Biology subjects

Milton, F.

Publications and source records attributed to Milton, F..

2 recordsLinked to original sources

bioRxiv2025

Seeing through the Static: Reduced Imagery Vividness in Aphantasia is Associated with Impaired Temporal Lobe Signal Complexity

Aphantasia is the inability to experience mental imagery in full wakefulness without any prominent perceptual deficits. Visual aphantasia is associated with differences in distributed brain networks, but its neurobiological underpinnings remain a mystery. We rationalised that aphantasia may arise due to impairments in the top-down control over visual imagination. We expected that this in turn would prevent the brains of aphantasic subjects from differentiating neural activity encoding the contents of imagination from the background noise of resting activity, particularly within the ventral temporal lobes. To test this hypothesis, we re-analysed functional magnetic resonance imaging data collected from aphantasics (n = 23) and controls (n = 20) during a simple perception and imagery task. We used two measures of informational complexity to quantify the complexity of the spatial pattern of thresholded BOLD signal in the participants temporal lobes during visual imagery. This spatial complexity was lower in aphantasics than controls during blocks of imagery, but not during perception (P < 0.05). We then performed dynamic functional connectivity analyses on the same data to demonstrate that the higher-order networks of aphantasics coupled abnormally with the temporal lobes during imagery (P < 0.05). These results provide a novel perspective, reframing aphantasia as an inability of the visual system to selectively activate regions encoding object-specific visual categories above background levels of noise.

neuroscience↗

bioRxiv2024

The effect of deferring feedback on rule-based and information-integration category learning.

Previous work has shown that deferring feedback significantly impairs two-dimensional information-integration category learning, often thought to recruit an implicit learning system, but leaves intact unidimensional rule-based learning, commonly assumed to engage an explicit system (Smith et al., 2014). These results were taken to support the influential COmpetition between Verbal and Implicit Systems (COVIS) dual-process theory. This conclusion has subsequently been challenged by the finding that this dissociation disappears when the number of relevant dimensions is matched between tasks (Le Pelley et al., 2019). However, as well as replacing a unidimensional rule-based task with a two-dimensional conjunction task, Le Pelley et al. also changed the stimuli that were used in their study making it unclear which of these alterations was driving the difference in results. The current paper directly examined how both category structure and stimulus type influence the deferred feedback effect. We replicated both the original sets of results but found that deferred feedback also impaired information-integration learning to a greater extent than a conjunction task when Smith et al.s original stimuli were used. This result suggests that the effect of deferred feedback on category learning is more complicated than has previously been documented and highlights the critical role the choice of stimuli has in determining whether the effect is obtained.

animal behavior and cognition↗