Long-latency Responses Research Articles

Preparatory cortical and spinal settings to counteract anticipated and non-anticipated perturbations

Little is known about how the central nervous system prepares postural responses differently in anticipated compared to non-anticipated perturbations. To investigate this, participants were exposed to translational and rotational perturbations presented in a blocked (anticipated) and a random (non-anticipated) design. The preparatory setting (‘central set’) was measured by H-reflexes, motor-evoked potentials (MEPs), and short-interval intracortical inhibition (SICI) shortly before perturbation onset in the soleus of 15 healthy adults. Additionally, the behavioral consequences of differential preparatory settings were analyzed by comparing the short- (SLR), medium- (MLR), and long-latency response (LLR) of the soleus after anticipated and non-anticipated rotations and translations. H-reflexes elicited before perturbation were different between conditions (p=0.023) with larger amplitudes in anticipated translations compared to anticipated rotations (37.0%; p=0.048). Reduced SICI was found in the three conditions containing perturbations compared to static standing (p<0.001). Muscular responses assessed after perturbations remained unchanged for the SLR and MLR, whereas the LLR was decreased in anticipated rotations (−36.2%; p=0.002) and increased in anticipated translations (16.7%; p=0.046) compared to the corresponding non-anticipated perturbation. As the SLR and MLR are organized at the spinal and the LLR at the cortical level, the preparatory setting seems to mainly influence cortically mediated postural responses. However, the modulation of the H-reflex before anticipated perturbations indicates that supraspinal centers adjusted Ia-afferent transmission for the soleus in a perturbation-specific manner. Intracortical inhibition was also modulated but differentiates to a lesser extent only between perturbation conditions and unperturbed stance.

Conditional control in visual selection.

Attention and eye movements provide a window into the selective processing of visual information. Evidence suggests that selection is influenced by various factors and is not always under the strategic control of the observer. The aims of this tutorial review are to give a brief introduction to eye movements and attention and to outline the conditions that help determine control. Evidence suggests that the ability to establish control depends on the complexity of the display as well as the point in time at which selection occurs. Stimulus-driven selection is more probable in simple displays than in complex natural scenes, but it critically depends on the timing of the response: Salience determines selection only when responses are triggered quickly following display presentation, and plays no role in longer-latency responses. The time course of selection is also important for the relationship between attention and eye movements. Specifically, attention and eye movements appear to act independently when oculomotor selection is quick, whereas attentional processes are able to influence oculomotor control when saccades are triggered only later in time. This relationship may also be modulated by whether the eye movement is controlled in a voluntary or an involuntary manner. To conclude, we present evidence that shows that visual control is limited in flexibility and that the mechanisms of selection are constrained by context and time. The outcome of visual selection changes with the situational context, and knowing the constraints of control is necessary to understanding when and how visual selection is truly controlled by the observer.

Social Desirability and Undesirability Effects on Survey Response latencies

This article looks at paradata in the form of response latencies to identify socially desirable response behaviour. Response latencies are used as proxies to infer information processing modes. So far, evidence is conflicted as to whether socially desirable responding is indicated by shorter or longer response latencies. Our results show that faster responses are associated with the reporting of desirable attitudes and behaviour while slower responses are linked with those that are undesirable. Trait desirability measures that do not take this difference in direction into account may be responsible for the often contradictory results of various researchers who have employed the method in the past.

Jumping the gun: Faster response latencies to deceptive questions in a realistic scenario

Most theories of lie detection assume that lying increases cognitive load, resulting in longer response latencies during questioning. However, the studies supporting this theory are typically laboratory-based, in settings with no specific validity in security contexts. Consequently, using virtual reality (VR), we investigated how response latencies were influenced in an ecologically valid environment of interest to security professionals. In a highly realistic airport security terminal presented in VR, a security officer asked participants yes/no questions about their belongings. We found that liars actually responded more quickly to questions on which they were lying than to questions on which they were telling the truth. A control group, who answered the same questions but were not lying, answered equally quickly for all questions. We argue that this decrease in response time is possibly an unconscious reaction to questions on which individuals must answer deceptively. These results call into question the generalizability of previous research and highlight the importance of ecological validity when researching lie detection. These findings also uncover a new potential tool for enhancing lie detection in real-world scenarios.

P143 Navigated transcranial magnetic stimulation of premotor cortex and long latency responses elicited in hand muscles during handwriting

Introduction The nTMS technique is often used in preoperative mapping of motor, speech and language related cortical areas in patients undergoing neurosurgical operation. Only few intraoperative studies investigated network underlying the production of written language and found that the superior premotor cortices close to the superior frontal sulcus was involved in handwritten production of words. The nTMS methodology for identification of the motor frontal areas involved in handwriting that can be used in preoperative mapping of patients is not yet established. Objectives To evaluate for the first time the feasibility of patterned rTMS protocol for locating premotor writing function in healthy volunteers. Materials & methods The ten healthy and right-handed volunteers (three female, and seven males, mean age 40.2 ± 11.17 (range 24–63 years) underwent rTMS of the left primary motor cortex (M1) and superior premotor cortices including the posterior part of superior and middle frontal gyri. Patterned bursts of rTMS consisted of 4 bursts of 4 stimuli each, with an interstimulus interval of 6 ms, and a burst repetition rate of 4 Hz were applied during writing to a dictation task and with EMG recording from right APB and FDI muscles. Two trains of these rTMS bursts were applied in a single trial, therefore after auditory presenting the sentence two rTMS trains (separated 2–7 s depending on the length of sentence) were given while the participant was writing with the pen. Results The rTMS of the left superior premotor cortex close to the superior frontal sulcus elicited long latency responses (LLRs) from the hand muscles with the latency of 70.72 ± 8.25 ms followed by MEPs (Fig. 1), as well as writing related disturbances (writing arrest, trembling, poor grapheme production, slow writing, lifting of the hand). Conclusion The application of rTMS to the premotor cortex close to superior frontal sulcus elicited writing interferences and LLR responses that were recorded in dominant hand muscle during writing. Further rTMS studies would be needed to clarify an exact neurophysiologic mechanism of LLR generation in hand muscles during voluntary writing task, as well as during different voluntary motor tasks. Although still preliminary, the results might have clinical value for preoperative use of rTMS in functional mapping of writing. Download high-res image (211KB) Download full-size image

Heaping at Round Numbers on Financial Questions: The Role of Satisficing

Survey responses to quantitative financial questions frequently display strong patterns of heaping at round numbers. This paper uses two studies to examine variation in rounding across questions and by individual characteristics. Rounding was more common for respondents low in ability, for respondents low in motivation, and for more difficult questions, all consistent with theories of satisficing. Questions that require more difficult information retrieval and integration of information exhibit more heaping. The use of records, which lowers task difficulty, reduces rounding as well. Higher episodic memory is associated with less rounding, and standard measures of motivation are negatively associated with rounding. These relationships, along with the fact that longer response latencies are associated with less rounding, all support the idea that rounding is a manifestation of satisficing on open-ended financial questions. Rounding patterns also appear remarkably similar across the two studies, despite being fielded in different modes and employing different question order and wording.

Heaping at Round Numbers on Financial Questions: The Role of Satisficing.

Survey responses to quantitative financial questions frequently display strong patterns of heaping at round numbers. This paper uses two studies to examine variation in rounding across questions and by individual characteristics. Rounding was more common for respondents low in ability, for respondents low in motivation, and for more difficult questions, all consistent with theories of satisficing. Questions that require more difficult information retrieval and integration of information exhibit more heaping. The use of records, which lowers task difficulty, reduces rounding as well. Higher episodic memory is associated with less rounding, and standard measures of motivation are negatively associated with rounding. These relationships, along with the fact that longer response latencies are associated with less rounding, all support the idea that rounding is a manifestation of satisficing on open-ended financial questions. Rounding patterns also appear remarkably similar across the two studies, despite being fielded in different modes and employing different question order and wording.

Differences in Glomerular-Layer-Mediated Feedforward Inhibition onto Mitral and Tufted Cells Lead to Distinct Modes of Intensity Coding.

Understanding how each of the many interneuron subtypes affects brain network activity is critical. In the mouse olfactory system, mitral cells (MCs) and tufted cells (TCs) comprise parallel pathways of olfactory bulb output that are thought to play distinct functional roles in odor coding. Here, in acute mouse olfactory bulb slices, we test how the two major classes of olfactory bulb interneurons differentially contribute to differences in MC versus TC response properties. We show that, whereas TCs respond to olfactory sensory neuron (OSN) stimulation with short latencies regardless of stimulation intensity, MC latencies correlate negatively with stimulation intensity. These differences between MCs and TCs are caused in part by weaker excitatory and stronger inhibitory currents onto MCs than onto TCs. These differences in inhibition between MCs and TCs are most pronounced during the first 150 ms after stimulation and are mediated by glomerular layer circuits. Therefore, blocking inhibition originating in the glomerular layer, but not granule-cell-mediated inhibition, reduces MC spike latency at weak stimulation intensities and distinct temporal patterns of odor-evoked responses in MCs and TCs emerge in part due to differences in glomerular-layer-mediated inhibition.SIGNIFICANCE STATEMENT Olfactory bulb mitral and tufted cells display different odor-evoked responses and are thought to form parallel channels of olfactory bulb output. Therefore, determining the circuit-level causes that drive these differences is vital. Here, we find that longer-latency responses in mitral cells, compared with tufted cells, are due to weaker excitation and stronger glomerular-layer-mediated inhibition.

Effects of Antipsychotic Drugs Haloperidol and Clozapine on Visual Responses of Retinal Ganglion Cells in a Rat Model of Retinitis Pigmentosa.

In the P23H rat model of retinitis pigmentosa, the dopamine D2 receptor antagonists sulpiride and eticlopride appear to improve visual responses of retinal ganglion cells (RGCs) by increasing light sensitivity of RGCs and transforming abnormal, long-latency ON-center RGCs into OFF-center cells. Antipsychotic drugs are believed to mediate their therapeutic benefits by blocking D2 receptors. This investigation was conducted to test whether haloperidol (a typical antipsychotic drug) and clozapine (an atypical antipsychotic drug) could similarly alter the light responses of RGCs in the P23H rat retina. Extracellular recordings were made from RGCs in isolated P23H rat retinas. Responses of RGCs to flashes of light were evaluated before and during bath application of a drug. Both haloperidol and clozapine increased light sensitivity of RGCs on average by ∼0.3 log unit. For those ON-center RGCs that exhibit an abnormally long-latency response to the onset of a small spot of light, both haloperidol and clozapine brought out a short-latency OFF response and markedly reduced the long-latency ON response. The selective serotonin 5-HT2A antagonist MDL 100907 had similar effects on RGCs. The effects of haloperidol on light responses of RGCs can be explained by its D2 receptor antagonism. The effects of clozapine on light responses of RGCs on the other hand may largely be due to its 5-HT2A receptor antagonism. Overall, the results suggest that antipsychotic drugs may be useful in improving vision in patients with retinitis pigmentosa.

Perturbation Predictability Can Influence the Long-Latency Stretch Response.

Perturbations applied to the upper limbs elicit short (M1: 25–50 ms) and long-latency (M2: 50–100 ms) responses in the stretched muscle. M1 is produced by a spinal reflex loop, and M2 receives contribution from multiple spinal and supra-spinal pathways. While M1 is relatively immutable to voluntary intention, the remarkable feature of M2 is that its size can change based on intention or goal of the participant (e.g., increasing when resisting the perturbation and decreasing when asked to let-go or relax following the perturbation). While many studies have examined modulation of M2 between passive and various active conditions, through the use of constant foreperiods (interval between warning signal and a perturbation), it has also been shown that the magnitude of the M2 response in a passive condition can change based on factors such as habituation and anticipation of perturbation delivery. To prevent anticipation of a perturbation, most studies have used variable foreperiods; however, the range of possible foreperiod duration differs between experiments. The present study examined the influence of different variable foreperiods on modulation of the M2 response. Fifteen participants performed active and passive responses to a perturbation that stretched wrist flexors. Each block of trials had either a short (2.5–3.5 seconds; high predictability) or long (2.5–10.5 seconds; low predictability) variable foreperiod. As expected, no differences were found between any conditions for M1, while M2 was larger in the active rather than passive conditions. Interestingly, within the two passive conditions, the long variable foreperiods resulted in greater activity at the end of the M2 response than the trials with short foreperiods. These results suggest that perturbation predictability, even when using a variable foreperiod, can influence circuitry contributing to the long-latency stretch response.

Bouncing on Mars and the Moon-the role of gravity on neuromuscular control: correlation of muscle activity and rate of force development.

On our astronomical neighbors Mars and the Moon, bouncing movements are the preferred locomotor techniques. During bouncing, the stretch-shortening cycle describes the muscular activation pattern. This study aimed to identify gravity-dependent changes in kinematic and neuromuscular characteristics in the stretch-shortening cycle. Hence, neuromuscular control of limb muscles as well as correlations between the muscles' pre-activation, reflex components, and force output were assessed in lunar, Martian, and Earth gravity. During parabolic flights, peak force (Fmax), ground-contact-time, rate of force development (RFD), height, and impulse were measured. Electromyographic (EMG) activities in the m. soleus (SOL) and gastrocnemius medialis (GM) were assessed before (PRE) and during bounces for the reflex phases short-, medium-, and long-latency response (SLR, MLR, LLR). With gradually decreasing gravitation, Fmax, RFD, and impulse were reduced, whereas ground-contact time and height increased. Concomitantly, EMG_GM decreased for PRE, SLR, MLR, and LLR, and in EMG_SOL in SLR, MLR, and LLR. For SLR and MLR, Fmax and RFD were positively correlated to EMG_SOL. For PRE and LLR, RFD and Fmax were positively correlated to EMG_GM. Findings emphasize that biomechanically relevant kinematic adaptations in response to gravity variation were accompanied by muscle- and phase-specific modulations in neural control. Gravitational variation is anticipated and compensated for by gravity-adjusted muscle activities. Importantly, the pre-activation and reflex phases were differently affected: in SLR and MLR, SOL is assumed to contribute to the decline in force output with a decreasing load, and, complementary in PRE and LLR, GM seems to be of major importance for force generation.

Functional specialization of areas along the anterior-posterior axis of the primate prefrontal cortex.

Functional specialization of areas along the anterior-posterior axis of the lateral prefrontal cortex has been speculated but little evidence exists about distinct neurophysiological properties between prefrontal sub-regions. To address this issue we divided the lateral prefrontal cortex into a posterior-dorsal, a mid-dorsal, an anterior-dorsal, a posterior-ventral, and an anterior ventral region. Selectivity for spatial locations, shapes, and colors was evaluated in six monkeys never trained in working memory tasks, while they viewed the stimuli passively. Recordings from over two thousand neurons revealed systematic differences between anterior and posterior regions. In the dorsal prefrontal cortex, anterior regions exhibited the largest receptive fields, longest response latencies, and lowest amount of information for stimuli. In the ventral prefrontal cortex, posterior regions were characterized by a low percentage of responsive neurons to any stimuli we used, consistent with high specialization for stimulus features. Additionally, spatial information was more prominent in the dorsal and color in ventral regions. Our results provide neurophysiological evidence for a rostral-caudal gradient of stimulus selectivity through the prefrontal cortex, suggesting that posterior areas are selective for stimuli even when these are not releant for execution of a task, and that anterior areas are likely engaged in more abstract operations.

Peripheral optogenetic stimulation induces whisker movement and sensory perception in head-fixed mice.

We discovered that optical stimulation of the mystacial pad in Emx1-Cre;Ai27D transgenic mice induces whisker movements due to activation of ChR2 expressed in muscles controlling retraction and protraction. Using high-speed videography in anesthetized mice, we characterize the amplitude of whisker protractions evoked by varying the intensity, duration, and frequency of optogenetic stimulation. Recordings from primary somatosensory cortex (S1) in anesthetized mice indicated that optogenetic whisker pad stimulation evokes robust yet longer latency responses than mechanical whisker stimulation. In head-fixed mice trained to report optogenetic whisker pad stimulation, psychometric curves showed similar dependence on stimulus duration as evoked whisker movements and S1 activity. Furthermore, optogenetic stimulation of S1 in expert mice was sufficient to substitute for peripheral stimulation. We conclude that whisker protractions evoked by optogenetic activation of whisker pad muscles results in cortical activity and sensory perception, consistent with the coding of evoked whisker movements by reafferent sensory input.

Neurophysiologic markers of primary motor cortex for laryngeal muscles and premotor cortex in caudal opercular part of inferior frontal gyrus investigated in motor speech disorder: a navigated transcranial magnetic stimulation (TMS) study.

Transcranial magnetic stimulation studies have so far reported the results of mapping the primary motor cortex (M1) for hand and tongue muscles in stuttering disorder. This study was designed to evaluate the feasibility of repetitive navigated transcranial magnetic stimulation (rTMS) for locating the M1 for laryngeal muscle and premotor cortical area in the caudal opercular part of inferior frontal gyrus, corresponding to Broca's area in stuttering subjects by applying new methodology for mapping these motor speech areas. Sixteen stuttering and eleven control subjects underwent rTMS motor speech mapping using modified patterned rTMS. The subjects performed visual object naming task during rTMS applied to the (a) left M1 for laryngeal muscles for recording corticobulbar motor-evoked potentials (CoMEP) from cricothyroid muscle and (b) left premotor cortical area in the caudal opercular part of inferior frontal gyrus while recording long latency responses (LLR) from cricothyroid muscle. The latency of CoMEP in control subjects was 11.75±2.07ms and CoMEP amplitude was 294.47±208.87µV, and in stuttering subjects CoMEP latency was 12.13±0.75ms and 504.64±487.93µV CoMEP amplitude. The latency of LLR in control subjects was 52.8±8.6ms and 54.95±4.86 in stuttering subjects. No significant differences were found in CoMEP latency, CoMEP amplitude, and LLR latency between stuttering and control-fluent speakers. These results indicate there are probably no differences in stuttering compared to controls in functional anatomy of the pathway used for transmission of information from premotor cortex to the M1 cortices for laryngeal muscle representation and from there via corticobulbar tract to laryngeal muscles.

Posttraumatic Stress and Attentional Bias towards Cancer-Related Stimuli in Parents of Children Recently Diagnosed with Cancer.

ObjectivesTo investigate whether posttraumatic stress symptoms (PTSS) are related to attentional bias towards cancer-related stimuli among parents of children recently diagnosed with cancer.MethodsSixty-two parents completed questionnaires measuring PTSS, depression, and anxiety and the emotional Stroop task via the Internet. The emotional Stroop task included cancer-related words, cardiovascular disease-related words, and neutral words.ResultsParticipants were split in two groups based on the median of PTSS: High-PTSS and Low-PTSS. There was a significant interaction between word-type and group and a planned contrast test of this interaction indicated that the High-PTSS group had longer response latencies on cancer-related words compared to the other word-type and group combinations.ConclusionsFindings suggest that PTSS are related to attentional bias towards cancer-related stimuli among parents of children recently diagnosed with cancer. Implications of this finding for the understanding of PTSS in this population, future research, and clinical practice are discussed.

Compliance on neuropsychological performance validity testing in patients with borderline personality disorder.

Complaints of cognitive dysfunction are common in patients with borderline personality disorder (BPD), and they are often accompanied by deficits on neuropsychological testing. Prior studies of BPD, however, did not evaluate compliance on neuropsychological performance validity testing, which could partially account for cognitive deficits observed in patients. The aims of the current study were to evaluate the frequency at which patients with BPD show less than adequate compliance on performance validity testing, and whether patients showing less compliance perform lower on standardized neuropsychological measures. Fifty outpatients with BPD completed the Victoria Symptom Validity Test, a 2-alternative, forced-choice recognition test as part of a larger neuropsychological test battery for research on cognitive functioning in BPD. As a group, patients with BPD made more errors and had longer response latencies on seemingly difficult items as compared to healthy individuals. Based on established guidelines for interpretation of performances on the Victoria Symptom Validity Test, 2% of the sample was classified as probably not compliant, 10% questionably compliant, and 88% compliant. Patients with questionably or probably not compliant performances had lower estimated premorbid intellectual functioning and displayed poorer response control on neuropsychological testing than compliant patients. These findings highlight the value of incorporating performance validity testing in neuropsychological studies of patients with BPD and suggest that prior research on the disorder should be interpreted with caution because the results may not be based on valid performances.

The Effect of Stimulus Intensity and Carrier Frequency on Auditory Middle- and Long-Latency Evoked Potentials Using a Steady-State-Response Approach.

The purpose of this study was to measure magnitude changes of auditory steady-state responses (ASSRs) and respective transient middle- and long-latency responses as a function of stimulus intensity and carrier frequency. The literature lacks clear consensus, including relationship to loudness. A cohort of 48 adults with normal hearing was examined from a companion study (Tlumak, Durrant, & Delgado, 2015) on effects of aging. ASSRs were elicited by repeated tone-burst stimuli presented at rates of 40 and 0.75 Hz at 3 frequencies and 5 levels of stimulus intensity. The design also permitted scrutiny of any gender bias to the results. Similar to derived transient response findings, ASSR magnitude (harmonic sum) systematically increased with intensity. Input-output function only at 0.75 Hz approximated a log-log linear function. However, slopes fell well below that of doubling of loudness per 10 dB SPL. Results failed to demonstrate significance as a function of carrier frequency and gender for both repetition rates. Effects of stimulus intensity, carrier frequency, and gender on ASSRs were similar to those of their transient counterparts. Findings remain disappointing for objective loudness estimation. Results suggest only a clear linkage to the long-latency response and the 0.75-Hz magnitude but require careful consideration of limitations/underlying mechanisms when measuring loudness-related effects.

ID 228 – Combining evoked potentials and EEG reactivity for coma prognosis

The combined study of short- and long-latency responses remains restricted to a few university hospitals. Here we review results in 85 consecutive comatose patients (60% anoxic) studied with short- and long-latency AEPs and SEPs combined with EEG reactivity in a non-university hospital setting. We confirm the ominous prognosis associated with bilateral absence of brainsem and primary N20/Pa,whatever the coma atiology. Preservation of short-latency EPs does not have a significant positive predictive value, and was followed by death or PVS in 1/3rd cases. Presence of short- and long-latency responses (N20 + Pa + N100) had a strong positive predictive value for awakening from coma if they were associated with reactive EEG (85% of awakening). N100 and EEG reactivity were strongly associated; their dissociation (N100 present but non-reactive EEG) was followed in 6% of cases by vegetative state. Unilateral suppression of N20, with preservation of all other responses was associated with sensorimotor handicap on awakening. We underscore the prognostic usefulness of short + long-latency EPs + EEG in coma, and show its feasibility in non-university hospitals. The 85% ratio of awakening when N100 associates to reactive EEG stresses the importance of coupling the two measures for improving prognosis.

Mismatch negativity and neural adaptation: Two sides of the same coin. Response: Commentary: Visual mismatch negativity: a predictive coding view.

Mismatch negativity and neural adaptation: Two sides of the same coin. Response: Commentary: Visual mismatch negativity: a predictive coding view.

A field experiment of workers’ responses to proximity warnings of static safety hazards on construction sites

This paper describes an experimental study of workers’ responses to proximity warnings of static safety hazards on construction sites using a location-based proximity warning system named the Proactive Construction Management System (PCMS). A method of evaluating workers’ responses to proximity warnings is proposed. The method consists of six variables: warning time and distance (the time and the minimum distance to a hazard when a worker receives a warning), dangerous time and distance (the time and the minimum distance to the hazard when the worker comes close to the hazard), and response time and distance (the difference between dangerous time and warning time, and the difference between dangerous distance and warning distance). Finally, whether a worker responds to a warning is evaluated against a two-second threshold and a two-meter threshold in terms of response time and distance respectively.The experiment was conducted over 17 workdays with the participation of 72 workers and resulted in 5391 warnings on a real-life construction project in Shanghai, China. The workers’ responses were analyzed with respect to two factors: building trades and a-priori risk levels. The research found that workers responded to proximity warnings actively, but slightly differently across the selected building trades; carpenters had longer response latency in hazardous areas than ironworkers did, and response percentages were high for hazardous areas with high risks. The results also show evidence that PCMS has the potential to improve workers’ safety performance. The limitations of the present study and future research directions are also addressed.