A generative adversarial model of intrusive imagery in the human brain

Abstract

The mechanisms underlying the subjective experiences of mental disorders remain poorly understood. This is partly due to long-standing over-emphasis on behavioral and physiological symptoms and a de-emphasis of the patient's subjective experiences when searching for treatments. Here, we provide a new perspective on the subjective experience of mental disorders based on findings in neuroscience and artificial intelligence (AI). Specifically, we propose the subjective experience that occurs in visual imagination depends on mechanisms similar to generative adversarial networks that have recently been developed in AI. The basic idea is that a generator network fabricates a prediction of the world, and a discriminator network determines whether it is likely real or not. Given that similar adversarial interactions occur in the two major visual pathways of perception in people, we explored whether we could leverage this AI-inspired approach to better understand the intrusive imagery experiences of patients suffering from mental illnesses such as post-traumatic stress disorder (PTSD) and acute stress disorder. In our model, a nonconscious visual pathway generates predictions of the environment that influence the parallel but interacting conscious pathway. We propose that in some patients, an imbalance in these adversarial interactions leads to an overrepresentation of disturbing content relative to current reality, and results in debilitating flashbacks. By situating the subjective experience of intrusive visual imagery in the adversarial interaction of these visual pathways, we propose testable hypotheses on novel mechanisms and clinical applications for controlling and possibly preventing symptoms resulting from intrusive imagery.

Fig. 1.

Perceptual Reality Monitoring Model of PTSD Flashbacks. (A) The reality monitoring process. An external stimulus triggers competing representations during perceptual processing. Current representations of reality are compared to ongoing prediction influenced by previous memory. The discriminator performs reality monitoring to decide whether a representation is current reality or internally generated (e.g., imagery). (B) Neurodynamic model of PTSD intrusive imagery. Magnocellular neurons primarily feed the dorsal visual pathway. The parvocellular neurons feed the ventral visual pathway. A generator sends top-down predictions influenced by the M pathway that influence bottom-up processing in the P pathway. A discriminator in the prefrontal cortex (PFC) decides whether a given percept stems from reality or imagination based on the sensory information available from both pathways. During intrusive imagery, generations related to a traumatic experience coming from the M pathway influence bottom-up processing in the P pathway. Overly realistic imagery is then presented to the PFC discriminator. A faulty discriminator indicates that this imagery represents reality causing the intrusive experience to occur.