Response Latency Research Articles

Face and face pareidolia in patients with temporal lobe epilepsy indicates different neural processing: an event-related potential study

BackgroundVisual perception of face images or face pareidolia can be evaluated with event-related potentials (ERP) for healthy subjects and patients with neurological conditions. In this study, we aimed to analyse event-related potential components such as P100, N100, N170, and vertex-positive potential (VPP) in response to face pareidolia perception in temporal lobe epilepsy (TLE) patients.MethodsERPs were recorded during the pareidolia test. Waveforms were analzyed and current source density (CSD) maps were generated.ResultsCSD profiles were shown to be interpretable when face and face pareidolia conditions. N100, P100, and N170 components showed larger amplitudes and longer latency in epilepsy patients in response to face pareidolia stimuli compared to real face images. However, the N170 component latency did not differ significantly between epilepsy patients and healthy participants, while the larger amplitude and longer latency of N100 and P100 responses were evoked in healthy patients.ConclusionsOur results indicate a difference in the neural mechanisms of processing real face information and pareidolia face-like information in TLE patients.

Neural correlates of trait anxiety in sensory processing and distractor filtering.

Evidence suggests that trait anxiety relates to cognitive processing and behavior. However, the relationships between trait anxiety and sensory processing, goal-directed performance and sensorimotor function are unclear, particularly in a multimodal context. This study used electroencephalography to evaluate whether trait anxiety influenced visual and tactile event-related potentials (ERPs), as well as behavioral distractor cost, in a bimodal sensorimotor task. Twenty-nine healthy young adults completed the State-Trait Anxiety Inventory. Participants were directed to focus on either tactile or visual stimuli while disregarding the other modality, responding to target stimulus amplitude with a proportional grip. Previous research suggests that somatosensory N70 and visual P2 ERPs serve as markers of attentional relevance, with attention also impacting the visual P3 ERP. It was hypothesized that trait anxiety would modulate the ERPs susceptible to attentional modulation (tactile N70, visual P2 and P3) and not affect behavioral performance. Trait anxiety showed a large, significant interaction with attention for visual P3 latency in response to unimodal visual stimuli, with a positive relationship between P3 latencies and trait anxiety when attending toward the stimulus and negative when attending away. A large, positive main effect of trait anxiety on visual N1 amplitude for bimodal stimuli was also detected. As predicted, trait anxiety related to ERPs but not behavioral distractor cost. These findings suggest that trait anxiety modulates visual but not somatosensory processing correlates based on attention. The absence of overt behavioral performance effects suggests compensatory mechanisms may offset underlying differences in sensory processing.

Examining modal and amodal language processing in proficient bilinguals: evidence from the modality-switch paradigm.

Recent discussions have emphasized the significance of embodied processing in language comprehension. Nevertheless, continuous debates persist regarding the relative contribution of modal (embodied) and amodal (abstract) processing of language. The current study investigated the contribution of modal processing in the first (L1) and second (L2) language, hypothesizing higher level of abstract amodal symbol processing in L2 than L1, since the correspondence of L1 and L2 (i.e., the symbol-to-symbol assignment) is in the foreground when learning L2. We employed the modality-switch paradigm (Pecher et al., 2003) in both German and French versions with proficient sequential German and French bilinguals (N = 79). Participants were presented with noun-adjective pairs (e.g., keys - jingling) in both languages and decided whether the adjective could be applied to the noun. This task repeatedly requires switching modality between trials, (e.g., from auditory [keys - jingling] to olfactory [soap - perfumed]), typically causing switch costs on response latency as compared to maintaining the modality. Contrary to the hypothesis, we observed modality switch effects (MSE) in both L1 and L2. This result suggests that embodied language processing occurs not only in the first language but also extends to the second language thus challenging the assumption that L2 processing predominantly involves abstract amodal symbol processing. Notably, however, significant L1 and L2 MSEs were found for French, whereas for German already the L1 effect was rather weak (though significant); the corresponding L2 effect was not significant. Thus, the results hinted at differences between languages regarding the relative role of modal and amodal processing.

Child-Hayling test for French school-aged children: psychometric properties and normative data

ABSTRACT The Hayling Completion Sentence Test (HSCT) is dedicated to assess inhibition of the dominant response and includes two conditions, an automatic condition in which the participants are asked to complete sentences properly and an inhibition condition in which the participants were asked to produce a word completely unrelated to the sentence. The aim of our study was 1) to adapt, 2) to evaluate the psychometric properties and 3) to standardize the HSCT into a French-school-aged pediatric population. We developed the Child-Hayling Test, a child adaptation of the adult French version of the HSCT. The reliability and validity of the Child-Hayling Test were then evaluated in a sample of 134 children aged 6–11 years. In the inhibition condition, children had lower response latency, as they get older. No effect of gender was observed. Reliability indices were low to moderate. Concerning the convergent and divergent validity, response latencies in the Child-Hayling Test correlated with latency scores in the Barre-Joe inhibition test, whereas the Child-Hayling Test scores were not related to children’s lexical abilities. The Child-Hayling Test was then administered to 393 typically developing 6- to 11-year-old children. Normative data were calculated in the inhibition condition using a regression-based approach. Regression equations to calculate Z scores are provided for clinical use. In addition, we proposed a clear guideline on how to score children’s inhibition responses. The Child-Hayling Test provides a useful tool for assessing prepotent response inhibition in children and can be recommended for use in clinical research and practice.

Association of hyperventilation-induced heart rate variability and sudden unexpected death in epilepsy in drug-resistant epilepsy.

Within the general epilepsy population, the incidence of Sudden Unexpected Death in Epilepsy (SUDEP) ranges from approximately 0.35 to 2.3 per 1,000 individuals per year. We aimed to evaluate the relationship between SUDEP risk factors and heart rate variability (HRV) parameters as a potential biomarker of SUDEP in patients with drug-resistant epilepsy (DRE). There were 52 patients diagnosed with DRE and under follow-up, and controls including 45 healthy subjects, included in the study. Hyperventilation-induced HRV (HRVHV) parameters, including the standard deviation of all RR intervals (SDRR), mean heart rate (HR), root mean squares of successive differences (RMSSD), SD of mean NN intervals recordings (SDANN), and HRV triangular index, were assessed during resting. To predict the risk of SUDEP, the relationship between HRV parameters and SUDEP risks was evaluated using the Risk Assessment for Sudden Death in Epilepsy (SUDEP-7) Risk Inventory. No statistically significant difference was found in sympathetic skin response (SSR) latency and amplitudes between the patient and control groups. In comparing healthy control subjects with patients experiencing DRE, we observed significant decreases in SDRRHV and hyperventilation-induced RMSSD (RMSSDHV) values, specifically within HRVHV. Notably, a significant correlation emerged concerning the RMSSDHV values (p < 0.01), when examining the correlation between the SUDEP-7 inventory and HRVHV parameters. This correlation between RMSSDHV and the SUDEP-7 Risk Inventory in patients with DRE represents a novel and consequential finding, suggesting its potential as an indicator of SUDEP risk.

Effects of Korean red ginseng on auditory, cognitive, and liver functions in a naturally aged mouse model

BackgroundKorean Red Ginseng and ginsenosides have been studied for their efficacy against various diseases, including those related to aging. However, most aging studies use D-galactose to induce aging, which often does not accurately represent natural aging. This study aimed to verify improvements in auditory, cognitive, and liver function through administering red ginseng to an 18-month-old naturally aging mouse model. MethodsAuditory function was assessed using Auditory Brainstem Response (ABR) and Auditory Middle Latency Response (AMLR). Cognitive function was evaluated electrophysiologically with P300 and mismatch negativity (MMN), and behaviorally using the Y-maze. Additionally, biochemical tests and histological analysis were conducted to assess liver function. The effects of red ginseng on gene expression regulation were also examined in the cochlea, auditory cortex, and liver, focusing on age-related disease processes. ResultsRed ginseng significantly decreased hearing thresholds and improved central auditory function. It also enhanced cognitive behavior and function in response to external stimulation. Furthermore, red ginseng regulated alkaline phosphatase (ALP), albumin (Alb), and total protein (TP) levels, notably decreasing aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels. Hematoxylin and eosin (H&E) staining of liver tissue showed significant improvement in fat droplets. These effects appear to be mediated by the regulation of aging-related genes Dec, c-Jun, Stat5b, and Lims2. ConclusionThese results suggest that red ginseng improves auditory, cognitive, and liver functions in a naturally aged mouse model.

Spared ulnar nerve injury results in increased layer III–VI excitability in the pig somatosensory cortex

This study describes cortical recordings in a large animal nerve injury model. We investigated differences in primary somatosensory cortex (S1) hyperexcitability when stimulating injured and uninjured nerves and how different cortical layers contribute to S1 hyperexcitability after spared ulnar nerve injury. We used a multielectrode array to record single-neuron activity in the S1 of ten female Danish landrace pigs. Electrical stimulation of the injured and uninjured nerve evoked brain activity up to 3 h after injury. The peak amplitude and latency of early and late peristimulus time histogram responses were extracted for statistical analysis. Histological investigations determined the layer of the cortex in which each electrode contact was placed. Nerve injury increased the early peak amplitude compared with that of the control group. This difference was significant immediately after nerve injury when the uninjured nerve was stimulated, while it was delayed for the injured nerve. The amplitude of the early peak was increased in layers III–VI after nerve injury compared with the control. In layer III, S1 excitability was also increased compared with preinjury for the early peak. Furthermore, the late peak was significantly larger in layer III than in the other layers in the intervention and control group before and after injury. Thus, the most prominent increase in excitability occurred in layer III, which is responsible for the gain modulation of cortical output through layer V. Therefore, layer III neurons seem to have an important role in altered brain excitability after nerve injury.

Toddlers' visual exploration during decisions predicts uncertainty monitoring 1 year later.

The longitudinal relation between toddlers' behaviors in uncertain situations (e.g., information seeking, hesitation) and preschoolers' uncertainty monitoring was investigated (between 2014 and 2019 in Northern California; Time 1: N = 183, M = 28.99 months, 53% female, 67.8% White; Time 2: N = 159, M = 41.64 months, 52.2% female). Eye movements and response latencies were recorded as children identified a target from two partially occluded (Time 1) or degraded (Time 2) images. Confidence ratings for identifications were collected at Time 2. At Time 1, gaze transitions between response options, but not response latencies and mental state language, predicted Time 2 uncertainty monitoring. Overall, these findings provide the first direct evidence of connections between toddlers' uncertainty behaviors and preschoolers' uncertainty monitoring.

A comparative study of auditory and non-auditory characteristics of congenital, early, and late-onset auditory neuropathy spectrum disorder

BackgroundThe study explored the differences in audiological and non-audiological characteristics between congenital, early-onset, and late-onset auditory neuropathy spectrum disorder (ANSD). Ninety-five individuals diagnosed with ANSD were included in the study. They were divided into three groups congenital ANSD—children (30 individuals, 60 ears), adults with early-onset ANSD (30 individuals, 56 ears), and adults with late-onset ANSD (35 individuals, 62 ears). The non-audiological characteristics (gender, laterality, and risk factors) and audiological characteristics (behavioral and electrophysiological measures) were compared between the three groups.ResultsDiscriminant analyses showed that the pure tone average, audiogram configuration, and speech thresholds were the best auditory predictors of onset-based group differences in ANSD (congenital and early-onset versus late-onset ANSD). While the congenital and early-onset group showed poorer pure-tone and speech thresholds, along with flat configuration, the late-onset group demonstrated relatively better thresholds and other configurations (rising, tent-shaped, cookie-bite). In addition, long latency responses were delayed or absent in children with congenital ANSD, indicative of onset coding deficits at the cortical level.ConclusionsThe study highlights the audiological differences between congenital, early-, and late-onset ANSD groups. These differences could be because of variations in etiology, pathophysiology, site of lesion, or genetic variability between the groups, which needs to be explored further.

Comparison of Multifrequency Narrow-Band CE-Chirp and Tone Burst Evoked Cervical Vestibular Evoked Myogenic Potentials.

Cervical vestibular evoked myogenic potentials (cVEMPs) are inhibitory myogenic responses that have commonly been elicited using a variety of stimuli. Yet the comparison of the effects of multifrequency tone bursts and narrow-band Claus Elberling chirps (NB CE-chirps) on cVEMPs has never been studied in homogeneous age groups. The present study focused on comparing the effect of multifrequency NB CE-chirps and tone bursts on the various parameters of cVEMP responses in normal-hearing younger adults. A within-group study design was applied, and purposive sampling was utilized for the collection of the data sample. The present study involved the elicitation of NB CE-chirp and tone burst-evoked cVEMPs across four-octave frequencies in 25 normal-hearing younger adults. NB CE-chirp and tone burst evoked cVEMPs were found to have a 100% response rate for all frequencies except 4,000 Hz. Across frequencies, P1 and N1 latencies were seen to be significantly shorter for NB CE-chirps than tone bursts at 500 Hz and 1,000 Hz stimulation. No differences were seen in the P1N1 amplitudes and interaural asymmetry ratio between the two stimuli across all four-octave frequencies. Furthermore, we found a significantly higher number of ears tuned to NB CE-chirps than tone bursts at 500 Hz. Comparative differences in the latencies of cVEMP responses between and within stimuli could be due to the variation in stimuli duration. Also, the difference in amplitudes across stimulation frequencies might have resulted due to the predominance of saccular responses at lower mechanical resonance frequencies. Thus, the tuning was also seen at 500 Hz and was relatively higher for NB CE-chirps than tone bursts.

Delayed Cortical Responses During Reactive Balance After Stroke Associated With Slower Kinetics and Clinical Balance Dysfunction.

Slowed balance and mobility after stroke have been well-characterized. Yet the effects of unilateral cortical lesions on whole-body neuromechanical control is poorly understood, despite increased reliance on cortical resources for balance and mobility with aging. Objective. We tested whether individuals post stroke show impaired cortical responses evoked during reactive balance, and the effect of asymmetrical interlimb contributions to balance recovery and the evoked cortical response. Using electroencephalography, we assessed cortical N1 responses evoked over fronto-midline regions (Cz) during backward support-surface perturbations loading both legs and posterior-lateral directions that preferentially load the paretic or nonparetic leg in individuals' post-stroke and age-matched controls. We tested relationships between cortical responses and clinical balance/mobility function, as well as to center of pressure (CoP) rate of rise (RoR) during balance recovery. Cortical N1 responses were smaller and delayed after stroke (P < .047), regardless of perturbation condition. In contrast to controls, slower cortical response latencies associated with lower clinical function in stroke (Mini Balance Evaluation Systems Test: r = -.61, P = .007; Timed-Up-and-Go: r = .53, P = .024; walking speed: r = -.46, P = .055). Paretic-loaded balance recovery revealed slower CoP RoR (P = .012) that was associated with delayed cortical response latencies (r = -.70, P = .003); these relationships were not present during bilateral and nonparetic-loaded conditions, nor in the older adults control group. Individuals after stroke may be limited in their balance ability by the slowed speed of their cortical responses to destabilization. In particular, paretic leg loading may reveal cortical response impairments that reflect reduced paretic motor capacity.

Attribute expansion relation extraction approach for smart engineering decision‐making in edge environments

SummaryIn sedimentology, the integration of intelligent engineering decision‐making with edge computing environments aims to furnish engineers and decision‐makers with precise, real‐time insights into sediment‐related issues. This approach markedly reduces data transfer time and response latency by harnessing the computational power of edge computing, thereby bolstering the decision‐making process. Concurrently, the establishment of a sediment knowledge graph serves as a pivotal conduit for disseminating sediment‐related knowledge in the realm of intelligent engineering decision‐making. Moreover, it facilitates a comprehensive exploration of the intricate evolutionary and transformative processes inherent in sediment materials. By unveiling the evolutionary trajectory of life on Earth, the sediment knowledge graph catalyzes a deeper understanding of our planet's history and dynamics. Relationship extraction, as a key step in knowledge graph construction, implements automatic extraction and establishment of associations between entities from a large amount of sedimentary literature data. However, sedimentological literature presents multi‐source heterogeneous features, which leads to a weak representation of hidden relationships, thus decreasing the accuracy of relationship extraction. In this article, we propose an attribute‐extended relation extraction approach (AERE), which is specifically designed for sedimentary relation extraction scenarios. First, context statements containing sediment entities are obtained from the literature. Then, a cohesive hierarchical clustering algorithm is used to extend the relationship attributes between sediments. Finally, mine the relationships between entities based on AERE. The experimental results show that the proposed model can effectively extract the hidden relations and exhibits strong robustness in dealing with redundant noise before and after sentences, which in turn improves the completeness of the relations between deposits. After the relationship extraction, a proprietary sediment knowledge graph is constructed with the extracted triads.

Can cultural distance be a factor in bilingual processing? Report from primed translation recognition task of Rongmei–Meitei bilinguals

Abstract Bilingual language processing literature has pointed out that all bilinguals are not equal and many of the differences in processing strategies can be traced to ‘the bilingual experience’. This is true for the famed bilingual advantage debate as well, as the control process associated with bilinguals can be dependent on many factors in the behavioural ecology of the bilingual groups. In this light, the current study investigates bilingual language processing in the Rongmei Naga community in Manipur, North East India. The Rongmeis speak two indigenous/heritage languages as their first and second language: Rongmei and Meitei. These two languages belong to the same language family and the communities speaking them live side by side. The paper investigates the effect of community specific cues on language processing through a primed translation recognition task. The task is carried out on two groups of bilinguals: (educated, urbane) young group and (less educated, rural) old group. The result of the study shows that the mismatch condition has an adverse effect on the response latency across groups and translation directions, thus pointing to the possibility that in spite of cultural and linguistic closeness, prevailing social dimensions may be pointers for possible impact of such cues.

Latency-aware scheduling for data-oriented service requests in collaborative IoT-edge-cloud networks

Edge computing facilitates the collaboration of physical devices at the network edge to support nearby computing requests, in order to reduce long-distance sensory data transmission from Internet of Things (IoT) devices to the remote cloud. An IoT-edge-cloud network is constructed, where sensory data collected by IoT devices is aggregated to the physically adjacent edge nodes and is transmitted between these edge nodes for achieving task processing, and the cloud acts as a central controller with global scheduling, considering the latency sensitivity of service requests and capacity limitation of physical devices. These service requests are decomposed into multiple data-oriented tasks with certain logical relations, and the satisfaction of service requests is implemented in such a collaborative IoT-edge-cloud network. In this setting, a data-oriented task scheduling mechanism is presented through considering data aggregation, data transmission and task processing in a latency-efficient and energy-saving fashion, which is formulated as a constrained objective optimization problem. We develop an improved Genetic Algorithm-based Task Scheduling (iGATS) approach, where task scheduling decisions are regarded as chromosome codings, fitness function and genetic operators are designed to solve the formulated problem. Simulation experiments are evaluated, and numerical results show that our iGATS outperforms other baseline techniques for reducing response latency, improving temporal satisfaction of service requests, and maintaining load-balancing across the whole network.

Development and Initial Testing of an Artificial Intelligence-Based Virtual Reality Companion for People Living with Dementia in Long-Term Care.

Background/Objectives: Feelings of loneliness are common in people living with dementia (PLWD) in long-term care (LTC). The goals of this study were to describe the development of a novel virtual companion for PLWD living in LTC and assess its feasibility and acceptability. Methods: The computer-generated virtual companion, presented using a head-mounted virtual reality display, was developed in two stages. In Stage 1, the virtual companion asked questions designed to encourage conversation and reminiscence. In Stage 2, more powerful artificial intelligence tools allowed the virtual companion to engage users in nuanced discussions on any topic. PLWD in LTC tested the application at each stage to assess feasibility and acceptability. Results: Ten PLWD living in LTC participated in Stage 1 (4 men and 6 women; average 82 years old) and Stage 2 (2 men and 8 women; average 87 years old). Session lengths ranged from 0:00 to 5:30 min in Stage 1 and 0:00 to 53:50 min in Stage 2. Speech recognition issues and a limited repertoire of questions limited acceptance in Stage 1. Enhanced conversational ability in Stage 2 led to intimate and meaningful conversations with many participants. Many users found the head-mounted display heavy. There were no complaints of simulator sickness. The virtual companion was best suited to PLWD who could engage in reciprocal conversation. After Stage 2, response latency was identified as an opportunity for improvement in future versions. Conclusions: Virtual reality and artificial intelligence can be used to create a virtual companion that is acceptable and enjoyable to some PLWD living in LTC. Ongoing innovations in hardware and software will allow future iterations to provide more natural conversational interaction and an enhanced social experience.

Pharmacokinetics and thermal anti-nociceptive effects of oral morphine in horses.

Morphine is an effective analgesic in horses, however, IV administration at therapeutic doses has been shown to produce dose-dependent neuroexcitation and unwanted gastrointestinal effects. The analgesic effects of morphine have, at least in part, been attributed to the morphine-6-glucuronide (M6G) metabolite. Oral administration to horses results in comparable M6G concentrations to that achieved following IV administration of a therapeutic dose without the adverse effects. The anti-nociceptive effects have not yet been reported. In the current study the thermal anti-nociceptive effects of single and multiple oral doses of morphine were assessed. Six horses received a single 0.2 mg/kg IV dose of morphine and multiple oral doses of 0.8 mg/kg morphine every 12 h for 4.5 days. Blood samples were collected throughout administration, morphine, and metabolite concentrations determined and pharmacokinetic analysis performed. Drug related behavior and physiologic responses were recorded. Response to noxious stimuli was evaluated by determining thermal threshold latency in response to the application of heat. The maximum concentrations of M6G were higher following oral administration compared to IV and the combined morphine and M6G concentrations exceeded that of IV administration starting at 2 h. Oral administration of 0.8 mg/kg morphine provided and maintained comparable anti-nociception effects to IV morphine with less adverse effects, following single and multiple doses. Morphine was well tolerated following oral administration with less excitation and minimal effects on gastrointestinal borborygmi scores compared to IV administration. Results of the current study warrant further investigation of the anti-nociceptive effects of oral morphine administration to horses.

Slow negative potentials in the pre-stimulus period in norm and patients with the first episode of schizophrenia

Behavioral data (correct response latency and errors number increase) indicate a significant decrease in the task performance efficiency in patients with the first episode of schizophrenia, compared to the norm. At the same time the SNP 1, 2, 3 amplitudes were found to enhance in the patients group, compared to the norm, which may reflect a compensatory activation of predictive attention and inhibition cortical networks for increase the response efficiency. Intergroup differences in the topography of the SNP1 and SNP2 peaks amplitude suggest “disorganization” of the left hemisphere cognitive control cortical networks at the early stage of schizophrenia. It is assumed that the SNP 1, 2, 3 components can be considered as potentially significant clinically markers of cognitive control disorders in schizophrenia.

Cognitive effects of early life exposure to PCBs: Sex-specific behavioral, hormonal and neuromolecular mechanisms involving the brain dopamine system.

Endocrine-disrupting chemicals (EDCs) are environmental toxicants that disrupt hormonal and neurodevelopmental processes. Among these chemicals, polychlorinated biphenyls (PCBs) are particularly concerning due to their resistance to biodegradation and tendency to bioaccumulate. PCBs affect neurodevelopmental function and disrupt the brain's dopamine (DA) system, which is crucial for attentional, affective, and reward processing. These disruptions may contribute to the rising prevalence of DA-mediated neuropsychiatric disorders such as ADHD, depression, and substance use disorders. Notably, these behaviors are sexually dimorphic, in part due to differences in sex hormones and their receptors, which are targets of estrogenic PCBs. Therefore, this study determined effects of early life PCB exposure on behaviors and neurochemistry related to potential disruption of dopaminergic signaling. Male and female Sprague Dawley rats were exposed to PCBs or vehicle perinatally and then underwent a series of behavioral tests, including the sucrose preference test to measure affect, conditioned orienting to assess incentive-motivational phenotype, and attentional set-shifting to evaluate cognitive flexibility and response latency. Following these tests, rats were euthanized, and we measured serum estradiol (E2), midbrain DA cells, and gene expression in the midbrain. Female rats exposed perinatally to A1221 exhibited decreased sucrose preference, and both male and female A1221 rats had reduced response latency in the attentional set-shifting task compared to vehicle counterparts. Conditioned orienting, serum estradiol (E2), and midbrain DA cell numbers were not affected in either sex; however, A1221-exposed male rats displayed higher expression of estrogen receptor alpha ( Esr1 ) in the midbrain and non-significant effects on other DA-signaling genes. Additionally, E2 uniquely predicted behavioral outcomes and DAergic cell numbers in A1221-exposed female rats, whereas DA signaling genes were predictive of behavioral outcomes in males. These data highlight sex-specific effects of A1221 on neuromolecular and behavioral phenotypes.

Beyond self-report: Measuring visual, auditory, and tactile mental imagery using a mental comparison task

Finding a reliable and objective measure of individual differences in mental imagery across sensory modalities is difficult, with measures relying on self-report scales or focusing on one modality alone. Based on the idea that mental imagery involves multimodal sensorimotor simulations, a mental comparison task (MCT) was developed across three studies and tested on adults (n = 96, 345, and 448). Analyses examined: (a) the internal consistency of the MCT, (b) whether lexical features of the MCT stimuli (word length and frequency) predicted performance, (c) whether the MCT related to two widely used self-report scales, (d) response latencies and accuracies across the visual, auditory, and tactile modalities, and (e) whether MCT performance was independent of processing speed. The MCT showed evidence of reliability and validity. Responses were fastest and most accurate for the visual modality, followed by the auditory and tactile. However, consistent with the idea that self-report questionnaires index a different aspect of mental imagery, the MCT showed minimal correlations with self-report imagery. Finally, relations between MCT scales remained strong after controlling for processing speed. Findings are discussed in relation to current understanding and measurement of mental imagery.

Characterization of subthalamic nucleus deep brain stimulation evoked resonant neural activity in a large animal model: A pilot study

Recent reports have described stimulation evoked resonant neural activity (ERNA) recorded in the subthalamic nucleus (STN) and globus pallidus internus (GPi) of patients during Deep Brain Stimulation (DBS) surgery. The constraints imposed during intraoperative recordings in patients limit the opportunity for in-depth study of new findings such as ERNA. In this pilot study, we leverage a large animal model to focus on detailed characterization of ERNA. Bilateral DBS leads were implanted in the STN in three ovine subjects and externalized for chronic use with custom stimulation and recording circuitry. ERNA was reliably recorded from the STN region in all three subjects with distinct specificity to recording and stimulation sites/contacts. Basic neural response characteristics such as input/output behavior, frequency response and strength/duration curves were evaluated. ERNA amplitude was highly dependent upon stimulation frequency, due to the interaction of the underlying resonant activity and the evoked response from each stimulus pulse. The results could be predicted by a mathematical model of constructive/destructive phase interference, and importantly, the evoked response latency. Significant time dependent dynamics in these evoked potentials were observed, which will be critically important to understand for future clinical applications. Based upon these recordings from leads in the STN region of healthy ovine subjects, these data confirm that DBS evokes high frequency resonant activity in the basal ganglia network. The clinical utility of ERNA remains to be demonstrated, but its direct association with DBS therapy makes it an interesting biomarker for potential use in contact selection and closed loop therapy.