Sex difference in cue strategy in a modified version of the Morris water task: correlations between brain and behaviour.

Background: Sex differences in spatial memory function have been reported with mixed results in the literature, with some studies showing male advantages and others showing no differences. When considering estrus cycle in females, results are mixed at to whether high or low circulating estradiol results in an advantage in spatial navigation tasks. Research involving humans and rodents has demonstrated males preferentially employ Euclidean strategies and utilize geometric cues in order to spatially navigate, whereas females employ landmark strategies and cues in order to spatially navigate.

Mental rotational ability is correlated with spatial but not verbal working memory performance and P300 amplitude in males.

This study investigated how both sex and individual differences in a mental rotation test (MRT) influence performance on working memory (WM). To identify the neural substrate supporting these differences, brain electrical activity was measured using the event-related potential technique. No significant sex differences were observed in a test of verbal WM, however males were significantly faster than females to respond to probe stimuli in a test of spatial WM.

Enriched childhood experiences moderate age-related motor and cognitive decline.

Aging is associated with deterioration of skilled manual movement. Specifically, aging corresponds with increased reaction time, greater movement duration, segmentation of movement, increased movement variability, and reduced ability to adapt to external forces and inhibit previously learned sequences. Moreover, it is thought that decreased lateralization of neural function in older adults may point to increased neural recruitment as a compensatory response to deterioration of key frontal and intra-hemispheric networks, particularly of callosal structures.

Seasonal and sex differences in the hippocampus of a wild rodent.

Studies across and within species suggest that hippocampus size is sexually dimorphic in polygamous species, but not in monogamous species. Although hippocampal volume varies with sex, season and mating system, few studies have simultaneously tested for sex and seasonal differences. Here, we test for sex and seasonal differences in the hippocampal volume of wild Richardson's ground squirrels (Urocitellus richardsonii), a polygamous species that lives in matrilineal, kin-based social groups and has profound sex differences in behavior.

Housing environment and sex affect behavioral recovery from ischemic brain damage.

In previous work from our laboratory, we have developed a model of stroke that allows the comparison of stroke injury across age groups (10-day old, 63-day old, 180-day old rats). In this current study, we incorporated environmental enrichment to determine whether this form of rehabilitation alters behavioral recovery, and whether age and/or sex interacts with enrichment. Our results indicated that ischemic male rats that were housed in standard cages (shoebox housed) performed the poorest on two tasks of motor ability, and that this performance was related to the size of the lesion.

Phase 2 protein inducers in the diet promote healthier aging.

Oxidative stress drives many aging-associated problems. Because oxidative stress can be decreased by induction of phase 2 proteins, we hypothesized that incorporating the phase 2 protein inducer 2(3)-tert-butyl-4-hydroxyanisole (tBHA) into the diet would result in healthier aging. C57BL/6 mice were placed either on control mouse chow diet or on chow containing tBHA and were examined at 6, 12, and 18 months.

Drive for muscularity, body comparison, and social physique anxiety in men and women.

The presented study tested a model of the relationship between the drive for muscularity (DM), three aspects of body comparison (general, weight-, and muscle-related), and social physique anxiety in college men and women. The findings demonstrated that those with higher levels of DM engaged in more frequent body-related comparisons in all three areas. Greater frequency of both Weight- and Muscle-Related Body Comparison was then predictive of higher levels of social physique anxiety.

Hypoxia ischemia affects ultrasonic vocalization in the neonatal rat.

Perinatal hypoxic-ischemic encephalopathy results in a spectrum of pathologies related to the degree of initial infarct and environmental factors, including maternal interactions. Infants actively influence their environment by crying; rat pups produce ultrasonic vocalizations (USVs). Our study observed that ischemic pups engage in less time producing USVs and make fewer USVs overall, with male ischemic pups experiencing reductions in more categories than females.

Can a reward-based behavioural test be used to investigate the effect of protein-energy malnutrition on hippocampal function?

Our laboratory is investigating the effects of protein-energy malnutrition (PEM) on cognitive outcome following global ischemia. Here, we investigated whether PEM independently impairs working memory in the T-maze and if the associated food reward reverses PEM. Gerbils were fed 12.

Enriched environment and the effect of age on ischemic brain damage.

Stroke affects all age groups from the newborn to the elderly. Previous work from our laboratory has shown that despite a greater susceptibility to brain damage, the immature brain recovers more rapidly and to a greater extent than does the more mature nervous system. In the current study, we examined the influence of environmental enrichment on the effects of age on the brain damaging effects of stroke.

Visuomotor system uses target features unavailable to conscious awareness.

After lesions to primary visual cortex, patients lack conscious awareness of visual stimuli. Interestingly, however, some retain the ability to make accurate judgments about the visual world (i.e.

Female advantage for object location memory in peripersonal but not extrapersonal space.

The neural representation of peripersonal space may be distinct from the representation of extrapersonal space. Sex differences in the performance of motor tasks might relate to proximity to the body. In the spatial domain, females excel at tasks performed in peripersonal space, like the Object Location Memory Task (OLMT), whereas males excel at tasks performed in extrapersonal space, such as navigation.

Evidence for the influence of testosterone in the performance of spatial navigation in a virtual water maze in women but not in men.

Testosterone (T) may be associated with enhanced spatial navigation in a number of rodent species, although the nature of the relation is equivocal. Similarly, numerous studies in humans generally have found that T is associated with enhanced spatial ability on a variety of paper and pencil tasks that may relate to navigational ability. However, relatively few studies have reported effects of T on navigational ability in humans.

The influence of aging on recovery following ischemic brain damage.

Stroke is a health hazard that affects all age groups, however the impact of age on brain injury following ischemia remains largely unexamined. We examined the extent to which age, from the newborn to mature adult, affects behavioral recovery following similar degrees of ischemic brain damage. We utilized a model that produces comparable volumes of brain damage between the different ages.

Photographer preference or image purpose? An investigation of posing bias in mammalian and non-mammalian species.

Portraits of human adults typically exhibit leftward biases--that is, they depict individuals with their left cheek prominently featured. The purpose of this study was to determine if photographs of human infants and photographs of non-human animals also display these leftward biases. We observed significant leftward biases in photographs of infants and non-human animals.

When advertising turns "cheeky"!

Portraits typically exhibit leftward posing biases, with people showing more of their left cheek than their right. The current study investigated posing biases in print advertising to determine whether the product advertised affects the posing bias. As the posing bias may be decreasing over time, we also investigated changes in posing biases over a span of more than 100 years.

Men are more accurate than women in aiming at targets in both near space and extrapersonal space.

Men excel at motor tasks requiring aiming accuracy whereas women excel at different tasks requiring fine motor skill. However, these tasks are confounded with proximity to the body, as fine motor tasks are performed proximally and aiming tasks are directed at distal targets. As such, it is not known whether the male advantage on tasks requiring aiming accuracy is because men have better aim or is better in the proximal domain in which the task is usually presented.

Rightward biases in free-viewing visual bisection tasks: implications for leftward responses biases on similar tasks.

Neurologically normal individuals exhibit strong leftward response biases during free-viewing perceptual judgments of brightness, quantity, and size. When participants view two mirror-reversed objects and they are forced to choose which object appears darker, more numerous, or larger, the stimulus with the relevant feature on the left side is chosen 60-75% of the time. This effect could be influenced by inaccurate judgments of the true centre-point of the objects being compared.

Protein-energy malnutrition impairs functional outcome in global ischemia.

We investigated whether protein-energy malnutrition (PEM) exacerbates brain injury in global ischemia. It was hypothesized that PEM would increase secondary brain damage by worsening ischemia-induced depletion of glutathione (GSH) and increasing oxidative stress. Adult male gerbils were fed an adequate protein (12.

A new model for determining the influence of age and sex on functional recovery following hypoxic-ischemic brain damage.

Stroke is a disorder affecting the lives of all age groups, and particularly those at the opposite ends of the age spectrum. It is generally believed that the immature brain is more resistant to damage resulting from a hypoxic/ischemic injury, and that it is also more 'plastic' in terms of its ability to recover. Evidence from our laboratory, and a host of others, has indicated, however, that the developing brain may in fact be more sensitive to injury resulting from hypoxia-ischemia.

Involvement of extracellular regulated kinase and p38 kinase in hippocampal seizure tolerance.

The mechanisms underlying brain seizure tolerance, a phenomenon in which brief periods of seizures protect brain against the lethal effects of subsequent sustained seizures, are poorly understood. Because brain seizure tolerance and brain ischemia tolerance likely share certain common mechanisms, the recent evidence that activation of extracellular regulated kinase (ERK) and p38 kinase pathways plays a critical role in ischemic preconditioning suggests that a similar mechanism may underlie brain seizure tolerance. We investigated the hypothesis in a rat kainic acid preparation of seizure preconditioning and tolerance, which was established by induction of one episode of priming epileptic status lasting for 20 min on the first day and another episode of sustained epileptic status lasting for 2 hr on the second day.

Selective antiepileptic effects of N-palmitoylethanolamide, a putative endocannabinoid.

Purpose: The purpose of this study was to determine whether N-palmitoylethanolamide (PEA), a putative endocannabinoid, would be effective against kindled amygdaloid seizures. For a comparison with earlier work, we also tested the effectiveness of PEA against pentylenetetrazol (PTZ)-induced convulsions.

Methods: Kindling electrodes were implanted bilaterally in the amygdala in 32 Long-Evans rats.

Febrile convulsions affect ultrasonic vocalizations in the rat pup.

Febrile convulsions are common among preschool children and are studied experimentally with hyperthermia in rat pups. Although heat-induced convulsions (HC+) can affect behaviors in adulthood, to date no one has examined the effects on behavior in the neonatal period. We examined the effects of HC+ on ultrasonic vocalizations (USVs) and mother-pup interactions in P10- and P12-aged rat pups.

Throwing accuracy during prism adaptation: male advantage for throwing accuracy is independent of prism adaptation rate.

Previous studies have found that men are more accurate at throwing an object at a target than are women, independent of experience. However, these studies' results are based on average scores from multiple trials. As such, it is unknown whether the male advantage results from superior throwing accuracy or from a superior ability to calibrate subsequent throws.