Animated brightfield light micrograph of pyramidal neurons (nerve cells) in the human cerebral cortex. Cortical pyramidal neurons (black; Cajal Golgi stain) are pyramidal shaped nerve cells with a primary, elongated dendritic extension (apical dendrite). The cerebral cortex is a layer of nervous tissue that is outermost to the cerebrum of the mammalian brain. It is called the grey area (grey matter) of the brain due to nerve fibres that lack insulation (myelin sheath). The cerebral cortex covers the cerebrum and cerebellum. It consists of up to six horizontal layers. Layer 3, the external pyramidal layer, contains the pyramidal nerve cells. The cerebral cortex plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. Magnification: x40 when shortest axis printed at 25 millimetres.