Pairs Of Stimuli Research Articles

Synaptic dynamics linked to widespread elevation of H-reflex before peripheral denervation in amyotrophic lateral sclerosis.

Changes in Hoffmann reflex (H-reflex) exhibit heterogeneity among patients with amyotrophic lateral sclerosis (ALS), likely due to phenotype diversity. Current knowledge primarily focuses on soleus H-reflex, which may demonstrate an initial increase before subsequent decline throughout the disease course. The main objective was to investigate other muscles, to determine whether H-reflex changes could be associated with patient phenotype (onset site, functional disabilities). Additional experiments were performed to elucidate the neurophysiological mechanisms underlying H-reflex modifications. In age- and sex-matched groups of controls and patients, we compared H-reflex recruitment curves in soleus, quadriceps, and forearm flexors. Additionally, we examined H-reflex and motor evoked potential (MEP) recruitment curves in quadriceps. Last, to assess potential changes in monosynaptic excitatory post-synaptic potentials (EPSPs) of both peripheral and cortical origins, we analyzed peri-stimulus time histograms (PSTH) and peristimulus frequencygrams (PSF) of single motor units, along with H-reflex occurrence after paired pulse stimuli. The ratio between maximal amplitudes of H-reflex and direct motor response increased in all muscles, irrespective of disease onset, and was found positively correlated with exaggerated osteotendinous reflexes and spasticity, but depressed in patients on-riluzole. This finding was accompanied by a reduction in MEP size and no changes in PSTH, PSF, and paired-pulse H-reflex probability. It is speculated that spinal interneurons may compensate for potential depression of monosynaptic EPSPs in ALS. From a clinical perspective, while the added value of H-reflex to osteotendinous reflex evaluation may be limited, it can serve as a valuable quantitative biomarker of pyramidal dysfunction in clinical trials.

Anticipating multisensory environments: Evidence for a supra-modal predictive system

Our perceptual experience is generally framed in multisensory environments abundant in predictive information. Previous research on statistical learning has shown that humans can learn regularities in different sensory modalities in parallel, but it has not yet determined whether multisensory predictions are generated through a modality-specific predictive mechanism or instead, rely on a supra-modal predictive system. Here, across two experiments, we tested these hypotheses by presenting participants with concurrent pairs of predictable auditory and visual low-level stimuli (i.e., tones and gratings). In different experimental blocks, participants had to attend the stimuli in one modality while ignoring stimuli from the other sensory modality (distractors), and perform a perceptual discrimination task on the second stimulus of the attended modality (targets). Orthogonal to the task goal, both the attended and unattended pairs followed transitional probabilities, so targets and distractors could be expected or unexpected. We found that participants performed better for expected compared to unexpected targets. This effect generalized to the distractors but only when relevant targets were expected. Such interactive effects suggest that predictions may be gated by a supra-modal system with shared resources across sensory modalities that are distributed according to their respective behavioural relevance.

Drosophila require both green and UV wavelengths for sun orientation but lack a time-compensated sun compass.

Celestial orientation and navigation are performed by many organisms in contexts as diverse as migration, nest finding and straight-line orientation. The vinegar fly, Drosophila melanogaster, performs menotaxis in response to celestial cues during tethered flight and can disperse more than 10 km under field conditions. However, we still do not understand how spectral components of celestial cues and pauses in flight impact heading direction in flies. To assess individual heading, we began by testing flies in a rotating tether arena using a single green LED as a stimulus. We found that flies robustly perform menotaxis and fly straight for at least 20 min. Flies maintain their preferred heading directions after experiencing a period of darkness or stopping flight, even up to 2 h, but reset their heading when the LED changes position, suggesting that flies do not treat this stimulus as the sun. Next, we assessed the flies' responses to a UV spot alone or a paired UV-green stimulus - two dots situated 180deg apart to simulate the solar and antisolar hemispheres. We found that flies respond to UV much as they do to green light; however, when the stimuli are paired, flies adjust for sudden 90deg movements, performing sun orientation. Lastly, we found no evidence of a time-compensated sun compass when we moved the paired stimuli at 15degh-1 for 6 h. This study demonstrates that wavelength influences how flies respond to visual cues during flight, shaping the interpretation of visual information to execute an appropriate behavioral response.

Discerning equivalence relations from displayed but not previously learned stimulus pairs

A method was devised to determine whether participants could discern stimulus equivalence (SE) relations between stimuli without prior training, but simply via visual inspection of an array of premise pairs. On each of a series of slides nine circles containing different colours were paired together in boxes in different ways on each slide to embody three 3-member equivalence classes. Below this “study” array of boxes were two “choice” boxes, with two colours derived from the same equivalence class in one, and colours from two different classes in the other. Participants were instructed to choose the box in which the colours were seemingly combined “according to the pairs above”. Then on a final “sort” slide they were asked, in relation to its array, to allocate the nine colours into groups of their own choosing. Twenty-two undergraduate students, some naïve and some with some prior experience of standard equivalence experiments, participated in this experiment. Participants 1–11, in addition to trials in which the within-class choice was a symmetric or transitive pair, were given extra “baseline” trials with a simple copy of one of the array pairs in the within-class choice box. Such “baseline” trials were omitted for the remaining participants. On the choice trials about half of the participants systematically selected the within-class alternatives. There was some indication that prior experience made this more likely, whereas inclusion of “baseline” trials seemingly had a negative effect. Participants who systematically selected the within-class alternatives mostly also sorted the colours into the appropriate three equivalence groups. Some methodological refinements and extensions of this “plain sight” procedure are proposed, and the analytical potential of comparing performance on these with that on standard MTS procedures is discussed.

Efficient Neural Decoding Based on Multimodal Training.

Neural decoding methods are often limited by the performance of brain encoders, which map complex brain signals into a latent representation space of perception information. These brain encoders are constrained by the limited amount of paired brain and stimuli data available for training, making it challenging to learn rich neural representations. To address this limitation, we present a novel multimodal training approach using paired image and functional magnetic resonance imaging (fMRI) data to establish a brain masked autoencoder that learns the interactions between images and brain activities. Subsequently, we employ a diffusion model conditioned on brain data to decode realistic images. Our method achieves high-quality decoding results in semantic contents and low-level visual attributes, outperforming previous methods both qualitatively and quantitatively, while maintaining computational efficiency. Additionally, our method is applied to decode artificial patterns across region of interests (ROIs) to explore their functional properties. We not only validate existing knowledge concerning ROIs but also unveil new insights, such as the synergy between early visual cortex and higher-level scene ROIs, as well as the competition within the higher-level scene ROIs. These findings provide valuable insights for future directions in the field of neural decoding.

The Role of the Rat Prefrontal Cortex and Sex Differences in Decision-Making.

The prefrontal cortex is critical for decision-making across species, with its activity linked to choosing between options. Drift Diffusion Models (DDMs) are commonly employed to understand the neural computations underlying this behavior. Studies exploring the specific roles of regions of the rodent prefrontal cortex in controlling the decision process are limited. This study explored the role of the prelimbic cortex (PLC) in decision-making using a two-alternative forced-choice task. Rats first learned to report the location of a lateralized visual stimulus. The brightness of the stimulus indicated its reward value. Then, the rats learned to make choices between pairs of stimuli. Sex differences in learning were observed, with females responding faster and more selectively to high-value stimuli than males. DDM analysis found that males had decreased decision thresholds during initial learning, whereas females maintained a consistently higher drift rate. Pharmacological manipulations revealed that PLC inactivation reduced the decision threshold for all rats, indicating that less information was needed to make a choice in the absence of normal PLC processing. Mu opioid receptor stimulation of the PLC had the opposite effect, raising the decision threshold and reducing bias in the decision process towards high-value stimuli. These effects were observed without any impact on the rats' choice preferences. Our findings suggest that PLC has an inhibitory role in the decision process and regulates the amount of evidence that is required to make a choice. That is, PLC activity controls "when", but not "how", to act.Significance Statement This study reports causal evidence for a part of the rat prefrontal cortex, the prelimbic cortex, in controlling the amount of information needed to make a choice. Results were based on reversible inactivation using the GABA-A agonist muscimol and by stimulation of mu opioid receptors using intra-cortical infusions of the selective mu agonist DAMGO. We also found evidence for a sex difference in learning and performing a visually guided two-alternative forced-choice task. Drift Diffusion Models found that females had stable decision processes throughout learning, and showed a persistent bias against the lower value option. By contrast, males exhibited changes in their decision processes, notably reducing the amount of information needed to make choice over the period of early choice learning.

Valence sound symbolism facilitates classification of vowels and emotional facial expressions.

Research on iconicity or sound symbolism chronicles associations between aspects of word meaning and word form. In valence sound symbolism, specifically, vowels were demonstrated to be associated with valence, so that the vowel /i/ (as in English sea) is judged to fit positively valenced stimuli, whereas the vowel /o/ (as in German Boot) is judged to fit negatively valenced stimuli. However, because previous findings were based on judgments or name invention tasks, they may reflect deliberate strategies. The present research aims to demonstrate the automaticity of valence sound symbolism in online language processing by means of a speeded response task. A total of 163 participants performed a speeded categorization task in which they were requested to classify one of two simultaneously presented stimuli, pseudowords containing the vowels /i/ or /o/ and pictures with positive or negative emotional facial expressions. Thus, stimulus pairings could be either congruent (/i/-words and positive expressions; /o/-words and negative expressions) or incongruent (/i/-words and negative expressions; /o/-words and positive expressions). We observed faster and more accurate responses for congruent over incongruent combinations (the simple effects were significant for positive but not for negative expressions). Thus, sound symbolic congruency (vs. incongruency) of an irrelevant stimulus facilitated responses, which accords with an automatic process contributing to valence sound symbolism and indicates that valence sound symbolism is deeply engrained in the human cognitive system. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

B - 115 How Training Conditions Impact Performance on a Theoretically-Derived Learning Instrument

Abstract Objective Few neuropsychological measures were developed using an explicit theory that accounts for individual performance. We developed a novel associative learning measure to address this limitation and investigated whether training conditions could influence accuracy and response time. Methods Fifty young, community-dwelling adult participants completed the novel relational learning task, which explicitly trained two stimulus pairs (A- > B, A- > C) and involved a single common stimulus. Participants identify six unique relationships between stimuli: trained relations (A- > B, A- > C), mutually entailed relations (B- > A, C- > A), and combinatorial relations (B- > C, C- > B). Participants were randomly assigned to a congruent (A is opposite B, A is opposite C) or incongruent (A is opposite B, B is the same as C) training condition and completed the procedure when stimuli were observably (e.g., color-coded shapes) or arbitrarily related (e.g., letters). Results Comparisons of accuracy between training conditions using Bayesian independent samples t-tests found moderate evidence of no reliable difference between training groups when stimuli were observably related (BF01 = 3.4, δ = 0.06) and arbitrarily related (BF01 = 3.5, δ = 0.03). Comparisons of response time found strong evidence that participants took longer to identify relations when receiving incongruent training when the stimuli were visually related (BF10 = 38.8, δ = 0.9) but inconclusive evidence when the stimuli were arbitrarily related (BF10 = 1.5, δ = 0.49) (See Table 1). Conclusion These findings suggest that manipulating training conditions does not appreciably impact the ability to identify relationships between stimuli accurately. However, training appears to increase the response time needed to identify visibly related stimuli accurately. While this is a promising theoretically-derived learning paradigm, further research is required for validation in clinical practice.

The interplay of multiple unconditioned stimuli in evaluative conditioning: A weighted averaging framework for attitude formation via stimulus co-occurrences.

Evaluative conditioning (EC) is a key effect in attitude formation, leading to changes in the liking of neutral attitude objects due to their pairing with positive or negative stimuli. Despite EC's significance, current theories and most empirical findings are limited to stimulus pairings with a single affective stimulus at a time. In contrast, social environments often involve more complex combinations of affective stimuli. In this article, we introduce a novel framework grounded in information integration research to understand how conditioned attitudes develop in the presence of multiple affective stimuli. Through 10 experiments with different designs, measures, materials, and pairing procedures, we find that individuals' conditioned attitudes follow the average valence of all affective stimuli present with a stronger weighting of negative stimuli. This weighted averaging rule bears two implications for EC in more complex stimulus combinations. First, EC effects are nonmonotonous, such that additional stimuli of the same valence do not produce incremental EC effects. Second, EC effects are interdependent, such that the impact of one stimulus is weakest when accompanied by another negative stimulus and strongest when no other affective stimulus is present. We examine different cognitive processes underlying this weighted averaging rule, including potential differences in pairing memory or changes in the affective stimuli's valence when other stimuli are present. Our findings present a novel theoretical perspective on EC and offer valuable insights into attitude change from stimulus co-occurrences in stimulus-rich environments. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Effects of instructed visual imagining on emergent conditional discriminations.

Visual imagining has been proposed to play a role in the emergence of derived stimulus relations. We examined whether test-relevant visual imagining during baseline training would, accordingly, facilitate emergent visual-visual conditional discriminations at test. Adult participants (n = 75) were randomly assigned to three groups. Baseline tact training established conditional discriminations among sets of image samples and textual comparisons (AC/BD), and baseline intraverbal training established conditional discriminations among pairs of textual stimuli (CD). Two groups received tact before intraverbal training, and one group received the reverse sequence. During intraverbal training, one of the former groups was instructed to visualize the images that went with the textual stimuli. These instructions did not affect participants' retrospective self-reports of test-relevant visual imagining during training. Nevertheless, they produced a large effect on correct responding in an image-matching test (AB/BA) that followed intraverbal training. This effect was independent of baseline retention.

Transcranial alternating current stimulation can modulate the blink reflex excitability. Effects of a 10- and 20-Hz tACS session on the blink reflex recovery cycle in healthy subjects.

The blink reflex excitability, assessed through paired electrical stimuli responses, has been modulated using traditional non-invasive neurostimulation techniques. Recently, transcranial Alternating Current Stimulation (tACS) emerged as a tool to modulate brain oscillations implicated in various motor, perceptual, and cognitive functions. This study aims to investigate the influence of 20-Hz and 10-Hz tACS sessions on the primary motor cortex and their impact on blink reflex excitability. Fifteen healthy volunteers underwent 10-min tACS sessions (intensity 1mA) with active/reference electrodes placed over C4/Pz, delivering 20-Hz, 10-Hz, and sham stimulation. The blink reflex recovery cycle (BRrc) was assessed using the R2 amplitude ratio at various interstimulus intervals (ISIs) before (T0), immediately after (T1), and 30min post-tACS (T2). Both 10-Hz and 20-Hz tACS sessions significantly increased R2 ratio at T1 (10-Hz: p = 0.02; 20-Hz: p < 0.001) and T2 (10-Hz: p = 0.01; 20-Hz: p < 0.001) compared to baseline (T0). Notably, 20-Hz tACS induced a significantly greater increase in blink reflex excitability compared to sham at both T1 (p = 0.04) and T2 (p < 0.001). This study demonstrates the modulatory effect of tACS on trigemino-facial reflex circuits, with a lasting impact on BRrc. Beta-band frequency tACS exhibited a more pronounced effect than alpha-band frequency, highlighting the influential role of beta-band oscillations in the motor cortex on blink reflex excitability modulation.

Non-symbolic estimation of big and small ratios with accurate and noisy feedback

The ratio of two magnitudes can take one of two values depending on the order they are operated on: a ‘big’ ratio of the larger to smaller magnitude, or a ‘small’ ratio of the smaller to larger. Although big and small ratio scales have different metric properties and carry divergent predictions for perceptual comparison tasks, no psychophysical studies have directly compared them. Two experiments are reported in which subjects implicitly learned to compare pairs of brightnesses and line lengths by non-symbolic feedback based on the scaled big ratio, small ratio or difference of the magnitudes presented. Results of Experiment 1 showed all three operations were learned quickly and estimated with a high degree of accuracy that did not significantly differ across groups or between intensive and extensive modalities, though regressions on individual data suggested an overall predisposition towards differences. Experiment 2 tested whether subjects learned to estimate the operation trained or to associate stimulus pairs with correct responses. For each operation, Gaussian noise was added to the feedback that was constant for repetitions of each pair. For all subjects, coefficients for the added noise component were negative when entered in a regression model alongside the trained differences or ratios, and were statistically significant in 80% of individual cases. Thus, subjects learned to estimate the comparative operations and effectively ignored or suppressed the added noise. These results suggest the perceptual system is highly flexible in its capacity for non-symbolic computation, which may reflect a deeper connection between perceptual structure and mathematics.

Task-based default mode network connectivity predicts cognitive impairment and negative symptoms in first-episode schizophrenia.

Individuals diagnosed with schizophrenia (SZ) demonstrate difficulty distinguishing between internally and externally generated stimuli. These aberrations in "source monitoring" have been theorized as contributing to symptoms of the disorder, including hallucinations and delusions. Altered connectivity within the default mode network (DMN) of the brain has been proposed as a mechanism through which discrimination between self-generated and externally generated events is disrupted. Source monitoring abnormalities in SZ have additionally been linked to impairments in selective attention and inhibitory processing, which are reliably observed via the N100 component of the event-related brain potential elicited during an auditory paired-stimulus paradigm. Given overlapping constructs associated with DMN connectivity and N100 in SZ, the present investigation evaluated relationships between these measures of disorder-related dysfunction and sought to clarify the nature of task-based DMN function in SZ. DMN connectivity and N100 measures were assessed using EEG recorded from SZ during their first episode of illness (N = 52) and demographically matched healthy comparison participants (N = 25). SZ demonstrated less evoked theta-band connectivity within DMN following presentation of pairs of identical auditory stimuli than HC. Greater DMN connectivity among SZ was associated with better performance on measures of sustained attention (p = .03) and working memory (p = .09), as well as lower severity of negative symptoms, though it was not predictive of N100 measures. Together, present findings provide EEG evidence of lower task-based connectivity among first-episode SZ, reflecting disruptions of DMN functions that support cognitive processes. Attentional processes captured by N100 appear to be supported by different neural mechanisms.

Occasional Reinforced Extinction as a Method for Relapse Prevention: A Critical Systematic Review and Future Directions

Abstract Introduction Extinction is more vulnerable than the original acquisition memory, as relapse phenomena have systematically shown in the literature with different species and procedures. One strategy potentially useful to mitigate relapse is occasional reinforced extinction (ORE). In contrast to a standard extinction procedure, this strategy consists of the inclusion of a gradual and sparse number of conditioned stimulus–unconditioned stimulus pairings within the extinction phase. Here, we provide a comprehensive review of the available literature on ORE. Method We conducted a literature search using three databases (Web of Science, Scopus, and PsycInfo) in July 2022, with an additional citation search. We collected data on different variables of interest, like the relapse phenomena being studied, the outcome measures, or the specific effects obtained. Results A total of 350 studies were identified from the main database search, including 10 in the review. Five additional studies from the citation search were also included. The final sample consisted of 15 empirical reports. The observed procedural variability makes it difficult to evaluate the effectiveness of ORE to reduce different forms of relapse as the strategy has not consistently shown a general advantage over standard extinction. Conclusion The current evidence assessing the effectiveness of ORE does not appear to be consistent, although there are plenty theoretical studies recommending and discussing the potential effectiveness of such technique. Moreover, the lack of conclusive laboratory evidence calls into question how general the potential benefits of its use in clinical settings would be.

Cling together, swing together? Assessing indirect retrieval of stimulus-response bindings for associated stimuli.

When a stimulus is paired with a response, a stimulus-response (SR) binding (or event file) is formed. Subsequent stimulus repetition retrieves the SR binding from memory, which facilitates (impedes) performance when the same (a different) response is required. We aimed to explore whether indirect retrieval of SR bindings by a newly learnt associated stimulus is possible. Participants first went through a learning task to acquire novel stimulus-stimulus associations. The same stimulus pairs were then presented in a prime-probe task to assess direct and indirect retrieval effects. Participants responded by classifying word color in prime and probe trials. Probe words were either identical to prime words (test for direct retrieval) or corresponded to the associated stimulus (test for indirect retrieval) or were unrelated words (baseline). Independently of word relation, response relation (repetition vs. change) across prime and probe trials was manipulated. In two highly powered preregistered studies (total N = 260) using different types of stimulus associations, we obtained evidence for direct retrieval due to identical word repetition in the probe. Crucially, evidence for indirect retrieval upon presentation of an associated probe word was absent. Controlling for memory of each stimulus-stimulus association did not alter the findings. Our results show that indirect retrieval through newly acquired associations does not occur at the level of SR bindings, at least not for recently acquired stimulus-stimulus associations. Our study illustrates the scope of binding principles and highlights boundary conditions for the stimulus properties that can elicit automatic response retrieval.

Comparing child word associations to adult associative norms: Evidence for child-specific associations with a strong priming effect in 3-year-olds

Investigating how infants first establish relationships between words is a necessary step towards understanding how an interconnected network of semantic relationships develops in the adult lexical-semantic system. Stimuli selection for these child studies is critical since words must be both familiar and highly imageable. However, there has been a reliance on adult word association norms to inform stimuli selection in English infant studies to date, as no resource currently exists for child-specific word associations. We present three experiments that explore the strength of word–word relationships in 3-year-olds. Experiment 1 collected children’s word associations (WA) (N = 150; female = 84, L1 = British English) and compared them to adult associative norms (Moss & Older, 1996; Nelson et al., 2004 (Behavior Research Methods, Instruments, & Computers, 36(3), 402–407)). Experiment 2 replicated WAs from Experiment 1 in an online adaptation of the task (N = 24: 13 female, L1 = British English). Both experiments indicated a high proportion of child-specific WAs not represented in adult norms (Moss & Older, 1996; Nelson et al., 2004 (Behavior Research Methods, Instruments, & Computers, 36(3), 402–407)). Experiment 3 tested noun–noun WAs from these responses in an online semantic priming study (N = 40: 19 female, L1 = British English) and found that association type modulated priming (F(2.57, 100.1) = 13.13, p <. 0001, generalized η2 = .19). This research presents a resource of child-specific imageable noun–noun word pair stimuli suitable for testing young children in word recognition and semantic priming studies.

Bridging the Gap Between Metamemory and Attitude Formation: Judgments of Learning Predict Evaluative Conditioning Effects Above and Beyond Memory

Evaluative Conditioning (EC), the change in liking towards a neutral stimulus due to its pairing with a positive/negative unconditioned stimulus, is a central effect in attitude formation. Current research emphasizes the role of explicit memory in EC. However, human memory is no passive information-storage device, but people actively monitor and control their own memory processes. In the present research, we examined whether people can monitor their memory processes in attitude formation via EC and let participants predict whether they will remember the stimulus pairings in the future (judgments of learning, JOLs). In seven preregistered experiments, judgments of learning predicted actual memory of stimulus pairings above chance, showing that people can indeed monitor their memory in EC. Higher JOLs were also associated with stronger EC effects. Surprisingly, actual memory explained this effect only to a small degree. Following a Brunswikian perspective, we identified several variables contributing to the correlation between JOLs and the EC effect, such as the extremity of the unconditioned stimuli, the fit between conditioned and unconditioned stimuli, and the feeling of processing ease, which all correlated with higher JOLs and stronger EC effects. Further experiments showed the robustness of these effects across different boundary conditions, such as whether judgments and memory tests target the valence or the identity of the stimuli. Our results attest to the role of metamemory in attitude formation via EC, whereby expecting that one will remember a stimulus predicts actual memory but also the size of the EC effect over and above actual memory. By integrating two previously unrelated research areas, our studies provide important theoretical insights into both attitude formation and metamemory.

Timing-dependent synergies between motor cortex and posterior spinal stimulation in humans.

Volitional movement requires descending input from the motor cortex and sensory feedback through the spinal cord. We previously developed a paired brain and spinal electrical stimulation approach in rats that relies on convergence of the descending motor and spinal sensory stimuli in the cervical cord. This approach strengthened sensorimotor circuits and improved volitional movement through associative plasticity. In humans, it is not known whether posterior epidural spinal cord stimulation targeted at the sensorimotor interface or anterior epidural spinal cord stimulation targeted within the motor system is effective at facilitating brain evoked responses. In 59 individuals undergoing elective cervical spine decompression surgery, the motor cortex was stimulated with scalp electrodes and the spinal cord was stimulated with epidural electrodes, with muscle responses being recorded in arm and leg muscles. Spinal electrodes were placed either posteriorly or anteriorly, and the interval between cortex and spinal cord stimulation was varied. Pairing stimulation between the motor cortex and spinal sensory (posterior) but not spinal motor (anterior) stimulation produced motor evoked potentials that were over five times larger than brain stimulation alone. This strong augmentation occurred only when descending motor and spinal afferent stimuli were timed to converge in the spinal cord. Paired stimulation also increased the selectivity of muscle responses relative to unpaired brain or spinal cord stimulation. Finally, clinical signs suggest that facilitation was observed in both injured and uninjured segments of the spinal cord. The large effect size of this paired stimulation makes it a promising candidate for therapeutic neuromodulation. KEY POINTS: Pairs of stimuli designed to alter nervous system function typically target the motor system, or one targets the sensory system and the other targets the motor system for convergence in cortex. In humans undergoing clinically indicated surgery, we tested paired brain and spinal cord stimulation that we developed in rats aiming to target sensorimotor convergence in the cervical cord. Arm and hand muscle responses to paired sensorimotor stimulation were more than five times larger than brain or spinal cord stimulation alone when applied to the posterior but not anterior spinal cord. Arm and hand muscle responses to paired stimulation were more selective for targeted muscles than the brain- or spinal-only conditions, especially at latencies that produced the strongest effects of paired stimulation. Measures of clinical evidence of compression were only weakly related to the paired stimulation effect, suggesting that it could be applied as therapy in people affected by disorders of the central nervous system.

A behavioral advantage for the face pareidolia illusion in peripheral vision

Investigation of visual illusions helps us understand how we process visual information. For example, face pareidolia, the misperception of illusory faces in objects, could be used to understand how we process real faces. However, it remains unclear whether this illusion emerges from errors in face detection or from slower, cognitive processes. Here, our logic is straightforward; if examples of face pareidolia activate the mechanisms that rapidly detect faces in visual environments, then participants will look at objects more quickly when the objects also contain illusory faces. To test this hypothesis, we sampled continuous eye movements during a fast saccadic choice task—participants were required to select either faces or food items. During this task, pairs of stimuli were positioned close to the initial fixation point or further away, in the periphery. As expected, the participants were faster to look at face targets than food targets. Importantly, we also discovered an advantage for food items with illusory faces but, this advantage was limited to the peripheral condition. These findings are among the first to demonstrate that the face pareidolia illusion persists in the periphery and, thus, it is likely to be a consequence of erroneous face detection.

Learning to Choose: Behavioral Dynamics Underlying the Initial Acquisition of Decision-Making.

Current theories of decision-making propose that decisions arise through competition between choice options. Computational models of the decision process estimate how quickly information about choice options is integrated and how much information is needed to trigger a choice. Experiments using this approach typically report data from well-trained participants. As such, we do not know how the decision process evolves as a decision-making task is learned for the first time. To address this gap, we used a behavioral design separating learning the value of choice options from learning to make choices. We trained male rats to respond to single visual stimuli with different reward values. Then, we trained them to make choices between pairs of stimuli. Initially, the rats responded more slowly when presented with choices. However, as they gained experience in making choices, this slowing reduced. Response slowing on choice trials persisted throughout the testing period. We found that it was specifically associated with increased exponential variability when the rats chose the higher value stimulus. Additionally, our analysis using drift diffusion modeling revealed that the rats required less information to make choices over time. These reductions in the decision threshold occurred after just a single session of choice learning. These findings provide new insights into the learning process of decision-making tasks. They suggest that the value of choice options and the ability to make choices are learned separately and that experience plays a crucial role in improving decision-making performance.