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I believe that as a young person living in the 21st century, everyone is no stranger to learning this social activity. As a basic, non-reproductive function, learning is an activity that can be performed by both sexes. So can we assume that the memories and underlying mechanisms between different genders are also similar?
But for now, some memory tasks are known to exist, and there are indeed gender differences. For example, in space tasks with multiple approaches to solving, females and females are more likely to choose landmark cues, while males and males are more inclined to spatial cues. It has also been proven that in various species, males typically show a distinctly better memory than females in space missions.
Researchers generally believe that sex differences in memory plasticity mechanisms are caused by increases and fluctuations in estrogen and progesterone levels after puberty, especially in women. This suggests that the memory mechanisms of prepubertal animals, males and females should be similar.
Still, sex differences in the brain are driven by hormones as well as sex chromosomes, which in turn prevents us from thinking of prepubertal memory mechanisms as similar.
Long-term enhancement (LTP) refers to a long-term increase in synaptic efficacy, closely related to learning-related forebrain rhythms.
In Nature Neuroscience in January 2022, Aliza A Le and colleagues [1] focused on the currently under-studied, but very critical, puberty, looking at when sex differences in LTP and memory arise and what happens during this critical developmental period that causes these differences.
Surprisingly: Contrary to expectations, they found significant gender differences in prepubertal memory, and even stranger: the differences were directed in the opposite direction to those of adult animals.
Manifested in young female mice and rats exhibiting lower LTP thresholds than males, Theta Burst Stimulation (TBS) induces strong LTP in female animals but not in males. Similarly, in both spatial memory tasks, prepubertal females showed super-strong memories of both object recognition tasks and plot-like odor memory tasks, while males failed to learn these tasks.
Figure 1: Differences in LTP and memory between female (left) and male (right) mice and rats before puberty (upper) and post-(lower).
However, after puberty, the differences in LTP and these memory performances are reversed — young adult females exhibit higher LTP thresholds and require additional training to learn spatial tasks, while younger adult males exhibit lower LTP thresholds and complete spatial memory tasks more quickly. But this does not mean that adult females become unable to learn after puberty, and in nonspatial memory tasks, females show strong memory.
Aliza A Le et al. also showed that during puberty, changes in female and male hippocampal LTPs and memory are driven by different mechanisms. After experiencing puberty, the number of alpha5-GABAA receptor subunits of inhibitory synapses in the CA1 region of females increases, the inhibitory postsynaptic current increases and the NMDA receptor (NMDAR)-mediated LTP component decreases, blocking the α5-GABAA receptor subunit using allosteric modulators is able to salvage TBS-induced LTP and the spatial memory capacity of adult females, but has no effect on prepubertal females, indicating that input from CA3 to CA1, The increase in α5-GABAA mediates changes in LTP and memory during puberty in females.
Inhibition of the α5-GABAA receptor has a similar enhancement effect in prepubertal and postpubertal males, but changes in the α5-GABAA receptor do not enhance POSTPU and spatial memory in males after puberty.
This paper also repeatedly validated the sex differences in LTP: adult females rather than males need to α estrogen receptors (ERα), and further found that this sex difference does not appear during adolescence. Conversely, prepubertal females also need ERα to achieve LTP. While the α5-GABAA subunit receptor enhances feed-forward inhibition, the authors believe that an increase in ERα in adult female hippocampus can partially compensate for NMDAR-mediated LTP loss.
By highlighting pre-adolescent sex differences and patterns of post-adolescent change in male and female sex, Aliza A Le et al. provide a framework for understanding prepubertal challenges as well as various sex-biased disorders after puberty (e.g., adolescent stress and immunocompromisedness).
Because numerous studies have shown that chronic stress during adolescence only impairs hippocampal-dependent learning and synaptic plasticity in adult women [2]; maternal immune activation only impairs cognitive function in adult men [3].
Summary
This paper is a refreshing solution to the mechanisms of memory and synaptic plasticity function specific to women, and presents a number of references to the role of circulating hormones in triggering or maintaining sex differences around puberty. From a behavioral point of view, perhaps we should also ask: How does the sex difference reversal of synaptic plasticity in adolescence interact with other sex differences that arise during this period? Includes an increased risk of anxiety and depression.
Adolescence is indeed a key stage of growth for every teenager, parent schools should pay special attention to the education of this node, to teach according to their aptitudes, to give full play to individual advantages, I believe that every child can shine in various fields under the correct guidance!
bibliography
1. Le, A.A., et al., Prepubescent female rodents have enhanced hippocampal LTP and learning relative to males, reversing in adulthood as inhibition increases. Nat Neurosci, 2022. 25(2): p. 180-190.
2. Hyer, M.M., et al., Chronic adolescent stress causes sustained impairment of cognitive flexibility and hippocampal synaptic strength in female rats. Neurobiol Stress, 2021. 14: p. 100303.
3. Gogos, A., et al., Sex differences in the effect of maternal immune activation on cognitive and psychosis-like behaviour in Long Evans rats. Eur J Neurosci, 2020. 52(1): p. 2614-2626.
Compiled by Zoey's Shortsword (Brainnews Creative Team)
Reviewer: Simon (Brainnews Editorial Board)