Sylvain Fiset

Maternal Iron Deficiency Alters Essential Fatty Acid and Eicosanoid Metabolism and Increases Locomotion in Adult Guinea Pig Offspring

Iron deficiency (ID) is the most prevalent worldwide nutritional deficiency. Groups at risk of developing ID anemia are infants and pregnant women, even in industrialized countries. Our goal in this study was to evaluate the long-term consequences of maternal ID on the offsprings fatty acid and eicosanoid metabolism, behavior, and spatial memory. Female guinea pigs consumed iron-sufficient (IS) and -deficient (ID) diets for 14 d before mating and throughout pregnancy and lactation. Dietary iron restriction resulted in ID in pregnant females. On postnatal d 9, all offspring (ID and IS) were weaned to the IS diet and at 42 d, all offspring were iron replete. Locomotion was tested in pups on postnatal d 24 and 40 and spatial memory from d 25 to 40. Pups from the ID group were significantly more active in the open field at both times of testing, whereas spatial memory, tested in a Morris water maze, was comparable in both groups. On postnatal d 42, liver, RBC, and brain fatty acid composition were measured. Dihomogammalinolenic [20:3(n-6)], docosapentaenoic [22:5(n-3)], and docosahexaenoic [22:6(n-3)] acid contents were significantly higher in brain phospholipids of offspring born to ID dams. Prostaglandin E(2) and F(2alpha) concentrations were also significantly higher in brains of offspring born to ID dams. This demonstrates that moderate ID during gestation and lactation results in alterations of brain fatty acid and eicosanoid metabolism and perturbation in behavior in adult offspring.

Landmark-Based Search Memory in the Domestic Dog (Canis familiaris)

Recent studies have suggested that any animal that relies on landmark-based search memory encodes and uses metric properties of space to navigate. So far, however, metric information provided by landmarks has been predominantly investigated in avian species. In the present study, I investigated whether the domestic dog (Canis familiaris), a mammalian species, encodes the distance and direction from landmarks. Dogs were trained to find a ball hidden next to an array of two distinct landmarks that remained at a constant location in a room from trial to trial. After training, the dogs were occasionally tested on unrewarded conditions where the array was either left in its usual position or shifted laterally, perpendicularly, or diagonally relative to the rear wall of the room. Although the dogs significantly shifted their search as a function of the displacement of the landmarks, they did not search at the predicted coordinates of the goal relative to the shift of the landmarks, suggesting that the global cues available in the testing room were also encoded and used by dogs to locate the position of the goal.

Egocentric search for disappearing objects in domestic dogs: evidence for a geometric hypothesis of direction

In several species, the ability to locate a disappearing object is an adaptive component of predatory and social behaviour. In domestic dogs, spatial memory for hidden objects is primarily based on an egocentric frame of reference. We investigated the geometric components of egocentric spatial information used by domestic dogs to locate an object they saw move and disappear. In experiment 1, the distance and the direction between the position of the animal and the hiding location were put in conflict. Results showed that the dogs primarily used the directional information between their own spatial coordinates and the target position. In experiment 2, the accuracy of the dogs in finding a hidden object by using directional information was estimated by manipulating the angular deviation between adjacent hiding locations and the position of the animal. Four angular deviations were tested: 5, 7.5, 10 and 15°. Results showed that the performance of the dogs decreased as a function of the angular deviations but it clearly remained well above chance, revealing that the representation of the dogs for direction is precise. In the discussion, we examine how and why domestic dogs determine the direction in which they saw an object disappear.

Spatial memory of domestic dogs (Canis familiaris) for hidden objects in a detour task.

Spatial memory of domestic dogs (Canis familiaris) for hidden objects was investigated via a visible displacement problem of object permanence with a detour paradigm. Experiment 1 showed that dogs were able to spontaneously locate a disappearing object in a detour situation. In Experiments 2 and 3, dead reckoning and allocentric spatial information were put in conflict. Results revealed that dogs simultaneously encoded both sources of information when they had to bypass an obstacle to locate a hidden object. Experiment 3 also revealed that, over the course of testing, dogs gradually learned to rely predominantly on allocentric cues when the detour involved several reorientations. The current study reveals that spatial memory of dogs for hidden objects in a detour task was guided by flexibility in processing spatial information. Dogs could simultaneously encode dead reckoning and allocentric information to locate a disappearing object and used them hierarchically according to the complexity of the detour they encountered in the environment.

Comment on “Differential Sensitivity to Human Communication in Dogs, Wolves, and Human Infants”

Topál et al. (Reports, 4 September 2009, p. 1269) reported that dogs’ sensitivity to reading and using human signals contributes to the emergence of a spatial perseveration error (the A-not-B error) for locating objects. Here, I argue that the authors’ conclusion was biased by two confounding factors: the use of an atypical A-not-B search task and an inadequate nonsocial condition as a control.

Evidence for averaging of distance from landmarks in the domestic dog

Several studies in landmark use have shown that animals locate spatial positions by predominantly using perpendicular distance from extended surfaces over distance from individual landmarks. In the current study, I investigated whether the domestic dog encodes perpendicular distance from surfaces and whether they estimate distances from multiple cues. Dogs were first trained to locate a ball hidden at an equal and constant distance between an individual landmark and one wall (Experiment 1) or two walls (Experiment 2). On occasional unrewarded tests, the landmark was shifted laterally, perpendicularly or diagonally relative to one wall. Data revealed that the dogs largely determined where to search by averaging the distance from the walls of the room and the distance from the individual landmark. This study provides additional evidence that domestic dogs use metric properties of space to find a spatial location by use of landmarks. Although the present results are in accordance with the vector sum model, they are also consistent with current theories of spatial memory.

Prenatal Iron Deficiency in Guinea Pigs Increases Locomotor Activity but Does Not Influence Learning and Memory.

The objective of the current study was to determine whether prenatal iron deficiency induced during gestation in guinea pigs affected locomotor activity and learning and memory processes in the progeny. Dams were fed either iron-deficient anemic or iron-sufficient diets throughout gestation and lactation. After weaning, all pups were fed an iron-sufficient diet. On postnatal day 24 and 40, the pups’ locomotor activity was observed within an open-field test, and from postnatal day 25 to 40, their learning and memory processes were assessed within a Morris Water Maze. The behavioural and cognitive tests revealed that the iron deficient pup group had increased locomotor activity, but solely on postnatal day 40, and that there were no group differences in the Morris Water Maze. In the general discussion, we propose that prenatal iron deficiency induces an increase in nervousness due to anxiety in the progeny, which, in the current study, resulted in an increase of locomotor activity.

Increase serum cortisol in young guinea pig offspring in response to maternal iron deficiency

Iron deficiency (ID) has been reported as a risk factor in the pathology of attention-deficit/hyperactivity disorder, although the mechanisms seem unclear. Previous results from our research group showed that guinea pig offspring born from ID dams were significantly more active in the Open Field Test than the controls. This behavior could potentially be associated to stress. We therefore hypothesized that maternal iron deficiency (MID) elevates the offspring serum cortisol, a biomarker of stress, during childhood and possibly at mature age. Twenty-four female guinea pigs were fed an iron-sufficient (IS) diet (114 mg/kg) or ID diet (11.7 mg/kg) during the gestation and lactation. Pups in both groups were weaned at postnatal day (PNd) 9 and given an IS diet. Hematocrit and serum cortisol levels were measured in dams at every trimester of gestation and in pups at PNd24 and 84. We found no impact of MID on dams cortisol values. However, our findings indicate that MID increased cortisol secretion in the offspring during childhood, cortisol values being significantly elevated in ID than IS pups at PNd24 (P < .05). During adulthood (PNd84), both groups showed comparable cortisol levels. The elevated cortisol secretion observed in the offspring born from ID mothers during childhood may indicate increased stress reactivity which may have contributed to the higher level of activity when tested in a novel open environment. These findings suggest that MID can potentially act as internal stressor affecting the early development conceivably leading to increased stress levels in the children.

Impact of maternal iron deficiency on the auditory functions in the young and adult guinea pig

Objectives: The aim of this study was to evaluate the hearing function in the guinea pig offspring at post-natal day (PNd) 24 and PNd84 born from dams suffering from iron deficiency during pregnancy and lactation by using the auditory brainstem response (ABR). Method: Female guinea pigs (n = 24 per dietary group) were fed an iron sufficient (IS) diet (114 mg/kg) or an iron deficient (ID) diet (11.7 mg/kg) during the gestation and lactation periods. Pups in both groups were weaned at PNd9 and given the IS diet. The hematocrit level was measured at every trimester of pregnancy and at the day of sacrifice in dams and at PNd24 and PNd84 in pups. The animal body weight was measured on every second day until the day of sacrifice. The ABR was used in pups to measure the hearing threshold using a broad range of stimulus intensities and latency at 100 and 80 dB in response to 2, 4, 8, 16, and 32 kHz tone pips at PNd24 and 84. Results and discussion: No significant difference between dietary groups was measured in hearing threshold and absolute latencies in pups at PNd24 and PNd84. Although the ID offspring (n = 16) did not differ in brainstem transmission times (BTTs) at 80 dB compare to the IS siblings (n = 25) at PNd24, they showed significant delayed inter-peak latency (IPL) I-IV at 100 dB suggesting a delayed BTT. At PNd84, the latency of all peaks including IPL I-IV at 80 and 100 dB significantly decreased and was also similar in pups from both dietary groups suggesting a better brain maturation. This is the first study investigating the long-term impact of maternal iron deficiency on the auditory functions in the guinea pig offspring during early development to adulthood.

Cognitive Development in Gray Wolves: Development of Object Permanence and Sensorimotor Intelligence with Respect to Domestic Dogs

In this chapter, we explore whether domestic dogs and gray wolves share a similar cognitive development with regards to how they represent physical and/or social objects. To reach this objective, we examine two key components of the Piagetian theory of cognitive development in the gray wolf: object permanence and sensorimotor intelligence. We detail how the capacity to search and locate disappearing objects develops in wolves and compare these data with those observed in previous studies with dogs. We then further describe an observational study of sensorimotor intelligence with these wolves. Overall, the results suggest that the development of object permanence is similar in dogs and wolves, both species reaching Stage 5b of object permanence by the age of 11 weeks. In terms of sensorimotor intelligence, Stage 4 was the upper limit of sensorimotor intelligence we observed in wolves. Moreover, up to 6 weeks of age, the behaviors of wolf puppies are directed predominantly towards their conspecifics, and by Week 8, wolves’ interest in inanimate object increases significantly. In discussion, we explore the factors affecting the development of object permanence and sensorimotor intelligence in canines.