Sensory Processing Sensitivity: theory, evidence and directions In recent years, scientific interest in sensory processing sensitivity (SPS), a personality trait that captures inter-individual differences in the processing, perception and response to both negative and positive stimuli, has grown exponentially. This review summarises the recent literature on SPS to discuss a number of central themes, including its assessment, relation to other personality traits, effects on cognition and mental health, and its (neuro)biological basis. We also identify existing knowledge gaps and capitalise on a general theory of brain function, predictive processing, to provide a novel mechanistic account of SPS. This account offers a unified explanation for the phenotypic consequences of enhanced sensory sensitivity and can serve as a guide for future research.
Concurrent processing of the prosodic hierarchy is supported by cortical entrainment and phase-amplitude coupling Models of phonology posit a hierarchy of prosodic units that is relatively independent from syntactic structure, requiring its own parsing. It remains unexplored how this prosodic hierarchy is represented in the brain. We investigated this foundational question by means of an electroencephalography (EEG) study. Thirty young adults listened to German sentences containing manipulations at different levels of the prosodic hierarchy. Evaluating speech-to-brain cortical entrainment and phase-amplitude coupling revealed that prosody’s hierarchical structure is maintained at the neural level during spoken language comprehension. The faithfulness of this tracking varied as a function of the hierarchy’s degree of intactness as well as systematic interindividual differences in audio-motor synchronization abilities. The results underscore the role of complex oscillatory mechanisms in configuring the continuous and hierarchical nature of the speech signal and situate prosody as a structure indispensable from theoretical perspectives on spoken language comprehension in the brain.
Seeing fast and slow: the influence of music-induced affective states and individual sensory sensitivity on visual processing speed There is a speed-accuracy trade-off in perception. The ability to quickly extract sensory information is critical for survival, while extended processing can improve our accuracy. It has been suggested that emotions can change our style of processing, but their influence on processing speed is not yet clear. In three experiments, combining online and laboratory studies with different emotion induction procedures, we investigated the influence of both affective states, manipulated with music, and individual traits in sensory-processing sensitivity on the ability to rapidly segregate two visual flashes. Across studies, the musical manipulations pushed participants towards either rapid or slow processing. Individual variations in sensory-processing sensitivity modulated these effects. Our findings demonstrate that affective states, influenced by music, can shift the balance between fast and slow visual processing, altering our perceptual experience. These results also emphasise the interaction of individual traits in sensory processing and affective states.
Alpha oscillations protect auditory working memory against distractors in the encoding phase Alpha oscillations are proposed to serve the function of inhibition to protect items in working memory from intruding information. In a modified Sternberg paradigm, alpha power was initially found to increase at the anticipation of strong compared to weak distractors, reflecting the active gating of distracting information from interfering with the memory trace. However, there was a lack of evidence supporting the inhibition account of alpha oscillations in later studies using similar experimental design with greater temporal disparity between the encoding phase and the presentation of the distractors. This temporal disparity might have dampened the demands for inhibition. To test the hypothesis that alpha inhibition takes place when distractors are temporally close to the encoding phase, here we designed a modified Sternberg paradigm where distractors were sandwiched between targets in the encoding phase to ensure that they compete for working memory resources. Using electroencephalography (EEG), we replicated the finding that alpha power increased for strong compared to weak distractors. The effect was present throughout the encoding phase, not only upon the presentation of distractors but also before and after the presentation of distractors, providing evidence for both proactive and reactive inhibition of distractors at the neuronal level. Meanwhile, the effect was restricted to the context of high but not low target-to-distractor ratio. The results suggest that the distractors being temporally close to the encoding phase of more targets might be a boundary condition of the generation of alpha oscillations for gating.
Right middle occipital gyrus is associated with egocentric spatial orientation during body tilt: Evidence from a repetitive transcranial magnetic stimulation study Accurate perception of the orientation of external objects relative to the body, known as egocentric spatial orientation, is fundamental to performing action. Previously, we found via behavioural and magnetic resonance imaging voxel-based morphometry studies that egocentric spatial orientation is strongly distorted when the whole body is tilted with respect to gravity, and that the magnitude of this perceptual distortion is correlated with the grey matter volume of the right middle occipital gyrus (rMOG). In the present study, we further validated the association between the neural processing in the rMOG and the perceptual distortion by transiently suppressing neural activity in this region using low-frequency repetitive transcranial magnetic stimulation (rTMS) and evaluating the consequent effect on perceptual distortion. Our results showed that rTMS over the rMOG significantly reduced perceptual distortions when the body was tilted in the frontal plane, while it did not affect egocentric spatial orientation in the upright position. No significant changes in perceptual distortion were observed when rTMS was applied to another cortical candidate (the right temporo-parietal junction). These results provide evidence that neural processing in the rMOG is associated with body tilt-related perceptual distortion, suggesting that the rMOG may be engaged in egocentric spatial orientation related to gravitational information.
Synaptic Gα12/13 signaling establishes hippocampal PV inhibitory circuits Combinatorial networks of cell adhesion molecules and cell surface receptors drive fundamental aspects of neural circuit establishment and function. However, the intracellular signals orchestrated by these cell surface complexes remain less understood. Here, we report that the Gα12/13 pathway lies downstream of several GPCRs with critical synaptic functions. Impairment of the Gα12/13 pathway in postnatal hippocampal neurons diminishes inhibitory inputs without altering neuronal morphology or excitatory transmission. Gα12/13 signaling in hippocampal CA1 neurons in vivo selectively regulates PV interneuron synaptic connectivity, supporting an inhibitory synapse subtype-specific function of this pathway. Our studies establish Gα12/13 as a signaling node that shapes inhibitory hippocampal circuitry.
Brain change trajectories in healthy adults correlate with Alzheimer’s related genetic variation and memory decline across life Throughout adulthood and ageing our brains undergo structural loss in an average pattern resembling faster atrophy in Alzheimer’s disease (AD). Using a longitudinal adult lifespan sample (aged 30-89; 2–7 timepoints) and four polygenic scores for AD, we show that change in AD-sensitive brain features correlates with genetic AD-risk and memory decline in healthy adults. We first show genetic risk links with more brain loss than expected for age in early Braak regions, and find this extends beyond APOE genotype. Next, we run machine learning on AD-control data from the Alzheimer’s Disease Neuroimaging Initiative using brain change trajectories conditioned on age, to identify AD-sensitive features and model their change in healthy adults. Genetic AD-risk linked with multivariate change across many AD-sensitive features, and we show most individuals over age ~50 are on an accelerated trajectory of brain loss in AD-sensitive regions. Finally, high genetic risk adults with elevated brain change showed more memory decline through adulthood, compared to high genetic risk adults with less brain change. Our findings suggest quantitative AD risk factors are detectable in healthy individuals, via a shared pattern of ageing- and AD-related neurodegeneration that occurs along a continuum and tracks memory decline through adulthood.
FAST functional connectivity implicates P300 connectivity in working memory deficits in Alzheimer’s disease Measuring transient functional connectivity is an important challenge in electroencephalogram (EEG) research. Here, the rich potential for insightful, discriminative information of brain activity offered by high-temporal resolution is confounded by the inherent noise of the medium and the spurious nature of correlations computed over short temporal windows. We propose a methodology to overcome these problems called filter average short-term (FAST) functional connectivity. First, a long-term, stable, functional connectivity is averaged across an entire study cohort for a given pair of visual short-term memory (VSTM) tasks. The resulting average connectivity matrix, containing information on the strongest general connections for the tasks, is used as a filter to analyze the transient high-temporal resolution functional connectivity of individual subjects. In simulations, we show that this method accurately discriminates differences in noisy event-related potentials (ERPs) between two conditions where standard connectivity and other comparable methods fail. We then apply this to analyze an activity related to visual short-term memory binding deficits in two cohorts of familial and sporadic Alzheimer’s disease (AD)-related mild cognitive impairment (MCI). Reproducible significant differences were found in the binding task with no significant difference in the shape task in the P300 ERP range. This allows new sensitive measurements of transient functional connectivity, which can be implemented to obtain results of clinical significance.