypothesis of depression: reversal learning in a naturalistic psychiatric sample
- Sophie C. A. Brolsma, Janna N. Vrijsen, Eliana Vassena, Mojtaba Rostami Kandroodi, M. Annemiek Bergman, Philip F. van Eijndhoven, Rose M. Collard, Hanneke E. M. den Ouden, Aart H. Schene, Roshan Cools
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- Journal:
- Psychological Medicine / Volume 52 / Issue 2 / January 2022
- Published online by Cambridge University Press:
- 15 June 2020, pp. 303-313
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Background
Classic theories posit that depression is driven by a negative learning bias. Most studies supporting this proposition used small and selected samples, excluding patients with comorbidities. However, comorbidity between psychiatric disorders occurs in up to 70% of the population. Therefore, the generalizability of the negative bias hypothesis to a naturalistic psychiatric sample as well as the specificity of the bias to depression, remain unclear. In the present study, we tested the negative learning bias hypothesis in a large naturalistic sample of psychiatric patients, including depression, anxiety, addiction, attention-deficit/hyperactivity disorder, and/or autism. First, we assessed whether the negative bias hypothesis of depression generalized to a heterogeneous (and hence more naturalistic) depression sample compared with controls. Second, we assessed whether negative bias extends to other psychiatric disorders. Third, we adopted a dimensional approach, by using symptom severity as a way to assess associations across the sample.
MethodsWe administered a probabilistic reversal learning task to 217 patients and 81 healthy controls. According to the negative bias hypothesis, participants with depression should exhibit enhanced learning and flexibility based on punishment v. reward. We combined analyses of traditional measures with more sensitive computational modeling.
ResultsIn contrast to previous findings, this sample of depressed patients with psychiatric comorbidities did not show a negative learning bias.
ConclusionsThese results speak against the generalizability of the negative learning bias hypothesis to depressed patients with comorbidities. This study highlights the importance of investigating unselected samples of psychiatric patients, which represent the vast majority of the psychiatric population.
From “Her” Problem to “Our” Problem: Using an Individual Lens Versus a Social-Structural Lens to Understand Gender Inequity in STEM
- Kathi N. Miner, Jessica M. Walker, Mindy E. Bergman, Vanessa A. Jean, Adrienne Carter-Sowell, Samantha C. January, Christine Kaunas
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- Journal:
- Industrial and Organizational Psychology / Volume 11 / Issue 2 / June 2018
- Published online by Cambridge University Press:
- 19 June 2018, pp. 267-290
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Increasing the representation of women in science, technology, engineering, and mathematics (STEM) is one of our nation's most pressing imperatives. As such, there has been increased lay and scholarly attention given to understanding the causes of women's underrepresentation in such fields. These explanations tend to fall into two main groupings: individual-level (i.e., her) explanations and social-structural (i.e., our) explanations. These two perspectives offer different lenses for illuminating the causes of gender inequity in STEM and point to different mechanisms by which to gain gender parity in STEM fields. In this article, we describe these two lenses and provide three examples of how each lens may differentially explain gender inequity in STEM. We argue that the social-structural lens provides a clearer picture of the causes of gender inequity in STEM, including how gaining gender equity in STEM may best be achieved. We then make a call to industrial/organizational psychologists to take a lead in addressing the societal-level causes of gender inequality in STEM.
Prefrontal cortical thinning links to negative symptoms in schizophrenia via the ENIGMA consortium
- E. Walton, D. P. Hibar, T. G. M. van Erp, S. G. Potkin, R. Roiz-Santiañez, B. Crespo-Facorro, P. Suarez-Pinilla, N. E. M. van Haren, S. M. C. de Zwarte, R. S. Kahn, W. Cahn, N. T. Doan, K. N. Jørgensen, T. P. Gurholt, I. Agartz, O. A. Andreassen, L. T. Westlye, I. Melle, A. O. Berg, L. Morch-Johnsen, A. Færden, L. Flyckt, H. Fatouros-Bergman, Karolinska Schizophrenia Project Consortium (KaSP), E. G. Jönsson, R. Hashimoto, H. Yamamori, M. Fukunaga, N. Jahanshad, P. De Rossi, F. Piras, N. Banaj, G. Spalletta, R. E. Gur, R. C. Gur, D. H. Wolf, T. D. Satterthwaite, L. M. Beard, I. E. Sommer, S. Koops, O. Gruber, A. Richter, B. Krämer, S. Kelly, G. Donohoe, C. McDonald, D. M. Cannon, A. Corvin, M. Gill, A. Di Giorgio, A. Bertolino, S. Lawrie, T. Nickson, H. C. Whalley, E. Neilson, V. D. Calhoun, P. M. Thompson, J. A. Turner, S. Ehrlich
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- Journal:
- Psychological Medicine / Volume 48 / Issue 1 / January 2018
- Published online by Cambridge University Press:
- 26 May 2017, pp. 82-94
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Background
Our understanding of the complex relationship between schizophrenia symptomatology and etiological factors can be improved by studying brain-based correlates of schizophrenia. Research showed that impairments in value processing and executive functioning, which have been associated with prefrontal brain areas [particularly the medial orbitofrontal cortex (MOFC)], are linked to negative symptoms. Here we tested the hypothesis that MOFC thickness is associated with negative symptom severity.
MethodsThis study included 1985 individuals with schizophrenia from 17 research groups around the world contributing to the ENIGMA Schizophrenia Working Group. Cortical thickness values were obtained from T1-weighted structural brain scans using FreeSurfer. A meta-analysis across sites was conducted over effect sizes from a model predicting cortical thickness by negative symptom score (harmonized Scale for the Assessment of Negative Symptoms or Positive and Negative Syndrome Scale scores).
ResultsMeta-analytical results showed that left, but not right, MOFC thickness was significantly associated with negative symptom severity (βstd = −0.075; p = 0.019) after accounting for age, gender, and site. This effect remained significant (p = 0.036) in a model including overall illness severity. Covarying for duration of illness, age of onset, antipsychotic medication or handedness weakened the association of negative symptoms with left MOFC thickness. As part of a secondary analysis including 10 other prefrontal regions further associations in the left lateral orbitofrontal gyrus and pars opercularis emerged.
ConclusionsUsing an unusually large cohort and a meta-analytical approach, our findings point towards a link between prefrontal thinning and negative symptom severity in schizophrenia. This finding provides further insight into the relationship between structural brain abnormalities and negative symptoms in schizophrenia.
Transformation in Escherichia coli: studies on the nature of donor DNA after uptake and integration
- W. P. M. Hoekstra, H. E. N. Bergmans, E. M. Zuidweg
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- Journal:
- Genetical Research / Volume 35 / Issue 3 / June 1980
- Published online by Cambridge University Press:
- 14 April 2009, pp. 279-289
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Chromosomal E. coli DNA appears to be sensitive towards in vivo DNA restriction when transformed to a restrictive E. coli recipient. It is therefore concluded that transforming chromosomal donor DNA is present in a double-stranded form immediately after uptake.
Genetic analysis of E. coli transformants, obtained with UV-irradiated donor DNA under conditions that exclude photorepair, show, especially in a uvrB recipient, loss of donor DNA information compared with the situation where DNA was not subjected to UV-irradiation. Similar conclusions were arrived at after genetic analysis of transductants obtained with UV-irradiated particles of the generalized transducing phage P1. The processing in E. coli of DNA after P1 transduction is thus similar to that of transforming DNA. The observations are discussed and a possible explanation based on single-stranded DNA integration is presented in detail.
Tansley Review No. 116 Cyanobacterium–plant symbioses
- A. N. RAI, E. SÖDERBÄCK, B. BERGMAN
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- Journal:
- The New Phytologist / Volume 147 / Issue 3 / September 2000
- Published online by Cambridge University Press:
- 23 October 2000, pp. 449-481
- Print publication:
- September 2000
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Summary 449
I. INTRODUCTION 450
II. THE PARTNERS 451
1. Cyanobionts and their role 451
2. Hosts and their role 453
3. Location of cyanobionts in their hosts 455
III. INITIATION AND DEVELOPMENT OF SYMBIOSES 458
1. Initiation of symbioses 458
2. Geosiphon pyriforme 458
3. Cyanolichens 459
4. Liverworts and hornworts 460
5. Azolla 460
6. Cycads 461
7. Gunnera 461
IV. THE SYMBIOSES 462
1. Geographical distribution and ecological significance 462
2. Benefits to the partners 462
(a) Benefits to the cyanobionts 462
(b) Benefits to the hosts 463
3. Duration and stability 463
4. Mode of transmission and perpetuation 463
5. Recognition between the partners 464
6. Specificity and diversity 464
7. Symbiosis-related genes 465
8. Modifications of the cyanobiont 466
(a) Growth and morphology 466
(b) Photosynthesis and carbon metabolism 467
(c) Glutamine synthetase 467
(d) Heterocysts 469
(e) N2fixation 470
9. Nutrient exchange 471
(a) Carbon 471
(b) Nitrogen 472
V. EVOLUTIONARY ASPECTS 472
VI. ARTIFICIAL SYMBIOSES 474
VII. FUTURE OUTLOOK AND PERSPECTIVES 475
1. Cryptic symbioses 476
2. Developmental profile of symbiotic tissues 476
3. Sensing and signalling 476
4. Genetic aspects 476
5. Physiological and biochemical aspects of nutrient exchange 477
6. Microaerobiosis 477
7. Potential applications 477
Acknowledgements 477
References 477
Cyanobacteria are an ancient, morphologically diverse group of prokaryotes with an oxygenic photosynthesis. Many cyanobacteria also possess the ability to fix N2. Although well suited to an independent existence in nature, some cyanobacteria occur in symbiosis with a wide range of hosts (protists, animals and plants). Among plants, such symbioses have independently evolved in phylogenetically diverse genera belonging to the algae, fungi, bryophytes, pteridophytes, gymnosperms and angiosperms. These are N2-fixing symbioses involving heterocystous cyanobacteria, particularly Nostoc, as cyanobionts (cyanobacterial partners). A given host species associates with only a particular cyanobiont genus but such specificity does not extend to the strain level. The cyanobiont is located under a microaerobic environment in a variety of host organs and tissues (bladder, thalli and cephalodia in fungi; cavities in gametophytes of hornworts and liverworts or fronds of the Azolla sporophyte; coralloid roots in cycads; stem glands in Gunnera). Except for fungi, the hosts form these structures ahead of the cyanobiont infection. The symbiosis lasts for one generation except in Azolla and diatoms, in which it is perpetuated from generation to generation. Within each generation, multiple fresh infections occur as new symbiotic tissues and organs develop. The symbioses are stable over a wide range of environmental conditions, and sensing–signalling between partners ensures their synchronized growth and development. The cyanobiont population is kept constant in relation to the host biomass through controlled initiation and infection, nutrient supply and cell division. In most cases, the partners have remained facultative, with the cyanobiont residing extracellularly in the host. However, in the water-fern Azolla and the freshwater diatom Rhopalodia the association is obligate. The cyanobionts occur intracellularly in diatoms, the fungus Geosiphon and the angiosperm Gunner a. Close cell–cell contact and the development of special structures ensure efficient nutrient exchange between the partners. The mobile nutrients are normal products of the donor cells, although their production is increased in symbiosis. Establishment of cyanobacterial–plant symbioses differs from chloroplast evolution. In these symbioses, the cyanobiont undergoes structural–functional changes suited to its role as provider of fixed N rather than fixed C, and the level of intimacy is far less than that of an organelle. This review provides an updated account of cyanobacterial–plant symbioses, particularly concerning developments during the past 10 yr. Various aspects of these symbioses such as initiation and development, symbiont diversity, recognition and signalling, structural–functional modifications, integration, and nutrient exchange are reviewed and discussed, as are evolutionary aspects and the potential uses of cyanobacterial–plant symbioses. Finally we outline areas that require special attention for future research. Not only will these provide information of academic interest but they will also help to improve the use of Azolla as green manure, to enable us to establish artificial N2-fixing associations with cereals such as rice, and to allow the manipulation of free-living cyanobacteria for photobiological ammonia or hydrogen production or for use as biofertilizers.
Whole-body metabolism of glucose and lactate in productive sheep and cows
- G. D. Baird, J. G. Van Der Walt, E. N. Bergman
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- Journal:
- British Journal of Nutrition / Volume 50 / Issue 2 / September 1983
- Published online by Cambridge University Press:
- 09 March 2007, pp. 249-265
- Print publication:
- September 1983
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1. Constant infusions of D-[U-14C]glucose, D-[6−3H]glucose and L-[U-14C]lactate were used to determine rates of apparent turnover, de novo production, disposal and interconversions of glucose and lactate, together with total recycling of glucose-C, in ewes and dairy cows during late pregnancy and early lactation. The cows were also examined while being fasted. In the fed animals, infusions were made within 5 h after the morning meal when steady-state conditions appeared to exist.
2. In the ewes, circulating concentrations of glucose and lactate, and magnitudes of apparent turnovers of glucose and lactate, tended to be higher during lactation than during pregnancy, while the extent of interconversions of glucose and lactate tended to be lower.
3. Although the metabolic pattern seen in the cows appeared to be similar to that of the ewes during pregnancy, there were clear differences during lactation. Thus, in the lactating cows, as compared with the lactating ewes, circulating concentrations of glucose and lactate were lower, as was apparent lactate turnover related to metabolic body-weight. Furthermore, the percentage of lactate turnover converted to glucose was higher.
4. In the cows, fasting was characterized by low rates of apparent turnover of glucose and lactate and relatively high rates of interconversion of the two compounds.
5. The results indicated that, under the conditions used in this study and when feeding is to recommended levels, carbohydrate metabolism in ewes is more precarious during late pregnancy than during early lactation, while in dairy cows it is more or less equally precarious in both physiological states.
6. A further conclusion is that the extent of glucose–lactate interconversions, and thus Cori cycle activity, seems to be lower in ruminants than in other species.
Tissue glucose and lactate metabolism and interconversions in pregnant and lactating sheep
- J. G. van der Walt, G. D. Baird, E. N. Bergman
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- Journal:
- British Journal of Nutrition / Volume 50 / Issue 2 / September 1983
- Published online by Cambridge University Press:
- 09 March 2007, pp. 267-280
- Print publication:
- September 1983
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1. Continuous infusions of [14C]glucose and [14C]lactate on separate days, and measurements of blood flow-rate, were used to obtain values for rates of unidirectional metabolism and of interconversion of glucose and lactate in the portal-drained viscera, liver and hind-quarters of ewes during late pregnancy and early lactation. All infusions were made within 5 h after the morning meal, when steady-state conditions appeared to exist.
2. Use was made of ewes that had been appropriately catherized during pregnancy, and whose catheter remained patent through into lactation.
3. The liver was the main source of glucose production (67–70%) during both pregnancy and lactation. Other sources were the portal-drained viscera (absorbed glucose) and, presumably, the kidneys. Over 80% of the glucose was utilized by the peripheral tissues with approximately 35–40% of utilization being attributable to the hind-quarters.
4. Of the total lactate production, 76% occurred in the peripheral tissues during pregnancy but only 36% during lactation. While the liver utilized 73% of lactate during pregnancy, this value fell to only 42% during lactation, at which time the portal-drained viscera utilized 26% of the lactate.
5. During pregnancy, approximately 80% of the lactate arose from glucose, chiefly in peripheral tissues, while at least 12% of the glucose arose from lactate, chiefly in the liver. During lactation the extent of these interconversions was decreased.
6. Despite the interconversions, whole-body turnover rates for glucose and lactate were under- or overestimated by only 4–10% and 2–5% respectively. Furthermore, a comparison of turnover rates obtained with [U-14C]- and [6−3H]glucose indicated that there was only 6 and 2% recycling of glucose-C during pregnancy and lactation respectively.
7. Under the conditions employed in this study, lactate does not appear to be a major precursor of glucose in the ruminant, and most of the lactate taken up by the liver must be used for purposes other than gluconeogenesis, such as oxidation or alternative anabolic pathways.
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