Animal Learning Research Articles

Sex-Dependent Effects of Chronic Microdrive Implantation on Acquisition of Trace Eyeblink Conditioning

Neuroscience techniques, including in vivo recording, have allowed for a great expansion in knowledge; however, this technology may also affect the very phenomena researchers set out to investigate. Including both female and male mice in our associative learning experiments shed light on sex differences on the impact of chronic implantation of tetrodes on learning. While previous research showed intact female mice acquired trace eyeblink conditioning faster than male and ovariectomized females, implantation of chronic microdrive arrays showed sexually dimorphic effects on learning. Microdrive implanted male mice acquired the associative learning paradigm faster than both intact and ovariectomized females. These effects were not due to the weight of the drive alone, as there were no significant sex-differences in learning of animals that received “dummy drive” implants without tetrodes lowered into the brain. Tandem mass tag mass spectrometry and western blot analysis suggest that significant alterations in the MAPK pathway, acute inflammation, and brain derived neurotrophic factor may underlie these observed sex- and surgery-dependent effects on learning.

Representation learning in the artificial and biological neural networks underlying sensorimotor integration.

The integration of deep learning and theories of reinforcement learning (RL) is a promising avenue to explore novel hypotheses on reward-based learning and decision-making in humans and other animals. Here, we trained deep RL agents and mice in the same sensorimotor task with high-dimensional state and action space and studied representation learning in their respective neural networks. Evaluation of thousands of neural network models with extensive hyperparameter search revealed that learning-dependent enrichment of state-value and policy representations of the task-performance-optimized deep RL agent closely resembled neural activity of the posterior parietal cortex (PPC). These representations were critical for the task performance in both systems. PPC neurons also exhibited representations of the internally defined subgoal, a feature of deep RL algorithms postulated to improve sample efficiency. Such striking resemblance between the artificial and biological networks and their functional convergence in sensorimotor integration offers new opportunities to better understand respective intelligent systems.

Providence and the magnitude of the universe

AbstractWhy did God create a vast universe? Various answers are discussed and rejected: (a) for its beauty; (b) to instill a sense of the sublime in his intelligent creatures; (c) to demonstrate his glory, (d) to provide a home for extraterrestrial species; (e) to guarantee that the natural emergence of (intelligent) life, though extremely rare, happens nonetheless somewhere; (f) for no reason at all, because the human notion of efficiency does not apply to God's actions. Instead, this paper suggests that the universe is intended for space settlements. Several objections to this proposal are considered and deemed unconvincing.

Effects of Dangshen Yuanzhi Powder on learning ability and gut microflora in rats with memory disorder

Ethnopharmacological relevanceYuanzhi Powder is a commonly used traditional Chinese medical formulae for its potency in enhancing memory and learning. In clinical practice, Yuanzhi Powder is a classic formula in TCM to treat amnesia of the type “deficiency of Qi, turbid phlegm harasses the head and eyes, and stagnation of phlegm converting into the fire”. Our previous study showed that Yuanzhi Power, used together with Codonopsis Radix (Dangshen Yuanzhi Power, DYP), could improve learning and memory ability in animals with memory disorder (MD) and its efficacy is superior or equivalent to that of the Yuanzhi Power. Aim of studyThis study aimed to explore the regulatory mechanism of DYP through the “bacteria-gut-brain axis". Materials and methodsThe SD rats were divided randomly into control, model, positive, DYP-L, and DYP-H groups. Except for the control group, the rats were intraperitoneally injected with D-Gal (400 mg/kg) and gavaged with aluminum chloride (200 mg/kg) every day for 50 days. The rats in the DYP group were gavaged with DYP (6.67 and 13.34 g/kg, respectively) from the 15th day, once a day. The rats in the positive group were similarly administrated with piracetam (0.5 g/kg). The rats' bodyweight was recorded from the 16th day. The learning and memory ability of animals was tested by Morris water maze. The levels of MCP-1, NF-L, NSE, and TNF-α in serum were determined by Elisa kit, while the histopathology of duodenum and colon tissues was examined by H & E staining. The diversity of intestinal flora was sequenced and analyzed. In order to reveal the role of intestinal flora in DYP treatment of MD, the intestinal flora composition and the correlation analysis of intestinal flora and the above biochemical indexes were investigated. The intestinal flora function and biological metabolic pathways were predicted and analyzed by the KEGG database. ResultsThe MD animals’ learning and spatial memory ability decreased significantly, compared with the normal group, accompanied by weight increase and intestinal flora disorder. DYP can improve the learning and memory ability of MD animals, and its efficacy may exert through the following ways: (i) callback the abnormal biochemical indexes of MCP-1, NF-L, NSE, and TNF-α; (ii) decreasing the relative ratio of Firmicutes/Bacteroidetes and repairing the pathology of MD animal intestinal mucosa; and (iii) the regulation of DYP on biochemical blood indexes of MD animals was significantly correlated with the regulation of intestinal flora; (iv) DYP rats showed a strong correlation between cognitive ability improvement and bodyweight loss; (v) besides, DYP could also regulate the metabolic pathways of carbohydrate, amino acid, nucleotide, and energy by affecting related biological functions. ConclusionsThe results supported that DYP can improve MD animals' learning and memory ability by restoring the intestinal flora disorder and callback the abnormal biochemical indexes in serum, closely related to the “bacteria-gut-brain axis".

Postnatal oxytocin treatment improves survival and neurodevelopmental outcomes in an animal model of neonatal abstinence syndrome

Prenatal exposure to drugs of abuse results in neonatal abstinence syndrome (NAS). NAS causes significant morbidity and is associated with costly and lengthy hospitalization. Current pharmacotherapy is suboptimal with no FDA approved treatments. We examined the effect of postnatal oxytocin treatment on survival and neurodevelopmental outcomes in rats prenatally exposed to opioids or benzodiazepines. Sprague-Dawley rat dams were injected with escalating doses of morphine (10–50 mg/kg/day) or diazepam (2–15 mg/kg/day) throughout gestation. In an initial experiment, exposed rat pups received subcutaneous injections of 2 mg/kg oxytocin or saline for the first 10 postnatal days and survival rates were assessed. In a second experiment, exposed rat pups received subcutaneous injections of 0.3, 1, or 2 mg/kg oxytocin or saline for the first 10 postnatal days and survival and body weight were assessed for 30 days. In animals surviving through adolescence, neurodevelopmental outcomes and biological parameters (blood glucose, corticosterone, aldosterone) were also measured. Postnatal oxytocin treatment improved survival in animals prenatally exposed to morphine or diazepam. Preliminary evidence showed that postnatal oxytocin treatment improves long-term learning and memory processes in animals prenatally exposed to morphine or diazepam. These findings highlight the potential of oxytocin as a novel treatment for NAS resulting from prenatal exposure to opioids or benzodiazepines.

Explaining the effectiveness of fear extinction through latent-cause inference

Acquiring fear responses to predictors of aversive outcomes is crucial for survival. At the same time, it is important to be able to modify such associations when they are maladaptive, for instance in treating anxiety and trauma-related disorders. Standard extinction procedures can reduce fear temporarily, but with sufficient delay or with reminders of the aversive experience, fear often returns. The latent-cause inference framework explains the return of fear by presuming that animals learn a rich model of the environment, in which the standard extinction procedure triggers the inference of a new latent cause, preventing the unlearning of the original aversive associations. This computational framework had previously inspired an alternative extinction paradigm – gradual extinction – which indeed was shown to be more effective in reducing the return of fear. However, the original framework was not sufficient to explain the pattern of results seen in the experiments. Here, we propose a formal model to explain the effectiveness of gradual extinction in reducing spontaneous recovery and reinstatement effects, in contrast to the ineffectiveness of standard extinction and a gradual reverse control procedure. We demonstrate through quantitative simulation that our model can explain qualitative behavioral differences across different extinction procedures as seen in the empirical study. We verify the necessity of several key assumptions added to the latent-cause framework, which suggest potential general principles of animal learning and provide novel predictions for future experiments.

Animal Welfare and Environmental Ethics

Abstract Bernard Rollin’s main concerns are domestic and research animals. Such animals have endured less suffering as a result of Rollin’s seminal work. Animals are of moral concern because they have conscious interests, or telos. Rollin’s use of telos is plausible though more specialized than usual. Rollin has theoretical or in-principle ideals that are unlikely to be accepted as current practice. In result he adopts more moderate moral principles. In the fair-contract, husbandry dimension of agriculture, the farmer takes care of the cows and pigs, recognizing their rights, and then eats them, or sells them to be eaten. He reaches a strange combination of kinship and chasm separating human and animal minds. Rollin’s account of any deeper environmental ethics for a biospheric Earth is unsatisfactory, any respect for life beyond sentience, especially his concepts of global ecosystems.

Different minds

Animal intelligence takes many forms, but there may be a way of comparing them – and seeing how we fit in, finds Ute Eberle

Afterword: Some Illustrations

Afterword: Some Illustrations

Effects of pituitary hormones deficiency from the specific pituitary lobes on learning, memory and survival behavior in the Wistar rat

The role of the different adenohypophyseal hormones (GH, PRL, ACTH, TSH, LH and FSH) and neurohypophyseal (AVP and OXY) hormones on animal behavior, memory and learning have been stablished, however the role of lobe‐specific hormones on these cerebral functions has been not completely dilucidated. Here we study the specific pituitary hormone deficiencies in hypophysectomized (HYPOX), with anterior lobectomized (AL) and neurointermediate lobectomized (NIL) rats, subject to novel object recognition (NOR), forced swim (FS) and prepulse inhibition (PPI) tests. For comparisons the intact control (IC) and sham operated (SHAM) groups were also included. The NOR test that evaluate different phases of learning and memory in rodents, showed that memory discrimination index (DI) significantly increased in the NIL group, indicating that AVP and OXY deficiency negatively affect the ability of short and medium‐term memory. The FS test assess survival and motivation behavior; results showed that AL, NIL and HYPOX groups induced a loss in motivation and will to survive (increased immobility time); these observations may be partially explained by: 1) the significant deficiency of metabolic hormones (GH, ACTH‐corticosterone, TSH‐thyroid hormones and LH‐FSH‐testosterone hormones) whose decrease also induced significant loss in both mass muscle and body weight in AL and HYPOX groups and, 2) the decreased survival and motivational behavior induced by the AVP and OXY deficiency (NIL‐induced), thus supporting the view of the motivational and survival role of these hormones. The IPP test evaluates the rat ability to respond to potentially harmful acoustic stimuli and long‐term memory; results showed that AL animals did not show any sign of learning (expressed as very low inhibition percentage), whereas, interestingly, the HYPOX group (without any pituitary hormones) the long‐term memory was not significantly affected. In conclusion these results support the important role of the several pituitary hormones mainly neurohypophyseal hormones (AVP and OXY) controlling important brain functions necessary for learning, memory, and survival. These experimental models will allow in the future to study specifically the role of each pituitary hormone on the different aspects of animal behavior such as memory, motivation, generosity, adaptation, among others.

Nietzschean Perspectives on Intelligence: In Need of More Plurality for Making Sense of Intelligence

Philosophers as well as scientists in psychology, neuroscience, animal cognition research etc. have not found satisfying answers to what intelligence is with their crude, overly systematic and reductive approaches. At the same time, both recent findings about the capabilities of smart animals such as corvids (Nieder et al., 2020) or octopi (Godfrey-Smith, 2018) and novel types of Artificial Intelligence (AI), from social robots to cognitive assistants, are provoking the demand for new answers for meaningful comparison with other kinds of intelligence. In this paper, we devote ourselves to addressing this need by proposing an open malleable and loose framework for making sense of intelligence in humans, other animals and AI, which is ultimately based on causal learning as the central theme of intelligence. The goal is not just to describe, but mainly to explain queries like why one kind of intelligence is more intelligent than another, whatsoever the intelligence.

Sonic Collaborations between Humans, Non-human Animals and Artificial Intelligences: Contemporary and future aesthetics in more-than-human worlds

This article sketches a theoretical framework that allows the conceptual inclusion of non-human animals and artificial intelligences in human sonic collaborations. Post-humanist concepts that question the categorical divide between nature and culture, following Donna Haraway and Bruno Latour, converge with contemporary, non-adaptationist evolutionary aesthetics. Therefore, the anthropocentric ‘othering’ of non-humans gives way to a concept of a more-than-human sociality of sound. We offer some theoretical propositions for the extension of socially engaged sound practices to collaborations between humans and non-human animals and between humans and artificial intelligences, and then exemplify such multispecies sonic collaborations by analysing some existing projects from the fields of sound art and musical performance. After drawing some more general conclusions from these analyses, we hint at potential aesthetical and ethical parallels between animal and AI creative agency. Finally, we point out a few questions we see as important for future advanced settings of such collaborations, especially when it comes to assemblages of different AI technologies and to future concepts of animal–computer interaction that might enable non-human animals and artificial intelligence to cooperate creatively.

High Fructose and High Fat Diet Impair Different Types of Memory through Oxidative Stress in a Sex- and Hormone-Dependent Manner.

Metabolic syndrome (MetS) contributes to the spread of cardiovascular diseases, diabetes mellitus type 2, and neurodegenerative diseases. Evaluation of sex- and hormone-dependent changes in body weight, blood pressure, blood lipids, oxidative stress markers, and alterations in different types of memory in Sprague–Dawley rats fed with a high fat and high fructose (HFHF) diet were evaluated. After 12 weeks of feeding the male and female rats with HFHF, body weight gain, increase in blood pressure, and generation of dyslipidemia compared to the animals fed with chow diet were observed. Regarding memory, it was noted that gonadectomy reverted the effects of HFHF in the 24 h novel object recognition task and in spatial learning/memory analyzed through Morris water maze, males being more affected than females. Nevertheless, gonadectomy did not revert long-term memory impairment in the passive avoidance task induced by HFHF nor in male or female rats. On the other hand, sex-hormone–diet interaction was observed in the plasma concentration of malondialdehyde and nitric oxide. These results suggest that the changes observed in the memory and learning of MetS animals are sex- and hormone-dependent and correlate to an increase in oxidative stress.

Effects of dopamine modulation on chronic stress-induced deficits in reward learning.

Anhedonia is characteristically preceded by chronic stress, likely involving downstream effects of glucocorticoid alterations on dopamine (DA) function. To elucidate the neural underpinnings of this interaction, we examined whether acute pharmacological modulation of DA alters reward learning after chronic mild stress (CMS). Forty-eight male Wistar rats were exposed to a 21-day CMS regime (n = 48 nostress controls) before completing the probabilistic reward task (PRT), a well-validated cross-species test of reward learning. We first examined whether stress-induced reward dysfunction could be restored by systemic injections of low-dose amisulpride (AMI), which increases DA transmission via D2-like autoreceptor blockade. Then, we investigated region-specific effects through bilateral infusions of quinpirole (QUIN), a D2-like receptor agonist, into either the nucleus accumbens core (NAcc) or medial prefrontal cortex (mPFC). Blunted reward learning in CMS animals was reversed by acute AMI administration, but this treatment did not alter reward learning in the no stress group. Elevated adrenal gland weight, a proxy for stress reactivity, predicted lower reward learning in the untreated CMS group. This effect was extinguished following AMI treatment. These findings might be attributed to significantly higher D2 receptor density in the NAcc of high stress reactive animals. To this end, NAcc QUIN infusions potentiated reward learning relative to mPFC QUIN infusions in CMS rats, but there was no effect in no stress control rats. Collectively, these findings suggest that DA modulation reverses stress-induced reward dysfunction, even among the most stress-reactive animals. The effect might depend on D2-like receptor activation in the mesolimbic system.

The use of tracking/man trailing dog results as evidence in courts

Results achieved by man trailers/trackers is often accepted as evidence in courts. To be used as such, the results should be founded on scientific proof. With respect to the uniqueness of human individual scent, there is sufficient scientific foundation, but with respect to animal learning and cognition we now know that great care must be taken to ensure animals are responding to the intended cue. A review of man trailing studies indicate that these do not prove the essential question: are the dogs responding to the individual human odor cue when matching a scent article to a track? A suggestion is made for testing individual dogs based on guidelines set by the Scientific Working Group on the use of Dogs and Orthogonal Detector Guidelines. Finally, points that should be addressed when assessing such evidence in courts are provided.

Acute lead acetate induces neurotoxicity through decreased synaptic plasticity-related protein expression and disordered dendritic formation in nerve cells.

Lead (Pb) is a widespread environmental heavy metal that can damage the cerebral cortex and hippocampus, and reduce the learning and memory ability in humans and animals. In vivo and in vitro models of acute lead acetate exposure were established to further study the mechanism of neurons injury. In this study, 4-week-old female Kunming mice were randomly divided into four groups. Each group was treated with distilled water with different Pb concentrations (0, 2.4, 4.8 and 9.6mM). Mice were killed, and brain tissues were collected to detect the changes in synaptic plasticity-related protein expression. Furthermore, Neuro-2A cells were treated with 0, 5, 25 and 50μM lead acetate for 24h to observe the changes in cell morphology and function. In in vivo experiment, results showed that the expression levels of cytoskeleton-associated and neural function-related proteins decreased in a dose-dependent manner in the mouse brain tissue. In in vitro experiment, compared with the control group, Pb treatment groups were observed with smaller and round cells, decreased cell density and number of synapses. In the Pb exposure group, the survival rate of nerve cells decreased evidently, and the permeability of the cell membrane was increased. Western blot results showed that the expression of cytoskeleton-associated and function-related proteins decreased gradually with increased Pb exposure dose. Confocal laser scanning microscopy results revealed the morphological and volumetric changes in Neuro-2A cells, and a dose-dependent reduction in the number of axon and dendrites. These results suggested that abnormal neural structures and inhibiting expression of synaptic plasticity-related proteins might be the possible mechanisms of Pb-induced mental retardation in human and animals, thereby laying a foundation for the molecular mechanism of Pb neurotoxicity.

Picturizing Animals in the Arabic, Persian and Turkish - Azerbaijani Proverbs: A Comparative Study

Animals have a special place in human thought and life throughout history since they were used as a symbol to refer to different purposes in stories and proverbs. So, they play an important role in the people's culture and literature. Thus, animal behaviors and characteristics were not the same for all nations due to the geographic nature of each nation, the impact of animals' in it, and to the beliefs, customs and traditions of each nation.From this standpoint, we found that there were many common beliefs among nations regarding animals and their behaviors. At the same time, we found that there were different images and characteristics that were drawn in the minds of these nations about animals and reflected in their proverbs. Basically, this research compares the image of animals in the Arabic, Persian and Turkish-Azerbaijani proverbs showing the common and different images of animals in these proverbs. Keywords: Arabic, Persian, Turkish-Azerbaijani proverbs, animals, image, symbol.

Tribute to E. J. Capaldi: Celebration of a Psychological Scientist

Abstract E. J. (John) Capaldi (1928–2020) made numerous contributions to experimental psychology in his long career at the University of Texas at Austin and Purdue University. He was a pioneer in the area of animal learning and cognition, known for his sequential theory of partial reinforcement extinction effects. His research in this area and in memory and counting phenomena was conducted for the most part with rats running in straight alley mazes under various sequences of trial outcomes (e.g., reward, nonreward, variations in reward size). John's other interests included the sequential theory applied to Pavlovian conditioning, evolutionary theory, and psychology of science. More generally, John was a scientist to the core who served as a role model to those who knew him. His career centered on the values of science and rigorous critical thinking based in empirical data, coupled with a curiosity and openness to different and new ideas in psychology.

Can There be Thought Without Words?—Donald Davidson on Language and Animal Minds

In a couple of short papers, Donald Davidson holds that a creature cannot think unless it is the interpreter of the speech of another. At first blush, speaking a language is, therefore, a necessary condition for thought. His controversial claims has led many to regard him as a follower of the Cartesian tradition wherein languageless creatures are nothing but mindless machines. Against this widely shared interpretation, in this paper we put forward a more charitable interpretation of Davidson’s claims. According to our reading, Davidson never meant to argue that languageless creatures do not think. Instead, the only thing his arguments purport to show is that one will never be in a position to confirm that they do. This paper consists of a defense of the idea that Davidson is better seen as endorsing radical skepticism as to whether languageless creatures think.

Minocycline reverses developmental arsenic exposure-induced microglia activation and functional alteration in BALB/c mice

Arsenic activates microglia and exerts bystander effects on neuron. The present study is focused to test whether minocycline, a second generation antibiotic, can reverse the effect of developmental arsenic exposure on microglial activation and function. Pregnant Balb/c dams were gavaged with sodium arsenite (0.38 mg/kg bd wt) from gestational day 5 (GD5) till post natal day 21 (PND21) and then one group of pups continued till PND59 with arsenic gavage. Minocycline (33 mg/kg bd wt) was administered intraperitoneally two weeks till sacrifice, every alternate day. Mice were sacrificed on PND22 and PND60 and used for various assays. Primary microglial were isolated (ex vivo microglia) from experimental animals and used to measure reactive oxygen species (ROS), nitric oxide (NO), cytokine production and phagocytosis. The whole brain lysate was used for western blot analysis of microglial marker CD68 and synaptic marker, post synaptic density protein 95 (PSD95). For real-time PCR analysis of triggering receptor expressed on myeloid cells 2 (TREM2) and PSD95, RNA isolated from whole brain was used. The study reveals that minocycline administration reversed arsenic-induced increased expression of CD68, ROS, NO, cytokine production, phagocytosis and TREM2 expression. Arsenic-induced reduced expression of PSD95 protein was reversed by minocycline, although the mRNA of PSD95 was unaltered among different groups. Finally, we have checked the learning and memory response of the experimental animals using Y-maze test to correlate the arsenic-induced altered level of synaptic protein. Taken together, the present study finds minocycline to reduce arsenic-induced microglial activation and function which in turn reverses the arsenic-induced impaired learning and memory response.