I don't want to get into any copyright trouble here by posting the whole article, but I think a couple of the boxes are well worth the risk, because As Wolbers and Hegarty note, the individual differences model they propose focuses on internal, neuro-cognitive differences, rather than the nature-nurture questions that might underly them. But the boxes bring up some of these issues:
Sex differences
There have now been several demonstrations of a human male advantage in virtual maze tasks and in spatial learning from navigational experience [11,14,19,53,54], somewhat paralleling sex differences in animal species [55].
Although sex differences are sometimes more pronounced when tested in simulated environments [14,54], they occur with testing in both real and virtual environments [56] and when the analyses control for video game experience that is often greater in males than in females [19]. Superior performance by males is not found in all tasks at the environmental scale. It is typical when people learn spatial layout from direct experience, but not when they learn from maps, and is also more pronounced in measures of survey knowledge than in measures of route knowledge [53,56]. Furthermore, female performance can vary with hormonal fluctuations, such that women can perform as well as males during low-estrogen stages of their cycle [57]. Object location memory often shows an advantage in favor of females, although this can depend on the type of objects, whether self-motion is involved, and the degree of metric precision required [58,59].
Although sex differences are sometimes more pronounced when tested in simulated environments [14,54], they occur with testing in both real and virtual environments [56] and when the analyses control for video game experience that is often greater in males than in females [19]. Superior performance by males is not found in all tasks at the environmental scale. It is typical when people learn spatial layout from direct experience, but not when they learn from maps, and is also more pronounced in measures of survey knowledge than in measures of route knowledge [53,56]. Furthermore, female performance can vary with hormonal fluctuations, such that women can perform as well as males during low-estrogen stages of their cycle [57]. Object location memory often shows an advantage in favor of females, although this can depend on the type of objects, whether self-motion is involved, and the degree of metric precision required [58,59].
Intriguingly, there appear to be qualitative differences in the environmental cues and strategies that women and men use during navigation and orientation. Women typically report navigating on the basis of local landmarks and familiar routes, whereas men report using cardinal directions, environmental geometry and metric distances [60,61], a result which has been supported by neuroimaging findings [62].
Although women do not differ from men in dependence on or ability to use landmarks, they depend less on geometry when reorienting to an environment [11] and are relatively more impaired at finding a target based on directional cues (i.e. environmental slope, [60]). Women also require more environmental cues to remain oriented in an environment [10] and have difficulty following navigation directions based on cardinal directions and metric distances [21].
Thus, strategy preferences can reflect proficiency differences between the sexes in use of geometric cues, as well as relative cue salience. In terms of causal factors, there is increasing evidence for the influence of sex hormones on navigational performance [25,57,63–65], and several evolutionary theories have been proposed [66]. However, men and women also differ in navigational experience [54,67] and there is some evidence that wayfinding anxiety mediates the differences between the sexes in navigational performance [67].
And this one:
The impact of genetic factors
The structural and functional integrity of neuronal circuits is jointly determined by environmental and physiological factors, the latter including genetic predispositions. Genetic association studies in animals have demonstrated various genetic influences on hippocampal processes involved in spatial navigation [78]. Specific examples include the brain derived neurotrophic factor (BDNF) that is known for its role in activity-dependent plasticity and hippocampal long-term potentiation.
Both processes are thought to underlie the formation of new learning and memories, and suppression of BDNF synthesis impairs spatial learning in rodents [79]. Although direct effects of BDNF on human navigational learning remain to be established, BDNF modulation of hippocampal engagement is a key process in the initial acquisition of information about novel indoor and outdoor scenes [80]. In addition, polymorphisms of the BDNF gene have also been associated with hippocampal volume [81], which could contribute to preferences for specific strategies in a navigational task [46].
The structural and functional integrity of neuronal circuits is jointly determined by environmental and physiological factors, the latter including genetic predispositions. Genetic association studies in animals have demonstrated various genetic influences on hippocampal processes involved in spatial navigation [78]. Specific examples include the brain derived neurotrophic factor (BDNF) that is known for its role in activity-dependent plasticity and hippocampal long-term potentiation.
Both processes are thought to underlie the formation of new learning and memories, and suppression of BDNF synthesis impairs spatial learning in rodents [79]. Although direct effects of BDNF on human navigational learning remain to be established, BDNF modulation of hippocampal engagement is a key process in the initial acquisition of information about novel indoor and outdoor scenes [80]. In addition, polymorphisms of the BDNF gene have also been associated with hippocampal volume [81], which could contribute to preferences for specific strategies in a navigational task [46].
A second route for genetic predispositions to affect hippocampal processing and hence navigational abilities involves pattern separation. To distinguish between environments or regions within an environment, hippocampal subfields create orthogonal representations [82]. This ability to pattern separate is directly related to neurogenesis in the dentate gyrus, which is in turn controlled by several genes [83]. Given that ablation of pattern separation in mice induces deficits in spatial learning in a radial arm maze [84], it appears probable that individual genetic predispositions that control hippocampal neurogenesis can have direct effects on
navigational abilities via differences in pattern separation.
Finally, as spatial navigation also involves executive control processes that involve subdivisions of the prefrontal cortex [33,85], genes that regulate prefrontal functioning should have the potential to influence navigational abilities. For example, given the dopaminergic metabolism in the prefrontal cortex, the gene producing catechol-O-methyltransferase (COMT) is thought to have a major impact on functions such as the manipulation of information [86] and the resolution of uncertainty [87], both of which are involved in spatial navigation. Moreover, COMT polymorphisms also affect prefrontal–hippocampal coupling [88], which is crucial for navigational planning [35].
Finally, as spatial navigation also involves executive control processes that involve subdivisions of the prefrontal cortex [33,85], genes that regulate prefrontal functioning should have the potential to influence navigational abilities. For example, given the dopaminergic metabolism in the prefrontal cortex, the gene producing catechol-O-methyltransferase (COMT) is thought to have a major impact on functions such as the manipulation of information [86] and the resolution of uncertainty [87], both of which are involved in spatial navigation. Moreover, COMT polymorphisms also affect prefrontal–hippocampal coupling [88], which is crucial for navigational planning [35].
Taken together, although the existing animal findings strongly suggest genetic influences on navigational abilities, a direct demonstration remains to be established in humans. Given the complexity of spatial navigation, genetic variability is likely to affect navigational functions at multiple processing stages.
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