Cerebral folds. Close-up of the cerebral folds or convolutions seen on the surface of a human brain that has had it's meninges (protective membrane) removed. These grooves and bulges that make up the cerebrum of the human brain greatly increase it's surface area. The cerebrum is the largest and most developed part of the human brain, being responsible for conscious thought and memory. The cells on it's surface are known as the cerebral cortex. This is mostly made of grey cells and called the grey matter. Millions of nerve connections below the cortex connect the nerve cells of the grey matter to other nerve cells in the brain.