2nd Stimulus Research Articles

Contralateral Selectivity of Upper-Limb Motor Pools via Targeted Stimulation of the Cervical Spinal Cord.

Fourteen participants with intact nervous systems completed two laboratory visits, during which posterior root-muscle reflexes (PRMRs) were evoked via a 3 × 3 cathode matrix applied over the cervical spine. An incremental recruitment curve at the C7 vertebral level was initially performed to attain resting motor threshold (RMT) in each muscle. Paired pulses (1 ms square monophasic with inter-pulse interval of 50 ms) were subsequently delivered at a frequency of 0.25 Hz at two intensities (RMT and RMT + 20%) across all nine cathode positions. Evoked responses to the 1st (PRMR1) and 2nd (PRMR2) stimuli were recorded in four upper-limb muscles. A significant effect of the spinal level was observed in all muscles for PRMR1, with greater responses being recorded caudally. Contralateral stimulation significantly increased PRMR1 in Biceps Brachii (p < 0.05, F = 4.9, η2 = 0.29), Flexor Carpi Radialis (p < 0.05, F = 4.9, η2 = 0.28) and Abductor Pollicis Brevis (p < 0.01, F = 8.9, η2 = 0.89). Post-activation depression (PAD) was also significantly increased with contralateral stimulation in Biceps Brachii (p = 0.001, F = 9.3, η2 = 0.44), Triceps Brachii (p < 0.05, F = 5.4, η2 = 0.31) and Flexor Carpi Radialis (p < 0.001, F = 17.4, η2 = 0.59). A level of unilateral motor pool selectivity may be attained by altering stimulus intensity and location during cervical tSCS. Optimising these parameters may improve the efficacy of this neuromodulation method in clinical cohorts.

The comparative study of the early stages of sensory and sensory-motor information processing in aggressive and non-aggressive schizophrenic patients

To study the early stages of sensory (P50 suppression) and sensorimotor (prepulse modification of acoustic startle reaction - ASR) information processing in aggressive and non-aggressive patients with schizophrenia. Two groups (aggressive group A, 44 s. and non-aggressive group NA, 27 s.) and 48 healthy people were studied using oculography and encephalography. Symptoms of schizophrenia were assessed by PANSS. The analysis of ASR and P50 revealed the increased ASR latency, deficit of prepulse inhibition (PPI) with 60 ms leading interval, and P50 suppression in patients compared to controls. Aggressive behavior impacted on lateral features of ASR changes in the group A. The increase of ASR amplitude and the decline of prepulse facilitation were found in the group NA. The P50 analysis revealed the increased P50 amplitude and the shortened latency in response to 2nd stimulus in the pair. The increase in scores on item G14 of the PANSS (Poor impulse control) in the group A and its correlations with ASR and P50 parameters in this group suggested the important role of impulsivity in aggressive behavior in the studied sample of aggressive patients. ASR and P50 characteristics in the group NA are associated with increased sensitivity to incoming stimuli and such personality traits as increased alertness and fear, which might inhibit aggression. Thus, indicators of the early stages of information processing can be considered as potential predictors of aggressive behavior.

Habituation of the Interlimb Reflex (ILR) Over the Biceps Brachii Muscle After Electrical Stimuli Over the Sural Nerve.

Up to now relatively little is known about interlimb reflexes (ILR). Especially it is not well known whether ILR may habituate or not to subsequent stimuli. The main aim of the present investigation was to explore the short term habituation behavior of ILR. The electromyogram was recorded over the tonically active biceps brachii (BB) muscle in 11 healthy subjects contralateral and ipsilateral to supramaximum electrical stimuli (9–12 mA) that were delivered at 1.0 and 0.4 Hz over the left sural nerve. In addition, a selective averaging method was used to investigate the influence of preceding stimuli on the ILR. Thus, 30 blocks of 3 subsequent stimuli were used. All 1st ILR of each block were averaged together. Averages were also obtained for 2nd and 3rd ILR. While ILR amplitudes gained significantly both ipsilateral and contralateral to the stimulus (p < 0.05) after train stimuli as compared with single stimuli, ILR amplitudes showed a significant decrease at 1.0 Hz versus 0.4 Hz stimuli. ILR amplitudes decreased significantly after the 2nd and 3rd stimulus relative to the 1st (p < 0.05). ILR can be recorded bilaterally remote from the stimulus site. Furthermore, ILR show clear short term habituation behavior.

Neural Correlate of Transition Violation and Deviance Detection in the Songbird Auditory Forebrain.

Deviants are stimuli that violate one's prediction about the incoming stimuli. Studying deviance detection helps us understand how nervous system learns temporal patterns between stimuli and forms prediction about the future. Detecting deviant stimuli is also critical for animals' survival in the natural environment filled with complex sounds and patterns. Using natural songbird vocalizations as stimuli, we recorded multi-unit and single-unit activity from the zebra finch auditory forebrain while presenting rare repeated stimuli after regular alternating stimuli (alternating oddball experiment) or rare deviant among multiple different common stimuli (context oddball experiment). The alternating oddball experiment showed that neurons were sensitive to rare repetitions in regular alternations. In the absence of expectation, repetition suppresses neural responses to the 2nd stimulus in the repetition. When repetition violates expectation, neural responses to the 2nd stimulus in the repetition were stronger than expected. The context oddball experiment showed that a stimulus elicits stronger neural responses when it is presented infrequently as a deviant among multiple common stimuli. As the acoustic differences between deviant and common stimuli increase, the response enhancement also increases. These results together showed that neural encoding of a stimulus depends not only on the acoustic features of the stimulus but also on the preceding stimuli and the transition patterns between them. These results also imply that the classical oddball effect may result from a combination of repetition suppression and deviance enhancement. Classification analyses showed that the difficulties in decoding the stimulus responsible for the neural responses differed for deviants in different experimental conditions. These findings suggest that learning transition patterns and detecting deviants in natural sequences may depend on a hierarchy of neural mechanisms, which may be involved in more complex forms of auditory processing that depend on the transition patterns between stimuli, such as speech processing.

Pupil response hazard rates predict perceived gaze durations

We investigated the mechanisms for evaluating perceived gaze-shift duration. Timing relies on the accumulation of endogenous physiological signals. Here we focused on arousal, measured through pupil dilation, as a candidate timing signal. Participants timed gaze-shifts performed by face stimuli in a Standard/Probe comparison task. Pupil responses were binned according to “Longer/Shorter” judgements in trials where Standard and Probe were identical. This ensured that pupil responses reflected endogenous arousal fluctuations opposed to differences in stimulus content. We found that pupil hazard rates predicted the classification of sub-second intervals (steeper dilation = “Longer” classifications). This shows that the accumulation of endogenous arousal signals informs gaze-shift timing judgements. We also found that participants relied exclusively on the 2nd stimulus to perform the classification, providing insights into timing strategies under conditions of maximum uncertainty. We observed no dissociation in pupil responses when timing equivalent neutral spatial displacements, indicating that a stimulus-dependent timer exploits arousal to time gaze-shifts.

First- and second-order contrast sensitivity functions reveal disrupted visual processing following mild traumatic brain injury

Vision is disrupted by traumatic brain injury (TBI), with vision-related complaints being amongst the most common in this population. Based on the neural responses of early visual cortical areas, injury to the visual cortex would be predicted to affect both 1st order and 2nd order contrast sensitivity functions (CSFs)—the height and/or the cut-off of the CSF are expected to be affected by TBI. Previous studies have reported disruptions only in 2nd order contrast sensitivity, but using a narrow range of parameters and divergent methodologies—no study has characterized the effect of TBI on the full CSF for both 1st and 2nd order stimuli. Such information is needed to properly understand the effect of TBI on contrast perception, which underlies all visual processing. Using a unified framework based on the quick contrast sensitivity function, we measured full CSFs for static and dynamic 1st and 2nd order stimuli. Our results provide a unique dataset showing alterations in sensitivity for both 1st and 2nd order visual stimuli. In particular, we show that TBI patients have increased sensitivity for 1st order motion stimuli and decreased sensitivity to orientation-defined and contrast-defined 2nd order stimuli. In addition, our data suggest that TBI patients’ sensitivity for both 1st order stimuli and 2nd order contrast-defined stimuli is shifted towards higher spatial frequencies.

The response decrease of auditory evoked potentials by repeated stimulation – Is there evidence for an interplay between habituation and sensitization?

ObjectivesTo assess whether the response decrement of auditory evoked potentials (AEPs) after stimulus repetition is affected by an interplay between sensitization and habituation. MethodsAEPs were recorded in 18 healthy participants. Stimulation consisted of trains with eight tones. The 6th stimulus of each train was a frequency deviant. The N100 amplitude to the 1st stimulus of the train was quantified in each trial. Trials with initially strong N100 responses and with initially weak N100 responses were averaged separately. ResultsFor the total trial sample, the N100 and P200 amplitudes decreased from the 1st to the 2nd stimulus of the train but not thereafter. Trials with an initially strong N100 response were qualified by likewise larger N100 amplitudes to the 2nd stimulus, as compared to trials with initially weak N100 responses, and were characterized by a pronounced N100 amplitude decrease from standards to deviants. ConclusionOur findings are difficult to reconcile with the view that the response decrement of AEP components after stimulus repetition is modulated by sensitization and habituation, as no evidence for either of these two processes could be obtained. SignificanceThe study provides further evidence against habituation as underlying mechanism for the AEP decrement after stimulus repetition.

The efficiency of second order orientation coherence detection

Neurons in early visual cortex respond to both luminance- (1st order) and contrast-modulated (2nd order) local features in the visual field. In later extra-striate areas neurons with larger receptive fields integrate information across the visual field. For example, local luminance-defined features can be integrated into contours and shapes. Evidence for the global integration of features defined by contrast-modulation is less well established. While good performance in some shape tasks has been demonstrated with 2nd order stimuli, the integration of contours fails with 2nd order elements. Recently we developed a global orientation coherence task that is more basic than contour integration, bearing similarity to the well-established global motion coherence task. Similar to our previous 1st order result for this task, we find 2nd order coherence detection to be scale-invariant. There was a small but significant threshold elevation for 2nd order relative to 1st order. We used a noise masking approach to compare the efficiency of orientation integration for the 1st and 2nd order. We find a significant deficit for 2nd order detection at both the local and global level, however the small size of this effect stands in stark contrast against previous results from contour-integration experiments, which are almost impossible with 2nd order stimuli.

The evoked activity of the dorsal root afferent fibres of the spinal cord of white rats in experimental diabetes mellitus

We analyzed the functional status of the dorsal root of spinal cord in experimental diabetes mellitus (DM), for instance the parameters of the action potential (AP): threshold, chronaxy and the dynamics of the dorsal root excitability. It was revealed the 1,5 times increase in threshold of excitation when compared to the control animals (P<0,001), the amplitude of AP decreased by 21,7% (P<0,05). It was also revealed a significant increase in response to the 2nd stimulus under applying the paired stimuli on the sciatic nerve in animals with experimental DM. Under applying the stimuli of increasing intensity there was found significant decrease in the amplitude of the AP in animals of the experimental group. It was concluded that hyperglycemia made changes to the processes of excitability and refractoriness in the afferent fibers of the spinal cord.

78. Neurophysiological markers of disrupted anticipatory expectancy in the adult ADHD disease

The assessment of the Attention Deficit/Hyperactivity Disorder (ADHD) in adults is often challenging, particularly due to the absence of specific diagnostic criteria. We applied a non-motor triplet protocol in a ADHD population to study the anticipatory attention as reflected by the slow cortical potential named Stimulus Preceding Negativity(SPN). We recorded 26 ADHD patients and 26 control subjects who did not receive any task instructions. We delivered trains of three stimuli belonging to the acoustic or the electric modality. In the first session(Triplet Same) the three stimuli belong to the same modality. In the second session(Triplet Different) the third stimulus belongs to the alternative modality. Grand-average waveforms were analyzed to evaluate the presence of the SPN in the interval time preceding the 1st, 2nd and 3rd stimulus. The ADHD group showed a significant N1 amplitude reduction in response to S1 and also a significant attenuation of the SPN before electric stimuli. We hypothesized that an abnormal attention processing combined with a dysfunction in emotional awareness may impair the anticipatory expectancy to the upcoming salient stimuli. We think that our findings may reflect an atypical attentional processing in the ADHD group, providing an additional level of analysis to the clinical psychiatric evaluation.

Might Cortical Hyper-Responsiveness in Aging Contribute to Alzheimer’s Disease?

Our goal is to understand the neural basis of functional impairment in aging and Alzheimer’s disease (AD) to be able to characterize clinically significant decline and assess therapeutic efficacy. We used frequency-tagged ERPs to word and motion stimuli to study the effects of stimulus conditions and selective attention. ERPs to word or motion increase when a task-irrelevant 2nd stimulus is added, but decrease when the task is moved to that 2nd stimulus. Spectral analyses show task effects on response power without 2nd stimulus effects. However, phase coherence shows both 2nd stimulus and task effects. Thus, power and coherence are dissociably modulated by stimulus and task effects. Task-dependent phase coherence successively declines in aging and AD. In contrast, task-dependent spectral power increases in aging, only to decrease in AD. We hypothesize that age-related declines in signal coherence, associated with increased power generation, stresses neurons and contributes to the loss of response power and the development of functional impairment in AD.

1st and 2nd order stimuli reaction time measures are very sensitive to mild traumatic brain injuries.

1st and 2nd order stimuli reaction time measures are very sensitive to mild traumatic brain injuries.

P 1. Repetition suppression in sensorimotor system to adapt cortex to stimuli

Repetition suppression (RS) (Grill-Spektor et al., 2006) of auditory evoked potentials (AEPs) is well known. As the sound stimulus is repeated, AEPs (N100 responses) decrease in amplitude and habituate (Fruhstorfer, 1971) . Recently, RS was demonstrated during mental imaging of movement (Hohlefeld et al., 2011) and repetition of hand gestures (Hamilton and Grafton, 2009) . These studies suggest that RS could have a role in motor control, while lacking evidence of causal relation between neuroimaging data and cortical motor output. This can be studied using transcranial magnetic stimulation (TMS). We studied whether the output of central motor network is controlled by RS with the hypothesis that RS could be a part of motor control mechanisms. Six right-handed healthy subjects (5 male) aged 22–58 years participated in the study. We measured RS of the cortical N100 responses with electroencephalography (EEG) (Näätänen and Picton, 1987) . We utilized a standard protocol in studying auditory habituation. Tones were delivered to the subject’s right ear at 60 dB above hearing threshold. The paradigm comprised of 160 tones in 40 trains, 4 tones within a train. The inter-train interval (ITI) was 20 s while the ISI between the tones within a train was 1s (Furubayashi et al., 2000) . Subsequently, the primary motor cortex area was comprehensively mapped using navigated TMS to locate the optimal cortical representation area of right first dorsal interosseous muscle. The resting motor threshold (rMT) was determined for each subject. Subsequently, we conducted a stimulation protocol with TMS at 120% of the rMT similar to that used in the auditory stimulation. During this, EEG and EMG responses were recorded. RS was evident in the cortical N100 response to auditory stimuli (31–37% decrease in amplitude) as well as to TMS (43–58% decrease in amplitude). More importantly, we also observed RS in the MEPs. The MEPs to the 2nd, 3rd and 4th stimulus in the train were 42–46% lower in amplitude than that to the 1st stimulus ( Fig. 1 ). The effect was similar in all subjects. In a control measurement with peripheral electric stimulation of ulnar nerve, we found no such effect. Our finding of RS in the central motor network is crucial for understanding the general control mechanisms of the motor cortex. However, the mechanism cannot be yet explained unequivocally. It appears that like more complex sensory networks, basic motor network in M1 is able to habituate to repeated stimuli. The recorded suppression of MEPs and TMS-EEG activity resembles the auditory habituation, which suggests that they all share same neuronal mechanisms of suppression. Hypothetically, the suprathreshold TMS may modulate the release of synaptic transmitters of the motor cortex and hence affect cortical excitability. One possible explanation for RS in a motor network is a servo-like mechanism by negative feedback from S1 after sensory feedback from movement (Catani et al., 2012) . We suggest that RS may be a general servomechanism of the cortex not limited to perception and control of the cortical input.

Temporal and Spatial Dependence of Adaptation on Ganglion Cells

Author(s): Amin, Aakash; Moazzezi, Reza; Werblin, Frank | Abstract: One of the visual system’s many tasks is to be able to distinguish objects from the background. The ability to do this is limited and affected by the relationship between the object (or stimulus) of interest and the background. Adaptation in retinal neurons is the process of changing the cell’s response to a stimulus according to that stimulus’s background. When the stimulus is hard to discern from the background, the retina adapts by improving its sensitivity to low contrast. The large response range maintained by adaptation comes at a cost, however. Adaptation complicates neural coding by making the brain interpret identical stimuli as different based on differences in background. In order to further our understanding of adaptation, this study modified the background to be in terms of time and space rather than light intensity as is the norm. By changing the interval between two circular stimuli (inter-stimuli interval; IsI) of the same diameter, and by changing the diameter over a common IsI, we measured a ganglion cell’s output for one stimulus relative to another stimulus. the results show saturation (loss of output to the 2nd stimulus) of stimuli at lower IsIs. Also, the degree of saturation for a given IsI depends on the diameter of the stimulus. These combinations of results illustrate the temporal and spatial dependence of adaptation on ganglion cells. A larger-diameter stimulus involves multiple neurons surrounding the ganglion cell being recorded so various pathways most likely influence that cell’s ultimate output. Rapid stimuli (low IsI) can be defined as having large mean luminosity that directly affects ganglion cell output.

The adaptive pattern of the auditory N1 peak revealed by standardized low-resolution brain electromagnetic tomography

The N1 peak in the late auditory evoked potential (LAEP) decreases in amplitude following stimulus repetition, displaying an adaptive pattern. The present study explored the functional neural substrates that may underlie the N1 adaptive pattern using standardized Low Resolution Electromagnetic Tomography (sLORETA). Fourteen young normal hearing (NH) listeners participated in the study. Tone bursts (80 dB SPL) were binaurally presented via insert earphones in trains of 10; the inter-stimulus interval was 0.7 s and the inter-train interval was 15 s. Current source density analysis was performed for the N1 evoked by the 1st, 2nd and 10th stimuli (S 1, S 2 and S 10) at 3 different timeframes that corresponded to the latency ranges of the N1 waveform subcomponents (70–100, 100–130 and 130–160 ms). The data showed that S 1 activated broad regions in different cortical lobes and the activation was much smaller for S 2 and S 10. Response differences in the LAEP waveform and sLORETA were observed between S 1 and S 2, but not between the S 2 and S 10. The sLORETA comparison map between S 1 and S 2 responses showed that the activation was located in the parietal lobe for the 70–100 ms timeframe, the frontal and limbic lobes for the 100–130 ms timeframe, and the frontal lobe for the 130–160 ms timeframe. These sLORETA comparison results suggest a parieto-frontal network that might help to sensitize the brain to novel stimuli by filtering out repetitive and irrelevant stimuli. This study demonstrates that sLORETA may be useful for identifying generators of scalp-recorded event related potentials and for examining the physiological features of these generators. This technique could be especially useful for cortical source localization in individuals who cannot be examined with functional magnetic resonance imaging or magnetoencephalography (e.g., cochlear implant users).

Introducing the reflex probability maps in the quantification of nociceptive withdrawal reflex receptive fields in humans

The aim of the present study was to improve the assessment of reflex receptive fields (RRF) in humans, using reflex sensitivity and reflex probability maps. Repeated electrical stimulation was applied to elicit the nociceptive withdrawal reflex (NWR) in fifteen healthy volunteers using two stimulation paradigms: fixed (FSI) and adjusted (ASI) stimulation intensities. Stimulation was applied on sixteen sites in the foot sole, and pain intensity ratings and EMG responses were recorded. RRF sensitivity and probability maps were derived, and RRF areas were calculated. During FSI, the stimulation intensities were constant and the pain ratings dropped significantly ( p < 0.01). In contrast, during ASI the pain ratings were stable, but there was a significant increase in the stimulation intensities ( p < 0.01). None of the paradigms altered significantly the RRF areas, but the FSI paradigm had lower estimation error ( p < 0.01). In all cases, the estimation error remained under 10% and 5% after five and ten repetitions, respectively. The 2nd stimulus in the train consistently rendered larger and more reliable RRF areas than the 1st stimulus. The present analysis can be useful in order to identify the most adequate stimulation parameters and quantification variables for RRF assessment in experimental and clinical pain research.

Short-term habituation of auditory evoked potential and neuromagnetic field components in dependence of the interstimulus interval

Repeated auditory stimulation results usually in a response decrement of event-related potential components. In the current study, we investigated the impact of the interstimulus interval (ISI) on the response decrement. Healthy subjects were stimulated with trains of five tones, with an ISI of 600, 1,200, or 1,800 ms within the trains. Auditory evoked potentials (AEP) were recorded from the vertex, as well as neuromagnetic auditory evoked fields (AEF) from the left temporal region. Stimulus repetition led to a response decrement for the studied AEP components (N100 and P200) and AEF components (N100m and P200m). However, for all used ISIs, there was no further response decrement after the 2nd stimulus. The ISI affected only the magnitude but not the kind of the response decrement. No evidence for a gradual response decrement was revealed at any used ISI. This finding indicates that the response decrement is probably due to the refractoriness of cell assemblies involved in the generation of AEP and AEF components, rather than the result of a genuine habituation process. The finding questions habituation as the mechanism behind short-term decrements of AEP/AEF components.

Attention effects on sensory gating — Intracranial and scalp recordings

The function of sensory gating is usually studied in paired-click experiments and quantified by the decrease of the event-related potential (ERP) component P50 and other ERP components from the 1st to the 2nd stimuli. The impact of attention on these gating measures is still not fully resolved. In the current study, the impact of attention on sensory gating was studied by scalp and intracranial recordings. The study sample consisted of epilepsy and tumor patients undergoing presurgical evaluation by means of implanted electrodes. In the unattend condition, patients had no overt task. In the active condition, patients had to count simultaneously trials with paired clicks, as well as interspersed trials with single clicks. The ERPs in the active condition were characterized by an underlying negativity both for scalp and neocortical recordings, reaching their maximum at the N100 latency of the 2nd stimulus. A time–frequency analysis revealed that this attention effect comprised only low frequency signals (< 3 Hz). In line with that, P50 amplitude and P50 gating were unaffected by attention when data were filtered from 10 to 50 Hz. In addition, attention effects were revealed for intrahippocampal ERP components and for induced high frequency neocortical gamma band activity. Findings indicate that N100 and P200 gating measures can potentially be affected by attention and have to be interpreted carefully when studying clinical populations.

Sensory gating in intracranial recordings — The role of phase locking

For patients with schizophrenia, a deficient gating (or filtering) of sensory input has been described. One major approach to study this sensory gating is to measure event-related potentials (ERPs) in response to paired clicks. In these experiments, sensory gating is quantified as amplitude reduction of the ERP components P50 and N100 from the 1st to the 2nd stimulus. In ERP studies brain electrical signals are averaged over single trials. Alterations in phase locking might be one factor contributing to the observed deficits in sensory gating, but findings have been inconclusive as yet. In particular, the contribution of different frequency bands to the deficit required further investigation. We studied N100 gating by intracranial recordings in a sample of epilepsy patients and subdivided the group into good and poor gators of the intracranial ERP component N100. Data were evaluated by frequency specific wavelet-based phase and power analyses. Poor N100 gators had an increased phase locking in the frequency range from 6.0–15.1 Hz after the 2nd stimulus, as compared to good gators. Other group differences were apparent already before the 2nd stimulus. Poor gators had less phase locked beta band activity (20.2–30.0 Hz) than good gators 200–315 ms after the onset of the 1st stimulus. Within the group of poor gators, lower values of phase locking in this frequency range were also associated with lower gating ratios. The reduced beta band response in response to the 1st stimulus may reflect poorer memory encoding of the 1st stimulus in poor gators. This in turn might lead to increased demands to process the 2nd stimulus.

An action sequence withheld in memory can delay execution of visually guided actions: The generalization of response compatibility interference.

Withholding an action plan in memory for later execution can delay execution of another action, if the actions share a similar (compatible) action feature (i.e., response hand). This phenomenon, termed compatibility interference (CI), was found for identity-based actions that do not require visual guidance. The authors examined whether CI can generalize to both identity-based and location-based actions that require visual guidance. Participants withheld a planned action based on the identity of a stimulus and then immediately executed a visually guided action (touch response) to a 2nd stimulus based on its color identity (Experiment 1), its spatial location (Experiment 2), or an intrinsic spatial location within an object (Experiment 3). Results showed CI for both left- and right-hand responses in Experiment 1. However, CI occurred for left- but not right-hand responses in Experiment 2 and 3. This suggests that CI can generalize to visually guided actions under cognitive control but not to actions that invoke automatic visual-control mechanisms where the left hemisphere may play a special role (C. Gonzalez, T. Ganel, & M. Goodale, 2006). The code occupation account for CI (G. Stoet & B. Hommel, 2002) is also discussed.