New Neurobiological Processes Occurring During Puberty

New study reveals that sex differences in learning and memory mechanisms are triggered by biological events that occur during puberty, as studied by the researchers of the University of California, Irvine.

These findings show prepubescent female rodents have much better hippocampal long-term potentiation (LTP) and spatial learning than same-age males, but puberty has opposite consequences for synaptic plasticity in the two sexes.

‘Sex differences in learning and memory mechanisms are triggered by biological events that occur during puberty.’

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The results of this study was recently published in Nature Neuroscience.

Since the late-19th century, there has been a general consensus in the scientific community that men perform better than women in spatial tasks, while women excel in learning tasks related to verbal meaning, while there is a general debate about why there is difference.

“The surprising conclusion from our results is that the polarization of sex differences in hippocampal synapses and related learning reverses in females and males from before to after puberty,” said Christine Gall, PhD, co-corresponding author, and distinguished professor and chair of anatomy and neurobiology at the UCI School of Medicine.

“This occurs because of distinct developmental changes. Thresholds for plasticity and encoding spatial information increase in females and decease in males.”

Puberty is a critical landmark in brain maturation and results in a wide variety of sex differences in behavior, but little is known about how it affects the substrates for memory encoding.

Researchers have identified a female mechanism that increases LTP levels and decreases spatial memory before and after puberty. Gender differences have been demonstrated for hippocampus-based processes and are driven by different basic mechanisms.

In females only, inhibitory syncope in the CA1 field of the hippocampus reveals an increase in the levels of GABAA receptors containing the a5 subunit. This increase is associated with synaptic plasticity and increased inhibition of synaptic plasticity and memory. A5 receptors are associated with anxiety, which are subjected to changes at the beginning of the estrus cycle. The researchers found that pharmacological suppression of a5-GABAA receptors restored LTP and memory encoding in females to pre-puberty levels. “Our team proposes that the emergent female pattern may favor learning in complex circumstances while the emergent male pattern favors rapid acquisition of simpler material. This idea suggests that optimal teaching strategies need to reflect previously unsuspected brain differences between the sexes and how these are dramatically adjusted during puberty,” Gall said.

“The vast majority of studies have begun with analyses of young adult male rodents. Females use somewhat different memory mechanisms than do males and therefore may respond differently to drugs and gene mutations. This new research demonstrates the need for new sexually differentiated approaches for the development of therapeutic treatments and their applications at different life stages.”

Further research will be conducted to determine whether changes in the sex-specific LTP range identified in the hippocampus during postpartum life are evident in other areas of the brain and affect the encryption of different types of memory.

Anatomy & Neurobiology Graduate Student Aliza Le, Researcher Julie Lauterborn, Associate Project Scientist Yousheng Jia, Assistant Project Scientist Weisheng Wang, Postdoctoral Researcher Conor Cox, and Psychiatry & Human Behavior Professor and Co-corresponding Author Gary Lynch, all from the UCI School of Medicine, contributed to this study.

This work has been funded by National Institute of Mental Health training grant T32-MH119049-02; Eunice Kennedy Shriver National Institute of Child Health and Human Development grant HD-089491; National Science Foundation grant BCS-1941216; National Institute on Drug Abuse grant DA-044118; Office of Naval Research grant N00014182114; and National Institutes of Health grant T32 AG00096-34.

Source-Medindia