Robin Carhart-Harris and David Nutt's Psychedelic Neuroscience Research Collaboration

Robin Carhart-Harris and David Nutt’s research collaboration joined an unconventional question about the unconscious to a psychopharmacology laboratory equipped to investigate it. Nutt initially thought Carhart-Harris’s proposed psychedelic research was unrealistic; he nevertheless offered him a PhD, first directing him toward a more conventional study of MDMA and the serotonin system. In 2009, with Amanda Feilding’s funding and the necessary approvals, their partnership reached its defining experiment: imaging the brain under Psilocybin and finding, contrary to expectation, not a general surge of activity but a measurable reduction concentrated in the Default mode network.

An unlikely route into the laboratory

Carhart-Harris came to Nutt with an unusual combination of interests. He had studied psychoanalysis and was absorbed by the writings of Freud and Jung, but he was dissatisfied that dreams and free association seemed to be the principal ways of exploring the unconscious. He wondered whether a drug could provide another route. His question brought him to Nutt in 2005, when Nutt was working in Bristol. Carhart-Harris also mentioned that Amanda Feilding might provide funding for psychedelic research, but that prospect did not make the proposal immediately persuasive.

Nutt’s first response was blunt: Carhart-Harris lacked neuroscience experience, and the project seemed far-fetched. The encounter might have ended there. Instead, Carhart-Harris persisted, and Nutt offered him a PhD with a staged plan: begin with a more straightforward investigation of MDMA’s effects on the serotonin system, then consider psychedelic research later. Their collaboration thus began neither with immediate agreement nor with a ready-made psychedelic program, but with a compromise that gave the younger researcher a route into Nutt’s laboratory and an opportunity to build the expertise his original proposal required.

Nutt’s own public profile formed a revealing backdrop to the partnership. In 2009, he was dismissed from the government’s Advisory Council on the Misuse of Drugs after publicly arguing for empirical comparisons of drug-related risks, including the relative risks of alcohol, cannabis, MDMA, and LSD. His readiness to defend controversial conclusions did not mean that he accepted Carhart-Harris’s idea without scrutiny: he initially regarded it as unrealistic and later advised against Carhart-Harris volunteering for the first Psilocybin imaging session. The relationship combined openness to a contested research field with attention to the practical and methodological demands of conducting it.

From a deferred proposal to brain imaging

The proposed second stage arrived in 2009. Carhart-Harris, now holding a PhD and working in Nutt’s laboratory at Imperial College London, obtained approval from the National Health Service and the Home Office to study Psilocybin’s effects on the brain. Funding from Feilding helped make the project possible. LSD was added to the research program a few years later, but the first imaging experiment used Psilocybin.

Carhart-Harris offered to be the first volunteer. He thought it was honest to undergo the procedure himself before administering the drug to other people and placing them in a scanner. He also told Nutt that he was anxious and might not be in the best psychological state. Nutt discouraged him for two reasons: concern about Carhart-Harris’s readiness and the possibility that participating could compromise his objectivity as a researcher. A colleague instead became the first volunteer, receiving an injection of Psilocybin before entering a functional magnetic resonance imaging (fMRI) scanner. The decision made the experiment’s roles clear: Carhart-Harris could lead the research without being its first subject.

The team’s aim was to identify neural correlates of psychedelic experience—physical changes in the brain corresponding to what volunteers experienced. Using brain-imaging technologies, the researchers sought to observe changes as they unfolded, rather than infer them only from volunteers’ later descriptions. The project therefore connected Carhart-Harris’s original interest in inaccessible mental processes with Nutt’s laboratory’s capacity to test hypotheses through psychopharmacology and imaging.

The finding that overturned the prediction

Carhart-Harris expected the scans to show increased activity, particularly in regions associated with emotion. He imagined that the results might resemble the dreaming brain. That expectation was consistent with earlier published findings from Franz Vollenweider, whose data indicated that psychedelics stimulated brain activity, especially in the frontal lobes, which support executive and other higher cognitive functions.

The first results instead showed decreases in blood flow, one of the measures used in fMRI as a proxy for brain activity. The unexpected result prompted the team to question whether something had gone wrong. A second measure, based on changes in oxygen consumption and used to locate areas of elevated activity, corroborated the initial pattern. The team concluded that Psilocybin reduced brain activity, with the decline concentrated in the Default mode network. The result mattered not simply because it contradicted Carhart-Harris’s prediction, but because the unexpected pattern gave the collaboration a new object of inquiry.

Carhart-Harris then investigated what was known about the network. The Default mode network had entered brain science only in 2001, when Marcus Raichle described it in a landmark paper. It links parts of the cerebral cortex with deeper structures involved in memory and emotion. Its activity had been noticed through a feature of brain-imaging experiments: areas that became active when participants had no assigned mental task. This made the network relevant to the research question that had first drawn Carhart-Harris toward psychoanalysis—the activity of the mind when attention is not occupied by an external task, including daydreaming, rumination, reflection on the self, and mental travel through time.

Collaboration within a wider research revival

The project’s significance extended beyond the two researchers. Its launch depended on the convergence of Carhart-Harris’s longstanding interest in psychoanalysis and the unconscious, Nutt’s laboratory and supervision, and Feilding’s financial support. Institutional approvals were also necessary. The collaboration therefore took shape through a network of intellectual, clinical, financial, and regulatory conditions rather than through an isolated scientific insight.

It also belonged to a field shaped by earlier research and practice. The book describes how psychedelic treatment had previously relied on attentive therapists and carefully managed environments, while attempts to isolate the drug in neutral rooms with minimal human engagement produced worse experiences and failed to reproduce earlier treatment results. Such contrasts made questions of method central to psychedelic research: an imaging study could measure physiological changes, but its findings did not by themselves settle what those changes meant for experience or treatment.

The wider history also included work outside formal institutions. Underground guides inherited practices and professional lineages from earlier researchers and therapists, and later university teams drew on some of that experience when considering guided sessions and music. This history helps place the Nutt–Carhart-Harris partnership within a research revival that had multiple sources, even as their work brought psychedelic investigation back into an authorized neuroscience laboratory.

The book likewise cautions against turning promising findings into settled claims of broad therapeutic efficacy. Earlier studies had sometimes overstated results, and small or uncontrolled trials could not establish the same conclusions as larger, rigorously designed studies. The value of Carhart-Harris and Nutt’s collaboration lies most securely in the research it enabled and the question it sharpened: a psychedelic state could be investigated both as a reported human experience and as a pattern of measurable changes in the brain. Their partnership began with skepticism and a deferred proposal; its first major result was a surprise that redirected the inquiry.