Spatial Discrimination Research Articles

Novelty-like activation of locus coeruleus protects against deleterious human pretangle tau effects while stress-inducing activation worsens its effects.

The earliest abnormality associated with Alzheimer's disease (AD) is the presence of persistently phosphorylated pretangle tau in locus coeruleus (LC) neurons. LC neuron numbers and fiber density are positive predictors of cognition prior to death. Using an animal model of LC pretangle tau, we ask if LC activity patterns influence the sequelae of pretangle tau. We seeded LC neurons with a pretangle human tau gene. We provided daily novelty‐ or stress‐associated optogenetic activation patterns to LC neurons for 6 weeks in mid‐adulthood and, subsequently, probed cognitive and anatomical changes. Prior LC phasic stimulation prevented spatial and olfactory discrimination deficits and preserved LC axonal density. A stress‐associated activation pattern increased indices of anxiety and depression, did not improve cognition, and worsened LC neuronal health. These results argue that variations in environmental experiences associated with differing LC activity patterns may account for individual susceptibility to development of AD in humans.

Kainate Receptors Regulate the Functional Properties of Young Adult-Born Dentate Granule Cells

Both inhibitory and excitatory neurotransmitter receptors can influence maturation and survival of adult-born neurons in the dentate gyrus; yet how these two neurotransmitter systems affect integration of new neurons into the existing circuitry are still not fully characterized. Here we demonstrate that glutamate receptors of the kainate receptor (KAR) subfamily are expressed in adult-born dentate granule cells (abDGCs) and that through their interaction with GABAergic signaling mechanisms alter the functional maturation of adult-born cells during a critical period of their development. Both the intrinsic properties and synaptic connectivity of young abDGCs were affected. Timed KAR loss in a cohort of young adult-born neurons in mice disrupted their performance in a spatial discrimination task but not in a hippocampal-dependent fear conditioning task. Together these results demonstrate the importance of KARs in the proper functional development of young abDGCs.

Contribution of a method of assessing minimum audible angle in headphones

ObjectivesThe main objective of this study was to test the feasibility of measuring minimum audible angle in headphones with different reference positions in the horizontal plane, and comparing different types of pre-recorded head-related transfer functions. The secondary objective was to assess spatial discrimination performance in simulated unilateral hearing loss by measuring the minimum audible angle under monaural conditions using headphones. Materials and methodsMinimum audible angle was assessed in 27 normal-hearing subjects, to test their spatial discrimination abilities, using 4 datasets of pre-recorded head-related transfer functions: 2 recorded on mannequins (KU100, KEMAR), and 2 individualized head-related transfer function datasets (TBM, PBM). Performance was evaluated at 3 reference positions (0°, 50° and 180°) in 1 binaural and 2 monaural conditions. ResultsKU100 generated minimum audible angle values smaller than KEMAR in frontal and lateral position P<0.005), with a suggestive difference (P<0.05) compared to TBM and PBM in the frontal and lateral planes. Comparison between binaural and monaural conditions showed significant differences in frontal position for MON-c (contralateral) and MON-i (ipsilateral) (P<0.001), in lateral position for MON-c only (P<0.001) and in posterior position for MON-c and MON-i (P<0.001). ConclusionThis study suggests that evaluation of spatial discrimination capacity using minimum audible angle with the KU100 head-related transfer dataset was reliable and robust.

Enhancement of select cognitive domains with rosiglitazone implicates dorsal hippocampus circuitry sensitive to PPARγ agonism in an Alzheimer's mouse model

IntroductionSeveral clinical studies have tested the efficacy of insulin‐sensitizing drugs for cognitive enhancement in Alzheimer's disease (AD) patients, as type 2 diabetes (T2D) is a well‐recognized risk factor for AD. Pilot studies assessing FDA‐approved diabetes drugs in subjects with early‐stage disease have found cognitive benefit in subjects comorbid for insulin resistance. In AD mouse models with concomitant insulin resistance, we have shown that 4 weeks of RSG can reverse peripheral and central insulin resistance concomitant with rescue of hippocampus‐dependent fear learning and memory and hippocampal circuitry deficits in 9‐month‐old (9MO) Tg2576 mice with no effect in wild‐type (WT) mice. Bioinformatics analysis of genomic and proteomic data reveals an intimate link between PPARγ and MAPK/ERK signaling in the hippocampus. We then demonstrated a direct interaction between PPARγ and phospho‐ERK in vitro and in vivo during memory consolidation. The translational value of this discovery is evidenced by the positive correlational relationship between human AD postmortem brain levels of pERK‐PPARγ nuclear complexes with cognitive reserve.MethodsWe tested whether insulin sensitizer therapy could rescue spatial navigation, context discrimination, and object recognition learning and memory in aged wild‐type and Tg2576 mice in addition to hippocampus‐dependent contextual fear learning and memory, as we have previously reported.ResultsWe found that rosiglitazone treatment improved cognitive domains that predominantly rely upon the dorsal hippocampus rather than those that additionally engage the ventral hippocampus.ConclusionThese results suggest that insulin sensitizer therapy with rosiglitazone improved age‐ and AD‐related learning and memory deficits in circuit selective ways.

Intraspecific variation in inhibitory motor control in guppies, Poecilia reticulata.

Inhibitory control (IC) is the ability to overcome impulsive or prepotent but ineffective responses in favour of more appropriate behaviours. The ability to inhibit internal predispositions or external temptations is vital in coping with a complex and variable world. Traditionally viewed as cognitively demanding and a main component of executive functioning and self-control, IC was historically examined in only a few species of birds and mammals but recently a number of studies has shown that a much wider range of taxa rely on IC. Furthermore, there is growing evidence that inhibitory abilities may vary within species at the population and individual levels owing to genetic and environmental factors. Here we use a detour-reaching task, a standard paradigm to measure motor inhibition in nonhuman animals, to quantify patterns of interindividual variation in IC in wild-descendant female guppies, Poecilia reticulata. We found that female guppies displayed inhibitory performances that were, on average, half as successful as the performances reported previously for other strains of guppies tested in similar experimental conditions. Moreover, we showed consistent individual variation in the ability to inhibit inappropriate behaviours. Our results contribute to the understanding of the evolution of fish cognition and suggest that IC may show considerable variation among populations within a species. Such variation in IC abilities might contribute to individual differences in other cognitive functions such as spatial learning, quantity discrimination or reversal learning.

Pragmatic spatial sampling for wearable MEG arrays

Several new technologies have emerged promising new Magnetoencephalography (MEG) systems in which the sensors can be placed close to the scalp. One such technology, Optically Pumped MEG (OP-MEG) allows for a scalp mounted system that provides measurements within millimetres of the scalp surface. A question that arises in developing on-scalp systems is: how many sensors are necessary to achieve adequate performance/spatial discrimination? There are many factors to consider in answering this question such as the signal to noise ratio (SNR), the locations and depths of the sources, density of spatial sampling, sensor gain errors (due to interference, subject movement, cross-talk, etc.) and, of course, the desired spatial discrimination. In this paper, we provide simulations which show the impact these factors have on designing sensor arrays for wearable MEG. While OP-MEG has the potential to provide high information content at dense spatial samplings, we find that adequate spatial discrimination of sources (< 1 cm) can be achieved with relatively few sensors (< 100) at coarse spatial samplings (~ 30 mm) at high SNR. After this point approximately 50 more sensors are required for every 1 mm improvement in spatial discrimination. Comparable discrimination for traditional cryogenic systems require more channels by these same metrics. We also show that sensor gain errors have the greatest impact on discrimination between deep sources at high SNR. Finally, we also examine the limitation that aliasing due to undersampling has on the effective SNR of on-scalp sensors.

In vivo biomolecular imaging of zebrafish embryos using confocal Raman spectroscopy

Zebrafish embryos provide a unique opportunity to visualize complex biological processes, yet conventional imaging modalities are unable to access intricate biomolecular information without compromising the integrity of the embryos. Here, we report the use of confocal Raman spectroscopic imaging for the visualization and multivariate analysis of biomolecular information extracted from unlabeled zebrafish embryos. We outline broad applications of this method in: (i) visualizing the biomolecular distribution of whole embryos in three dimensions, (ii) resolving anatomical features at subcellular spatial resolution, (iii) biomolecular profiling and discrimination of wild type and ΔRD1 mutant Mycobacterium marinum strains in a zebrafish embryo model of tuberculosis and (iv) in vivo temporal monitoring of the wound response in living zebrafish embryos. Overall, this study demonstrates the application of confocal Raman spectroscopic imaging for the comparative bimolecular analysis of fully intact and living zebrafish embryos.

Audiovisual integration improves task performance in AD and bvFTD

AbstractBackgroundComplex analysis of sensory inputs, such as auditory scene analysis and spatial localisation, is impaired in Alzheimer’s disease (AD) and behavioural variant frontotemporal dementia (bvFTD). Multisensory integration research demonstrates that synchronous stimulation in one sense (e.g. vision) can modify processing of suboptimal sensory inputs from another sense (e.g. hearing) in the healthy brain. However, the potential benefit of multisensory stimulation to reduce common symptoms in dementia has not been fully examined.MethodPatients living with AD (n = 20) or bvFTD (n = 12), and healthy age‐matched controls (n = 18) were recruited to perform three brief cognitive tasks: 1. Cocktail party effect, identify a name spoken in a noisy environment; 2. Spatial ventriloquism, discriminate the location of an auditory stimulus (left/right of centre); and 3. Detect a suboptimal visual stimulus. Task performance was compared between unisensory, audiovisual congruent, and audiovisual incongruent conditions, and between groups.Result1. Identification of spoken names in a noisy auditory environment was significantly worse for both patient groups than controls. All groups performed significantly better when viewing an accompanying video of congruent lip movements. The AD group showed some improvement for incongruent videos that cued the onset of the spoken name. 2. Auditory spatial discrimination was significantly worse in the AD group than controls, but both groups were significantly biased by the locations of the accompanying visual stimulus. The bvFTD group was only influenced by spatially incongruent visual stimulation. 3. Detection of a near‐threshold peripheral visual stimulus was improved by a synchronous auditory stimulus, irrespective of spatial congruency, in the bvFTD and control groups. In the AD group, only spatially congruent or neutral auditory stimuli benefitted visual stimulus detection.ConclusionCongruent audiovisual stimulation improves the ability of people living with AD or bvFTD to understand voices in a noisy environment, locate auditory sounds, and detect unreliable visual events. Congruency of audiovisual stimulation in different domains (e.g. semantic, spatial) provides evidence for disease‐specific stratification of multisensory integration profiles. As such, multisensory integration provides a mechanism to improve reliability of sensory inputs and the potential to alleviate symptoms in daily life if tailored according to disease.

Western diet, obesity and bariatric surgery sequentially modulated anxiety, eating patterns and brain responses to sucrose in adult Yucatan minipigs

Palatable sweet/fatty foods overconsumption is a major risk factor for obesity and eating disorders, also having an impact on neuro-behavioural hedonic and cognitive components comparable to what is described for substance abuse. We hypothesized that Yucatan minipigs would show hedonic, cognitive, and affective neuro-behavioral shifts when subjected to western diet (WD) exposure without weight gain, after the onset of obesity, and finally after weight loss induced by caloric restriction with (RYGB) or without (Sham) gastric bypass. Eating behavior, cognitive and affective abilities were assessed with a spatial discrimination task (holeboard test) and two-choice feed tests. Brain responses to oral sucrose were mapped using 18F-FDG positron emission tomography. WD exposure impaired working memory and led to an “addiction-type” neuronal pattern involving hippocampal and cortical brain areas. Obesity induced anxiety-like behavior, loss of motivation, and snacking-type eating behavior. Weight loss interventions normalized the motivational and affective states but not eating behavior patterns. Brain glucose metabolism increased in gustatory (insula) and executive control (aPFC) areas after weight loss, but RYGB showed higher responses in inhibition-related areas (dorsal striatum). These results showed that diet quality, weight loss, and the type of weight loss intervention differently impacted brain responses to sucrose in the Yucatan minipig model.

Neuroprotection of the Developing Brain by Dexmedetomidine Is Mediated by Attenuating Single Propofol-induced Hippocampal Apoptosis and Synaptic Plasticity Deficits.

Dexmedetomidine (DEX) has neuroprotective effects and its efficacy was determined in propofol-treated pups. Postnatal day (P) 7 rats were exposed to propofol and DEX to investigate the induced apoptosis-related gene expression. Furthermore, synaptic structural changes at the cellular level were observed by electron microscopy. Induction of hippocampal long-term potentiation (LTP) of P30 rats and long-lasting performance of spatial discrimination at P30 and P60 were evaluated. After a single propofol exposure to P7 rats, DEX pretreatment effectively rescued the profound apoptosis seen in hippocampal neurocytes, and strongly reversed the aberrant expression levels of Bcl2-like 1 (BCL2L1), matrix metallopeptidase 9 (MMP-9) and cleaved caspase 3 (CC3), and sharply enhanced synaptic plasticity. However, there were no significant differences in escape latency or crossing times in a probe test. This was accompanied by no obvious reduction in search strategies among the rat groups. No impairment of long-term learning and memory in P30 or P60 rats was detected when using a single dose propofol treatment during the most vulnerable period of brain development. DEX was shown to ameliorate the rodent developmental neurotoxicity caused by a single neonatal propofol challenge, by altering MMP-9, BCL2L1 and CC3 apoptotic signaling.

Impact of canine epilepsy on judgement and attention biases

Idiopathic epilepsy (IE) is the most common chronic neurological condition in dogs, characterised by recurrent seizure activity and associated with negative behavioural and cognitive changes. We hypothesised that IE would negatively impact putative affective state, with dogs with IE exhibiting a more pessimistic judgement bias and more negative attention bias than controls. Dogs were tested in a previously-validated spatial judgement bias task, and a novel auditory attention bias task testing attention to sounds with different valence or salience (neutral, novel pre-habituated, threatening). Sixty-eight dogs (IE = 33, Control = 35) were tested, of which n = 37 acquired the spatial discrimination and responses to judgement bias probes were tested (IE = 19, Control = 18), and n = 36 were tested for responses to sounds (IE = 20, Control = 16). Study groups did not significantly differ by age, sex, breed or neuter-status (p > 0.05). Main effects of study group were not significant in judgement bias (F1,102 = 0.20, p = 0.658) or attention bias tasks (F3,102 = 1.64, p = 0.184). In contrast with our hypotheses, there was no evidence that IE altered cognitive biases in this study population; however, dogs with IE were significantly more likely to be unable to learn the spatial discrimination task (p = 0.019), which may reflect IE-related cognitive deficits. Developing methods to test affective state without excluding cognitively impaired individuals is a future challenge for animal welfare science.

Non-informative vision improves spatial tactile discrimination on the shoulder but does not influence detection sensitivity

Vision of the body has been reported to improve tactile acuity even when vision is not informative about the actual tactile stimulation. However, it is currently unclear whether this effect is limited to body parts such as hand, forearm or foot that can be normally viewed, or it also generalizes to body locations, such as the shoulder, that are rarely before our own eyes. In this study, subjects consecutively performed a detection threshold task and a numerosity judgment task of tactile stimuli on the shoulder. Meanwhile, they watched either a real-time video showing their shoulder or simply a fixation cross as control condition. We show that non-informative vision improves tactile numerosity judgment which might involve tactile acuity, but not tactile sensitivity. Furthermore, the improvement in tactile accuracy modulated by vision seems to be due to an enhanced ability in discriminating the number of adjacent active electrodes. These results are consistent with the view that bimodal visuotactile neurons sharp tactile receptive fields in an early somatosensory map, probably via top-down modulation of lateral inhibition.

Natural ITD statistics predict human auditory spatial perception.

A neural code adapted to the statistical structure of sensory cues may optimize perception. We investigated whether interaural time difference (ITD) statistics inherent in natural acoustic scenes are parameters determining spatial discriminability. The natural ITD rate of change across azimuth (ITDrc) and ITD variability over time (ITDv) were combined in a Fisher information statistic to assess the amount of azimuthal information conveyed by this sensory cue. We hypothesized that natural ITD statistics underlie the neural code for ITD and thus influence spatial perception. To test this hypothesis, sounds with invariant statistics were presented to measure human spatial discriminability and spatial novelty detection. Human auditory spatial perception showed correlation with natural ITD statistics, supporting our hypothesis. Further analysis showed that these results are consistent with classic models of ITD coding and can explain the ITD tuning distribution observed in the mammalian brainstem.

Trait affective differences influence behavioral flexibility in virtual spatial and non-spatial discrimination tasks

Affect and cognitive control processes are closely related, however, most studies have assessed state affect or affective disorders. The current study investigates the relationship between individual differences in trait affectivity and flexibility in spatial navigation and stimulus discrimination tasks. Beck Depression Inventory-II (BDI-II), Beck Anxiety Inventory (BAI), and the Positive and Negative Affectivity Scale (PANAS) were given to 82 participants followed by an intradimensional/extradimensional (ID/ED) set-shifting task in which navigation was reinforced based on visual stimuli colocalized with a goal or based on the spatial location of the goal. Higher BDI and NA predicted greater trials-to-criteria during ED shift, but not initial learning or ID shifting. Participants who failed to meet criteria during either ID or ED set-shifting (N = 16) had significantly higher scores for NA, BDI, and BAI compared to individuals who successfully met criterion (N = 56) with this relationship being primarily observed in males. The current findings indicate that negative affectivity is associated with poor performance in behavioral flexibility.

The identification of the primal wine production with the protected designation of origin with the appliance of cluster metrics

The article considers the guidelines of the choice of identification criteria, allowing to verify and confirm the geographical name of the origin of domestic primal wine production, thereby confirming their legal status. A priori the production of wine with protected designation of origin includes the use of certain raw materials with predetermined organoleptic and physical-chemical characteristics, which can be confirmed by respective tests. The aim of the work was to develop a robust differentiating criterion that allows one to determine the authenticity and origin of wine materials relative to the standard. Material and methods. The authors presented a clustering technique, which allows on the basis of test results and developed digital identification criteria to verify the origin of wine materials from Krasnodar and Rostov-on-Don regions. As a criterion, the data from the analysis of mineral and trace element composition of primal wine production in these regions have been used. Results. The article postulates following: the main concern of clustering, methods of identification from the perspective of food production using food regression model, information on fundamental clustering metrics, fields of appliance according to the approach of the identification of the product with indication of geographic place of origin. Based on the results of the analysis of the content of 21 mineral substances (10 in μg/l and 11 in mg/l), a regressive model of the primal wine production was built. Based on this model, cluster centers were identified. The resultant model allows us to distinguish the two mentioned wine regions and form a spatial digital discrimination criterion based on the proximity to one of the established cluster centers. Conclusion. The proposed model can be adapted to identify the production of different branches of the food industry.

Genetic Alzheimer’s Disease Risk Affects the Neural Mechanisms of Pattern Separation in Hippocampal Subfields

The hippocampal subfields perform distinct operations during acquisition, differentiation, and recollection of episodic memories, and deficits in pattern separation are among the first symptoms of Alzheimer's disease (AD). We investigated how hippocampal subfields contribute to pattern separation and how this is affected by Apolipoprotein-E (APOE), the strongest AD genetic risk factor. Using ultra-high-field (7T) functional magnetic resonance imaging (fMRI), APOE-ε3-ε3 carriers predominantly recruited cornu ammonis 3 (CA3) during a spatial mnemonic discrimination task, whereas APOE-ε3-ε4 and APOE-ε3-ε2 carriers engaged CA3 and dentate gyrus (DG) to the same degree. Specifically, APOE-ε3-ε4 carriers showed reduced pattern separation in CA3, whereas APOE-ε3-ε2 carriers exhibited increased effects in DG and pattern separation-related functional connectivity between DG and CA3. Collectively, these results demonstrate that AD genetic risk alters hemodynamic responses in young pre-symptomatic individuals, paving the way for development of biomarkers for preclinical AD.

Deep spatio-frequency saliency detection

Despite the wide success in many vision tasks, it is still challenging for Convolutional Neural Networks (CNNs) to perform saliency detection due to their limited receptive fields and lack of enough discriminative contexts until very late layers. In this paper, beyond spatial convolution, we propose a Spatio-Frequency Network (SFNet) that exploits spatio-frequency clues to effectively enlarge the receptive fields of CNN layers and more importantly, strengthen their spatial discrimination for better saliency detection. In particular, the proposed SFNet contains a carefully designed Frequency Residual Module (FRM) that captures the holistic representation of the whole image within the frequency domain. The FRM leverages discrete and inverse discrete wavelet transformation to alternatively transfer global spatial features into frequency domains, to assist fast and accurate salient object detection. Besides, SFNet also includes an Aggregation of Frequency and Spatial Feature (AFSF) module to jointly integrate the two domain features guided by saliency results in a top-down manner. In this way, the aggregation features per layer contain rich holistic contexts, and the network can eventually explore more complete salient object parts and details by progressively integrating saliency predictions. Extensive experiments on six widely-used saliency detection datasets clearly demonstrate the advantages of our proposed model compared with state-of-the-arts.

Linked Sources of Neural Noise Contribute to Age-related Cognitive Decline.

Healthy aging is associated with a multitude of structural changes in the brain. These physical age-related changes are accompanied by increased variability in neural activity of all kinds, and this increased variability, collectively referred to as "neural noise," is argued to contribute to age-related cognitive decline. In this study, we examine the relationship between two particular types of neural noise in aging. We recorded scalp EEG from younger (20-30 years old) and older (60-70 years old) adults performing a spatial visual discrimination task. First, we used the 1/f-like exponent of the EEG power spectrum, a putative marker of neural noise, to assess baseline shifts toward a noisier state in aging. Next, we examined age-related decreases in the trial-by-trial consistency of visual stimulus processing. Finally, we examined to what extent these two age-related noise markers are related, hypothesizing that greater baseline noise would increase the variability of stimulus-evoked responses. We found that visual cortical baseline noise was higher in older adults, and the consistency of older adults' oscillatory alpha (8-12 Hz) phase responses to visual targets was also lower than that of younger adults. Crucially, older adults with the highest levels of baseline noise also had the least consistent alpha phase responses, whereas younger adults with more consistent phase responses achieved better behavioral performance. These results establish a link between tonic neural noise and stimulus-associated neural variability in aging. Moreover, they suggest that tonic age-related increases in baseline noise might diminish sensory processing and, as a result, subsequent cognitive performance.

Understanding interlaminar toughening of unidirectional CFRP laminates with carbon nanotube veils

The introduction of nanostructured interlayers is one of the most promising strategies for interlaminar reinforcement in structural composites. In this work, we study the failure mechanism and interlayer microstructure of aerospace-grade structural composites reinforced with thin veils of carbon nanotube produced using an industrialised spinning process. Samples of unidirectional carbon fiber/epoxy matrix composites interleaved with different composition CNT veils were prepared using hot press method and tested for interlaminar fracture toughness (IFT), measured in Mode-I (opening) and Mode-II (in-plane shear), and for interlaminar shear strength (ILSS), evaluated by the short beam shear (SBS) test. The crack propagation mode could be directly determined through fractography analysis by electron microscopy and resin/CNT spatial discrimination by Raman spectroscopy, showing a clear correlation between interlaminar reinforcement and the balance between cohesive/adhesive failure mode at the interlayer region. Composites with full resin infiltration of the CNT veils give a large increase of Mode II IFT (88%) to 1500 J/m2 and a slight enhancement of apparent interlaminar shear strength (6.5%), but a decrease of Mode I IFT (−21%). A toughening factor, defined as the relative increase in toughness per interleaf-to-ply thickness ratio, give a record-high value of 15.8 for Mode II IFT. The results help establish the role of interlayer infiltration, interlaminar crossings and formation of a carbon fiber bridgings, for interlaminar reinforcement with interleaves.

Use of cognitive bias as a welfare tool in poultry.

In human psychology, the link between cognition and emotions is broadly accepted. However, the idea of using the interaction between cognition and emotions as a tool for a better understanding of animal emotions or for welfare assessment is relatively new. The first avian species used in cognitive bias tests was the European starling followed by the domestic chicken and other species. The most frequently used paradigm is the affect-induced judgment bias. There are many variations of the judgment bias tests in birds. The test itself is preceded by discrimination training. Discrimination tasks vary from visual cue discrimination, discrimination of time intervals to spatial location discrimination. During the discrimination training, birds flip or do not flip the lids of the food dishes, and their latency to approach the cues in a straight alley maze, in a two-choice arena, or different locations in spatial judgment task arena are measured. Alternately, the birds fulfill operant tasks in a Skinner box. Before or after the discrimination training phase, birds are subjected to manipulations that are hypothesized to induce positive or negative emotional states. In the last stage, birds are subjected to judgment bias tests. The assumption is that animals in a negative affective state would more likely respond to ambiguous cues, as if they predict the negative event, than animals in a more positive state. However, the results of some avian studies are inconsistent, particularly those studying the effect of environmental enrichment. In starlings, each of the three studies has supplied conflicting results. In poultry, none of the four studies demonstrated a positive effect of environmental enrichment on emotional states. Only the study using unpredictable stressors in combination with environmental complexity showed that animals kept in a more complex environment are more optimistic. Manipulation of the social environment seems to be more effective in judgment bias induction. Conflicting results could be attributable to the design of the tests, the manner of affect induction, or the data analysis. Further optimization and validation of avian cognitive bias tests could help to avoid problems such as the loss of ambiguity. New methods of attention and memory bias testing are promising. However, regardless of the abovementioned complications, a cognitive bias paradigm is a valuable tool, which can help us better understand avian emotions and assess poultry welfare.