La importancia de la oxitocina en el vínculo entre perros y personas / The relevance of oxytocin in the dog-human bond

Dadas las crecientes investigaciones acerca de las habilidades sociocognitivas de los perros domésticos, recientemente se renovó el interés hacia sus correlatos fisiológicos. Particularmente se está indagando en el papel de la oxitocina (OT), una neurohormona que modula las conductas afiliativas y sociocognitivas de diversas especies. El objetivo del presente trabajo es realizar una revisión de los estudios sobre los efectos de la OT en las conductas sociocognitivas en perros. Se analizarán los trabajos que miden OT endógena y los efectos de la administración exógena. Asimismo, se presentarán las posibles áreas de aplicación, así como la dirección de futuras investigaciones en el área.

Given the growing investigation on the dog-human bond and sociocognitive skills of domestic dogs, the focus of research has recently been shifted towards its physiological correlates. Oxytocin (OT), a neuro-hormone that modulates affiliative and sociocognitive behaviors in a wide number of species, has received particular interest. The aim of this paper is to review studies which focus on the effects of OT on the socio-cognitive behaviors in dogs. These works were divided into investigations that measured endogenous and exogenous administration of OT. Several endogenous OT studies measure OT concentration in dogs using samples of blood, urine or saliva. In these studies, OT effects on affiliative interactions, mutual gazing and stressful situations were found. Physical contact and gazing were affiliative interactions which modulated the OT release. In addition, proximity and contact seeking were associated with OT release in stressful situations. Exogenous OT studies measure the physiological and behavioral effects of OT intranasal administration. These studies were grouped into research that found effects of OT in social interaction, gaze, communication, and cognitive bias in dogs. In the social interaction studies, intranasal OT was found to improve affiliative behaviors with both interspecifics and conspecifics. In gazing studies, this neuro-hormone was found to increase gazing towards the region of human eyes, even in threatening contexts. Regarding communicative effects, OT modulated the ability to follow human communicative cues in dogs. Moreover, was found that OT increased positive cognitive bias and induced positive expectations. Although there is evidence of OT influencing behavior on both sexes, some studies have found differences based on gender. For example, the females had longer gaze duration toward humans, improved following of human communicative cues such as pointing and looked more at projected images on a screen than males. These effects could be explained by the interaction of the OT system and the estrogen levels in females. Concerning the applied area, OT could beused in the treatment of canine behavioral problems such as social deficits, phobias and separation anxiety. Moreover, it could facilitate integration in dogs with poor early socialization, like shelter or abandoned dogs. In addition, it could improve the training in rescue and assistance dogs. However, further research is needed since there are no follow-up reports of treatments in dogs. In conclusion, OT increases affiliative behaviors in dogs both towards humans and their conspecifics. Regarding endogenous OT studies, effects were found with both brief interactions ranging between 3 and 4 minutes, as well as long-term interactions, between 25 and 30 minutes. In exogenous OT studies, although there is no consensus on the amounts of OT to be administered, effects were found with 2 IU / kg,12, 24 and 40 IU on at least one of the measured variables. Specifically, nasal OT enhances the ability to use human communicative cues, induces positive expectations about neutral stimuli, and increases gaze both toward human eyes and to socially relevant stimuli. A number of exogenous OT studies showed differential effects on sex. Female dogs had greater responses to exogenous OT administration than males. Therefore, sex should be a variable to be considered in future studies. In sum, although the studies in this field are incipient, OT appears to be key in the interaction between dogs and humans since it participates in the interspecific bond, affiliative behaviors and socio-cognitive skills in domestic dogs.

Interspecific social skills in a highly socialized Aguará Guazú (maned wolf, Chrysocyon brachyurus). A pilot-subject study

Some beliefs seem to be more resilient to change and extinction than others. This paper argues that some of the strong beliefs held by humans have deep biological roots in our evolutionary past, and the neuronal pathways and structures that support them can be found in other species. This paper describes four basic universal criteria present in persistent beliefs: intuitibility, predictability, reliability and utility (IPRU). The paper argues that the study of belief as a modern scientific discipline will require consideration of the evolutionary context through which the neural pathways associated with belief formation, maintenance and endorsement have emerged. We also suggest that the study of religious belief has discouraged the adoption of an overarching framework for understanding our belief system in all its breadth. Our approach incorporates evolution-driven cognitive and affective biases, attachment mechanisms and reward expectation. Rather than operating as genuinely adaptive phenomena associated with evolutionary advantage, we suggest that belief systems emerge as a by-product of evolutionary pressures

Há crenças que parecem ser mais resilientes a mudanças e extinção do que outras. Este artigo argumenta que algumas das crenças humanas mais fortes têm raízes biológicas profundas em nosso passado evolutivo, e que vias e estruturas nervosas que as suportam podem ser encontradas em outra espécie. Este trabalho descreve quatro critérios universais básicos nas crenças persistentes: ser intuitiva, ser previsível, ser confiável e ser utilizável (IPRU). O trabalho argumenta que o estudo de crença como uma disciplina moderna demandará considerações sobre o contexto evolutivo, através do qual emergiram vias neurais associadas à formação, manutenção e apoio à crença. Também é sugerido que o estudo da crença religiosa tem desencorajado a adoção de um contexto abrangente para a compreensão de nosso sistema de crença em toda a sua profundidade. Abordagem aqui utilizada incorpora viés cognitivo movido pela evolução assim como viés afetivo, mecanismos de fixação e expectativas de recompensa. Sugerimos que os sistemas de crença emergiram como subproduto de pressões evolutivas, ao invés de operar como um processo genuinamente adaptativo associado a vantagens evolutivas

Estudios Sobre Cooperación en Perros Domésticos: una Revisión Crítica / Studies on Cooperation in Household Dogs: A Critical Review / Estudos sobre Cooperação em Cachorros Domésticos: uma Revisão Crítica

El análisis comparado de la cooperación contribuye al entendimiento tanto de sus orígenes evolutivos como de los mecanismos próximos involucrados en dicho fenómeno. Esta revisión se centra en estudios sobre cooperación en perros domésticos. Para ello se definieron conceptos relacionados con la cooperación, se describieron las razones filogenéticas y ontogenéticas que hacen del perro un buen modelo para el estudio de este fenómeno y se hizo una revisión crítica de los trabajos realizados en este campo. Fueron incluidas investigaciones sobre situaciones cooperativas y sobre las habilidades cognitivas involucradas. Se discuten hipótesis sobre los mecanismos próximos de esta habilidad que incluyen elementos emocionales, motivacionales y de aprendizaje asociativo.

The comparative analysis of cooperation contributes to the understanding of both its evolutionary origins and the proximate mechanisms involved in this phenomenon. This review focuses on studies of cooperation in household dogs, describing the phylogenetic and ontogenetic reasons that make dogs a good model for the study of this phenomenon, and carrying out a critical review of the research carried out in this field, particularly of research regarding cooperative situations and the cognitive abilities involved. The article also discusses hypotheses regarding the proximate mechanisms of this ability, which include emotional, motivational, and associative learning abilities.

A análise comparada da cooperação contribui para o entendimento tanto de suas origens evolutivas quanto dos mecanismos próximos envolvidos nesse fenômeno. Esta revisão se centraliza em estudos sobre cooperação em cachorros domésticos. Para isso, definiram-se conceitos relacionados com a cooperação, descreveram-se as razões filogenéticas e ontogenéticas que fazem do cachorro um bom modelo para o estudo desse fenômeno e fez-se uma revisão crítica dos trabalhos realizados nesse campo. Foram incluídas pesquisas sobre situações cooperativas e sobre as habilidades cognitivas envolvidas. Discutem-se hipóteses sobre os mecanismos próximos dessa habilidade que incluem elementos emocionais, motivacionais e de aprendizagem associativa.

¿Pueden los perros domésticos (canis lupus familiaris) reconocer expresiones emocionales humanas? una revisión crítica de las evidencias / Can domestic dogs (canis lupus familiaris) recognize human emotional expressions? a critical review of the evidence

Las expresiones emocionales tienen un papel fundamental en las interacciones de especies sociales, brindando información acerca del emisor, las características e importancia del estímulo o situación que desencadena tales interacciones, y también funcionan regulando los vínculos sociales. Los perros poseen notorias capacidades comunicativas hacia los humanos por lo que resulta interesante estudiar si estas habilidades se extienden al reconocimiento de las expresiones emocionales. Se han realizado diversas investigaciones acerca del reconocimiento de expresiones emocionales humanas en perros exponiéndolos a una situación representada por personas durante la evaluación, así como mediante el uso de imágenes, videos y grabaciones. El análisis de las evidencias permite concluir que los perros podrían distinguir entre distintas emociones humanas ya sea en presencia de modelos en vivo o mediante la observación de imágenes y modulan su conducta conforme esta discriminación, así como también pueden utilizar esta información como clave en la resolución de problemas. Sin embargo, aún no están claros los mecanismos que subyacen a estas habilidades.

Emotional expressions play a critical role in the interactions among individuals, particularly, in social species. They provide information about the sender and the characteristics and importance of the triggering stimulus or situation, also regulating social ties. Dogs have notorious communication skills towards humans, which makes the study of their ability to recognize human emotional expressions an interesting endeavor. There have been several studies in which dogs have been tested using real people in an experimental situation as well as images, video and audio recordings of people's expressions. The evidence suggests that dogs can discriminate between different human emotions either in the presence of live models or by looking at images. This type of information has been shown to modulate their behavior and to be used as cues to solve problems. However, the mechanisms underlying these abilities are not fully understood yet.

Evaluación del temperamento en perros de refugio y de familia. Un estudio comparativo / Avaliação do temperamento em cães de refúgio e de família. Um estudo comparativo / Evaluation of the temperament of shelter dogs and family pets. A comparative study

Este estudio comparó el desempeño de perros de refugio y de familia en una batería de pruebas comportamentales de temperamento, con el fin de evaluar si existe una asociación entre las condiciones de alojamiento en refugios (restricción social y espacial) y la aparición de alteraciones del comportamiento. Se utilizaron 30 perros domésticos mestizos a los que se les administró una batería de cuatro pruebas de temperamento: sociabilidad y miedo interespecífico, entrenabilidad, agresión interespecífica y miedo no social. Los resultados muestran que, comparados con los perros de familia, los perros de refugio permanecieron más tiempo cerca de la experimentadora en la prueba de sociabilidad y presentaron puntuaciones significativamente más elevadas en la prueba de miedo no-social.

The study compared the performance of shelter dogs and family pets in a battery of behavioral temperament tests, in order to evaluate whether there is an association between the living conditions in shelters (social and spatial restriction) and alterations of behavior. Thirty half-breed house dogs were given a battery of four temperament tests: sociability and interspecific fear, trainability, interspecific aggression, and non-social fear. Results show that, compared to family pets, shelter dogs remained close to the experimenter for a longer period during the sociability test and their scores were significantly higher in the non-social fear test.

Este estudo comparou o desempenho de cães de refúgio e de família em uma série de provas comportamentais de temperamento, com o objetivo de avaliar se existe uma associação entre as condições de alojamento em refúgios (restrição social e espacial) e o surgimento de alterações do comportamento. Utilizaram-se 30 cães domésticos mestiços aos quais foram dadas quatro provas de temperamento: sociabilidade e medo interespecífico, treinabilidade, agressão interespecífica e medo não social. Os resultados mostram que, comparados com os cães de família, os de refúgio permaneceram mais tempo perto da experimentadora na prova de sociabilidade e apresentaram pontuações significativamente mais elevadas nas provas de medo não social.

Mira lo que te muestro:¿Comunicación referencial entre perros domésticos (canis familiaris) y humanos? / Look what I show you: Referential communication between domestic dogs (canis familiaris) and humans?

Históricamente, la comunicación referencial fue considerada como exclusivamente humana. No obstante, recientemente se observó que los animales también pueden referirse hacia objetos externos. Para los perros domésticos, las personas proveen el acceso a los recursos valiosos, por lo que una adecuada comunicación con las mismas resulta fundamental. En este contexto, la comprensión y producción de señales comunicativas visuales cobran especial relevancia. Las evidencias revisadas indican que los perros detectan el estado atencional humano, siguen la orientación de la cabeza para hallar comida oculta y dirigen la atención del humano hacia un objeto fuera de su alcance, mediante la alternancia de la mirada. En función de ello, se sugiere que los perros se comunican de manera referencial con las personas. Sin embargo, esto no necesariamente implica que comprendan al otro como un agente intencional. Se discuten los posibles mecanismos involucrados así como las hipótesis acerca del origen de dichas capacidades.

Referential communication has been historically viewed as uniquely human because it is linked with the use of language. However, there is evidence indicating that animals can also communicate about external objects, by means of vocalizations or gestures. The use of gestures as pointing or gaze alternation involves the ability to direct the attention of an observer to a distal object or entity in the environment. This ability is shared with other species, especially those who live in captivity. For domestic dogs as for the species that live in captivity, humans provide the main resources for survival. For this reason a proper communication with them is essential. Visual social cues can be used to communicate emotional and mental states and so they allow us to predict other's behavior. In this context, both comprehension of the human gaze as well as the production of visual communicative signals by domestic dogs (Canis familiaris) have special relevance. The evidence reviewed in the present study indicate that dogs can detect cues associated with human attentional states as head orientation, behaving differently when the person remains attentive or inattentive. Also, they are able to follow human head direction to find hidden food in an object choice task, but not gaze direction. Moreover, dogs can direct human attention toward an out-of-reach object, alternating their own gaze between the human face and the target. On that basis, as dogs can detect, follow and direct human attention, it would be possible to suggest that they can referentially communicate with people about distal objects in the environment; however these capacities were principally observed in foraging contexts. Nevertheless this does not imply that dogs necessarily comprehend others as intentional beings. There are several hypotheses to explain the origin of these abilities in dogs, some postulate that the intense process of domestication to which them were submitted, provide them a special sensitivity to communicate with humans. Differently, others stress the importance of ontogeny. Although the domestication process would be essential for understanding dogs' ability to communicate with humans, the experience with people that they have throughout their lives is also involved in the acquisition of these skills. The two-stage hypothesis states that in addition to the domestication process, the sensitivity of a canid to human social cues depends on two types of ontogeny experience. First, interaction with humans during a sensitive developmental period leading to the acceptance of humans as social companions. Second, learning that is not restricted to a particular phase of development to utilize the location and movement of parts of the human body to locate sought-after objects. This would lead to a human-food association by conditioning processes. As domestic dogs spend most of their lives in human families, they have many opportunities to learn to use these signals. This hypothesis recognizes that the domestication of dogs provided a longer socialization period than that of other canids facilitating the acceptance of humans as social partners. However, the animal's contact with people during its ontogenetic development is essential, if this contact does not occur at the right time, communicative skills will not properly develop. Possibly, during thousands of years dogs have been learning to gaze at the human face as the shortest way to satisfy their needs. This gazing exchange thus became a privileged channel of communication between the two species.

Relación entre ll tipo de alojamiento y las resuestas de mirada, sociabilidad y miedo-apaciGuamiento en perros / Association between housing type and gaze, sociability, and fear-appeasement responses in dogs

El objetivo del presente artículo es estudiar si el alojamiento en refugios caninos altera las respuestas de mirar a la cara humana, el acercamiento y las conductas de miedo-apaciguamiento (cola y orejas bajas, agazapamiento) hacia una persona desconocida y si existe una relación entre estos comportamientos. Para ello se evaluaron ocho perros alojados por al menos dos años en un refugio y nueve perros de familia, adultos, mestizos y de ambos sexos. La evaluación se dividió en dos situaciones: una prueba de sociabilidad consistente en la exposición a la presencia de una persona desconocida que se comporta de manera pasiva, y una tarea comunicativa en la que una persona desconocida se coloca cerca de una fuente de comida que está a la vista pero inaccesible a los animales. Los resultados muestran que en ambas pruebas los perros de refugio mostraron mayores conductas de miedo-apaciguamiento hacia la persona, pero no mostraron diferencias en sus respuestas de acercamiento ni en la mirada a la cara humana. Sin embargo, la duración de la mirada en ambos grupos fue mayor en la tarea comunicativa, en la que había comida, a diferencia de la prueba de sociabilidad. En conclusión, el alojamiento en refugios alteraría algunas respuestas vinculadas al miedo-apaciguamiento, modificando la calidad del vínculo que puede establecerse entre ambas especies.

The aim of this work is to study the effects of housing conditions, shelter versus family house, on gaze response as well as on sociability and fear-appeasement (tail and ears down and crouching) behaviors. Also, the objective is to analyze whether there is a relationship between these behaviors. Eight shelter and nine family dogs, adult, both sexes and mixed breeds were assessed in a sociability test in which dogs were exposed to the presence of an unknown human who acted passively and a communicative task in which a person remain near a visible but unreachable source of food. Results showed that, in both tests, shelter dogs showed more fear-appeasement behaviors than family dogs but there were no differences in their approaching levels to the human. Moreover, the groups didn't show differences in their gaze response towards the human face. However, gaze duration was longer in the communicative task, where food was present, than in the sociability test, in both groups. In conclusion, housing in a shelter could modify some responses of the dogs related to fear-appeasement towards humans affecting the quality of the bond between them.

Neonatal treatment with clomipramine and depression: A review of behavioral and physiological findings

Many times in science, the discovery of a treatment that has certain effect happens accidentally while the scientists are investigating another phenomenon. This is the case of the discovery of a possible animal model of depression by the administration of clomipramine (CLI) during neonatal days. Adult animals exposed to CLI in neonatal days showed alterations in REM sleep (for example, the decrease of REM latency); lower weight, disruptions in locomotor activity (the increase in activity depend on the dark / light phase in which the test starts, when the animals were tested in the light phase they found increase in activity, but no changes were observed when the animals were tested in the dark phase); less intracraneal self-stimulation, lower saccharin and sucrose consumption, less suppression of the consummatory behavior, sexual alterations in males (for example, expressed as a lower number of mounts and ejaculations; no alterations were found in the activity of the Hypothalamic - Pituitary - Gonadal axis and the level of testosterone was normal), higher alcohol consumption, disruptions in the agonistic response (CLI - treated animals were significantly less aggressive than control groups) and in learning (in the passive avoidance task and 8 radial arm maze) compared to untreated animals (rats that received vehicle during neonatal days). Several of these abnormalities could be reversed with those treatments that are effective for treating depression in humans (antidepressive drugs, nicotine and REM sleep deprivation treatment). These results were obtained in male rats of different strains and in hamsters, and at different months, the majority of them at 3-4 months, and some of them after the sixth, this could be because some changes were caused with the decrement in the age of the animals, although further research is needed to elucidate this issue. Neuroendocrinal alterations analogous to those found in human depression were also discovered in CLI - treated rats, although the data is contradictory. These include Hypothalamic - Pituitary - Adrenal axis alterations; while it is true that some experimental results found that CLI - treated rats have a higher basal level of corticosterone than controls, others found that not only do they differ in basal level, also during the stress situation; circulating corticosterone increases less and returns more rapidly to basal levels than control groups. For this reason, we can conclude that if alterations in the HPA axis indeed exist in CLI - treated animals, it is still unclear in which way the deregulation is manifested. Other results support the hypothesis that alterations found in CLI - treated animals are due to alterations in serotoninergic transmission during a critical period of development, such as the neonatal stage; more specifically, a reduction in the hypothalamic concentration of serotonin, like a decrease in the neuronal firing in the dorsal raphe nucleus. An increase in cholinergic activity was also found, although the data in this field is not as vast as that found in relation to the neurotransmission of serotonin. All of these results suggest that rats treated with CLI during neonatal days present alterations in adulthood analogous to human depression, however other findings indicate that is not yet a valid model. Further research is needed, and we have to be cautious with the conclusions because there is some evidence suggesting that this is a promising model but other does not support its validity. If a model like the neonatal administration of CLI achieves the reproduction of some symptoms, neurophysiological and behavioral alterations of depression, the advantages are invaluable. In this sense, neonatal treatment with CLI is a very promising animal model for the study of depression.

El presente trabajo describe los principales resultados acerca de un nuevo y probable modelo animal de depresión. Este modelo se basa, paradójicamente, en la administración de un antidepresivo, clomipramina, a ratas neonatas. Cuando los animales alcanzan la adultez, muestran alteraciones comportamentales que pueden ser interpretadas como depresivas, como hiperactividad, descenso en la búsqueda de placer, anormalidades en el sueño, entre otras. Se analizan los posibles mecanismos neurofisiológicos y neuroendocrinos involucrados. A pesar de las limitaciones que ofrece un modelo animal, es importante cómo logra reproducir algunos síntomas hallados en la depresión y debido a esto las ventajas del mismo son invaluables. Además, pueden estudiarse los mecanismos cerebrales implicados en la patogénesis y tratamiento del trastorno que por razones éticas son impensables de llevar a cabo en humanos. Por ello, se considera de gran valor el estudio realizado con el modelo de clomipramina con la perspectiva de que se siga trabajando en la validación del mismo.

Cognición social en animales y humanos: ¿es posible establecer un Continuo? / Social cognition in animals and humans: Is it possible to establish a continuum?

El presente trabajo tiene como objetivo el análisis de estudios comparados en diversas especies sobre la cognición social, particularmente en los niños, chimpancés y perros domésticos. Si bien las dos primeras especies tienen un mayor parentesco filogenético, los perros, a diferencia de los chimpancés, viven en un contexto humano y comparten un ambiente similar al que experimentan los niños durante su desarrollo. Se analizan las tareas más utilizadas para evaluar capacidades vinculadas con la teoría de la mente, como el seguimiento de la mirada, el reconocimiento del estado atencional y de la perspectiva visual, la relación entre ver y saber así como la comprensión de que las creencias que guían el comportamiento pueden ser falsas. En el momento de comparar las habilidades cognitivas en diferentes especies, homologando las tareas experimentales, es necesario tener en cuenta las características propias de cada una de ellas. Estas comparaciones permiten determinar hasta qué punto estas capacidades son únicamente humanas. Los estudios analizados sugieren que existiría cierta continuidad en las tareas utilizadas así como en las habilidades evaluadas, a excepción de la de falsa creencia. Sin embargo, esta continuidad en los mecanismos involucrados en la cognición social aún es tema de debate.

The aim of the present study is to analyze comparative studies about social cognition in various species, particularly in children, chimpanzees and dogs. While the first two species are closely related, dogs, unlike chimpanzees, live in a human context and share a similar environment to that experienced by children during their development. In this line, we analyze the main tasks used to evaluate theory of mind related skills, such as gaze following, the recognition of others' attentional state and visual perspective taking, the relation between seeing and knowing and the understanding of others' false beliefs. When comparing the cognitive abilities of different species, it is necessary to homologate the experimental tasks taking into account species specific characteristics. These comparisons allow determining to what extent these skills are uniquely human. The evidence reviewed here suggests a continuum in the experimental procedures used as in the evaluated skills, except for the comprehension of false belief. However, the continuity of the mechanisms involved in social cognition is still debated.

Testosterona, emoción y cognición: Estudios en animales castrados / Testosterone, emotion and cognition: Castrated animals studies

Se informa una revisión de las principales investigaciones referidas al efecto de la depleción de las hormonas sexuales, mediante la gonadectomía, sobre el comportamiento de ratas macho adultas. Esta revisión se divide en dos grandes áreas: por un lado, se describen las líneas de investigación acerca del efecto de la castración sobre la emoción y por otro, se discuten los aportes relevantes relacionados con el efecto de la depleción de testosterona sobre la cognición. Los resultados de distintas investigaciones y métodos empleados sugieren que la depleción de testosterona tiende a provocar mayor ansiedad, disminuir los umbrales de dolor y a producir mayores respuestas de tipo depresivas. El reemplazo con testosterona puede revertir estos efectos. Los trabajos acerca de los efectos cognitivos señalan que existe una relación compleja y ambigua entre los andrógenos y la cognición. Algunos trabajos muestran efectos deletéreos cuando los animales sufren una depleción de testosterona; varios de ellos pueden ser revertidos con la administración de hormonas sexuales. Ahora bien, hay trabajos que muestran que la gonadectomía no siempre produce un déficit en el desempeño de los sujetos. Específicamente, se encuentra un deterioro cuando la memoria de trabajo es el foco de atención. En última instancia, se realiza una revisión de los mecanismos neurobiológicos implicados en el efecto de la gonadectomía sobre el comportamiento o distintas tareas. Los datos sugieren que la metabolización de la testosterona sería el componente efectivo en la reducción de la ansiedad y en el mejor desempeño observado en las tareas cognitivas.

Sexual behavior is a very important part in the life of animals, and sexual hormones, such as estrogen in females and testosterone in males, regulate the behavior of most mammals. Testosterone, the male sexual hormone, plays an important role in the development of the brain organization necessary for sexual behavior. Some evidences show that testosterone affects animal behavior and has an anxiolytic as well as analgesic effects on the behavior of rats, mice, dogs, and humans. For example, men who have higher endogenous levels of testosterone have a lower incidence of depression. Conversely, young hypogonad men, with low endogenous testosterone, are more likely to be diagnosed with anxiety or depressive disorders, and exhibit decreased performance in some cognitive tasks. In animal models of androgen deficiency, androgens can mediate both, affective and cognitive behavior. Removing rats primary source of endogenous androgens through androgen extirpation (i.e., castration or gonadectomy) results in increased anxiety-like behavior, and detriments in cognitive performance. In the present paper, we review the main research on the effect of sexual hormone depletion, through gonadectomy, on the behavior of adult male rats. There are different ways to study the influence of testosterone on emotion and cognition, the study of the sexual behavior, the study of the administration of testosterone and their metabolites and the effect of the depletion of testosterone. This review is arranged in two main sections: on the one hand, we describe studies about castration effects on animal emotion; on the other hand, we discuss most relevant contributions linked to the effect of testosterone depletion on cognition. To finish, there is a section where we explain the neurobiological mechanisms involved in emotion and cognition of animals with hormone depletion. Data suggests that testosterone modulates emotion, in particular anxiety, fear, pain, and depression responses. Results from different investigations using diverse methodologies suggest that testosterone depletion tends to cause higher anxiety and depressive-like responses and to lower pain thresholds; some of the tests used to evaluated emotion are: open field test, elevated plus maze, defensive burying, Vogel's paradigm, tail flick, hot plate, among others. In addition, testosterone replacement can reverse these effects in male rodents in some of these tests. Studies on the cognitive consequences of hormones point towards the existence of a complex and ambiguous relationship between androgens and cognition. Some studies show deleterious effects when animals are subjected to testosterone deletion, most of which can be reverted with sexual hormones administration, for example in the defensive freezing to electric shocks. However, there are several studies showing that gonadectomy does not always cause a performance deficit, and that the deficit may appear depending on certain variables of the studied tasks, in particular the time intervals among stimuli, for example in radial maze. More specifically, performance deteriorates when working memory is evaluated. To finish, we review the neurobiological mechanisms involved in the effect of gonadectomy on behavior. Similar findings occur when either emotion or cognition is assessed, though studies on this last area are scarcer. Data suggest that testosterone metabolism is the effective component in anxiety reduction and increased cognitive performance. In particular, evidence indicates that androgen and estrogen receptors would be involved in this phenomenon, and that these effects could be blocked through the administration of antagonist drugs. Last, it is important to stress that the relationship between testosterone and both emotion and cognition is extremely complex. There is no doubt that the gonads affect animal and human existence and thus more research is needed to continue studying and clarifying these relationships which play an important role in our existence.

El gesto de señalar: Una llave para la comunicación entre especies / Pointing gesture: A key for communication between species

El señalamiento puede ser definido como la acción que realiza un individuo, para dar una indicación directa a otro con respecto a un objetivo específico. Implica coordinar la atención visual del otro hacia una entidad distante. En la presente revisión se discuten los trabajos comparativos sobre la producción y comprensión del señalamiento. En cautiverio se observaron respuestas correctas al señalamiento humano para encontrar un objeto escondido en una amplia variedad de especies. En el trabajo que se informa se da especial énfasis a los estudios sobre comunicación entre perros domésticos y humanos, dado que han mostrado ser altamente exitosos utilizando claves sociales humanas para acceder a un refuerzo. Se discuten los posibles mecanismos involucrados, analizando la controversia acerca de la participación de factores cognitivos complejos del tipo de cognición social y teoría de la mente y las explicaciones más cautas sobre procesos de aprendizaje asociativo.

Communication between two animals takes place when an external observer can detect changes in the behavior of one of them, in response to certain signs emitted by the other one. The pointing gesture is a key element inside gestural communication. It can be defined as the action that an organism executes, to give a direct indication to other one, regarding a specific objective. This gesture is related to how an organism coordinates the visual attention of another one towards a distant entity. It has two principal functions: as declarative gesture, it implies an action that directs the attention of the receiver to an object or event of interest; as imperative gesture, some type of action is required from the receiver. In this paper, some studies focused on the production and, most of them, on the comprehension of pointing are discussed. Regarding the production of communicative cues, primates rarely point in their natural habitats, but captive chimpanzees usually point food out of their reach. There are few studies of communicative production in domestic dogs, and their focus is on the applied value of this ability as in hunting or rescue. This species use body posture, barks and gaze alternation (showing) as communicative cues. On the other hand, the most common test to evaluate whether animals can understand declarative gestures is the object-choice task, which forces subjects to use an indicatory gesture in order to find hidden food. In this test, the subject is given a choice between two possible food locations, usually opaque containers. The experimenter hides food in one of the containers and gives a cue (e.g. pointing, gazing, tapping, etc.) towards the aim container. The subject can choose one of the potential locations, following the human cue. Using pointing as a cue in situations of captivity, correct responses were observed in a wide variety of species including capuchin monkeys, orangutans, gorillas, chimpanzees, dolphins, domestic goats, cats, horses, seals and fur seals. In this paper we give special emphasis to the studies with domestic dogs, because they have shown to be especially skilful at the communicative version of the object choice task. The dogs are very skilful using a variety of cues, including pointing, looking, and bowing towards the object. Moreover, this successful performance takes place from the first trials and from early stages of development, without needing an explicit training. Regarding the elements of pointing gesture, a study has shown that an elevated arm position was the most relevant element in the composition of this signal, whereas the direction of the movement of the arm played a small relevance in the indication of the direction for the dog. The hand or the index fingers seem to be of special importance, while the arm and elbow were not effective signs. Furthermore, in some cases the dogs favour the social information even if there are physical cues that contradict it, such as visual or olfatory cues. We present comparative studies between domestic dogs and other species, including other canids like wolves and foxes, primates and cats. The superior performance of the dogs is analyzed. Finally, the possible mechanisms involved in this ability are discussed, analyzing the controversy between cognitive complex factors, such as social cognition and theory of mind (high level explanation), and more cautious explanations, such as associative learning processes (low level explanation). The relevance of these studies about communication is revealed in the great quantity of applied areas in which dogs are used, such as assistance to disabled persons, search and rescue of people, hunting, herding, defense, pets and others fields.

Comportamiento sexual y ansiedad / Sexual behavior and anxiety

En el presente trabajo se revisarán las investigaciones con animales no humanos que atañen a la relaciónexistente entre comportamiento sexual y ansiedad. Por una parte, los resultados más relevantes indicanque el comportamiento sexual posee un efecto de tipo ansiolítico o atenuante del estrés, que se manifiesta tantoen la conducta de los sujetos como a niveles fisiológicos o neuroendocrinos. Por otra parte, hay estudios quehacen referencia a la relación de signo contrario, es decir, cómo el estrés afecta el comportamiento sexual de losanimales.

The present work reviews the research about the relation between sexual behavior and anxiety in animals. Themost relevant results suggest that sexual behavior has an anxiolytic-like effect. This phenomenon is expressedon the subject’s behavior, besides the physiological and neuroendocrine levels. Also, the review includes studiesabout the opposite relation, it means, how the stress affects the animal’s sexual behavior.

Diferencias individuales en los perros domésticos (Canis familiaris): Revisión de las evaluaciones conductuales / Individual differences in domestic dogs (Canis familiaris): A behavioral assessment review

El estudio de las diferencias individuales en el comportamiento de los perros domésticos tiene un gran valor aplicado dado que permite una mejor selección de los mismos para cumplir las variadas funciones que tienen en la sociedad humana como perros guía, policía, compañía, rescatistas de personas, etc. En el trabajo que se informa se presenta una revisión de estudios sobre diferencias individuales en perros, basada únicamente en las baterías conductuales que evalúan un conjunto de rasgos del temperamento. Con este objetivo se realiza una breve descripción de cada batería de pruebas utilizadas en la literatura, analizando las definiciones operacionales de las variables evaluadas y los diferentes tipos de estímulos utilizados. Los rasgos mayormente evaluados son: temerosidad, agresividad, disposición al entrenamiento y sociabilidad. La temerosidad, en general es evaluada a través de la respuesta del animal ante la aparición de un estímulo súbito que puede ser intenso o no, como por ejemplo la reacción frente a un ruido fuerte, la apertura de un paraguas, o la aparición repentina de una figura humana. La agresividad se mide a través de la reacción frente a la amenaza o provocación por parte de un humano, la sustracción de un objeto o la confrontación con un perro dominante. La disposición al entrenamiento es estudiada a través de la respuesta del animal frente a diferentes estímulos como el juego con un trapo o una cuerda, el ejercicio de devolución de un objeto o la obediencia frente a distintos comandos. Por último, la sociabilidad se evalúa con la aparición o el acercamiento de un humano desconocido o con la exposición a un perro no familiar. Se discuten además las limitaciones metodológicas de las baterías así como también los importantes usos aplicados de las mismas.

A review of the research on individual differences in domestic dogs is presented in this paper. Temperament has been defined as the group of individual differences in behavior which is manifested steadily across situations and over time. It has been studied in a wide range of species including humans. Domestic dogs have undergone intense processes of selection on behavioral traits during domestication, and in the development of different breeds. These processes produced a great morphological, genetic and behavioral variability, which turned the dog in an interesting model for the study of individual differences. In this study we present a review of the different test batteries developed for the assessment of various behavioral traits. Test batteries are defined as standard experimental situations where a stimulus is used to provoke a behavior which is compared statistically to that of other individuals in the same situations, in order to classify the subjects. To achieve this aim, a brief description of seven batteries is given. Four of them evaluated dogs from breeding or train ing centers. Their aim was to select those animals which possess the most adequate traits to become guide or police dogs. The remaining batteries evaluated shelter dogs in order to elaborate a behavioral profile to improve the adoption process. In each battery described we analysed the operational definitions of the variables, the method used for scoring the animal's responses (overall vs. direct), the use of trained observers and the different types of stimuli used. The behavioral traits that are mainly assessed in dogs are fearfulness, aggressiveness, responsiveness to training, and sociability. Fearfulness is generally assessed through the appearance of a startling stimulus, which can be intense or not, such as the reaction towards a strong noise, the open ing of an umbrella, or the sudden appearance of a human figure. Aggressiveness is measured through the reaction towards a threat or provocation of a human being, the removal of an object, or the confrontation with a dominant dog. Responsiveness to train ing is studied through the response of the animal towards different stimuli, such as tug of war, retrieval, or obedience to commands. Finally, sociability is assessed with the appearance or approach of an unknown human being, or with the exposure to an unfamiliar dog. On the whole, the relevance of the assessment of these traits is fundamentally linked to the close relationship between dogs and humans. On the other hand, from a methodological point of view, it is important to note that most of the batteries evaluated a great number of subjects, which is difficult to achieve. Also, they allow to study behavioral variability in several traits at the same time, providing a large amount of information. Notably, several tests obtained predictive validity. The main difficulties presented by the temperament batteries are the diversity in nomenclature of the same traits and the variety of definitions used. Some of them even lack the reliability and validity requirements which are necessary to be considered measuring instruments. Furthermore, complex statistical analyses are done with unreliably obtained data. To conclude, despite the methodological limitations, temperament batteries have a great applied value. They allow the adequate selection of animals before the investment of valuable resources in their training, and a correct temperament evaluation can improve the adoption process of shelter dogs, diminishing the risk of relinquishment by predicting behavioral problems. The scope of this subject does not only matter to researchers interested in animal models of individual differences in behavior, but also to all the professionals who work in applied areas where dogs are an elemental part of the task, as the rescue or search of missing people, assisted therapy, drug detection, herding, etc.

Rasgos del temperamento de los perros domésticos (Canis familiaris): evaluaciones conductuales / Temperament traits of domestic dogs (Canis familiaris): Behavioural tests

Los rasgos del temperamento se definen como tendencias conductuales estables entre situaciones similares y a lo largo del tiempo. En el presente trabajo se revisan las pruebas conductuales diseñadas para la evaluación de rasgos aislados del temperamento en los perros domésticos. Para cada dimensión se describen los estímulos empleados, las respuestas evaluadas y el correlato fisiológico de las mismas. Los rasgos más estudiados fueron la temerosidad, la agresividad y la sociabilidad. Sin embargo, sólo la primera cuenta con correlatos fisiológicos bien establecidos. Finalmente, las evaluaciones conductuales resultan de suma importancia para la selección de los perros para las distintas funciones que cumplen en la sociedad humana: detección de drogas, compañía, guardia, rescate de personas, etc.

A temperament trait is defined as a stable behavioral tendency along time and among similar situations. This study intends to analyze the behavioral tests designed for the evaluation of isolated temperamental traits of domestic dogs. The type of stimulus used, the behaviors evaluated and the physiological substrates are described for each dimension. Fearfulness, aggressiveness and sociability were the most studied traits. Nevertheless, only the first one has well established physiological bases. Finally, behavioral tests are of great relevance for selecting dogs for the different roles that they perform in human society, such as drug detection, company, security, human rescue, etc.

Perspectivas clásicas y contemporáneas acerca de la memoria / Classic and contemporary perspectives on memory

Los seres humanos organizan los acontecimientos pasados como “memorias”, es decir, todo lo quese aprende se codifica y almacena en el cerebro, y de esta manera se guarda la información delentorno para adaptarse mejor a situaciones futuras. Las principales investigaciones sobre el estudiode la memoria se llevaron a cabo en la década del 70; las conclusiones más importantes se handerivado por un lado, de la experimentación animal y por otro, del estudio de los casos clínicos depacientes amnésicos. Se han propuesto numerosos sistemas de clasificación de la memoria. Enprimer lugar, los autores han distinguido entre las diferentes fases involucradas en el proceso deformación de la memoria: la memoria a corto y largo plazo. En segundo lugar, se han propuestodiferencias entre memorias declarativas y no declarativas. Finalmente, los investigadores han concebidola necesidad de evaluar la memoria de manera sistemática, tanto conductual comofarmacológicamente, en distintos momentos para poder tener acceso independiente al estudio delas diferentes fases o tipos de memoria. Esta aproximación al estudio de la memoria ha permitidola evaluación de los efectos de las drogas sobre la memoria y el entendimiento de los mecanismosmoleculares implicados en el proceso de la memoria. Este artículo hace además referencia a lasestructuras cerebrales implicadas en los diferentes fenómenos de la memoria evaluados.

Humans organize past events as memories, i.e. what we learn is encoded and stored in the brain,and by accumulating relevant environmental information we better cope with similar situations inthe future. The main research on memory began in the 70s and the most important conclusions havebeen derived, on the one hand, from animal experiments, and on the other hand, from clinicalstudies of amnesic patients. Many classification systems of memory have been proposed. First,authors have distinguished among the different phases involved in the process of memory formation:short-term and long-term memory. Second, declarative and non-declarative memories have beenrecognized. Last, researchers have conceived the need to evaluate memory in a systematic mannerthrough behavioral as well as pharmacological means, in different moments or times to be able tohave independent access to the study of the different memory phases or types of memory. Thisapproach to the study of memory has allowed evaluating drug effects on memory and alsounderstanding the molecular mechanisms involved in memory processes. In addition, this researchhas also aimed at studying brain regions implicated in the diverse memory phenomena underinvestigation.

Memoria emocional: efectos de la corticosterona sobre los recuerdos / Emotional memory: Effects of corticosterone on aversive memories

Las hormonas adrenales, administradas inmediatamente antes o después de una tarea de aprendizaje, modulan la memoria. Este efecto varía de acuerdo al tiempo y a la intensidad con que se incrementan las hormonas. La liberación o administración de glucocorticoides inmediatamente antes o después de una tarea, facilitan la memoria. Por el contrario, la elevación o administración de glucocorticoides antes de una prueba de aprendizaje, deteriora la evocaciónde la información previamente adquirida. En este trabajo se revisan los principales estudios realizados con animales y humanos acerca del papel de los glucocorticoides sobre la memoriade eventos aversivos. A su vez se describe el efecto de la elevación aguda y crónica de las hormonas adrenales sobre la memoria.

The adrenal hormones administered immediately before or after a learning task modulate memory. This effect varies according to time and intensity with which hormones increase. Therelease or administration of glucocorticoids 0before or after a task, facilitate memory. Althought, the elevation of glucocorticoids before a test of learning deteriorates evocation ofinformation previously learned. This paper presents a review of the animal and human´ studies on the role of glucocorticoids on the memory of aversive events. Also, this paper presents a description about the effect of acute and chronic elevation of adrenal hormones on memory.

Calidad de vida en perros alojados en refugios: intervenciones para mejorar su bienestar / Quality of life in shelter dogs: interventions to improve their welfare

Los refugios caninos tienen como finalidad albergar a los perros extraviados, vagabundos o abandonados. En Argentina, a diferencia de lo que sucede en países anglosajones, la estadía de los animales en los refugios se vuelve permanente, entre otras razones por la ausencia de políticas adecuadas de adopción. En el presente trabajo se revisan las investigaciones realizadas con perros alojados en refugios. La información recabada sugiere que éstos muestran alteraciones conductuales y fisiológicas similares a las que se observan en otras especies bajo condiciones de cautiverio. Esto indica que en dichas circunstancias el bienestar se encuentra comprometido.Con el objetivo de mejorar la calidad de vida de los animales se han llevado a cabo numerosas intervenciones como la introducción de objetos e interacciones sociales con humanos o conespecíficos arrojando resultados variables. Por otro lado, la implementación de evaluaciones conductuales puede ser de utilidad en el medio local mejorando el trabajo del personal de los refugios. A la luz de los resultados obtenidos se sugieren nuevas estrategias para la mejora del bienestar canino en los establecimientos de nuestra región.

Dog shelters have as purpose to lodge the missed, stray or relinquisheddogs. In Argentina, unlike what happens in Anglo-Saxon countries, theanimals stay in the shelters in a permanent way, in part due to the absence of suitable policies of adoption. In the present work, investigations about shelter dogs are reviewed. Data suggest that they show behavioral and physiological alterations similar to the ones observed in other species undercaptivity. This indicates that in the above mentioned circumstances the welfare is in danger. With the aim to improve the quality of life of the dogs, numerous interventions have been carried out but did not lead to conclusive results. For example, the introduction of objects and social interactions with humans or conspecifics were done. The implementation of behavioral evaluations in the local shelters can be useful to improve the staff’s duties. Taking account of the reviewed results, new strategies for the improvement of the canine welfare in the establishments of our region are suggested.

Comunicación entre perros domésticos (Canis familiaris) y hombres / Communication between domestic dogs (Canis familiaris)

Domestic dogs (Canis Familiaris) have shown to have a series of cognitive abilities which allow them to respond to signals given by humans. Specifically, dogs are able to detect and respond to signals such as the human visual and head orientation, as well as signals given by humans with the hands. We review the literature on dog social cognition. The evidence shows that dogs' abilities are greater than those of other canines, as well as those of other genetically related species such as primates, but whose ancestry did not share as much the human environment. Dogs communication ability seems to be a product of the domestication process. The reviewed research also indicates the importance of learning processes in these abilities.

Los perros domésticos (Canis familiaris) tienen una serie de habilidades cognitivas que le permiten responder exitosamente a diferentes señales dadas por humanos. Se revisan estudios de cognición social en perros poniendo énfasis en aquellos sobre emisión y comprensión de señales entre ambas especies y en los de aprendizaje por observación de modelos humanos. Las evidencias muestran que esta capacidad es mayor a la que tienen otros cánidos y a la de especies estrechamente emparentadas genéticamente al hombre pero que no convivieron con él; parecen ser producto del proceso de domesticación; por otra parte, los procesos de aprendizaje permiten desarrollarlas al máximo. Es necesario integrar los estudios etológicos con los de la psicología experimental para llegar a comprender este fenómeno.

Efectos cognitivos y emocionales del envejecimiento: aportes de investigaciones básicas para las estrategias de rehabilitación / Cognitive and emotional effects of aging: Basical research contributions to rehabilitation strategies

El envejecimiento normal produce una serie de cambios que se presentan asociados a una declinación general de las funciones fisiológicas. Como consecuencia surge un conjunto de déficit conductuales, cognitivos y emocionales. Aunque es relativamente artificial separar las funciones cognitivas de las emocionales, en esta revisión se presentan estudios conductuales y neurofisiológicos, especialmente realizados con modelos animales, que abordan los cambios que provoca el envejecimiento en cada una de esas áreas. Los resultados muestran un deterioro de los procesos cognitivos, especialmente de la memoria y las funciones ejecutivas, una persistencia en las respuestas previamente aprendidas y una desregulación frente a situaciones de estrés. Tanto en los modelos animales como en los humanos las alteraciones de la memoria y de las demás funciones cognitivas se atenúan si los sujetos vivieron en medios enriquecidos y si continuan estimulando, mediante prácticas y ejercicios, tales funciones. Se presenta una recopilación de investigaciones acerca de los tratamientos aplicados para mejorar la calidad de vida, realizadas por quienes se valieron de estudios básicos para desarrollarlos. Las intervenciones conductuales son las más efectivas para atenuar los efectos del envejecimiento e incluyen el mantenimiento y cuidado general de la salud y una dieta adecuada, el ejercicio físico y un entrenamiento específico y continuado de las funciones cognitivas

El papel de la corteza prefrontal en la motivación y en la conducta intencional / The rol of the prefrontral cortex in the motivation and the intentional behavior

La corteza prefontral (CPF) tiene una función esencial el procesamiento de reforzadores así como en planificación de las conductas dirigidas a obtener dicha metas. Se presenta una revisión de los principales hallazgos obtenidos sobre la función de la CPF, en especial de las áreas orbitofrontal y dorsolateral. En conjunto, los datos indican que la corteza orbitofrontal en los vertebrados es necesaria para la detección y las expectativas de refuerzo mientras que la dorsolateral para la memoria de trabajo, la planificación y la conducta y la adquisición de aprendizajes complejos.

The prefrontal cortex (PFC) plays an essential role both in the localization and processing of reinforcers, as well as in goal-oriented behavior planning. We present here a review of the main evidences concerning the fuction of different PFC areas, Briefly, data suggest that orbifrontal cortex detects reinforcer expectancies, while dorsolateral cortex is related to working memory, planning and acquisition of complex behavior