What does the brain do differently when it can't generate mental images? Researchers use fMRI, electrical stimulation, and connectivity mapping to find out.
Fleming and Dijkstra · Cell Research
Researchers discovered that mental imagery reactivates the same sensory code as perception at the single-neuron level. This suggests that aphantasia may stem from how this shared activity is generated, modulated, or read out by the brain.
Koenig-Robert, Pace and Pearson · Psychological Review
Researchers propose that imagery reshapes spontaneous neural activity via inhibitory feedback rather than driving new spikes in early visual areas. This suggests the spectrum from aphantasia to hyperphantasia is driven by the strength of cortical inhibition.
Anderson and colleagues · Neuron
Mental imagery and perception overlap in transmodal association networks rather than unimodal sensory areas. This suggests that high-level brain systems, not just sensory reinstatement, are the primary drivers of mental imagery.
Redžepi and colleagues · Brain Sciences
Researchers found that visual imagery recruits ventral and dorsal streams, with deficits often caused by white-matter disconnection. This suggests aphantasia is a network-level condition where higher-order systems fail to engage visual representations.
Bartolomeo, Liu and Spagna · Neuropsychologia
The Fusiform Imagery Node (FIN) in the left hemisphere is a key hub for generating mental images across different domains. This suggests that aphantasia may result from impaired communication between the FIN and the prefrontal cortex.
Rollo and colleagues · Brain and Cognition
Bilateral temporal cortex stimulation significantly reduced the volitional control of auditory imagery while leaving vividness largely unaffected. This suggests that the ability to manipulate internal sounds relies on specific temporal-cortical dynamics distinct from those supporting image clarity.
Kutsche and colleagues · Cortex
Lesions causing aphantasia are all functionally connected to a specific region in the left ventral visual pathway called the fusiform imagery node. This provides causal evidence that this node's connections are key for voluntary visual imagery.
Kvamme and colleagues · NeuroImage
Vivid mental imagery is supported by high local efficiency and segregation in the imagery, occipital, and salience brain networks. This suggests that specialized, localized information transfer across these key networks is essential for vivid visualization.
Kronemer and colleagues · Neuroscience of Consciousness
Researchers found that visual imagery vividness positively correlates with the contrast and sharpness of negative afterimages. This suggests that afterimages and mental imagery may share top-down neural mechanisms in the brain.
Vetterlein and colleagues · Neurobiology of Pain
Imagining oneself in painful situations activates brain regions typically involved in actual pain processing, such as the somatosensory and motor cortices. This provides preliminary evidence for a neuronal imagination-perception overlap in pain.
Dijkstra · Vision
The early visual cortex represents fine-grained visual details during mental imagery in a similar way to perception. This suggests that the recruitment of these areas depends on the level of visual detail required by the mental image.
Dietz and colleagues · Cognitive Neuropsychology
Posterior cortical atrophy causes progressive impairment of higher-order visual functions due to degeneration in the brain's posterior regions. Recognizing these specific visual deficits is crucial for early diagnosis of this atypical Alzheimer's variant.
Sulfaro, Robinson and Carlson · Neuroscience of Consciousness
Researchers found that sensory input competes with mental imagery in a hierarchical neural network, preventing thoughts from dominating low-level sensory regions. This explains why mental imagery feels less vivid than real perception and how aphantasia arises from overweighted bottom-up signals.
Spagna and colleagues · Neuroscience & Biobehavioral Reviews
Researchers found that visual mental imagery relies on a core network in the left fusiform gyrus and fronto-parietal regions rather than early visual cortex. This suggests imagery is a top-down process initiated by prefrontal and semantic systems.
Dijkstra and colleagues · eLife
Neural activation during mental imagery occurs in the reverse order of perception, with high-level areas activating before low-level ones. This confirms that imagery is a top-down process driven by feedback from the brain's hierarchy.
Keogh, Bergmann and Pearson · eLife
In brain scans and magnetic stimulation tests, people with lower visual cortex activity and excitability had stronger imagery on an objective test. Lowering excitability with electrical stimulation strengthened imagery but not rated vividness.
Thorudottir and colleagues · Brain Sciences
An architect lost his visual imagery following a stroke despite maintaining normal performance on other visual and cognitive tasks. This suggests that the right lingual gyrus and left medial posterior fusiform gyrus are critical for mental imagery.
Kwok and colleagues · Psychological Science
Suppressed visual thoughts form sensory traces in the early visual cortex even when individuals report successful suppression. This provides an objective way to measure how nonconscious representations trigger thought-control failure.
Fulford and colleagues · Cortex
Low-vividness imagers activate a more widespread set of brain regions during visualization than high-vividness imagers. This suggests that individuals with weak mental imagery may use compensatory neural effort to perform imagery tasks.
Seiler, Newman-Norlund and Monsma · Psychology of Sport and Exercise
Good movement imagers activate more spatially distinct cortical sites than poor imagers during kinesthetic and external visual imagery. This suggests that high imagery ability is characterized by greater neural recruitment rather than increased neural efficiency.