Sex differences in learning from exploration

Chen, Cathy S.; Knep, Evan; Han, Autumn; Ebitz, R. Becket; Grissom, Nicola M.

doi:10.7554/elife.69748

Cited by 54 publications

(92 citation statements)

References 50 publications

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“…Pretraining has also been shown to reduce sex differences (Jonasson, 2005; Perrot-Sinal et al, 1996). Chen et al (2021) showed that sex in mice exerted a larger influence on decision-making in learning acquisition portion of tasks than once the task was learned. These results jointly suggest significant differences in decision-making between male and female rats which are more apparent during learning than memory.…”

Section: Discussionmentioning

confidence: 99%

Sex and estrous cycle in memory for sequences of events in rats.

Jayachandran¹,

Langius²,

Vertes³

et al. 2022

Behavioral Neuroscience

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The ability to remember sequences of events is fundamental to episodic memory. While rodent studies have examined sex and estrous cycle in episodic-like spatial memory tasks, little is known about these biological variables in memory for sequences of events that depend on representations of temporal context. We investigated the role of sex and estrous cycle in rats during training and testing stages of a cross-species validated sequence memory task (Jayachandran et al., 2019). Rats were trained on a two four-odor sequence memory task delivered on opposite ends of a linear track. Training occurred in six successive stages starting with learning to poke in a nose-port for ≥1.2 s; eventually demonstrating sequence memory by holding their nose in the port ≥1 s for in-sequence odors and <1 s for out-of-sequence odors. Performance was analyzed across sex and estrous cycle (proestrus, estrus, metestrus, and diestrus), the latter being determined by cellular composition of a daily vaginal lavage. We found no evidence of sex differences in asymptotic sequence memory performance, similar to humans performing an analogous task (Reeders et al., 2021). Likewise, no differences in sequence memory performance were found across the estrous cycle. Some caveats are that males acquired out-of-sequence trials faster during training with a 3-odor sequence, but this apparent advantage did not carry over to the 4-odor sequence. Additionally, males had shorter poke times overall which seem consistent with a decreased overall response inhibition because they occurred regardless of sequence demands. Together, these results suggest sex and estrous cycle are not major factors in sequence memory capacities.

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Section: Discussionmentioning

confidence: 99%

Sex and estrous cycle in memory for sequences of events in rats.

Jayachandran¹,

Langius²,

Vertes³

et al. 2022

Behavioral Neuroscience

View full text Add to dashboard Cite

show abstract

Section: Discussionmentioning

confidence: 99%

Sex differences in contextual pattern separation, neurogenesis, and functional connectivity within the limbic system

et al. 2022

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Background Females are more likely to present with anxiety disorders such as post-traumatic stress disorder (PTSD) compared to males, which are associated with disrupted hippocampal integrity. Sex differences in the structure and function of hippocampus exist. Here, we examined sex differences in contextual pattern separation, functional connectivity, and activation of new neurons during fear memory. Methods Two-month-old male and female Sprague-Dawley rats were injected with the DNA synthesis markers, iododeoxyuridine (IdU) and chlorodeoxyuridine (CldU) 3 weeks and 4 weeks before perfusion, respectively. One week after CldU injection, the rats underwent a context discrimination task in which rats were placed in context A (shock) and context A’ (no shock) every day for 12 days. On the test day, rats were placed in the shock context (context A) to measure fear memory and expression of zif268, an immediate early gene across 16 different limbic and reward regions. Repeated-measures or factorial analysis of variance was conducted on our variables of interest. Pearson product-moment calculations and principal component analyses on zif268 expression across regions were also performed. Results We found that females, but not males, showed contextual discrimination during the last days of training. On the test day, both sexes displayed similar levels of freezing, indicating equivalent fear memory for context A. Despite similar fear memory, males showed more positive correlations of zif268 activation between the limbic regions and the striatum, whereas females showed more negative correlations among these regions. Females showed greater activation of the frontal cortex, dorsal CA1, and 3-week-old adult-born dentate granular cells compared to males. Conclusions These results highlight the importance of studying sex differences in fear memory and the contribution of adult neurogenesis to the neuronal network and may contribute to differences in susceptibility to fear-related disorders such as post-traumatic stress disorder. Highlights Female rats, but not male rats, show faster discrimination during a contextual pattern separation task. Three-week-old adult-born neurons are more active in response to fear memory in females compared to males. Females had greater neural activation compared to males in the frontal cortex and dorsal CA1 region of the hippocampus in response to fear memory. Males and females show distinct patterns in functional connectivity for fear memory across limbic regions. Males have many positive correlations between activated new neurons of different ages between the dorsal and ventral hippocampus, while females show more correlations between activated new neurons and other limbic regions.

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“…In contrast, the two contexts in the present study shared the same geometric cues, making it more difficult for rats relying on geometric cues to discriminate between the two contexts. Together these results suggest that males and females process contextual information differently and/or males and females rely on different learning strategies during a fear-conditioning context discrimination task so that the availability of favored memory cues influences their performance during a given task [44,45]. Further research is needed to determine whether there are sex differences in strategy use during a contextual learning and to determine what types of memory cues contribute to the sex difference in the ability for contextual pattern separation.…”

Section: Discussionmentioning

confidence: 99%

Sex differences in contextual pattern separation, activation of new neurons, and functional connectivity within the limbic system

Yagi

Lee

Truter

et al. 2022

Preprint

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Sex differences in the structure and function of hippocampus exist. Here, we examined sex differences in contextual pattern separation, functional connectivity, and activation of new neurons during fear memory. Two-month-old male and female Sprague-Dawley rats were injected with the DNA synthesis markers, iododeoxyuridine (IdU) and chlorodeoxyuridine (CldU) three weeks and four weeks before perfusion, respectively. One week after CldU injection, the rats underwent a context discrimination task in which rats were placed in context A (shock) and context A' (no shock) every day for 12 days. On the test day, rats were placed in the shock context (context A) to measure fear memory and expression of zif268, an immediate early gene across 15 different limbic and reward regions. We found that females, but not males, showed contextual discrimination during the last days of training. On the test day, both sexes displayed similar levels of freezing, indicating equivalent fear memory for context A. Despite similar fear memory, males showed more positive correlations of zif268 activation between the limbic regions and the striatum, whereas females showed more negative correlations among these regions. Females showed greater activation of the frontal cortex, dorsal CA1, and 3-week-old adult-born dentate granular cells compared to males. These results highlight the importance of studying sex differences in fear memory and the contribution of adult neurogenesis to the neuronal network and may contribute to differences in susceptibility to fear related disorders such as post traumatic stress disorder.

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Sex differences in learning from exploration

Cited by 54 publications

References 50 publications

Sex and estrous cycle in memory for sequences of events in rats.

Sex and estrous cycle in memory for sequences of events in rats.

Sex differences in contextual pattern separation, neurogenesis, and functional connectivity within the limbic system

Sex differences in contextual pattern separation, activation of new neurons, and functional connectivity within the limbic system

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