Once you agree with Nick Valentine, it's time to locate Doctor Amari which can be found at the Memory Den in Goodneighbor outskirts of the old city. Let's begin with our next Main Mission of Fallout 4 Walkthrough: Dangerous Minds.
Start your mission with leaving Piper's office and open your Pip-Boy to fast travel to Park Street Station. Once you arrive at the station head north-east road which is just behind the huge stack of tires. Now the only thing you need to do keep following the objective marker, but before that you will be attacked by few super mutants which will appear from the left building.
Later Continue moving until you reach a red tall tower, take right from here and you'll notice a signboard for Goodneighbor. From that junction, you need to take another right turn and keep moving straight until you reach the blue door to go through.
Now head straight and approach the bald-headed man on the left of the road. He will inform you about some needed insurance if available and you need to reply him with the 'Back off' option as you need to avoid the threatening remarks. Once you're done with the conversation you need to make sure to tell Hancock tat you're alright and select 'I feel you' to bring things to a close' option.
Now head to the gun shop to your left and then enter the pod-filled chamber on the right there you'll see Valentine is having a conversation with women on the stage. Go ahead and talk to him and he will inform you about Amari's current location which is downstairs. Head down from the southeast doorway until you reach the room where Doctor Amari is Waiting.
Talk to Doctor Amari and let Nick also explain Amari about your story and ask her to help you. First you need to handover Kellogg's brain augmenter and then request Amari to explain. Later Nick will ask you to insert the chip in his brain and wait for the sequence to play. Once the test fails you need to inquire about how to access Kellogg’s brain and unlock it. Amari will then inform you and Nick together can access the memories, so let's begin with it.
To begin with Kellogg's Memories, Open the Memory Lounger, get inside and settle. Once the simulation begins you'll see a bit of haze nearby and as it clears you need to head to the last room and start examining the objects and people to know the right path. In the kitchen, you'll see one more sequence so continue and keep repeating the process by viewing the memories with the corridor, bar, warehouse, Vault 111 and at last his time with Shaun.
After the last scene is ended you've experienced the rogue scientist then turn on the television screen to get back in the real world. Again get back to Amari and talk to her about Virgil, she will be surprised and ask you to catch him in the Glowing Sea. Also, she will make you aware that you need to be prepared in order to face against Virgil. Later ask her for some cure with the radiations and in return she will suggest you some Rad-X and RadAway.
Note: You can find a Radiation Suit which acts like a Power armor and is Anti-radiation.
Now just make sure to assure Doctor Amari about your exploration at Glowing Sea and Then head upstairs where you'll find Valentine waiting for you to begin with the next Main quest and hence end of the Main Quest Mission part 7 comes to an End.