How to Build Occipital Lobes

Until now our brain has been built in the dark; it has no visual organs or pathways beyond the elementary brainstem eye movement circuitry already built in a previous chapter (see Chap. 2). To this end we require visual organs—eyes—containing light catchers called photoreceptors to synthesise movement, colour, shape, and depth information about the world. We also require efficient cabling to transfer these data to visual circuits within occipital lobes and other brain regions. The term occipital may be roughly (and unimaginatively) translated as located at the back of the head. We will need to perform some complicated biological processing of light signals, and we can partially complete this in the retina at the back of the eye, but we also need to transform these signals as they journey to occipital lobes at the back of the head. Through this transformative process, we can enhance, condense, extract, or fill-in visual data as it zips from the eye to the back of the brain, assembling and disassembling the visual scene at various pit-stops along the way. The distance between our eyes at the front of our head and occipital lobes at the back of the head provides us with crucial processing lag-time.