What are brain networks and why do they matter for women?

When you think about your brain at work, focusing on a task, reacting to a surprise, or drifting into daydream, it’s tempting to picture one “control center” doing the job. In reality, almost nothing in the brain works alone. Instead, your thoughts, feelings, and actions emerge from brain networks: groups of regions working together, like a well-practiced team, to accomplish specific goals.

Just as no single player wins a match without teammates, no single brain area “completes” a function entirely on its own. Most everyday activities (answering a tricky email, remembering a friend’s birthday, deciding to go for a run) require multiple regions working in sync.

The big three brain networks: CEN, SN, and DMN

Neuroscientists often talk about three major large-scale brain networks. Think of these as three specialist teams that hand the ball back and forth, and we all have them:

• Central Executive Network (CEN): Your focus and problem-solving network. It helps you hold information in mind, weigh options, and make decisions. When you’re planning your week, resisting the urge to check your phone, or calculating your budget, the CEN is in charge.
• Salience Network (SN): Your attention switchboard. It constantly scans for what’s important, both in the world and in your own body, and decides what to prioritize next. The SN is why you notice your name being spoken in a noisy room, or why your mood shifts when you sense pain or tension.
• Default Mode Network (DMN): Your resting and reflecting network. It switches on when your mind wanders (i.e. when you’re not doing anything in particular!), when you’re imagining the future, or when you’re processing your own memories and identity.

These networks don’t run in isolation. They coordinate constantly, with the SN often deciding when to flip the brain from introspection (DMN) into action (CEN), or back again. Essentially, your brain usually has one main network dominating, and “nodes”, or connections between networks, allow you to switch between them.

The role of nodes in brain networks

One of the most important of these hubs, “nodes” is the dorsolateral prefrontal cortex (DLPFC). You may have heard of it - as it is exactly the part of the brain that Nettle™ stimulates! The DLPFC is part of the CEN but also tightly connected to other networks, and acts like a bridge:

• It can help the brain exit the DMN when it’s time to stop daydreaming and start focusing.
• It can also dampen or regulate signals from the SN, preventing overreaction to minor distractions or stressors, when your brain incorrectly judges something random/insignificant as important.

Other nodes, like parts of the anterior insula (in the SN) or posterior cingulate cortex (in the DMN), play similar “switchboard” roles. This switching function is critical - it’s how the brain moves seamlessly between self-reflection, problem-solving, and reacting to important events. However, only the DLPFC is accessible through at-home brain stimulation, and is the reason behind NettleTM’s efficacy for managing mood and cognitive symptoms associated with periods.

How hormones shape brain networks in women

Here’s where it gets fascinating: in women, these networks aren’t fixed. Their connectivity and balance shift in response to hormonal changes: across the menstrual cycle, during and after pregnancy, and throughout menopause.

• Across the menstrual cycle: In the luteal phase, subtle progesterone-driven changes can affect the CEN’s efficiency in regulating attention and mood, while the DMN may show altered connectivity linked to self-focused thinking.
• During pregnancy and postpartum: DMN adaptations may help support maternal bonding and heightened responsiveness to emotional cues.
• In menopause: Declines in estrogen can influence both CEN and SN connectivity, sometimes affecting working memory, focus, and emotional regulation .

These shifts are not malfunctions. They are dynamic recalibrations allowing women to adapt to their changing bodies and minds. However, they can make certain cognitive or emotional tasks feel easier at some times and harder at others. If you experience brain fog or low mood during PMS, or are in perimenopause and struggling with anxiety, this may feel oddly familiar. Understanding this ebb and flow means you can work with your brain’s natural rhythms instead of feeling like you’re constantly fighting them.

Tracking your brain’s networks without a scan

You don’t need an fMRI (a type of brain scan that measures activity by detecting changes in blood flow) to sense what your brain networks are doing. By tracking your attention, mood, and energy, ideally alongside your cycle, you can start to map your own network “signatures.”

Patterns might emerge: maybe your focus is razor-sharp mid-cycle, but you’re more distractible just before your period. Or perhaps your creativity peaks when your DMN is more active, while structured problem-solving feels harder. This isn’t “overthinking” - it’s learning how your brain’s teams rotate and adjust.

From understanding to action

At Samphire Neuroscience, we believe that knowledge is the first intervention. That’s why our app (Samphire) helps you log experiences in a way that makes your brain’s shifting patterns visible and easier to understand. This awareness is a first step in working with your networks, not against them.

For those whose cycle-linked network changes cause distress, like mood swings, indecision, or emotional sensitivity, Nettle™ can go a step further. By delivering gentle, non-invasive brain stimulation to key nodes between brain networks, Nettle supports steadier top-down control. This means your networks can stay better balanced through hormonal shifts, without altering otherwise healthy hormone cycles.

In other words: you can’t stop your networks from adapting; but with the right tools, you can help them adapt in your favour.

References

• Pletzer, B., Kronbichler, M., Aichhorn, M., Bergmann, J., Ladurner, G., & Kerschbaum, H. H. (2010). Menstrual cycle and hormonal contraceptive use modulate human brain structure. Brain Research, 1348, 55–62.

• Pessoa, L. (2014). Understanding brain networks and brain organization. Physics of Life Reviews, 11(3), 400–435.

• Park, H.-J., & Friston, K. (2013). Structural and functional brain networks: From connections to cognition. Science, 342(6158), 1238411.

• Mosconi, L., Berti, V., Dyke, J., et al. (2021). Menopause impacts human brain structure, connectivity, energy metabolism, and amyloid-beta deposition. Scientific Reports, 11, 10867.

• Chu, T., Li, Y., Che, K., et al. (2022). Pregnancy leads to changes in the brain functional network: A connectome analysis. Brain Imaging and Behavior, 16(2), 811–819.

• Hoekzema, E., van Steenbergen, H., Straathof, M., et al. (2022). Mapping the effects of pregnancy on resting state brain activity, white matter microstructure, neural metabolite concentrations and grey matter architecture. Nature Communications, 13, 6931.

• Dufford, A. J., Erhart, A., & Kim, P. (2019). Maternal brain resting-state connectivity in the postpartum period. Journal of Neuroendocrinology, 31(5), e12737.

• Mueller, J. M., Pritschet, L., Santander, T., Taylor, C. M., Grafton, S. T., Jacobs, E. G., Carlson, J. M. (2021). Dynamic community detection reveals transient reorganization of functional brain networks across a female menstrual cycle. Network Neuroscience, 5(1), 125–144.

• Peña-Gómez, C., Sala-Lonch, R., Junqué, C., Clemente, I. C., Vidal, D., Bargalló, N., Falcón, C., Valls-Solé, J., Pascual-Leone, Á., & Bartrés-Faz, D. (2012). Modulation of large-scale brain networks by transcranial direct current stimulation evidenced by resting-state functional MRI. Brain Stimulation, 5(3), 252–263.