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Neuroradiological Insights into Visual Mental Imagery: Structural and Functional Imaging of Ventral and Dorsal Streams

DOI: 10.3390/brainsci16040345
Redžepi, S., Avdagić, E., Šahinović, A., & Pojskić, M. (2026). Neuroradiological insights into visual mental imagery: structural and functional imaging of ventral and dorsal streams. Brain Sciences, 16(4), 345. doi:10.3390/brainsci16040345

Abstract

Visual mental imagery, the ability to generate and manipulate internal visual experiences without direct sensory input, links perception with memory, planning, and higher cognition. In this targeted narrative review, we synthesize neuroimaging and lesion evidence on the brain basis of visual imagery, with a focus on neuroradiological correlates of the ventral and dorsal visual pathways. Unlike prior cognitive neuroscience reviews that primarily emphasize functional mechanisms, this review is neuroradiology-oriented and integrates lesion patterns and white-matter disconnection to support clinico-radiological interpretation of imagery complaints. Using a dual-stream framework, we contrast ventral occipito-temporal systems that preferentially support object imagery (appearance-based features such as form, faces/objects, and color, with texture remaining under-studied) with dorsal occipito-parietal systems that preferentially support spatial imagery (relations, transformations, and navigation). Across studies, imagery recruitment is strongly task- and stage-dependent: ventral regions are most often engaged during object-focused imagery, whereas parietal regions are prominent during spatial transformation tasks, with evidence for interaction between pathways when demands require both content and spatial operations. Structural and clinico-radiological findings indicate that imagery impairment can arise from focal posterior lesions and posterior neurodegenerative syndromes but also from network disruption affecting long-range connections that support top-down access to posterior representations. Finally, emerging work on aphantasia and hyperphantasia supports a network-level view in which imagery vividness relates to how effectively higher-order systems engage visual representations. We conclude that standardized, stream-sensitive tasks and multimodal approaches combining functional and structural imaging with lesion-based evidence are key to discovering clinically actionable biomarkers of imagery dysfunction.

Authors

  • Saleha Redžepi1
  • Edin Avdagić1
  • Ajša Šahinović1
  • Mirza Pojskić1

What This Study Is About

Researchers wanted to map out the brain’s "wiring" to understand how we create mental imagery—the ability to picture things in your mind. They specifically looked at how the brain separates the "what" (like the color of an apple) from the "where" (like where the apple is sitting on a table).

How They Studied It

This wasn't a single experiment with new volunteers. Instead, the authors performed a "narrative review," which is like being a science detective. They gathered and analyzed data from dozens of previous studies involving:
  • Brain scans (fMRI and MRI): Looking at which parts of the brain light up when people imagine things.
  • Lesion studies: Examining people who lost their "mind's eye" after a stroke or injury (called acquired aphantasia).
  • Aphantasia groups: Comparing people born with aphantasia (the inability to visualize) to those with typical imagery.

What They Found

The researchers found that the brain uses two distinct "highways" for imagery:
  • The Artist (Ventral Stream): This path handles the details—colors, shapes, and faces.
  • The Architect (Dorsal Stream): This path handles space—how objects rotate or where they are located.
The study discovered that aphantasia isn't usually caused by a "broken" visual center. Instead, it’s often a disconnection. The brain’s "hubs" for storing images might be perfectly fine, but the "cables" (white matter) that connect them to the front of the brain aren't passing the information through. This explains why some people can't see a "picture" of a house but can still mentally navigate through the rooms without getting lost.

What This Might Mean

This suggests that aphantasia is a "network" issue rather than a problem with just one spot in the brain. It also suggests that there are different *types* of aphantasia—some people might struggle with the "Artist" side, while others struggle with the "Architect" side.
However, because this was a review of many different studies using different methods, the authors are careful to say this suggests a pattern rather than proves it. They note that we need more standardized tests to truly understand the "wiring" differences.

One Interesting Detail

The study highlights that even if you have aphantasia, your brain might still be "visualizing" behind the scenes! Some research showed that the brain's visual tools still "fire" during tasks, but the person just isn't consciously aware of the image.
This summary was generated by AI and may contain errors. Always refer to the original paper for accuracy.