No evidence for embodiment: The motor system is not needed to keep action words in working memory

Increasing evidence implicates the sensorimotor systems with high-level cognition, but the extent to which these systems play a functional role remains debated. Using an elegant design, Shebani and Pulvermüller (2013) reported that carrying out a demanding rhythmic task with the hands led to selective impairment of working memory for hand-related words (e.g., clap), while carrying out the same task with the feet led to selective memory impairment for foot-related words (e.g., kick). Such a striking double dissociation is acknowledged even by critics to constitute strong evidence for an embodied account of working memory. Here, we report on an attempt at a direct replication of this important finding. We followed a sequential sampling design and stopped data collection at N=77 (more than five times the original sample size), at which point the evidence for the lack of the critical selective interference effect was very strong (BF01 = 91). This finding constitutes strong evidence against a functional contribution of the motor system to keeping action words in working memory. Our finding fits into the larger emerging picture in the field of embodied cognition that sensorimotor simulations are neither required nor automatic in high-level cognitive processes, but that they may play a role depending on the task. Importantly, we urge researchers to engage in transparent, high-powered, and fully pre-registered experiments like the present one to ensure the field advances on a solid basis.

Spatiotemporal context modulates encoding and retrieval of overlapping events

Overlap between events can lead to interference due to a tradeoff between encoding the present event and retrieving the past event. Temporal context information -- 'when' something occurred, a defining feature of episodic memory -- can cue retrieval of a past event. However, the influence of temporal overlap, or proximity in time, on the mechanisms of interference are unclear. Here, by identifying brain states using scalp electroencephalography (EEG) from male and female human subjects, we show the extent to which temporal overlap promotes interference and induces retrieval. In this experiment, subjects were explicitly directed to either encode the present event or retrieve a past, overlapping event while perceptual input was held constant. We find that the degree of temporal overlap between events leads to selective interference. Specifically, greater temporal overlap between two events leads to impaired memory for the past event selectively when the top-down goal is to encode the present event. Using pattern classification analyses to measure neural evidence for a retrieval state, we find that greater temporal overlap leads to automatic retrieval of a past event, independent of top-down goals. Critically, the retrieval evidence we observe likely reflects a general retrieval mode, rather than retrieval success or effort. Collectively, our findings provide insight into the role of temporal overlap on interference and memory formation.

Selectively Interfering With Intrusive but Not Voluntary Memories of a Trauma Film: Accounting for the Role of Associative Memory

Intrusive memories of a traumatic event can be reduced by a subsequent interference procedure, seemingly sparing voluntary memory for that event. This selective-interference effect has potential therapeutic benefits (e.g., for emotional disorders) and legal importance (e.g., for witness testimony). However, the measurements of intrusive memory and voluntary memory typically differ in the role of associations between a cue and the emotional memory “hotspots.” To test this, we asked participants to watch a traumatic film followed by either an interference procedure (reminder plus Tetris) or control procedure (reminder only). Measurement of intrusions (using a laboratory task) and voluntary memory (recognition for film stills) were crossed with the presence or absence of associative cues. The reminder-plus-Tetris group exhibited fewer intrusions despite comparable recognition memory, replicating the results of prior studies. Note that this selective interference did not appear to depend on associative cues. This involuntary versus voluntary memory dissociation for emotional material further supports separate-trace memory theories and has applied advantages.

Serca2a-Phospholamban Interaction Monitored by an Interposed Circularly Permutated Green Fluorescent Protein

Background: The interaction of phospholamban (PLB) and the sarcoplasmic reticulum Ca2+-ATPase (Serca2a) is a key regulator of cardiac contractility and a therapeutic target in heart failure (HF). PLB mediated increases in Serca2a activity improve cardiac function and HF. Clinically this mechanism can only be exploited by a general activation of the proteinkinase A (PKA) which is associated with side effects and adverse clinical outcomes. A selective interference of the PLB-Serca2a interaction is desirable but will require novel tools that allow for an integrated assessment of this interaction under both physiological and pathophysiological conditions. Methods: A circularly permutated green fluorescent protein (cpGFP) was interposed between Serca2a and PLB to result into a single Serca2a-cpGFP-PLB recombinant protein (SGP). Expression, phosphorylation, fluorescence and function of SGP were evaluated. Results: Expression of SGP-cDNA results in a functional recombinant protein at the predicted molecular weight. The PLB domain of SGP retains its ability to polymerize and can be phosphorylated by PKA activation. This increases the fluorescent yield of SGP by between 10% to 165% depending on cell line and conditions. Summary: A single recombinant fusion protein that combines Serca2a, a circularly permutated green fluorescent protein and PLB can be expressed in cells and can be phosphorylated at the PLB domain which markedly increases the fluorescence yield. SGP is a novel cellular Serca2a-PLB interaction monitor.

Selective Interference and the Evolution of Sex

Selection acts upon genes linked together on chromosomes. This physical connection reduces the efficiency by which selection can act because, in the absence of sex, alleles must rise and fall together in frequency with the genome in which they are found. This selective interference underlies such phenomena as clonal interference and Muller’s Ratchet and is broadly termed Hill-Robertson interference. In this review, I examine the potential for selective interference to account for the evolution and maintenance of sex, discussing the positive and negative evidence from both theoretical and empirical studies, and highlight the gaps that remain.

Targeting nucleic acids with a G-triplex-to-G-quadruplex transformation and stabilization using a peptide–PNA G-tract conjugate

The synergy between two recognizing units in a bi-functional peptide–PNA G-tract conjugate recognizes a three guanine-tracts motif to form an extra stable bimolecular complex, resulting in highly potent and selective interference to DNA metabolism.