recovering the brain from neurotoxic effects by black magic mushrooms

If these symptoms persist it would be prudent to see a neurologist.
Mushroom poisoning can lead to lifelong health complications. Some mimic leukemia when ingested .
A brain anomaly such as described can lead to seizures and worse..

That sounds serious. It sounds like your friend really needs medical treatment; and he sounds like he is lucky he has not had a lasting psychotic split from that trip, which I have heard some people have had. The responsible thing to do would be for him to see a psych for initial assessment.

Needs to get the attention out of his head, back into the body, doesnt matter how in the first place. Is it therapies, bio-energetics or supplements.

The following is no in no way a advice but>
After 10 years of instability (it got better over the years, much working with myself, and i had the time, couldnt work jobwise for a long time cause of this) for the same reason. Followed by many therapies, pharma-drugs, non-pharmaceutical drugs. No joke and quite simple lol -after all this years, a high dose of Phenibut did the last needed step for me. Simple cause it took the tension and a-ttention out of my head, without numbing me, alcohol always did, and made it possible to actually feel my body again > Bioenergetics...no spiritual hokus pokus shit, im far away from new age hippie Buddhism shit, in fact i think their energie stuff is something not to fuck with. No - Bioenergetics just means attention back into your body, something many depressed, anxious and from panic suffering people lost, the steady connection to their body below their heads(grounding).

This guy knows some tricks.
https://www.youtube.com/user/elliottsaidwhat/videos

But again. This was no advice just my story in a nutshell.

And sorry, the typos anrent real typos, i miss a few punctuation character, im on a German keyboard, with English keeyboard-layout and im also on a Ubuntu System and not Windows, which is from a USB-stick so i cant change it, and this let me stay pretty helpless.

Anyway go to a doctor but meanwhile try to concentrate your awarness on your body, like if your consciousness would be below your neck. The deeper, the better, it will ground you and gives your panic and your head a rest. Thats why Phenibut heplped me, i found no break from my head to feel my body again, cause my head always felt weird in a weird way lol, just not like it used to to, and by feeling it, it took in the same time my awareness at it, what made me play-try to fix...it, what then made me feel my head even more and even more not-normal for how i feel normally my head. Anyway Phenibut then broke that doom loop by giving me a short break to reclaim normal body/feelings by giving me complete calmness for a short time, and i took the chance.
And now im the happiest motherfucker around. Bang, and of story. Good luck, and go to a doctor at least preventive.

Psilocybe mushrooms aren't poisonous. They contain a derivative of DMT which gives it a psychedelic property.

If they were cultured improperly, then they're poisonous. Make sure they don't have mold in the future.

There's no scientific research that contradicts their neurogenerative and antioxidant/anti-inflammatory properties that would properly suggest they are neurotoxic. If you take too much, you generally become depressed and that can last a while. A bad trip in general can do some damage to your thought process so remember set and setting is important.

Basic stuff. Take activated charcoal away from nutrients you want to absorb. This binds to the bile and assists your detox organs in getting the toxins out of your body. Go on a low toxin diet to allow your inflamation to calm and your immune system to stop attacking nerve fibres and other vulnerable 'fuse' parts of the body and brain. I'm referinf mainly to the bulletproof diet as it is clear in its protocols for avoiding further toxins and there by allows the body to heal. Wahls protocol is useful too.
Toxins can cause brain injury. Aka poisons. Dr Daniel Amen has a free brain warriors course that would be useful. The panic attacks and nerve issues sound like brain injury. Fish oil. Magnesium citrate or malate. Zinc. Vitamin D3 are basics. Then you want to look at repair and support of mitochondria.

Ah yeah I ate some black shrooms once, was fucken terrifying and I've never enjoyed shrooms since. The body is designed to heal itself though and you can even come back stronger. Like lifting emotional weights haha.

I also thought of this, but it's an all care and no responsibility idea I throw out there. There is also Ayahuasca which gives you a trip possibly ten times as intense as psylocibin. Many people have used Ayahuasca and reported feeling incredibly balanced and at peace afterwards. There is a warning though: it is generally considered to be the chemical equivalent of ten years of therapy in one night from what I read. It is also not legal and can only be accessed at Ayahuasca retreats such as those held in the Amazon region. This typically involves a ceremony. It is also widely recommended to engage in an integration program involving meditation and (supervised) self reflection with regular walking and maybe even talking things through with a psych while you're at it.