The Internet enables us to connect with people, images and information in ways that were unimaginable 30 years ago. But with every click we are re-wiring the physical structure of our brains. Are we evolving or actively de-evolving down a dopamine-laced click-hole? In this episode meet a 17-year-old boy struggling with an addiction to online pornography; autistic technologists in Silicon Valley who are turning their genetic variation to an advantage; plus, Nootropics, a class of cognition-enhancing supplements that claims to rewire the brain.

Helen Czerski ventures beyond the visible spectrum in the final (and best) episode in this vibrant series, showing how electromagnetic radiation is so much broader than the narrow slice of reality we see with our eyes. Before delving into the details of UV, infrared and x-rays, Dr Czerski explores colour subjectivity by trying on a dress that recently divided the internet — to some it appeared blue and black, to others white and gold. It's a perfect fit. It's also a neat analogy of how people can have opposing views but both swear blind that their perspective is correct. The series ends with some amazing imaging techniques that show our bodies in a whole new light.

In the Youtube video galaxy a new star has been born: the ASMR videos. It stands for Autonomous Sensory Meridian Response, and refers to the pleasant feeling that users associate with this type of digital content. The physical reaction also changes significantly from individual to individual and people reportedly experience a pleasant feeling of tingling in the scalp, which can spread to the shoulders and back, and usually be accompanied by a feeling of relaxation and generalised well-being. The intensity of the response can also be very strong, so much so that some have used the word 'braingasm', literally 'brain orgasm' to express the feeling.
It's likely that you've already heard about it, but if not, this is the perfect opportunity to learn more about it. Especially because, for the first time, it seems that the benefits of ASMR videos have been scientifically proven.

The Internet is an uncontrollable labyrinth of content and imagery that operates under loose laws and partial anonymity - a new frontier where people can do anything and see anything, whether they should or not. In this lawless landscape, who's in control? The protectors? The abusers? In this episode meet the content moderators who watch the worst of the Internet so you don't have to; a convicted hacker whose punishment was the virtual prison of the unplugged; plus, a blackhat hacker who encrypts and holds computer files hostage.

We all project images of ourselves online - a curated identity that defines how we want to be perceived. But what temptations exist to embellish and what are the dark implications? In this episode, enter the world of Cyberbanging, where inner city youth are using social media to brag, conspire and incite violence; two African-American women bloggers who have turned the table on the trolls who threaten them; and the creator of Abdullah X, an online character who's trying to keep Muslim kids from falling under the spell of Islamic extremists.

With a little imagination, could a few terrorists sabotage a mighty nation? Perhaps even tear down modern civilization? The stability of the US, Europe, China, or any global power depends on high-speed digital communication. Our increasing dependence on digital devices and global interactivity may be placing us in grave danger. Scientists around the world are dealing with new threats such as body hacking, Trojan horse viruses, and brain-damaging Internet addiction. But what if the ultimate threat isn’t an attack on technology, but the technology? Could the final superpower be the disembodied mind of the Internet itself?