It's known that neural tissue can routinely re-generate in several species. The subject is intensely researched because of its potential to re-grow neural tissue which has been damaged, either due to disease (e.g. Parkinson's diseaseplugin-autotooltip__plain plugin-autotooltip_bigParkinson's disease

Also known as Parkinson disease, Parkinson's, idiopathic Parkinsonism, primary Parkinsonism, PD, or paralysis agitans - is a degenerative disorder of the central nervous system resulting from the death of dopamine-containing cells in the, Multiple sclerosisplugin-autotooltip__plain plugin-autotooltip_bigMultiple sclerosis

Multiple sclerosis (MS) is a severe persistent condition of the central nervous system in which the coating around nerve fibres (myelin) is damaged, causing a wide range of distressing symptoms varying in severity.

At any given time, it affects around 3 million people worldwide. , Poliomyelitisplugin-autotooltip__plain plugin-autotooltip_bigPoliomyelitis

"Nearly 100 years after its discovery poliovirus remains one of most thoroughly studied and best understood virus models for the molecular virologist. While poliovirus has been of vital importance for our insight into picornavirus biology at the cellular and biochemical level, it is ironic to note that, due to the early success in defeating poliomyelitis in the developed world through vaccination, etc), or by physical injuries.

There is currently no agreement as to whether new neural cells are (or could be) generated in adult humans :

The numbers of neurons born in the human hippocampus remains controversial; some studies have reported that in adult humans about 700 new neurons are added in the hippocampus every day, while other studies show that adult hippocampal neurogenesis does not exist in humans, or, if it does, it is at undetectable levels.

Source : Wikipedia

It's not presently known if humans can regrow brain cells : See :

"Our brains may be able to make new neurons throughout adulthood" New Scientist 25 March 2019

"We may be unable to grow new brain cells after we enter adulthood" New Scientist 16 Feb 2022.

Note: There is also a debate about whether adult learning induces the growth of new brain cells. The idea has not as yet been proven or disproven.

Also see : Limb Regenerationplugin-autotooltip__plain plugin-autotooltip_bigLimb Regeneration

Many animals, notably salamanders, axolotls, octopuses and starfish (etc) are able to regrow limbs (and other body parts) which have been lost through accidents or disease. Although mammals can regrow various tissues - notably skin, liver and tail tips - there is no ability to regrow limbs etc.