Learning enhances representations of taste-guided decisions in the mouse gustatory insular cortex.

Learning to discriminate overlapping gustatory stimuli that predict distinct outcomes-a feat known as discrimination learning-can mean the difference between ingesting a poison or a nutritive meal. Despite the obvious importance of this process, very little is known about the neural basis of taste discrimination learning. In other sensory modalities, this form of learning can be mediated by either the sharpening of sensory representations or the enhanced ability of "decision-making" circuits to interpret sensory information. Given the dual role of the gustatory insular cortex (GC) in encoding both sensory and decision-related variables, this region represents an ideal site for investigating how neural activity changes as animals learn a novel taste discrimination. Here, we present results from experiments relying on two-photon calcium imaging of GC neural activity in mice performing a taste-guided mixture discrimination task. The task allows for the recording of neural activity before and after learning induced by training mice to discriminate increasingly similar pairs of taste mixtures. Single-neuron and population analyses show a time-varying pattern of activity, with early sensory responses emerging after taste delivery and binary, choice-encoding responses emerging later in the delay before a decision is made. Our results demonstrate that, while both sensory and decision-related information is encoded by GC in the context of a taste mixture discrimination task, learning and improved performance are associated with a specific enhancement of decision-related responses.

The Chronic Effects of a Single Low-Intensity Blast Exposure on Phosphoproteome Networks and Cognitive Function Influenced by Mutant Tau Overexpression.

Blast-induced neurotrauma (BINT) is a pressing concern for veterans and civilians exposed to explosive devices. Affected personnel may have increased risk for long-term cognitive decline and developing tauopathies including Alzheimer's disease-related disorders (ADRD) or frontal-temporal dementia (FTD). The goal of this study was to identify the effect of BINT on molecular networks and their modulation by mutant tau in transgenic (Tg) mice overexpressing the human tau P301L mutation (rTg4510) linked to FTD or non-carriers. The primary focus was on the phosphoproteome because of the prominent role of hyperphosphorylation in neurological disorders. Discrimination learning was assessed following injury in the subsequent 6 weeks, using the automated home-cage monitoring CognitionWall platform. At 40 days post injury, label-free phosphoproteomics was used to evaluate molecular networks in the frontal cortex of mice. Utilizing a weighted peptide co-expression network analysis (WpCNA) approach, we identified phosphopeptide networks tied to associative learning and mossy-fiber pathways and those which predicted learning outcomes. Phosphorylation levels in these networks were inversely related to learning and linked to synaptic dysfunction, cognitive decline, and dementia including Atp6v1a and Itsn1. Low-intensity blast (LIB) selectively increased pSer262tau in rTg4510, a site implicated in initiating tauopathy. Additionally, individual and group level analyses identified the Arhgap33 phosphopeptide as an indicator of BINT-induced cognitive impairment predominantly in rTg4510 mice. This study unveils novel interactions between ADRD genetic susceptibility, BINT, and cognitive decline, thus identifying dysregulated pathways as targets in potential precision-medicine focused therapeutics to alleviate the disease burden among those affected by BINT.

No evidence of real-world equivalence in chickens (Gallus gallus domesticus) categorizing visually diverse images of natural stimuli presented on LCD monitors.

Category learning is often tested with similar images that have no significance outside of the experiment for the subjects. By contrast, in nature animals often need to generalize a behavioral response like "eat" across visually distinct stimuli, such as spiders and seeds. Forming functional categories like "food" and "predator" may require conceptual rather than purely perceptual generalization. We trained free-range chickens to classify images assigned to one of four categories based on putative functional significance: inanimate objects, predators, food, and non-competing vertebrates. Images were visually diverse within each category, discouraging classification by perceptual similarity alone. In Experiment 1, chickens classified 80 images into four categories. Chickens then generalized to 80 new exemplars in each of three successive generalization tests. In Experiment 2, chickens saw new types of images to test whether their generalization was perceptual or functional. For example, chickens saw images of skunks for the predator category after training with images of hawks and snakes. Chickens used the "predator" response with these new images for both predators and non-threatening vertebrates, but not for objects or food, and did not successfully generalize any category other than predator. In Experiment 3, chickens categorized fractals as "food," and three of four chickens categorized a range of vertebrates they had not previously encountered as "predators," suggesting that chickens did not see the images as representing real world objects and animals. These results highlight constraints on the use of computer-generated images to assess categorization of natural stimuli in chickens.

Hippocampal damage causes retrograde amnesia for objects' visual, but not odour, properties in male rats.

Damage to the hippocampus produces profound retrograde amnesia, but odour and object discrimination memories can be spared in the retrograde direction. Prior lesion studies testing retrograde amnesia for object/odour discriminations are problematic due to sparing of large parts of the hippocampus, which may support memory recall, and/or the presence of uncontrolled, distinctive odours that may support object discrimination. To address these issues, we used a simple object discrimination test to assess memory in male rats. Two visually distinct objects, paired with distinct odour cues, were presented. One object was associated with a reward. Following training, neurotoxic hippocampal lesions were made using N-methyl-D-aspartate (NMDA). The rats were then tested on the preoperatively learned object discrimination problem, with and without the availability of odour or visual cues during testing. The rats were also postoperatively trained on a new object discrimination problem. Lesion sizes ranged from 67% to 97% of the hippocampus (average of 87%). On the preoperatively learned discrimination problem, the rats with hippocampal lesions showed preserved object discrimination memory when tested in the dark (i.e., without visual cues) but not when the explicit odour cues were removed from the objects. Hippocampal lesions increased the number of trials required to reach criterion but did not prevent rats from solving the postoperatively learned discrimination problem. Our results support the idea that long-term memories for odours, unlike recall of visual properties of objects, do not depend on the hippocampus in rats, consistent with previous observations that hippocampal damage does not cause retrograde amnesia for odour memories.

Relationship between hippocampal gene expression and cognitive performance differences in visual discrimination learning task of male rats.

Learning to discriminate between environmental visual stimuli is essential to make right decisions and guide appropriate behaviors. Moreover, impairments in visual discrimination learning are observed in several neuropsychiatric disorders. Visual discrimination learning requires perception and memory processing, in which the hippocampus critically involved. To understand the molecular mechanisms underpinning hippocampus function in visual discrimination learning, we examined the hippocampal gene expression profiles of Sprague-Dawley rats with different cognitive performance (high cognition group vs. low cognition group) in the modified visual discrimination learning task, using high-throughput RNA sequencing technology. Compared with the low cognition group, bioinformatics analysis indicated that 319 genes were differentially expressed in the high cognition group with statistical significance, of which 253 genes were down-regulated and 66 genes were up-regulated. The functional enrichment analysis showed that protein translation and energy metabolism were up-regulated pathways, while transforming growth factor beta receptor signaling pathway, bone morphogenetic protein signaling pathway, apoptosis, inflammation response, transport, and glycosaminoglycan metabolism were down-regulated pathways, which were related to good cognitive performance in the visual discrimination learning task. Taken together, our finding reveals the differential gene expression and enrichment biological pathways related to cognitive performance differences in visual discrimination learning of rats, which provides us direct insight into the molecular mechanisms of hippocampus function in visual discrimination learning and may contribute to developing potential treatment strategies for neuropsychiatric disorders accompanied with cognitive impairments.

El odontograma como articulador de afectos: una aproximación etnográfica más allá de la representación / Dental Chart as an Articulator of Affects: An Ethnographic Approach beyond Representation / O odontograma como articulador de afetos: uma abordagem etnográfica para além da representação

Este artículo ofrece una exploración empírica y conceptual del odontograma, un dispositivo usado cotidianamente en la práctica odontológica para evaluar el estado dental. Se tomaron como base los aportes del "giro ontológico" y algunas de las propuestas más recientes de las teorías del afecto para reflexionar más allá de las concepciones epistemológicas de la representación. El propósito es comprender las relaciones materiales, corporales y afectivas puestas en acción en la formación odontológica en relación con el odontograma. Se tomó como caso de estudio un programa de educación odontológica ubicado en una ciudad intermedia de Colombia, particularmente lo ocurrido en prácticas clínicas y en reuniones de profesores. Para el análisis, se partió de la noción de momento etnográfico propuesta por Marilyn Strathern. Se encontraron diversas situaciones que muestran la capacidad del odontograma para articular afectos, como discutir convenciones, diligenciar con lápiz los formatos de la historia clínica, mover la silla de la unidad odontológica para ver los dientes, secar con la jeringa triple, explicar diferencias sutiles entre anatomía y patología, y evaluar los odontogramas hechos por los estudiantes. Se concluye que la relación entre la boca del paciente y el odontograma es compleja y de mutuo exceso, lo cual posibilita una experiencia más rica de los dientes

This paper offers an empirical and conceptual exploration of the dental chart, a tool used to assess dental status. It is built on the "ontological turn" and recent affect theories to reflect beyond the epistemological concept of representation. This paper aims to understand the material, embodied, and affective relationships implemented in dental training regarding the dental chart. A dental education program in an intermediate city in Colombia was taken as a case study, mainly what happened in clinical practices and faculty meetings. It adopted the notion of "ethnographic moment" proposed by Marilyn Strathern for the analysis. Diverse situations were observed, which demonstrated the capacity of the dental chart to articulate affects, such as discussing conventions, filling out clinical records using a pencil, moving the chair of the dental unit to see the teeth, drying with the triple syringe, explaining subtle differences between anatomy and pathology, and evaluating the dental charts carried out by the students. It was inferred that the relationship between the patient's mouth and the dental chart is complex and mutually excessive, enabling a richer experience of the teeth.

Este artigo oferece uma exploração empírica e conceitual do odontograma, um dispositivo usado diaria- mente na prática odontológica para avaliar o estado dentário. As contribuições da "virada ontológica" e algumas das propostas mais recentes das teorias do afeto foram tomadas como base para refletir para além das concepções epistemológicas da representação. O objetivo do texto é compreender as relações materiais, corporais e afetivas postas em ação na formação odontológica em relação ao odontograma. Um programa de educação odontológica localizado em uma cidade intermediária na Colômbia foi tomado como um estudo de caso, particularmente o que aconteceu nas práticas clínicas e nas reuniões de professores. Para a análise, partimos da noção de "momento etnográfico" proposta por Marilyn Strathern. Foram encontradas várias situações que mostram a capacidade do odontograma de articular afetos, como discutir convenções, preencher formatos de história clínica com lápis, mover a cadeira da unidade odontológica para ver os dentes, secar com a seringa tríplice, explicar diferenças sutis entre anatomia e patologia e avaliar os odontogramas feitos pelos alunos. Conclui-se que a relação entre a boca do paciente e o odontograma é complexa e de excesso mútuo, o que possibilita uma experiência mais rica dos dentes.

Efeitos do ensino remoto de emparelhamento auditivo-visual com letras na nomeação de letras em crianças com Síndrome de Down e Autismo / Effects of remote teaching of auditory-visual matching with letters on letter naming in children with Down Syndrome and Autism / Efectos de enseñar a distancia del emparejamiento auditivo-visual com letras para nombrar las letras em niños con Síndrome de Down y Autismo

Este artigo realizou uma replicação sistemática do estudo de Hayashi et al. (2013) e teve como objetivo ava-liar a emergência de nomeação de letras a partir do ensino de emparelhamento auditivo-visual, no contexto do ensino remoto, diante da pandemia de Covid-19. Participaram da pesquisa quatro alunos, de ambos os gêneros, com idades entre 5 e 10 anos, três deles com síndrome de Down e uma participante com Transtorno do Espectro Autista. A coleta de dados realizou-se por meio da plataforma Zoom, individualmente, e utilizou um software específico para programação e registro das respostas. O ensino constituiu na seleção da letra maiúscula impressa, apresentada na tela do computador simultaneamente com as demais letras impressas do conjunto, diante do nome da letra ditado. Na avaliação, a criança deveria nomear a letra. Foi empregado um delineamento de múltiplas sondagens entre conjuntos de letras. Os resultados mostraram que os quatros participantes apresentaram aumento da nomeação correta das letras após as sessões de ensino para a maio-ria dos conjuntos. Os dados indicaram que o procedimento de ensino pode ser uma alternativa viável para estabelecer o reconhecimento e nomeação de letras com pessoas público-alvo da educação especial, suple-mentando o ensino da escola regular e podendo ser conduzido por professores e familiares

This study aimed to replicate the study of Hayashi et al. (2013) and to assess the emergence of letter naming from the teaching of auditory-visual pairing, in the context of remote teaching, in view of the Covid-19 pandemic. Four students, of both genders, aged five to ten years, three of them with Down syndrome and one participant with Autistic Spectrum Disorder participated in the research. Data collection was performed using the Zoom platform, individually. Teaching consisted of the selection of the printed capital letter, presented on the computer screen simultaneously the printed letters of the set, and the letter name dictated. In the evaluation, the child named the letter. A design of multiple probes between sets of letters was used. The results showed that all four participants showed an increase in correct letter naming after the teaching sessions for most letter sets. The data indicated that the teaching procedure can be a viable alternative to establish the recognition and naming of letters with people who are the target audience of Special Education, supplementing regular school teaching and can be conducted by teachers and family members

Esta investigación tuvo como objetivo replicar el estudio de Hayashi et al. (2013) y evaluar el surgimiento de la denominación de letras desde la enseñanza del binomio auditivo-visual, en el contexto de la enseñanza remota, frente a la pandemia del Covid-19. Participaron en la investigación cuatro estudiantes, de ambos sexos, con edades entre 5 y 10 años, tres de ellos con síndrome de Down y uno con Trastorno del Espectro Autista. La colecta de datos se realizó a través de la plataforma Zoom, de forma individual. El proceso de enseñanza consistió en la selección de la letra mayúscula impresa presentada en la pantalla de la compu-tadora simultáneamente a las letras impresas del conjunto frente al nombre de la letra dictada. En la eva-luación, el niño nombró la letra. Se utilizó un diseño de sonorización múltiple entre conjuntos de letras. Los resultados mostraron que los cuatro participantes tuvieron un aumento en la denominación correcta de las letras después de las sesiones de enseñanza para la mayoría de los conjuntos de letras. Los datos indicaron que el procedimiento de enseñanza puede ser una alternativa viable para las personas que requieren de educación especial al establecer el reconocimiento y el nombramiento de las letras, este método puede ser un suplemento de la escolarización y puede llevarse a cabo por profesores y familiares.

Mushroom body output neurons MBON-a1/a2 define an odor intensity channel that regulates behavioral odor discrimination learning in larval Drosophila.

The sensitivity of animals to sensory input must be regulated to ensure that signals are detected and also discriminable. However, how circuits regulate the dynamic range of sensitivity to sensory stimuli is not well understood. A given odor is represented in the insect mushroom bodies (MBs) by sparse combinatorial coding by Kenyon cells (KCs), forming an odor quality representation. To address how intensity of sensory stimuli is processed at the level of the MB input region, the calyx, we characterized a set of novel mushroom body output neurons that respond preferentially to high odor concentrations. We show that a pair of MB calyx output neurons, MBON-a1/2, are postsynaptic in the MB calyx, where they receive extensive synaptic inputs from KC dendrites, the inhibitory feedback neuron APL, and octopaminergic sVUM1 neurons, but relatively few inputs from projection neurons. This pattern is broadly consistent in the third-instar larva as well as in the first instar connectome. MBON-a1/a2 presynaptic terminals innervate a region immediately surrounding the MB medial lobe output region in the ipsilateral and contralateral brain hemispheres. By monitoring calcium activity using jRCamP1b, we find that MBON-a1/a2 responses are odor-concentration dependent, responding only to ethyl acetate (EA) concentrations higher than a 200-fold dilution, in contrast to MB neurons which are more concentration-invariant and respond to EA dilutions as low as 10-4. Optogenetic activation of the calyx-innervating sVUM1 modulatory neurons originating in the SEZ (Subesophageal zone), did not show a detectable effect on MBON-a1/a2 odor responses. Optogenetic activation of MBON-a1/a2 using CsChrimson impaired odor discrimination learning compared to controls. We propose that MBON-a1/a2 form an output channel of the calyx, summing convergent sensory and modulatory input, firing preferentially to high odor concentration, and might affect the activity of downstream MB targets.

Searching for nothing: placing zero on the temporal continuum.

Generalization allows responses acquired in one situation to be transferred to similar situations. For temporal stimuli, a discontinuity has been found between zero and non-zero durations: responses in trials with no (or 0-s) stimuli and in trials with very short stimuli differ more than what would be expected by generalization. This discontinuity may happen because 0-s durations do not belong to the same continuum as non-zero durations. Alternatively, the discontinuity may be due to generalization decrement effects: a 0-s stimulus differs from a short stimulus not only in duration, but also in its presence, thus leading to greater differences in performance. Aiming to reduce differences between trials with and without a stimulus, we used two procedures to test whether a potential reduction in generalization decrement would bring performance following zero and non-zero durations closer. In both procedures, there was a reduction in the discontinuity between 0-s and short durations, supporting the hypothesis that 0-s durations are integrated in the temporal subjective continuum.

The Popcorn Illusion.

A popcorn popping is almost magical. And yet, the science of popcorn is safe and clear about the steps until the pop: the components, processes, and results of making popcorn. Nature has its own way to produce surprise in the form of "pops" (i.e., emergence, qualitative shifts). Emergent features spread throughout the life of taxa and individuals. A pop can be sudden and chaotic. And so is creativity. There is no incompatibility between creativity and naturalistic endeavors in science. Creativity is no god given gift blown inside humans. When creativity is defined by originality and spontaneity, it describes a feature with no past or present. I briefly summarize how one can see non-random innovation, no free occurring spontaneity, and non-heuristic effectiveness as features of behaviors that are not necessarily considered creative. Those three features reveal how traditional views of creativity undermine its real determiners and how it can be objectively defined and observed.

Study of the use in autonomy of intraoral scanning systems to optimise dental students' performances in fixed prosthodontics practical learning in second year.

AIM: The purpose of this study was to evaluate if the use of intraoral scanner analysis could help students to optimise their performance and their self-assessment abilities in prosthetic preparation without the teacher's assistance in the preclinical course. MATERIALS AND METHODS: Ninety-five second-year dental students were randomly divided into three groups: Control group (C), CeRec group (CR) and PrepCheck group (PC). Group C only use silicon keys to control the preparation thickness. The students in Group CR analysed their work with Cerec™ software. The Group PC use a pedagogic software (PrepCheck™) which allowed comparison with the "master" preparation. They used control tools preparations for three consecutive training sessions. Then a final assessment session without control tool to evaluate their performance was organised. All preparations were objectively evaluated thanks to stl. analysis software (Geomagic® Control X). Each preparation was compared with the master preparation by defining tolerance ranges. An objective overall score out of 20 was assigned to each preparation according to their degree of correspondence. In addition, a questionnaire was performed to analyse the students' perceptions regarding the use of intraoral camera. RESULTS: During the assessment session, no significant difference was revealed between the different groups with respect to the students' performance. The comparative analysis between the self-assessment scores and the objective scores using Geomagic® software showed that digital control tools did not help the student to improve their self-assessment abilities without the teacher's assistance. CONCLUSIONS: The intraoral cameras and specific pedagogic software in autonomy could not improve students' performance for teeth preparation and self-assessment abilities in second year. These digital tools facilitate objective feedback on preparation defects, but constructive criticism needs human reflection. The teacher's opinions and advice remain essential to develop their students' performance and self-assessment skills. The use of digital tools must be integrated in dentistry course to develop the interpret of the results and optimise feedback.

Stepwise learning of compound multidimensional visual stimuli by sorting out the dimensions of which they are composed in pigeons.

Pigeons (Columba livia) were trained on a stage-wise go/no-go visual discrimination task. Sixteen compound stimuli were created from all the possible combinations of two stimulus values from four separable visual dimensions: shape (circle/square), size (large/small), line orientation (horizontal/vertical), and brightness (dark/light). Starting with 1 S + and 1 S - that differed in all four-dimensional values, in our later steps, we added S - stimuli one by one, sharing at first 1, then 2, and then 3 dimensions with S + by sorting them out. When the pigeons had clearly shown attending to each of four dimensions, we presented all 16 stimuli. In this last stage, the pigeons correctly rejected most of the S - stimuli despite seeing them for the first time. Thus, to discriminate 16 unique multidimensional stimuli, it was not necessary to learn all of them as compound stimuli in such an approach. However, the 4 learnt dimensions did not give fully comprehensive information about all the new and unique compound stimuli presented in the last stage. Mistakes were associated with similarity to S + and with the order of dimensional learning. Most pigeons made mistakes in the discrimination of S - stimuli that shared 3 (some shared two) dimensions with S + . The knowledge of the first-learned dimension of compound stimuli was less reliable than the dimensions learned in the last stage.

Capuchin monkeys learn to use information equally well from individual exploration and social demonstration.

The limited evidence of complex culture in non-human primates contrasts strikingly with human behaviour. This may be because non-human primates fail to use information acquired socially as effectively as they use information acquired individually. Here, monkeys were trained on a stimulus discrimination task with a win-stay, lose-shift (WSLS) reward structure. In a social learning condition, the experimenter performed an information trial by choosing between the available stimuli; in an individual condition, monkeys made this choice themselves. The monkeys' subsequent test trials displayed the same stimulus array. They were rewarded for repetition of rewarded ('win-stay') and avoidance of unrewarded ('lose-shift') information trial selections. Nine monkeys reached our pre-determined performance criterion on the initial two-stimulus stage. Their ability to generalise the WSLS strategy was then evaluated by transfer to a three-stimulus stage. Minimal differences were found in information use between the social and individual conditions on two-stimuli. However, a bias was found towards repetition of the information trial, regardless of information source condition or whether the information trial selection was rewarded. Proficient subjects were found to generalise the strategy to three-stimuli following rewarded information trials, but performed at chance on unrewarded. Again, this was not found to vary by source condition. Overall, results suggest no fundamental barrier to non-human primates' use of information from a social source. However, the apparent struggle to learn from the absence of rewards hints at a difficulty with using information acquired from unsuccessful attempts; this could be linked to the limited evidence for cumulative culture in non-human primates.

Personality traits affect learning performance in dwarf goats (Capra hircus).

A wide range of species exhibit time- and context-consistent interindividual variation in a number of specific behaviors related to an individual's personality. Several studies have shown that individual differences in personality-associated behavioral traits have an impact on cognitive abilities. The aim of this study was to investigate the relationship between personality traits and learning abilities in dwarf goats. The behavior of 95 goats during a repeated open field (OF) and novel object test (NO) was analyzed, and two main components were identified using principal component analysis: boldness and activity. In parallel, the goats learned a 4-choice visual initial discrimination task (ID) and three subsequent reversal learning (RL) tasks. The number of animals that reached the learning criterion and the number of trials needed (TTC) in each task were calculated. Our results show that goats with the lowest learning performance in ID needed more TTC in RL1 and reached the learning criterion less frequently in RL2 and RL3 compared to animals with better learning performance in ID. This suggests a close relationship between initial learning and flexibility in learning behavior. To study the link between personality and learning, we conducted two analyses, one using only data from the first OF- and NO-test (momentary personality traits), while the other included both tests integrating only animals that were stable for their specific trait (stable personality traits). No relationship between personality and learning was found using data from only the first OF- and NO-test. However, stability in the trait boldness was found to have an effect on learning. Unbold goats outperformed bold goats in RL1. This finding supports the general hypothesis that bold animals tend to develop routines and show less flexibility in the context of learning than unbold individuals. Understanding how individual personality traits can affect cognitive abilities will help us gain insight into mechanisms that can constrain cognitive processing and adaptive behavioral responses.

Number-of-responses matching in pigeons (Columba livia): Choice biases following delay and no-sample tests.

In a symbolic matching-to-sample task, pigeons learned to discriminate between 5 and 15 key pecks (samples): different choices were correct following the smaller and the larger response requirements. Subsequently, accuracy was tested in delayed matching, with the delay spent in darkness, contrarily to previous studies, that used illuminated delays. On average, delayed choices reflected indifference between the choices, but individual analyses showed different biases, replicating previous findings. It has been suggested that the end result of a delay may be similar to presenting no sample to begin with, so we compared preferences following a delay and following trials where no pecks were required. Performance in the two situations differed and, on zero-peck trials, a bias towards the "small" choice was found. Finally, to assess if the "small" bias was due to stimulus generalization, we compared zero-peck trials and trials with small response requirements (ranging from one to four) and found a discontinuity between zero and non-zero samples that may seem to be at odds with a generalization account.

Cognitive flexibility in the wild: Individual differences in reversal learning are explained primarily by proactive interference, not by sampling strategies, in two passerine bird species.

Behavioural flexibility allows animals to adjust to changes in their environment. Although the cognitive processes that explain flexibility have been relatively well studied in psychology, this is less true for animals in the wild. Here we use data collected automatically during self-administered discrimination-learning trials for two passerine species, and during four phases (habituation, initial learning, first reversal and second reversal) in order to decompose sources of consistent among-individual differences in reversal learning, a commonly used measure for cognitive flexibility. First, we found that, as expected, proactive interference was significantly repeatable and had a negative effect on reversal learning, confirming that individuals with poor ability to inhibit returning to a previously rewarded feeder were also slower to reversal learn. Second, to our knowledge for the first time in a natural population, we examined how sampling of non-rewarding options post-learning affected reversal-learning performance. Sampling quantity was moderately repeatable in blue tits but not great tits; sampling bias, the variance in the proportion of visits to each non-rewarded feeder, was not repeatable for either species. Sampling behaviour did not predict variation in reversal-learning speed to any significant extent. Finally, the repeatability of reversal learning was explained almost entirely by proactive interference for blue tits; in great tits, the effects of proactive interference and sampling bias on the repeatability of reversal learning were indistinguishable. Our results highlight the value of proactive interference as a more direct measurement of cognitive flexibility and shed light on how animals respond to changes in their environment.

Quantitative abilities of invertebrates: a methodological review.

Quantitative abilities are widely recognized to play important roles in several ecological contexts, such as foraging, mate choice, and social interaction. Indeed, such abilities are widespread among vertebrates, in particular mammals, birds, and fish. Recently, there has been an increasing number of studies on the quantitative abilities of invertebrates. In this review, we present the current knowledge in this field, especially focusing on the ecological relevance of the capacity to process quantitative information, the similarities with vertebrates, and the different methods adopted to investigate this cognitive skill. The literature argues, beyond methodological differences, a substantial similarity between the quantitative abilities of invertebrates and those of vertebrates, supporting the idea that similar ecological pressures may determine the emergence of similar cognitive systems even in distantly related species.

Repeated reversals of concurrent olfactory discriminations in rats: A search for functional equivalence.

Equivalence class formation has been difficult to demonstrate in nonhumans, but one method that has been successful is a simple discrimination procedure in which contingencies associated with two sets of arbitrary discriminative stimuli are repeatedly reversed. Pigeons and sea lions shift responding after encountering the newly-reversed contingency with only a few set members, showing evidence of functional equivalence. We used this strategy to determine whether similar findings would occur in rats using olfactory stimuli. Rats were trained to nose-poke in the presence of six stimuli arbitrarily designated as members of the positive set; responses to the six members of the negative set were not reinforced. When discriminative performance was established, contingencies associated with each set were reversed and re-reversed each time subjects met a performance criterion. All subjects successfully acquired the concurrent simple discriminations and were exposed to between 12 and 60 reversals, but none showed clear evidence of functional class formation until a final procedure in which the stimulus sets that had been in place were arbitrarily rearranged. Acquisition with these new stimulus sets was impaired, showing that class membership generated by the original stimulus sets interfered with learning the new ones, thus providing evidence of functional equivalence.

Stimulus characteristics, learning bias and visual discrimination in zebrafish (Danio rerio).

Zebrafish is an emerging model in the study of brain function; however, knowledge about its behaviour and cognition is incomplete. Previous studies suggest this species has limited ability in visual learning tasks compared to other teleosts. In this study, we systematically examined zebrafish's ability to learn to discriminate colour, shape, size, and orientation of figures using an appetitive conditioning paradigm. Contrary to earlier reports, the zebrafish successfully completed all tasks. Not all discriminations were learned with the same speed and accuracy. Subjects discriminated the size of objects better than their shape or colour. In all three tasks, they were faster and more accurate when required to discriminate between outlined figures than between filled figures. With stimuli consisting of outlines, the learning performance of zebrafish was comparable to that observed in higher vertebrates. Zebrafish easily learned a horizontal-vertical discrimination task, but like many other vertebrates, they had great difficulty discriminating a figure from its mirror image. Performance was more accurate for subjects reinforced on one stimulus (green over red, triangle over circle, large over small). Unexpectedly, these stimulus biases occurred only when zebrafish were tested with filled figures, suggesting some causal relationship between stimulus preference, learning bias and performance.

Goffin's cockatoos discriminate objects based on weight alone.

Paying attention to weight is important when deciding upon an object's efficacy or value in various contexts (e.g. tool use, foraging). Proprioceptive discrimination learning, with objects that differ only in weight, has so far been investigated almost exclusively in primate species. Here, we show that while Goffin's cockatoos learn faster when additional colour cues are used, they can also quickly learn to discriminate between objects on the basis of their weight alone. Ultimately, the birds learned to discriminate between visually identical objects on the basis of weight much faster than primates, although methodological differences between tasks should be considered.