New Findings Uncover Brain Regions Responsible for Differentiating Imagination from Reality

Recent research led by University College London has identified specific areas of the brain that help distinguish between real experiences and imagined ones. This advancement enhances our understanding of the neural mechanisms involved in perception and imagination, which is crucial for understanding psychiatric conditions like schizophrenia where this distinction may be impaired.

The study focused on the fusiform gyrus, a region located behind the temples in the underside of the temporal lobe. This area plays a significant role in processing visual information and, as the study reveals, is instrumental in determining whether what we perceive originates from external stimuli or our own imagination. The findings suggest that the strength of neural activity in the fusiform gyrus can predict whether an individual perceives a stimulus as real or imagined.

In the experiment, 26 participants were shown visual patterns while simultaneously imagining similar or different patterns. They were tasked with identifying the presence of faint patterns against noisy backgrounds and rating the vividness of their mental images. Results showed that when individuals experienced vivid mental images and reported seeing real patterns, they often mistook their imagination for reality—especially when activity in the fusiform gyrus was heightened.

The research employed functional magnetic resonance imaging (fMRI) to monitor brain activity, revealing that increased activity in the fusiform gyrus correlated with participants' perception of stimuli as real, regardless of the actual presence of external input. Conversely, typical imagination involved weaker activation in this brain region, helping the brain keep internal thoughts separate from external perception.

Further, the study demonstrated that brain regions in the prefrontal cortex, including the anterior insula, work in conjunction with the fusiform gyrus to assess and decide whether an experience is real. When participants believed an imagined scene was real, activity in these prefrontal areas increased, highlighting their role in metacognition—thinking about our own thoughts.

Professor Steve Fleming explained that these findings indicate the visual cortex's activity patterns mirror the brain's ability to distinguish internally generated experiences from external stimuli. Dr. Nadine Dijkstra added that the intensity of sensory signals contributes to this differentiation task.

This research offers valuable insights into the neural basis of perception and imagination. Understanding how these processes can go awry in conditions like schizophrenia may inform future diagnostic and therapeutic strategies. Additionally, the results can influence the development of immersive virtual reality technologies by clarifying how and when imagined experiences may feel real.

The study was conducted in collaboration with experts including Professor Peter Kok and former UCL student Thomas von Rein, and it has been published in the journal Neuron.