Enhancing tube feeding method for neurosurgery: the application of improved PICC technique.

BACKGROUND AND PURPOSE: Peripherally inserted central catheter (PICC) used in neurosurgical patients requires changes in patients' head positions. However, such changes can worsen pressure on the brain tissue, lead to sudden acute brain herniation and respiratory arrest, resulting in a higher chance of patient death. This paper addresses the aforementioned problems by introducing a new PICC catheterization method. METHOD: In a retrospective study, the records of patients with PICC from April 2020 to April 2023 were reviewed, and they were divided into three groups based on the methods employed. The first group as the conventional group, involved changing patients' body positions during catheterization. The second group, as the intracavitary electrocardiographic (IECG) group, utilized intracavitary electrocardiographic monitoring and involved changing patients' body positions during catheterization. The third group as the intracavitary electrocardiographic with improved body positioning (IECG-IBP) group, catheterization was performed with guidance from intracavitary electrocardiographs and without changing the patients' body positions. The ECG changes among patients undergoing different catheter delivery methods were then compared, as well as the rate of catheter tip misplacement. RESULT: The study encompassed a total of 354 cases. Our findings reveal distinct P wave amplitude percentages among the groups: 0% in the conventional group, 88.46% in the IECG group, and 91.78% in the IECG-IBP group. Furthermore, the following catheter tip misplacement rates were recorded: 11.54% for the conventional group, 5.39% for the IECG group, and 5.47% for the IECG-IBP group. Significantly notable differences were observed in these two key indicators between the conventional group and the IECG-IBP group. Notably, the IECG-IBP group demonstrated a more favorable outcome compared to the IECG group. CONCLUSION: In patients with neurosurgical diseases, especially those with tracheostomy and nuchal stiffness, the IECG-IBP PICC catheter insertion method can effectively reduce the patient's neck resistance, does not increase the patient's headache and dizziness symptoms, and does not reduce the success of one-time catheterization. Rate and does not increase the incidence of jugular venous ectopia.

Prevention of hospital-acquired transnasal tube-related pressure injuries: a quality improvement project.

BACKGROUND: Nurses certified in wound, ostomy, and continence (WOC) monitored an increasing incidence of hospital-acquired transnasal tube-related pressure injuries (TTPIs) in a tertiary hospital. Hospital-acquired pressure injuries are one of the most common preventable complications of hospitalization; however, the significance of TTPI prevention must be considered alongside the safety of tube fixation to prevent unplanned extubations (UEs), which are serious adverse events. Thus, exploring a quality improvement (QI) project to effectively reduce the risk of TTPIs while safeguarding tube safety is urgently needed. PURPOSE: To decrease the incidence of TTPIs. METHODS: Inpatients from 2017 to 2018 were set as the control group, using routine precautions. Inpatients from 2019 to 2020 were set as the experimental group, and a bundle of training and clinical practice interventions was implemented to compare the incidence of TTPIs and UEs between the 2 groups. RESULTS: After improvement, the incidence of TTPIs reduced from 1.20% to 0.69%, the incidence of UEs reduced from 2.40% to 1.63%, and the differences were both statistically significant (P < .05). CONCLUSION: The QI project reduced the incidence of TTPIs and UEs, thereby protecting the nasal skin/mucosal surfaces, safeguarding tube fixation, and ultimately improving the quality of clinical care.

Development of an In Vitro Drug Release Method to Enable In Vitro-In Vivo Correlation of Potassium Chloride Extended-Release Tablets.

An in vitro drug release test was developed to establish a level A in vitro-in vivo correlation (IVIVC) for predicting the in vivo performance of potassium chloride extended-release (ER) matrix tablets. Three ER formulations of potassium chloride with different in vitro release rates were designed using the USP dissolution test, and their urinary pharmacokinetic profiles were evaluated in healthy subjects. Due to the lack of IVIVC with the USP method, experiments were designed to investigate the effects of in vitro test conditions on drug release in order to match in vitro drug release with in vivo behaviors of different formulations. The evaluated in vitro variables included the type of USP apparatus, surfactant, and ionic strength of the dissolution medium. Based on the study findings and data analysis, a discriminatory drug release method was successfully developed that enabled the establishment and validation of a level A IVIVC model of the potassium chloride ER tablet using urinary pharmacokinetic data. This method uses USP apparatus I at 50 rpm in 900 mL of 150 mM NaCl solution containing 40 mM sodium dodecyl sulfate at 37 °C. The current study highlights the value of investigating test conditions in developing a predictive in vitro test method for establishing IVIVC.

Prognostic Factors Influencing the Tinnitus Improvement After Idiopathic Sudden Sensorineural Hearing Loss Treatment.

PURPOSE: Logistic regression analysis was used to explore the factors that influence tinnitus improvement after idiopathic sudden sensorineural hearing loss (ISSNHL) treatment. MATERIALS AND METHODS: In this retrospective study, 137 ISSNHL patients with tinnitus were recruited at the Sun Yatsen Memorial Hospital of Sun Yat-sen University, China. They underwent audiological examinations, vestibular assessments, tinnitus examinations, a Tinnitus Handicap Inventory (THI) assessment and ISSNHL treatments. Logistic regression analysis was performed to investigate factors that affected tinnitus improvement. RESULTS: Participants were divided into an effective group (73 patients) and noneffective group (64 patients) according to THI scores before and after treatment. The effective group had better averaged hearing threshold than the noneffective group (effective group vs. noneffective group: 74.47 vs. 87.66 dB HL; t = 3.03, p < 0.05). Additionally, before intervention there were significant difference in profound audiogram configuration (effective group vs. noneffective group: 17.81% vs. 46.88%, x2 = 23.63; p < 0.001), mid tinnitus pitch (effective group vs. noneffective group: 19.18% vs. 35.94%, x2 = 6.58; p = 0.037) and mean THI scores (effective group vs. noneffective group: 57.07 ± 22.27 vs. 36.78 ± 24.41, t = -5.09, p < 0.001) between the effective and noneffective tinnitus groups. Logistic regression analysis showed that audiogram configurations (profound audiogram: OR = 0.10, 95% CI 0.01-0.72, p = 0.022), tinnitus pitch (mid tinnitus pitch: OR = 0.16, 95% CI 0.05-0.57, p = 0.004) and THI scores (OR = 1.05, 95% CI 1.03-1.07, p < 0.001) were independent factors associated with tinnitus improvement. CONCLUSION: Audiogram configuration, tinnitus pitch, and THI scores before intervention appear to be predictive of the effectiveness of acute tinnitus improvement following ISSNHL treatment.

Application of a surgical nursing cooperation program in laparoscopic pancreaticoduodenectomy.

BACKGROUND: To evaluate the value of programmed surgical nursing in laparoscopic pancreaticoduodenectomy (LPD) and summarize the experience. METHODS: The clinical data of 80 patients who received LPD in Sun Yat-sen Memorial Hospital from January 2017 to December 2018 were analyzed retrospectively. A total of 40 patients were treated with traditional surgical nursing as the control group in the earlier stage. Afterwards, another 40 cases in the experimental group were treated using the surgical nursing program. Operation time, blood loss, and satisfaction of surgeons were analyzed. RESULTS: In all, 80 cases were successfully completed, and no significant difference was observed in the preoperative data statistics between these two groups (P>0.05). Compared with the control group, the average operation time and the average blood loss of the experimental group were significantly reduced (288.9±11.14 vs. 364.5±10.84 min, P<0.05; 135.3±20.12 vs. 364.8±77.39 mL, P<0.05), and the satisfaction of surgeons was significantly higher (95% vs. 80%, P<0.05). CONCLUSIONS: Skilled execution of nursing cooperation is crucial in LPD. Through appropriate preoperative preparation, gaining mastery operation steps, remaining in sync with surgeons, and perfecting the management details, the surgical nursing cooperation program can improve the satisfaction of the surgeons and make operations more efficient.

A comparative study of surgical outcomes using a Colorado microdissection needle versus standard-size needle electrocautery in one-stage hypospadias repair using a transverse preputial island flap.

BACKGROUND: The purpose of this study was to compare the surgical outcomes of a Colorado microdissection needle (CMN) with that of a standard-size electrocautery needle in one-stage hypospadias repair using a transverse preputial island flap (TPIF). METHODS: The records of patients who received hypospadias repair from September 2012 to October 2013 were retrospectively reviewed. Patients were divided into a group that received repair using a CMN and those in which a standard-size electrocautery needle was used. Data collected and compared included age, types of hypospadias, duration of surgery, intraoperative blood loss, and postoperative edema and complications. RESULTS: There were 51 patients in the CMN group and 44 in the standard needle group, and the groups were similar with respect to age and type of hypospadias. The median surgery time for the CMN group was significantly shorter than that of the standard group (15.7 minutes vs. 20.6 minutes, respectively, P<0.001). At postoperative day 7 and day 30, the CMN group had significantly less patients with edema than the standard needle group (31.4% vs. 65.9%, P<0.01; and 37.3% vs. 79.5%, P<0.001, respectively). The overall complication rate has no significant difference between two groups. CONCLUSIONS: The use of CMN for tissue dissection and separation in hypospadias repair can facilitate foreskin degloving, shape the flap in a more efficient way, and help maintain adequate blood supply for the new urethra and its skin coverage.

Joint parameter estimation in the QTL mapping of ordinal traits.

With the rapid development of statistical genetics, the deep researches of ordinal traits have been gradually emphasized. The data of these traits bear relatively less information than those of continuous phenotypes, therefore it is more complex to map the quantitative trait loci (QTL) of ordinal traits. In this paper, the multiple-interval mapping method is considered in the genetic mapping of ordinal traits. By combining threshold model and statistical model, we build a cumulative logistic regression model to express the relationship between the ordinal data and the QTL genotypes. In order to make the interval mapping more straightforward, we treat the recombination rates as unknown parameters, and then simultaneously obtain the estimates of QTL positions, QTL effects and threshold parameters via the EM algorithm. We perform simulation experiments to investigate and compare the proposed method. We also present a real example to test the reasonableness of the considered model and estimate both model parameters and QTL parameters. Both results of simulations and example show that the method we proposed is reasonable and effective.

Development of In Vitro-In Vivo Correlation for Potassium Chloride Extended Release Tablet Formulation Using Urinary Pharmacokinetic Data.

PURPOSE: To develop and validate a Level A in vitro-in vivo correlation (IVIVC) for potassium chloride extended-release (ER) formulations. METHODS: Three prototype ER formulations of potassium chloride with different in vitro release rates were developed and their urinary pharmacokinetic profiles were evaluated in healthy subjects. A mathematical model between in vitro dissolution and in vivo urinary excretion, a surrogate for measuring in vivo absorption, was developed using time-scale and time-shift parameters. The IVIVC model was then validated based on internal and external predictability. RESULTS: With the established IVIVC model, there was a good correlation between the observed fraction of dose excreted in urine and the time-scaled and time-shifted fraction of the drug dissolved, and between the in vitro dissolution time and the in vivo urinary excretion time for the ER formulations. The percent prediction error (%PE) on cumulative urinary excretion over the 24 h interval (Ae0-24h) and maximum urinary excretion rate (Rmax) was less than 15% for the individual formulations and less than 10% for the average of the two formulations used to develop the model. Further, the %PE values using external predictability were below 10%. CONCLUSIONS: A novel Level A IVIVC was successfully developed and validated for the new potassium chloride ER formulations using urinary pharmacokinetic data. This successful IVIVC may facilitate future development or manufacturing changes to the potassium chloride ER formulation.

Coding Properties of Three Intrinsically Distinct Retinal Ganglion Cells under Periodic Stimuli: A Computational Study.

As the sole output neurons in the retina, ganglion cells play significant roles in transforming visual information into spike trains, and then transmitting them to the higher visual centers. However, coding strategies that retinal ganglion cells (RGCs) adopt to accomplish these processes are not completely clear yet. To clarify these issues, we investigate the coding properties of three types of RGCs (repetitive spiking, tonic firing, and phasic firing) by two different measures (spike-rate and spike-latency). Model results show that for periodic stimuli, repetitive spiking RGC and tonic RGC exhibit similar spike-rate patterns. Their spike- rates decrease gradually with increased stimulus frequency, moreover, variation of stimulus amplitude would change the two RGCs' spike-rate patterns. For phasic RGC, it activates strongly at medium levels of frequency when the stimulus amplitude is low. While if high stimulus amplitude is applied, phasic RGC switches to respond strongly at low frequencies. These results suggest that stimulus amplitude is a prominent factor in regulating RGCs in encoding periodic signals. Similar conclusions can be drawn when analyzes spike-latency patterns of the three RGCs. More importantly, the above phenomena can be accurately reproduced by Hodgkin's three classes of neurons, indicating that RGCs can perform the typical three classes of firing dynamics, depending on the distinctions of ion channel densities. Consequently, model results from the three RGCs may be not specific, but can also applicable to neurons in other brain regions which exhibit part(s) or all of the Hodgkin's three excitabilities.

Influence of Drug Properties and Formulation on In Vitro Drug Release and Biowaiver Regulation of Oral Extended Release Dosage Forms.

Bioequivalence (BE) studies are often required to ensure therapeutic equivalence for major product and manufacturing changes. Waiver of a BE study (biowaiver) is highly desired for such changes. Current regulatory guidelines allow for biowaiver of proportionally similar lower strengths of an extended release (ER) product provided it exhibits similar dissolution to the higher strength in multimedia. The objective of this study is to demonstrate that (1) proportionally similar strengths of ER tablets exhibiting similar in vitro dissolution profiles do not always assure BE and (2) different strengths that do not meet the criteria for dissolution profile similarity may still be bioequivalent. Four marketed ER tablets were used as model drug products. Higher and lower (half) strength tablets were prepared or obtained from commercial source. In vitro drug release was compared using multi-pH media (pH 1.2, 4.5, 6.8) per regulatory guidance. In vivo performance was assessed based on the available in vivo BE data or established in vitro-in vivo relationships. This study demonstrated that the relationship between in vitro dissolution and in vivo performance is complex and dependent on the characteristics of specific drug molecules, product design, and in vitro test conditions. As a result, proportionally similar strengths of ER dosage forms that meet biowaiver requirements per current regulatory guidelines cannot ensure bioequivalence in all cases. Thus, without an established relationship between in vitro and in vivo performance, granting biowaiver based on passing in vitro tests may result in the approval of certain bioinequivalent products, presenting risks to patients. To justify any biowaiver using in vitro test, it is essential to understand the effects of drug properties, formulation design, product characteristics, test method, and its in vivo relevance. Therefore, biowaiver requirements of different strengths of ER dosage forms specified in the current regulatory guidance should be reevaluated to assure consistent safety and efficacy among different strengths.

Dynamic Functional Brain Connectivity for Face Perception.

Face perception is mediated by a distributed brain network comprised of the core system at occipito-temporal areas and the extended system at other relevant brain areas involving bilateral hemispheres. In this study we explored how the brain connectivity changes over the time for face-sensitive processing. We investigated the dynamic functional connectivity in face perception by analyzing time-dependent EEG phase synchronization in four different frequency bands: theta (4-7 Hz), alpha (8-14 Hz), beta (15-24 Hz), and gamma (25-45 Hz) bands in the early stages of face processing from 30 to 300 ms. High-density EEG were recorded from subjects who were passively viewing faces, buildings, and chairs. The dynamic connectivity within the core system and between the extended system were investigated. Significant differences between faces and non-faces mainly appear in theta band connectivity: (1) at the time segment of 90-120 ms between parietal area and occipito-temporal area in the right hemisphere, and (2) at the time segment of 150-180 ms between bilateral occipito-temporal areas. These results indicate (1) the importance of theta-band connectivity in the face-sensitive processing, and (2) that different parts of network are involved for the initial stage of face categorization and the stage of face structural encoding.

Adaptation-dependent synchronization transitions and burst generations in electrically coupled neural networks.

A typical feature of neurons is their ability to encode neural information dynamically through spike frequency adaptation (SFA). Previous studies of SFA on neuronal synchronization were mainly concentrated on the correlated firing between neuron pairs, while the synchronization of neuron populations in the presence of SFA is still unclear. In this study, the influence of SFA on the population synchronization of neurons was numerically explored in electrically coupled networks, with regular, small-world, and random connectivity, respectively. The simulation results indicate that cross-correlation indices decrease significantly when the neurons have adaptation compared with those of nonadapting neurons, similar to previous experimental observations. However, the synchronous activity of population neurons exhibits a rather complex adaptation-dependent manner. Specifically, synchronization strength of neuron populations changes nonmonotonically, depending on the degree of adaptation. In addition, single neurons in the networks can switch from regular spiking to bursting with the increase of adaptation degree. Furthermore, the connection probability among neurons exhibits significant influence on the population synchronous activity, but has little effect on the burst generation of single neurons. Accordingly, the results may suggest that synchronous activity and burst firing of population neurons are both adaptation-dependent.

Ionic mechanisms underlying tonic and phasic firing behaviors in retinal ganglion cells: a model study.

In the retina, the firing behaviors that ganglion cells exhibit when exposed to light stimuli are very important due to the significant roles they play in encoding the visual information. However, the detailed mechanisms, especially the intrinsic properties that generate and modulate these firing behaviors is not completely clear yet. In this study, 2 typical firing behaviors­i.e., tonic and phasic activities, which are widely observed in retinal ganglion cells (RGCs)­are investigated. A modified computational model was developed to explore the possible ionic mechanisms that underlie the generation of these 2 firing patterns. Computational results indicate that the generation of tonic and phasic activities may be attributed to the collective actions of 2 kinds of adaptation currents, i.e., an inactivating sodium current and a delayed-rectifier potassium current. The concentration of magnesium ions has crucial but differential effects in the modulation of tonic and phasic firings, when the model neuron is driven by N-methyl-D-aspartate (NMDA) -type synaptic input instead of constant current injections. The proposed model has robust features that account for the ionic mechanisms underlying the tonic and phasic firing behaviors, and it may also be used as a good candidate for modeling some other firing patterns in RGCs.

Influence of drug property and product design on in vitro-in vivo correlation of complex modified-release dosage forms.

The present study examines how drug's inherent properties and product design influence the evaluation and applications of in vitro-in vivo correlation (IVIVC) for modified-release (MR) dosage forms consisting of extended-release (ER) and immediate-release (IR) components with bimodal drug release. Three analgesic drugs were used as model compounds, and simulations of in vivo pharmacokinetic profiles were conducted using different release rates of the ER component and various IR percentages. Plasma concentration-time profiles exhibiting a wide range of tmax and maximum observed plasma concentration (Cmax) were obtained from superposition of the simulated IR and ER profiles based on a linear IVIVC. It was found that depending on the drug and dosage form design, direct use of the superposed IR and ER data for IVIVC modeling and prediction may (1) be acceptable within errors, (2) become unreliable and less meaningful because of the confounding effect from the non-negligible IR contribution to Cmax, or (3) be meaningless because of the insensitivity of Cmax to release rate change of the ER component. Therefore, understanding the drug, design and drug release characteristics of the product is essential for assessing the validity, accuracy, and reliability of IVIVC of complex MR products obtained via directly modeling of in vivo data.

Phosphene object perception employs holistic processing during early visual processing stage.

Psychophysical studies have verified the possibility of recovering the visual ability by the form of low-resolution format of images, that is, phosphene-based representations. Our previous study has found that early visual processing for phosphene patterns is configuration based. This study further investigated the configural processing mechanisms of prosthetic vision by analyzing the event-related potential components (P1 and N170) in response to phosphene face and non-face stimuli. The results reveal that the coarse processing of phosphenes involves phosphene-specific holistic processing that recovers separated phosphenes into a gestalt; low-level feature processing of phosphenes is also enhanced compared with that of normal stimuli due to increased contrast borders introduced by phosphenes; while fine processing of phosphene stimuli is impaired reflected by reduced N170 amplitude because of the degraded detailed features in the low-resolution format representations. Therefore, we suggest that strategies that can facilitate the specific holistic processing stages of prosthetic vision should be considered in order to improve the performance when designing the visual prosthesis system.

Early event-related potential components in face perception reflect the sequential neural activities.

Event-related potential (ERP) studies report that early components P120, N170 and VPP are associated with face processing. Several lines of evidence suggest that VPP is the positive counterpart of N170, and they are generated by the same brain sources. However, whether P120 has a negative counterpart and the relations among these early components (i.e. P120, N170, VPP) remain unclear. In this study, the scalp electroencephalogram was recorded when the subjects passively viewed different stimuli, and ERP was calculated. The synchronization of electroencephalography signals between fronto-central and bilateral occipitotemporal sites was evaluated, and independent component analysis was employed to seek the face-sensitive independent components and their corresponding sources. We found that P120 had the negative counterpart, i.e., VN120; moreover, VN120-VPP and P120-N170 complexes were generated by the same sources located in fusiform gyrus, which reflected the same sequential neural activities of face processing.

Impaired neuronal synchrony after focal ischemic stroke in elderly patients.

OBJECTIVE: This study investigated whether cortical synchrony derived from electroencephalography (EEG) in elderly patients is impaired and if the impairment might reflect long-term functional recovery after stroke. METHODS: The scalp EEG signals of stroke patients (N=42) were collected within seven days after the onset of stroke and analyzed with phase synchronization (PS). Neurodeficit outcome was scored twice according to the National Institute of Health Stroke Scale (NIHSS): (1) at the same day of EEG recording and (2) two months after stroke. The correlation between cortical synchrony and NIHSS was analyzed. RESULTS: The level of synchronization between lesion and intact areas in the ipsilateral hemisphere was reduced significantly after stroke, while the synchronization among intact areas increased to 114% among the control subjects. Furthermore, the patients with lower inter-hemispheric synchrony after stroke were observed to have a higher NIHSS two months after stroke. CONCLUSIONS: Results indicated that the infarct broke down the cortical synchrony networks and affected large-scale neural communication. Inter-hemispheric synchrony was relevant to long-term functional recovery after stroke. SIGNIFICANCE: The prognostic value of PS for functional recovery after stroke might be helpful in understanding the alteration of cortical networks after ischemic injury.

Influences of brain development and ageing on cortical interactive networks.

OBJECTIVE: To study the effect of brain development and ageing on the pattern of cortical interactive networks. METHODS: By causality analysis of multichannel electroencephalograph (EEG) with partial directed coherence (PDC), we investigated the different neural networks involved in the whole cortex as well as the anterior and posterior areas in three age groups, i.e., children (0-10 years), mid-aged adults (26-38 years) and the elderly (56-80 years). RESULTS: By comparing the cortical interactive networks in different age groups, the following findings were concluded: (1) the cortical interactive network in the right hemisphere develops earlier than its left counterpart in the development stage; (2) the cortical interactive network of anterior cortex, especially at C3 and F3, is demonstrated to undergo far more extensive changes, compared with the posterior area during brain development and ageing; (3) the asymmetry of the cortical interactive networks declines during ageing with more loss of connectivity in the left frontal and central areas. CONCLUSIONS: The age-related variation of cortical interactive networks from resting EEG provides new insights into brain development and ageing. SIGNIFICANCE: Our findings demonstrated that the PDC analysis of EEG is a powerful approach for characterizing the cortical functional connectivity during brain development and ageing.

Influence of hypoxic-preconditioning on autonomic regulation following global ischemic brain injury in rats.

Experimental and clinical studies have shown that autonomic imbalance is associated with morbidity and mortality due to global ischemic brain injury following cardiac arrest (CA). Although hypoxic-preconditioning (HP) has shown promising neuro-protection in the subsequent ischemic brain injury, the underlying mechanisms and its influence on autonomic regulation have not yet well-understood. In this study, we utilized baroreflex sensitivity (BRS) to investigate the protective effect of HP on autonomic regulation. We investigated changes in heart rate, arterial blood pressure (BP), and BRS within 4h after CA in rats. The relationship between BRS and neurodeficit score (NDS) was analyzed. Although no significant differences were found in heart rate and BP before and after CA between the control and the preconditioned groups, both BRS and NDS of preconditioned rats were clearly higher than that of the control rats during recovery after CA. Furthermore, BRS in the first 4h after CA highly correlated with NDS 24h after CA. These results imply that treatment with HP improves autonomic regulation and protects the brain from ischemic injury. The correlation between BRS and NDS also suggests that BRS can be a prognostic criterion for the level of brain injury after CA.

Mental rotation differences between Chinese characters and English letters.

We investigated mental rotation and rotational uncertainty effect of Chinese characters and English letters, respectively by event-related potential (ERP) and behavior responses. The results indicated that subjects could mentally rotate Chinese characters and English letters at similar speed, but the total response time (RT) for Chinese characters was significantly longer. Rotational uncertainty effect was more prominent for Chinese characters than English letters in both behavior results and the amplitudes of P300 component. With the increase of orientation angle, the left-hemispheric dominance of P300 component was observed for English letters at parietal area, while Chinese characters did not show evident hemispheric asymmetry. Our results implied that significant difference of RT and ERP between different stimulus types is supposed to be in the sub-stages of the stimulus perceptual encoding and/or parity judgment.