BG3 Brain Puzzle Solution (Necrotic Laboratory)
How to solve the brain puzzle in Baldur's Gate 3's Necrotic Laboratory — connect the Reason, Memory, Emotion, and Speech nodes, plus the PS5/Xbox L3 cursor fix.
Quick Answer
The brain (brain-link) puzzle in the Necrotic Laboratory at the end of Act 2 asks you to connect four neural nodes — Reason, Memory, Emotion, and Speech — by tracing the colored threads. On controller, press L3 (left stick) to enter Cursor Mode first or you can't select nodes. Choose 'Begin to manipulate the mind' at the console, then route Reason along the uppermost path, Memory down to the floor and back up, Emotion through the center with a hard left, and Speech to fill the last open link. Completing it opens the door to the Blade of Oppressed Souls.
Jump to a moment 6 chapters
The brain-link puzzle in the Necrotic Laboratory is one of Act 2’s most confusing moments. Here’s how to connect all four neural nodes — plus the controller fix that trips up console players.
Short Answer
The brain (brain-link) puzzle in the Necrotic Laboratory at the end of Act 2 asks you to connect four neural nodes — Reason, Memory, Emotion, and Speech — by tracing the colored threads. On controller, press L3 (left stick) to enter Cursor Mode first, or you can’t select nodes. Choose “Begin to manipulate the mind” at the console, then route Reason along the uppermost path, Memory down to the floor and back up, Emotion through the center with a hard left, and Speech to fill the last open link. Completing it opens the door to the Blade of Oppressed Souls.
Key Takeaways
- The puzzle is in the Necrotic Laboratory (Illithid Oubliette) beneath Moonrise Towers, late Act 2.
- Controller fix: press L3 (left stick) to enter Cursor Mode or you can’t click the links.
- At the console choose “Begin to manipulate the mind” to start the connect-the-dots sequence.
- Four nodes to wire: Reason, Memory, Emotion, Speech.
- Completing it opens the secret door to the Blade of Oppressed Souls / Waking Mind loot.
- Nearby, the Slack-Skinned Head grants the Githzerai Mind Barrier buff (advantage on INT saves).
How Do You Fix the Brain Puzzle on PS5 / Xbox?
Press L3 (the left stick) to enter Cursor Mode. On controller you can’t select the neural links by default — pressing L3 switches to Cursor Mode so you can click the nodes. Without it, the puzzle simply won’t respond, which is why so many console players think it’s bugged.
What Is the Brain Puzzle Solution?
Trace each colored thread along its path, then fill the last open link. Interact with the console and pick “Begin to manipulate the mind,” then wire the nodes in turn:
| Node | Path |
|---|---|
| Reason | Take the uppermost path — the upper link just above, straightforward to follow |
| Memory | Head down toward the floor center, then back up to the ceiling, then the right node |
| Emotion | Go straight into the center, make a hard left before the middle gap, follow the line to the back and loop toward center |
| Speech | Fill the remaining open link — it’s the last connection left |
When all four threads are connected, the puzzle completes and the door unlocks, giving you access to the loot inside.
Bonus: use the Slack-Skinned Head nearby to gain the permanent Githzerai Mind Barrier buff — advantage on Intelligence saving throws.
FAQ
Why isn’t the brain puzzle working on PS5 or Xbox?
You’re not in Cursor Mode. Press L3 (the left stick) to enable it, then you can select the neural nodes to connect them.
Where is the brain puzzle in Baldur’s Gate 3?
In the Necrotic Laboratory (Illithid Oubliette) beneath Moonrise Towers, near the end of Act 2.
What are the four brain puzzle nodes?
Reason, Memory, Emotion, and Speech. Each is a colored thread you trace along its path; connecting all four completes the puzzle.
What do you get for solving the brain puzzle?
It opens the secret door to loot including the Blade of Oppressed Souls and the Waking Mind.
What is the Slack-Skinned Head for?
Interacting with it grants the Githzerai Mind Barrier — a permanent buff giving advantage on Intelligence saving throws.
Related Guides
- How to Get Shadowheart to Spare the Nightsong — the other major Act 2 decision near Moonrise.
- Necromancy of Thay & Tharchiate Codex: Full Guide — more dark, high-value rewards.
Sources
- Brain Puzzle Solution: Necrotic Laboratory & Mind Flayer Colony Guide — original video walkthrough by Fusion Thunder.
Fusion Thunder
Founder & EditorI'm Fusion Thunder, the founder of Beyond Max Level. I'm a lifelong gamer and content creator who doesn't just play games — I like to push them to their absolute limits. This site is the written extension of my YouTube channel, @BeyondMaxLevel, where I break down the open-world epics and big RPGs worth going deep on into clear, no-fluff guides you can actually follow.
Related Guides
Guide BG3: Get Shadowheart to Spare the Nightsong (No Roll)
How to get Shadowheart to spare the Nightsong in Baldur's Gate 3 with no dice roll — the Trust mechanic, prerequisites, exact dialogue, and Selûne's Spear reward.
Guide BG3: How to Free Shadowheart from the Nautiloid Pod
How to free Shadowheart on the Nautiloid in Baldur's Gate 3 — find the Eldritch Rune, use the console (DC 10 Illithid check), or skip it with Barbarian, Wizard, or Warlock.
Guide BG3: Kill Commander Zhalk & Get the Everburn Blade
How to kill Commander Zhalk and get the Everburn Blade in Baldur's Gate 3 Honor Mode — the Command: Drop disarm, chest blockade, and 4-Nautiloid-tank explosion.