Remember walking in their shoes? The relation of self-referential source memory and emotion recognition

Deficits in the ability to read the emotions of others have been demonstrated in mental disorders, such as dissociation and schizophrenia, which involve a distorted sense of self. This study examined whether weakened self-referential source memory, being unable to remember whether a piece of information has been processed with reference to oneself, is linked to ineffective emotion recognition. In two samples from a college and community, we quantified the participants' ability to remember the self-generated versus non-self-generated origins of sentences they had previously read or partially generated. We also measured their ability to read others' emotions accurately when viewing photos of people in affect-charged situations. Multinomial processing tree modelling was applied to obtain a measure of self-referential source memory that was not biased by non-mnemonic factors. Our first experiment with college participants revealed a positive correlation between correctly remembering the origins of sentences and accurately recognising the emotions of others. This correlation was successfully replicated in the second experiment with community participants. The current study offers evidence of a link between self-referential source memory and emotion recognition.

Neural signatures of memory gain through active exploration in an oculomotor-auditory learning task

Active engagement improves learning and memory, and self- versus externally generated stimuli are processed differently: perceptual intensity and neural responses are attenuated. Whether the attenuation is linked to memory formation remains unclear. This study investigates whether active oculomotor control over auditory stimuli-controlling for movement and stimulus predictability-benefits associative learning, and studies the underlying neural mechanisms. Using EEG and eye tracking we explored the impact of control during learning on the processing and memory recall of arbitrary oculomotor-auditory associations. Participants (N = 23) learned associations through active exploration or passive observation, using a gaze-controlled interface to generate sounds. Our results show faster learning progress in the active condition. ERPs time-locked to the onset of sound stimuli showed that learning progress was linked to an attenuation of the P3a component. The detection of matching movement-sound pairs triggered a target-matching P3b. There was no general modulation of ERPs through active learning. However, we found continuous variation in the strength of the memory benefit across participants: some benefited more strongly from active control during learning than others. This was paralleled in the strength of the N1 attenuation effect for self-generated stimuli, which was correlated with memory gain in active learning. Our results show that control helps learning and memory and modulates sensory responses. Individual differences during sensory processing predict the strength of the memory benefit. Taken together, these results help to disentangle the effects of agency, unspecific motor-based neuromodulation, and predictability on ERP components and establish a link between self-generation effects and active learning memory gain.

Sensory suppression and increased neuromodulation during actions disrupt memory encoding of unpredictable self-initiated stimuli

Actions modulate sensory processing by attenuating responses to self- compared to externally generated inputs, which is traditionally attributed to stimulus-specific motor predictions. Yet, suppression has been also found for stimuli merely coinciding with actions, pointing to unspecific processes that may be driven by neuromodulatory systems. Meanwhile, the differential processing for self-generated stimuli raises the possibility of producing effects also on memory for these stimuli; however, evidence remains mixed as to the direction of the effects. Here, we assessed the effects of actions on sensory processing and memory encoding of concomitant, but unpredictable sounds, using a combination of self-generation and memory recognition task concurrently with EEG and pupil recordings. At encoding, subjects performed button presses that half of the time generated a sound (motor-auditory; MA) and listened to passively presented sounds (auditory-only; A). At retrieval, two sounds were presented and participants had to respond which one was present before. We measured memory bias and memory performance by having sequences where either both or only one of the test sounds were presented at encoding, respectively. Results showed worse memory performance - but no differences in memory bias -, attenuated responses, and larger pupil diameter for MA compared to A sounds. Critically, the larger the sensory attenuation and pupil diameter, the worse the memory performance for MA sounds. Nevertheless, sensory attenuation did not correlate with pupil dilation. Collectively, our findings suggest that sensory attenuation and neuromodulatory processes coexist during actions, and both relate to disrupted memory for concurrent, albeit unpredictable sounds.

A scaffoldless technique for self-generation of three-dimensional keratinospheroids on liquid crystal surfaces

We describe a new scaffold-free three-dimensional (3D) cell culture model using cholesteryl ester based lyotropic liquid crystal (LC) substrates. Keratinocytes were deposited randomly on the LC surface where they self-assembled into 3D microtissues or keratinospheroids. The cell density required to form spheroids was optimized. We investigated cell viability using dead/live cell assays. The adhesion characteristics of cells within the microtissues were determined using histological sectioning and immunofluorescence staining. Fourier transform infrared spectroscopy (FTIR) was used to characterize the biochemistry of the keratinospheroids. We found that both cells and microtissues could migrate on the LC surface. The viability study indicated approximately 80% viability of cells in the microtissues up to 20 days of culture. Strong intercellular adhesion was observed in the stratification of the multi-layered microspheroids using field emission-scanning electron microscopy (FE-SEM) and histochemical staining. The cytoskeleton and vinculins of the cells in the microtissues were expressed diffusely, but the microtissues were enriched with lipids and nucleic acids, which indicates close resemblance to the conditions in vivo. The basic 3D culture model based on LC may be used for cell and microtissue migration studies in response to cytochemical treatment.

I know what is missing here: electrophysiological prediction error signals elicited by omissions of predicted "what" but not "when"

In the present study we investigated the neural code of sensory predictions. Grounded on a variety of empirical findings, we set out from the proposal that sensory predictions are coded via the top-down modulation of the sensory units whose response properties match the specific characteristics of the predicted stimulus (Albright, 2012; Arnal and Giraud, 2012). From this proposal, we derive the hypothesis that when the specific physical characteristics of the predicted stimulus cannot be advanced, the sensory system should not be able to formulate such predictions, as it would lack the means to represent them. In different conditions, participant's self-paced button presses predicted either only the precise time when a random sound would be presented (random sound condition) or both the timing and the identity of the sound (single sound condition). To isolate prediction-related activity, we inspected the event-related potential (ERP) elicited by rare omissions of the sounds following the button press (see SanMiguel et al., 2013). As expected, in the single sound condition, omissions elicited a complex response in the ERP, reflecting the presence of sound prediction and the violation of this prediction. In contrast, in the random sound condition, sound omissions were not followed by any significant responses in the ERP. These results confirmed our hypothesis, and provide support to current proposals advocating that sensory systems rely on the top-down modulation of stimulus-specific sensory representations as the neural code for prediction. In light of these findings, we discuss the significance of the omission ERP as an electrophysiological marker of predictive processing and we address the paradox that no indicators of violations of temporal prediction alone were found in the present paradigm.

The effects of linguistic relationships among paired associates on verbal self-generation and recognition memory

Previous studies have shown that self-generated information is better remembered than information that has been read passively. To further examine this subsequent memory effect, we investigated the effect of five different linguistic relationships on memory encoding. Ninety subjects were administered 60 paired associates during an encoding condition: 30 of the second words from each pair were to be read aloud and 30 were to be self-generated from clues as to the correct word. Word pairs were composed of five linguistic relationships: category, rhyme, opposite, synonym, and association. Subsequently, subjects were presented with the words that were read or generated in a forced recognition memory task. Overall, reading accuracy was higher than generation accuracy during the encoding phase (all P < 0.001). During the recognition phase, subjects' performance was better on the generate than on the read conditions for opposite, synonym, category, and association relationships (all P < 0.05), with no difference in the rhyme relationship. These results confirm previous findings that self-generated information is better remembered than read information and suggest that this advantage may be mediated by using opposite, synonym, category, and association relationships, while rhyme relationship may not extend such an advantage. These findings may have implications for future studies of memory interventions in healthy controls and subjects with cognitive impairments.