The perceived costs and benefits of mentoring college students with intellectual disability on stereotype consistent and inconsistent tasks.

BACKGROUND: According to the stereotype content model, individuals with intellectual disability are perceived as having greater warmth-related traits (e.g. sociable and humorous) and fewer competence-related traits (e.g. independence and intelligence). METHODS: We examined college students' perceived costs and benefits of mentoring peers with intellectual disability on stereotype-consistent (i.e. socially oriented) or inconsistent (i.e. academically oriented) tasks. Participants read about peer mentoring programmes that helped college students with or without intellectual disability on socially or academically oriented tasks before reporting their perceived costs and benefits of peer mentoring. RESULTS: Mentoring students with intellectual disability was associated with greater benefits (i.e. connectedness between mentors and students, student utility and mentor benefits) on academically oriented tasks but greater costs for mentors on socially oriented tasks. Additionally, participants reported that they would experience greater positive feelings if they were to mentor a student with an intellectual disability. However, the perceived benefits to the student and some costs (i.e. discomfort, paternalism and costs to student) were not influenced by whether the student had an intellectual disability and the type of mentoring task. DISCUSSION: Results indicate individuals find greater rewards working with individuals with intellectual disability on stereotype-inconsistent tasks and offer suggestions for postsecondary education peer mentoring programmes.

Changes in human EEG alpha activity following exposure to two different pulsed magnetic field sequences.

The present study investigates the effects of a weak (+/-200 microT(pk)), pulsed, extremely low frequency magnetic field (ELF MF) upon the human electroencephalogram (EEG). We have previously determined that exposure to pulsed ELF MFs can affect the EEG, notably the alpha frequency (8-13 Hz) over the occipital-parietal region of the scalp. In the present study, subjects (n = 32) were exposed to two different pulsed MF sequences (1 and 2, used previously) that differed in presentation rate, in order to examine the effects upon the alpha frequency of the human EEG. Results suggest that compared to sham exposure, alpha activity was lowered over the occipital-parietal regions of the brain during exposure to Sequence 1, while alpha activity over the same regions was higher after Sequence 2 exposure. These effects occurred after approximately 5 min of pulsed MF exposure. The results also suggest that a previous exposure to the pulsed MF sequence determined subjects' responses in the present experiment. This study supports our previous observation of EEG changes after 5 min pulsed ELF MF exposure. The results of this study are also consistent with existing EEG experiments of ELF MF and mobile phone effects upon the brain.

Online corrections can produce illusory bias during closed-loop pointing.

This experiment examined whether the impact of pictorial illusions during the execution of goal-directed reaching movements is attributable to ocular motor signaling. We analyzed eye and hand movements directed toward both the vertex of the Müller-Lyer (ML) figure in a closed-loop procedure. Participants pointed to the right vertex of a visual stimulus in two conditions: a control condition wherein the figure (in-ML, neutral, out-ML) presented at response planning remained unchanged throughout the movement, and an experimental condition wherein a neutral figure presented at response planning was perturbed to an illusory figure (in-ML, out-ML) at movement onset. Consistent with previous work from our group (Heath et al. in Exp Brain Res 158:378-384, 2004; Heath et al. in J Mot Behav 37:179-185, 2005b), action-bias present in both conditions; thus illusory bias was introduced into during online control. Although primary saccades were influenced by illusory configurations (control conditions; see Binsted and Elliott in Hum Mov Sci 18:103-117, 1999a), illusory bias developed within the secondary "corrective" saccades during experimental trials (i.e., following a veridical primary saccade). These results support the position that a unitary spatial representation underlies both action and perception and this representation is common to both the manual and oculomotor systems.

Susceptibility to kindling and neuronal connections of the anterior claustrum.

The claustrum has been implicated in the kindling of generalized seizures from limbic sites. We examined the susceptibility of the anterior claustrum itself to kindling and correlated this with an anatomical investigation of its afferent and efferent connections. Electrical stimulation of the anterior claustrum resulted in a pattern of rapid kindling with two distinct phases. Early kindling involved extremely rapid progression to bilaterally generalized seizures of short duration. With repeated daily kindling stimulations, early-phase generalized seizures abruptly became more elaborate and prolonged, resembling limbic-type seizures as triggered from the amygdala. We suggest that the rapid rate of kindling from the anterior claustrum is an indication that the claustrum is functionally close to the mechanisms of seizure generalization. In support of our hypothesis, we found significant afferent, efferent, and often reciprocal connections between the anterior claustrum and areas that have been implicated in the generation of generalized seizures, including frontal and motor cortex, limbic cortex, amygdala, and endopiriform nucleus. Additional connections were found with various other structures, including olfactory areas, nucleus accumbens, midline thalamus, and brainstem nuclei including the substantia nigra and the dorsal raphe nucleus. The anatomical connections of the anterior claustrum are consistent with its very high susceptibility to kindling and support the view that the claustrum is part of a forebrain network of structures participating in the generalization of seizures.

The size of non-hippocampal brain regions varies by season and sex in Richardson's ground squirrel.

Sex- and season-specific modulation of hippocampal size and function is observed across multiple species, including rodents. Other non-hippocampal-dependent behaviors exhibit season and sex differences, and whether the associated brain regions exhibit similar variation with sex and season remains to be fully characterized. As such, we examined the brains of wild-caught Richardson's ground squirrels (RGS; Urocitellus richardsonii) for seasonal (breeding, non-breeding) and sex differences in the volumes of specific brain areas, including: total brain volume, corpus callosum (CC), anterior commissure (AC), medial prefrontal cortex (mPFC), total neocortex (NC), entorhinal cortex (EC), and superior colliculus (SC). Analyses of variance and covariance revealed significant interactions between season and sex for almost all areas studied, primarily resulting from females captured during the breeding season exhibiting larger volumes than females captured during the non-breeding season. This was observed for volumes of the AC, mPFC, NC, EC, and SC. Where simple main effects of season were observed for males (the NC and the SC), the volume advantage favoured males captured during the NBr season. Only two simple main effects of sex were observed: males captured in the non-breeding season had significantly larger total brain volume than females captured in the non-breeding season, and females captured during the breeding season had larger volumes of the mPFC and EC than males captured in the breeding season. These results indicate that females have more pronounced seasonal differences in brain and brain region sizes. The extent to which seasonal differences in brain region volumes vary with behaviour is unclear, but our data do suggest that seasonal plasticity is not limited to the hippocampus and that RGS is a useful mammalian species for understanding seasonal plasticity in an ecologically relevant context.

Organization of the septal organ projection to the main olfactory bulb in adult and newborn rats.

The septal organ, which is regarded as an olfactory subsystem, is a small patch of sensory epithelium located ventral to the main olfactory sheet on the septal wall of the nasal cavity. The only consensus to date regarding some proper area of projection of this subsystem is that the septal organ projects to the medial aspect of the main olfactory bulb. The purpose of our study was to analyze precisely the topographical organization of the bulbar projection of the septal organ in adult rats and in 3- to 15-day-old rats following WGA-HRP placements at the level of the septal epithelium. Results show that the septal organ projects exclusively to the posterior half of the main olfactory bulb and its projection area is mainly restricted to the ventromedial bulbar aspect. When the septal organ was fully injected, the pattern of bulbar projection was characterized by two types of glomerular labeling: 1) presence of single heavily labeled glomeruli identified as "septal" glomeruli, since they were mainly built up by afferents coming from the septal organ and (2) presence of a thin network of labeled septal fibers distributed in glomeruli which were mainly formed by afferents coming from the main olfactory epithelium. Although the pattern of mucosobulbar projection of the septal organ is already established in newborns, a significant increase in the number of "septal" glomeruli occurs during the first 15 postnatal days. Anatomical data indicate that even if the projection of the septal organ does not appear completely segregated in the olfactory bulb, this projection is not either exactly similar to that of the main olfactory epithelium.

Cellular expression of H and B antigens in the rat olfactory system during development.

Developmental expression of H and B antigens in the rat olfactory system was studied from the embryonic day 14 up to the postnatal day 30. The H antigen was detected in the olfactory and vomeronasal epithelia as early as fetal day 14, whereas the B antigen first appeared 2 days later. The anti-H reagent reacted strongly with sensory receptors and weakly with supporting cells in both epithelia, whereas the anti-B reagent was specific for olfactory receptors. In the main olfactory epithelium, the H antigen was expressed from fetal day 19 by most of the receptor cells, whereas the B determinant was expressed from fetal day 16 to postnatal day 3 by only a few neuroreceptors mostly located near the epithelial surface. After the postnatal day 3, B positive neurons increased in number from the periphery toward the deeper mucosal layers and they were distributed over 3/4 of the epithelial thickness in 15- and 30-day-old rats. In the main olfactory bulb, a widespread glomerular B staining with variable binding intensity between adjacent glomeruli was already observed at birth. The vomeronasal receptor cells and their axon terminals in the accessory olfactory bulb exhibited a comparable developmental expression of the B antigen. Results suggest that the B antigen could be regarded as a marker of neuronal maturation of both the olfactory and vomeronasal receptor cells; moreover, its first appearance in the receptor cells might be temporally related to the formation of synapses between receptor axons and deutoneurons in the bulb.

The neuroscience of spatial navigation: focus on behavior yields advances.

The development of the water maze as a laboratory approach to the study of spatial navigation has led to a large amount of research on the brain mechanisms of this ecologically important behavior. The procedural simplicity of this task belies its underlying complexity, which can complicate the interpretation of data obtained with the standard water maze procedure. In this review, recent experiments that used novel training procedures and detailed analyses of behavior are evaluated, together with related experiments, to clarify the brain mechanisms involved in this behavior. Pharmacological, lesion, and unit recording experiments demonstrate the existence of forebrain circuits for spatial navigation that are considerably more varied and extensive than was previously proposed, and involve various extrahippocampal structures. The use of novel and specialized procedures, together with a continued detailed focus on the behavior of animals in the maze, appears to be the most promising approach to understanding the mechanisms of spatial navigation.

Expression of netrin-1 and netrin-1 receptor, DCC, in the rat olfactory nerve pathway during development and axonal regeneration.

Netrin-1 is a bifunctional secreted protein that directs axon extension in various groups of developing axonal tracts. The transmembrane DCC (deleted in colorectal cancer) receptor is described as netrin-1 receptor and is involved in the attractive effects of netrin-1. In this study, we examined the spatio-temporal expression patterns of both netrin-1 and DCC in the rat olfactory system at different stages of development and during axonal regeneration following unilateral bulbectomy. High DCC expression was detected on the pioneer olfactory axons as they are extending toward the telencephalon. This expression was transient since from embryonic day 16 onwards, DCC was no longer detected along the olfactory nerve path. From embryonic day 14 until birth, DCC was also expressed within the mesenchyme surrounding the olfactory epithelium. During the same period, netrin-1 protein was detected along the trajectory of olfactory axons up to the olfactory bulb and its expression pattern in the nasal mesenchyme largely overlapped that of DCC. Moreover, netrin-1 continued to be present during the two first post-natal weeks, and a weak protein expression still persisted in the dorso-medial region of the olfactory epithelium in adult rats. While unilateral bulbectomy induced a transient up-regulation of netrin-1 in the lamina propria, particularly in the dorso-medial region of the neuroepithelium, no DCC expression was detected on the regenerating olfactory axons. In the developing olfactory bulb, the extension of mitral cell axons was associated with DCC presence while netrin-1 was absent along this axonal path. DCC was also highly expressed in the newly formed glomeruli after birth, and a weak DCC expression was still detected in the glomerular layer in adult rats. Taken together, these data support the notion that netrin-1, via DCC expressed on axons, may play a role in promoting outgrowth and/or guidance of pioneering olfactory axons toward the olfactory bulb primordium. Moreover, association of netrin-1 with mesenchymal DCC may provide a permissive environment to the growth of both pioneer and later-growing axons. The maintenance of netrin-1 expression in the nasal mesenchyme of adult rats as well as its regional up-regulation following unilateral bulbectomy infer that netrin-1, even in the absence of DCC, may be involved in the process of axonal growth of newly differentiated olfactory receptor neurons probably through the use of other receptors.

Further evidence for a role of the anterior claustrum in epileptogenesis.

The anatomy of the claustrum (CLA) has been well characterized, but its functional role remains uncertain. The results of recent research suggest that the CLA may be part of a network of structures involved in seizure generalization, and we set out to test this idea. To test persistence, seizures were kindled in the anterior CLA. Following a 14-day suspension of kindling, all rats required only one stimulation to evoke a stage 5 seizure. In another experiment, groups of rats received bilateral lesions of the anterior CLA before and after amygdaloid kindling. We found that small lesions of the anterior CLA retard amygdaloid kindling, but do not block the expression of generalized seizures. Lesions produced after amygdaloid kindling resulted in a shorter seizure duration, but had no marked effect on seizure expression. Another group of rats was tested for transfer of kindling between the anterior CLA and contralateral amygdala. We found an asymmetrical transfer of kindling to the CLA from the amygdala wherein amygdaloid kindling facilitated subsequent kindling of the CLA but kindling of the anterior CLA failed to facilitate kindling of the amygdala. The results add support to the notion that the CLA contributes to the development of generalized limbic seizures.

Detailed behavioral analysis of water maze acquisition under systemic NMDA or muscarinic antagonism: nonspatial pretraining eliminates spatial learning deficits.

A detailed behavioral analysis of water-maze acquisition showed that the N-methyl-D-aspartate (NMDA) antagonist NPC17742 and the muscarinic antagonist scopolamine caused sensorimotor disturbances in behaviors required for maze performances and that these correlated with acquisition impairments in both hidden and visible platform versions of the maze in male rats. Behavioral disturbances included thigmotaxic swimming, swimming over and deflecting off the platform, abnormal swim behavior, and hyperactivity. Rats familiar with the behavioral strategies involved in the task performed normally under NPC17742 or scopolamine. The results indicated that drug-induced sensorimotor disturbances contributed to poor acquisition scores in naive rats. NMDA or muscarinic activity may contribute to but do not appear to be essential for spatial learning in the water maze.

Detailed behavioral analysis of water maze acquisition under APV or CNQX: contribution of sensorimotor disturbances to drug-induced acquisition deficits.

N-methyl-D-aspartate (NMDA) receptor antagonists disrupt acquisition of the water maze and cause sensorimotor disturbances. In a detailed behavioral analysis in male rats, it was found that the NMDA antagonist DL-2-aminophosphonovaleric acid (APV) caused sensorimotor disturbances in behaviors required for maze performance and that these correlated with acquisition impairments in both hidden and visible platform versions of the maze. Behavioral disturbances included thigmotaxic swimming, swimming over and deflecting off the platform, abnormal swim behavior, and hyperactivity. Rats familiar with the behavioral strategies involved in the task performed normally under APV. The results are consistent with the known role of NMDA receptors in sensorimotor mechanisms and suggest that drug-induced sensorimotor disturbances contributed to poor acquisition scores in naive rats. NMDA may contribute to but does not appear to be essential for spatial learning in the water maze.

Effects of chronic low-level copper exposure on ultrastructure of the olfactory system in rainbow trout (Oncorhynchus mykiss).

This study investigated the effects of a chronic exposure to a low level of copper on cell populations of the olfactory system in yearling rainbow trout. Fish were sacrificed after 15, 30 and 60 days of copper exposure. Transmission electron microscopy was used to describe the sequence of subcellular changes occurring in three tissues, the sensory epithelium, the olfactory nerve and the olfactory bulb. Data show that a 15-day exposure to 20 micrograms/l of copper causes specific degeneration of all mature receptor cells as well as numerous immature neurons. Moreover, degenerating receptor cells exhibited morphological features of a cell death by apoptosis. After 30 days, and more specifically after 60 days of exposure, numerous clusters of cells were observed in the basal region of the epithelium, suggesting a great mitotic activity in this area. In parallel, an increased number of maturing receptor cells and goblet cells were observed, but no fully mature neurons were noted even after 60 days of exposure. In both the olfactory nerve and the olfactory bulb, the number of degenerating axons and terminals, which was high at 15 days, decreased with time and some process of glomerular reinnervation was detected after 60 days. A reactive hypertrophy of supporting, ensheathing and astrocytic cells was also observed in exposed fish, which demonstrates that these cell types are actively involved in the process of tissue scarring. Even though some signs of neuronal regeneration were reported during the time-course of exposure, indicating some fish acclimation, results raise the question of the olfactory function during such environmental stress.

The NMDA receptor antagonist, NPC 12626, reduces the pronociceptive effects of orphanin FQ and kappa opiate antinociception in the land snail, Cepaea nemoralis.

The heptadecapeptide, orphanin FQ or nociceptin (Phe-Gly-Phe-Thr-Gly-Ala-Arg-Lys-Ser-Ala-Arg-Lys-Leu-Ala-Asn-Gln), originally isolated from rat brain has been identified as an endogenous ligand for the orphan opioid-like receptor. Although orphanin FQ shares some sequence and structural homology with kappa-opioid peptides, it has been speculated to exert its effects through novel nonopioid mechanisms. Kappa opioids have also been suggested to have nonopioid actions in rodents involving the N-methyl-D-aspartate (NMDA) receptor. The present study examined the effects of the competitive NMDA antagonist, NPC 12626, on the antinociceptive effects of the specific kappa-opiate receptor agonist, U69,593, and the pronociceptive effects of orphanin FQ in an invertebrate system, the land snail, Cepaea nemoralis. NPC 12626 had no effect on the basal nociceptive sensitivity of snails, as measured by the latency of response to a thermal (40 degrees C) surface. As reported for rodents, NPC 12626 dose-dependently reduced U69,593-induced antinociception in a manner comparable to that produced by the specific kappa-opiate antagonist, nor-binaltorphimine, while slightly enhancing the antinociceptive effects of the predominately mu-opiate agonist, morphine. Similarly, NPC 12626 dose-dependently reduced the pronociceptive effects of orphanin FQ. These findings with the snail, Cepaea, indicate that NMDA systems/receptors are associated with the mediation of the nociceptive effects of both kappa opioids and orphanin FQ. They suggest an early evolutionary development and phylogenetic continuity of NMDA opioid and related neuropeptide interactions in the mediation of nociception.

Polypropylene pellets as an inexpensive reusable substitute for milk in the Morris milk maze.

A new inexpensive opaquing agent for the Morris milk maze is described. Small light-weight polypropylene pellets that float on the surface of the water were used to eliminate visual cues about the location of the hidden platform without impeding swimming or the use of distal spatial cues. Results obtained using the pellets are identical to those obtained with milk powder as an opaquing agent. An automatic tracking system works as well with the pellet as with the milk version of the maze.

Testing hypotheses of spatial learning: the role of NMDA receptors and NMDA-mediated long-term potentiation.

The role of NMDA receptors and NMDA-mediated hippocampal long-term potentiation (LTP) in spatial learning was studied in rats using the competitive, systemically administered NMDA receptor antagonists CGS19755 ((+/-)-cis-4-phosphonomethyl-2-piperidine carboxylic acid) and NPC17742 (2R,4R,5S-2-amino-4,5-(1,2-cyclohexyl)-7-phosphonoheptanoic acid). CGS19755 caused sensorimotor disturbances and disrupted acquisition of the water maze in naive rats. The sensorimotor disturbances were greatly reduced and maze learning was normal in spite of the blockade of dentate gyrus LTP by CGS19755 in rats that had first been familiarized with the general task requirements by non-spatial pretraining. In a second experiment, antagonism of NMDA receptors caused small, but reliable, impairments in Y-maze and visible platform visual discrimination tasks. The results indicate that NMDA receptors are not crucial for water maze acquisition using a spatial learning strategy, and that NMDA antagonists cause visual and other sensorimotor disturbances in naive rats that could help account for their poor performance in this task.

Topographical projection of the septal organ to the main olfactory bulb in rats: ontogenetic study.

Using the horseradish peroxidase (HRP) retrograde tracing method, we have studied the topographical organization of the projection of the septal organ to the main olfactory bulb in rats varying in age from 22 fetal days up to 15 postnatal days. For all developmental stages studied, receptor cells of the septal organ had their axons ending in a relatively circumscribed region of the olfactory bulb, which was the posterior ventromedial bulbar aspect. In younger animals, olfactory receptor cells were observed within the epithelial area isolating the septal organ from the olfactory epithelium, whereas this area was reported to be an exclusive respiratory region in adult rats. The complete disappearance of these receptor cells noted in 12-day-old rats was related to some ontogenetic process.

Ontogenesis of the functional activity of guinea-pig olfactory bulb: autoradiographic study with the 2-deoxyglucose method.

An ontogenetic study of [14C]2-deoxyglucose (2-DG) uptake within the olfactory bulbs was performed in 1-, 4-, 7- and 21 day-old guinea-pigs exposed to a pure chemical odor, ethyl acetoacetate (EAA). Whatever the age studied, the patterns of glomerular activity are characterized by restricted spots which extend along the bulb, and by sheets of increased density overlapping 10-30 contiguous glomeruli, found only on the lateral aspect of the bulb. Even if the main features of the 2-DG patterns related to EAA are already present at birth, a perceptible evolution of these patterns is observed during the first 3 postnatal weeks. The changes include on the one hand, an increase of the spot-like glomerular labeling which appears particularly prominently on the medial and dorsal aspects. On the other hand, whereas the restricted spots overlaying 1-3 glomeruli become more numerous with age, a decrease in size and in extension of the sheet-like glomerular activity is noted. The results confirm the high maturation level of the olfactory bulbs in newborn guinea-pigs. Some implications related to the mainly prenatal maturation of the olfactory system are discussed.

Metabolic mapping of functional activity in the olfactory projections of the rat: ontogenetic study.

An ontogenetic study of the uptake of [14C]2-deoxy-D-glucose (2-DG) within the direct olfactory bulb projections and the tertiary olfactory projections was performed on rats of 1, 9 and 21 days old. Animals were exposed either to ethyl acetoacetate or to nest odor. In newborns, most of the direct olfactory bulb projections - anterior olfactory nucleus, anterior part of the olfactory tubercle, piriform cortex and nucleus of the lateral olfactory tract - appear labelled on films and therefore seem functional. No evidence of 2-DG uptake can be brought out in the cortical amygdala nucleus. AS regards the tertiary olfactory projections, there is no apparent functional activity, neither in the medio-dorsal and medio-ventral thalamic nuclei nor in the hypothalamic nuclei, e.g. the lateral preoptic area and the lateral hypothalamus. In 9-day-old pups, the direct olfactory bulb projections and the tertiary olfactory projections appear well-contrasted. Moreover, the patterns of labelling within the direct olfactory bulb projections are comparable to those observed in 21-day-old rats and in adult. These data are correlated with the postnatal development of the discriminating ability of the rat.

Ontogenesis of the functional activity of rat olfactory bulb: autoradiographic study with the 2-deoxyglucose method.

An ontogenetic study of the uptake of [14C]2-deoxyglucose (2-DG) within the olfactory bulb was performed on rats of 3 age groups, 1, 9 and 21 days. Animals were exposed either to ethyl acetoacetate (EAA) or to a nest odor. Already in newborns, a glomerular activity characterized by small spots of increased 2-DG uptake, appeared in response to either odor stimulation. An ontogenetic development of this glomerular activity was observed with age: whereas the labeled glomerular foci were scanty in newborns, their number constantly increased with age until weaning; moreover, an increased proportion of foci overlaying 2 or 3 single glomeruli was noted in parallel with the postnatal maturation of the olfactory system. For the 3 age groups, whatever the odor stimulus, the glomerular activity seemed located in 2 main regions of the olfactory bulb, the lateral aspect and the posterior part of the medial aspect of the bulb. In newborns, no clear difference could be brought out between the patterns of glomerular activation related to EAA and to nest odor, respectively. In 9-day-old rats, the spatial patterns of distribution associated with the 2 odors were overlapping, but nevertheless different. These data are correlated with the postnatal maturation of the olfactory system.