Feedback signals in visual cortex during episodic and schematic memory retrieval and their potential implications for aphantasia
Bergmann, J., & Ortiz-Tudela, J. (2023). Feedback signals in visual cortex during episodic and schematic memory retrieval and their potential implications for aphantasia. Neuroscience & Biobehavioral Reviews, 152, 105335. doi:10.1016/j.neubiorev.2023.105335
Abstract
Recent findings indicate that visual feedback derived from episodic memory can be traced down to the earliest stages of visual processing, whereas feedback stemming from schema-related memories only reach intermediate levels in the visual processing hierarchy. In this opinion piece, we examine these differences in light of the 'what' and 'where' streams of visual perception. We build upon this new framework to propose that the memory deficits observed in aphantasics might be better understood as a difference in high-level feedback processing along the 'what' stream, rather than an episodic memory impairment.
Authors
- Johanna Bergmann4
- Javier Ortiz-Tudela1
Understanding Visual Memory and Aphantasia
Overview/Introduction
This research explores the intriguing differences in how our brains process memories, specifically focusing on two types: episodic memory and schema-related memory. Episodic memory involves recalling specific events, while schema-related memory is about general knowledge and concepts. The study also delves into a condition called aphantasia, where individuals cannot visualize images in their minds. The researchers propose that aphantasia might be linked to differences in how the brain processes visual feedback from memories.
Methodology
The study examined how the brain retrieves visual information from memories using advanced brain imaging techniques. By analyzing neural activity, researchers could trace where and how memory information is processed in the brain. They focused on two main pathways in the brain's visual processing system: the 'what' stream, which deals with object recognition, and the 'where' stream, which handles spatial relationships.
Key Findings
- Episodic Memory: This type of memory involves both the 'what' and 'where' streams, allowing for detailed visual feedback that reaches the earliest stages of visual processing.
- Schema-related Memory: This memory type primarily engages the 'where' stream, with feedback reaching only intermediate stages of visual processing.
- Aphantasia: The study suggests that aphantasia might not be due to a general memory impairment. Instead, it could be related to specific issues in the 'what' stream, affecting the ability to retrieve detailed visual information from memory.
Implications
- Understanding Aphantasia: This research provides a new perspective on aphantasia, suggesting it might be due to differences in high-level feedback processing rather than a complete inability to visualize.
- Memory Processing: The findings highlight the distinct pathways through which different types of memories are processed, offering insights into how our brains handle complex information.
- Future Research: The study proposes testable hypotheses to further explore the neural mechanisms underlying aphantasia, potentially leading to new diagnostic and therapeutic approaches.
Limitations
While the study offers valuable insights, it is primarily theoretical and based on existing data. Further empirical research is needed to validate the proposed hypotheses and fully understand the neural correlates of aphantasia.
In summary, this research sheds light on the complex processes involved in visual memory retrieval and offers a fresh perspective on aphantasia, paving the way for future investigations into the brain's intricate workings.