Serial Pattern Research Articles

A serial pattern scheme for a value-based predictive check-in system

A serial pattern scheme for a value-based predictive check-in system

Reappraisal of the early diagnostic value of serial analyses of western blot patterns for HIV infection in neonates

Objective: Serial Western Blot (WB) testing was utilized for the early diagnosis of neonatal HIV infection. Methods: Serum samples included five anti-HIV positive mother/child pairs and 57 newborns who received hepatitis B immunoglobulin and hepatitis B vaccine. Enzyme-linked immunosorbent assay (ELISA) and serial WB were supplemented by polymerase chain reaction (PCR) and gag sequencing studies. Results: Serial WB patterns between the five mothers and their newborns were initially identical. Reaction lines, however, declined progressively and proportionately in the three infants not HIV infected. Two newborns were diagnosed early to be HIV-positive by evaluating the intensifying and increasing WB reaction lines. For the group of newborns who underwent the hepatitis B control program, all WB reaction lines declined progressively with time and none of these infants were truly HIV infected. Conclusion: Serial WB is simple and reliable and may be used for the early diagnosis of HIV infection in infants.

Serial myoglobin quantitation in the early assessment of myocardial damage: A clinical study

Objectives: (a) To evaluate serial serum myoglobin pattern as an early marker of myocardial damage and compare it to conventional enzyme markers, and (b) to test the hypothesis that a patient admitted within 6 h of the onset of chest pain who has normal myoglobin concentrations that do not increase significantly in the first 2 h has not suffered a myocardial infarction (MI). Design and methods: A clinical study was conducted including 98 patients (62 males, 36 females) who presented to our Emergency Department with a diagnosis of possible MI. Patients with chest discomfort were selected to participate in the trial if their ECG was equivocal, their diagnosis was not obvious, and their treatment in hospital was to be the same as a MI patient until proven otherwise. Myoglobin measurements were made on admission and at 1 and 2 h thereafter. Quantitative myoglobin assays were performed by fluorometric enzyme immunoassay (STRATUS). Traditional cardiac enzymes were also measured. Results: The myoglobin assay had good precision with CVs less than 10%. The sensitivity and specificity for MI of the myoglobin assay were 0.77 and 1.00 at 1 h and 0.93 and 1.00 at 2 h, respectively. Of positive diagnoses, 90% were clear 1 h after admission. Serial myoglobin assays provided better predictive efficiency (0.96) than baseline ECG (0.70) or CK-MB (0.62) in the admission assessment of possible MI patients. Conclusions: Negative myoglobin serial assays can be used effectively to rule out MI. Positive myoglobin serial assays help in the early diagnosis of MI in uncomplicated patients.

A “random-walk” simulation model of multiple-pattern learning in a radial-arm maze

Wathen and Roberts (1994) reported rather surprising results of a radial maze study that on any interpretation requires postulation of previously unsuspected high-level cognitive processes in rats. In each of four arms of the eight-arm radial maze, a different serial pattern unfolded over trials; for example, in one of the arms reward and nonreward alternated over successive trials. On each trial, rats came to track successfully four different patterns simultaneously. The authors suggested that rats tracked the pattern by using some form of trial-number strategy; that is, the trial number indicated which arms contained the better rewards. This strategy could involve a hypothesis, considered unlikely by some, that rats are capable of keeping track of as many as eight successive events—as, for example, by counting. A simulation model that embodies a specific form of the trial-number hypothesis is described here, and the results of the simulation correlate remarkably well with the observed data. In addition, the model makes four separate predictions that are supported by Wathen and Roberts’s data and that seem beyond the scope of other available theories.

Serial Pattern Learning in Senescent Rats: A Comparison of Acquisition Performance with Young and Hippocampal-Lesioned Rats

The acquisition of a serial pattern was assessed in young (3-month), senescent (24-month), and hippocampal-lesioned rats. All animals were trained for 25 days on a four-element, nonmonotonic pattern consisting of 14, 0, 3, and 7 food pellets, respectively. Young rats were capable of distinguishing among the elements of the series, with the exception of the 3- and 7-pellet elements, as indexed by running times. Conversely, the senescent rats were largely incapable of patterned responding, and the tracking performance of the hippocampal-lesioned rats was intermediate between those of the young and old rats. Results are discussed in terms of the possible changes that accompany aging in rodents, including age-related changes in the hippocampal system.

Spatial and non-spatial learning in the rat following lesions to the nucleus locus coeruleus

The present experiment examined the effects of unilateral or bilateral locus coeruleus lesions on general activity, acquisition of a non-monotonic serial pattern (14-0-3-7 food pellets, respectively), and response learning acquisition in a Greek cross version of the Morris water maze. Sham-operated control rats were capable of tracking the elements of the serial pattern while rats with a unilateral locus coeruleus lesion were moderately impaired, and those with bilateral locus coeruleus lesions were severely impaired. A similar pattern of working memory deficits emerged in an analysis of the response-learning data in the Greek cross. The results are discussed in terms of the current understanding of norepinephrine and the locus coeruleus in learning and memory processes.

The eccentricity effect: target eccentricity affects performance on conjunction searches.

The serial pattern found for conjunction visual-search tasks has been attributed to covert attentional shifts, even though the possible contributions of target location have not been considered. To investigate the effect of target location on orientation x color conjunction searches, the target's duration and its position in the display were manipulated. The display was present either until observers responded (Experiment 1), for 104 msec (Experiment 2), or for 62 msec (Experiment 3). Target eccentricity critically affected performance: A pronounced eccentricity effect was very similar for all three experiments; as eccentricity increased, reaction times and errors increased gradually. Furthermore, the set-size effect became more pronounced as target eccentricity increased, and the extent of the eccentricity effect increased for larger set sizes. In addition, according to stepwise regressions, target eccentricity as well as its interaction with set size were good predictors of performance. We suggest that these findings could be explained by spatial-resolution and lateral-inhibition factors. The serial self-terminating hypothesis for orientation x color conjunction searches was evaluated and rejected. We compared the eccentricity effect as well as the extent of the orientation asymmetry in these three conjunction experiments with those found in feature experiments (Carrasco & Katz, 1992). The roles of eye movements, spatial resolution, and covert attention in the eccentricity effect, as well as their implications, are discussed.

Cognitive Performance During Respirator Wear in the Absence of Other Stressors

Reaction time, decision-making speed, and response accuracy were measured in 12 male and 5 female subjects performing computer-controlled tasks under nonexercise conditions during two 3.5-hour days, one with and one without (control) wearing a respirator, to assess the effects of respirator wear alone on cognitive performance. Tasks included measures of simple and choice reaction time (CRT), serial pattern matching, lexical discrimination (LD), visual selective attention, rapid visual scanning, and form discrimination (FD). Anxiety levels were assessed along with reaction time measures obtained at the start of each test day and after 1, 2, and 3 hours of testing. Reaction time and response accuracy did not differ significantly between respirator and control trials and were not changed over time. However, mean decision-making times were significantly faster during respirator wear compared to control for the LD (0.17±0.04 versus 0.19±0.05 sec) and FD (0.32±0.10 versus 0.36±0.12 sec) CRT tasks. Females exhibited significantly faster reaction times than males, but no differences within sex groups were observed between control and respirator trials. Response accuracy and decision-making speed did not differ within and between male and female groups for any reaction time tasks during respirator wear. The improvements in decision-making time observed during respirator wear probably reflect the effect of the respirator to increase arousal and improve focusing of attention by excluding peripheral visual stimuli. Furthermore, the results suggest that respirator wear over a relatively short period in the absence of other stressors should not inhibit cognitive function.

Cognitive performance during respirator wear in the absence of other stressors.

Reaction time, decision-making speed, and response accuracy were measured in 12 male and 5 female subjects performing computer-controlled tasks under nonexercise conditions during two 3.5-hour days, one with and one without (control) wearing a respirator, to assess the effects of respirator wear alone on cognitive performance. Tasks included measures of simple and choice reaction time (CRT), serial pattern matching, lexical discrimination (LD), visual selective attention, rapid visual scanning, and form discrimination (FD). Anxiety levels were assessed along with reaction time measures obtained at the start of each test day and after 1, 2, and 3 hours of testing. Reaction time and response accuracy did not differ significantly between respirator and control trials and were not changed over time. However, mean decision-making times were significantly faster during respirator wear compared to control for the LD (0.17 +/- 0.04 versus 0.19 +/- 0.05 sec) and FD (0.32 +/- 0.10 versus 0.36 +/- 0.12 sec) CRT tasks. Females exhibited significantly faster reaction times than males, but no differences within sex groups were observed between control and respirator trials. Response accuracy and decision-making speed did not differ within and between male and female groups for any reaction time tasks during respirator wear. The improvements in decision-making time observed during respirator wear probably reflect the effect of the respirator to increase arousal and improve focusing of attention by excluding peripheral visual stimuli. Furthermore, the results suggest that respirator wear over a relatively short period in the absence of other stressors should not inhibit cognitive function.

An investigation of the role of the hippocampus and the amygdala in the encoding of a serial pattern: Effects of a long inter-element interval

Previous research has provided convincing evidence that rats can learn to anticipate each element of a stimulus series consisting of differing reinforcement quantities. The present experiment examined the effects of electrolytic lesions of the hippocampus, amygdala, or combined hippocampal and amygdala lesions on the acquisition of a 14-7-3-0 monotonic pattern with a 5 min inter-element interval. Anticipation was operationally defined as faster running on 14- than on 7-pellet elements, 7- than on 3-pellet elements, and 3- than 0-pellet elements. Male Sprague-Dawley rats (sham and lesioned) received two trials a day for 30 days on the 14-7-3-0 pattern of food pellets. Anticipatory tracking developed rapidly in the control animals and not until the end of training in the hippocampus + amygdala-lesioned rats, while the rate of acquisition in the single lesion groups was intermediate between the two. The results are discussed in terms of temporal and working memory processes. Mediation of the temporal and affective attributes of memory are considered for each structure. The present experiment provided additional evidence for a hippocampal role in maintenance of a temporal record of the elements of the series, thus providing the rat with the ability to track which stimulus elements have been presented and to anticipate future elements. Finally, via a role in processing the affective and reinforcing properties of the task, the amygdala appears to play a role in mnemonic processes.

A Model for Binary Time Series Data with Serial Odds Ratio Patterns

SUMMARY Moment methods for analysing repeated binary responses using the marginal odds ratio as a measure of association have recently been proposed by several researchers. Using the generalized estimating equation (GEE) methodology, they estimated the regression parameters associated with the expected value of an individual's vector of binary responses. In addition, they estimated the marginal odds ratio between pairs of binary responses. In this paper, we discuss a model for binary time series data where the repeated responses on each individual may be unequally spaced in time. This model allows both the number of observations per individual and the times of measurement to vary between individuals. Our approach is to model the association between the binary responses using serial odds ratio patterns. This model can be thought of as a binary time series analogue of the exponential correlation pattern so commonly assumed for continuous time series data. Parameter estimates are obtained by using the GEE methodology. The model is illustrated with data from an arthritis clinical trial where the response variable is a binary self-assessment measurement.

Coding of hierarchical versus linear pattern structure in rats and humans.

In 3 experiments, rats and humans learned serial patterns composed of 24, 30, or 36 items. Patterns had a 2-, 3-, or 4-level hierarchical rule structure. In Experiments 1 and 2, patterns had either perfect hierarchical structure or 2 modified chunks that violated hierarchical structure, thus producing linear structure (i.e., nonhierarchical structure). For both rats and humans, pattern structure predicted pattern learning difficulty and also the nature and relative frequency of errors. Both treated chunks that were inconsistent with hierarchical structure as violation chunks, that is, they made errors that reflected their "tendency to regularize the perception of an irregular pattern" (F. Restle & B. L. Burnside, 1972). The results support the view that rats can abstract and encode a representation of multilevel hierarchical structure in serial patterns in much the same way as humans do in analogous tasks.

Sensitivity to violations of "run" and "trill" structures in rat serial-pattern learning.

Rats learned serial patterns composed of either "run" chunks (e.g., 123 234 ...) or "trill" chunks (e.g., 121 232 ...). For each type of pattern, 1 group of rats encountered an element at the end of the pattern that violated the run or trill structure. In both run and trill patterns, violations were unusually difficult for rats to learn, whereas corresponding elements in "perfect" patterns that did not violate pattern structure were easy. Additionally, rats' errors on violation elements conformed to the structure of the patterns in which they were embedded. Thus, rats were sensitive to the run or trill organization of their patterns and mastered the rules governing the pattern before learning "exceptions to the rule."

Electrophoretic analysis of hydroxyethyl-starch induced macroamylasemia.

Various species of hydroxyethyl-starch (HES) has been developed for use in the management of hypovolemia, and intravenous infusion of HES results in iatrogenic macroamylasemia. Clinically, recognition of macroamylasemia is important to distinguish them from other conditions that are attended by hyperamylasemia. Electrophoresis is a generally appricable test for detection of naturally occuring macroamylase, however, there is no information of about the detection of the iatrogenic macroamylase by electrophoretic analysis. We examined the serial amylase isoenzymes electrophoretic patterns of serum in 23 patients undergoing abdominal surgery. In them, 12 patients were dosed with 500-1, 000ml of 6% solution of the HES possessing a relative molecular mass of 30, 000-40, 000 combined with a molar hydroxyethyl group substitution of 0.50-0.55 upon operation. Electrophoretic analysis of the sera revealed that HES resulted in the characteristically anomalous electrophoretic pattern with cathodally migrating broaden amylase bands.

Short intertrial interval as a phrasing cue in the serial pattern learning in rats

Phrasing effect of short intertrial interval (ITI) on the serial pattern learning was investigated in a runway experiment. In acquisition, all 10 rats were given three repetitions of 14-7-3-1-0 subpattern daily over Days 1-80. For Group NP (non phrasing), all daily 15 trials were separated by a 15-min ITI. Group GP (good phrasing) and Group BP (bad phrasing) received the same procedure as Group NP except, instead of the 15-min ITI, a 15-s ITI was inserted between the 0 pellet and 14 pellets trial in the former, and a 15-s ITI was inserted between the 3 pellets and 1 pellet trial in the latter. Means of the last 4 days of acquisition as indicated by running speed showed that Group GP produced better anticipation of the 0 pellet trial than Group NP, and that Group BP produced the poorest anticipation. In Group BP, rats ran more slowly on the 1 pellet trial, that occurred after the 15-s ITI, than on the 0 pellet trial in each of the first and second subpatterns. These results suggest that a shorter ITI plays dual roles, as a phrasing cue and as a discriminative stimulus in the serial pattern learning as that does in reinforcement-nonreinforcement pattern learning.

Interseries Transfer and Effect of Retention Interval in Rats' Serial Pattern Learning

The experiment with 24 rats assessed the persistence of memory on formally defined rule structure of food quantity sequence using serial pattern learning followed by transfer test. In original training, monotonic (M) group was presented with the monotonic decreasing series consisting of two, three, or four different items of 45mg food pellets, whereas Random (R) group was provided with the random series in which items were arranged with no consistent relations among them. After the original training was finished, each of these basic groups was divided into two groups. Transfer training was begun on the day after the end of original training for groups MI and RI, whereas on the 21st day after the end of original training for groups MD and RD. In transfer training, all groups received a novel monotonic decreasing series containing 16-9-3-1-0 pellets. Throughout transfer training, groups MI and MD anticipated the 0 pellet item in this series significantly better than groups RI and RD, and any reliable difference was not observed between groups MI and MD, or groups RI and RD. These results indicate that rats' memory for the sequentially arranged food quantities with simple rule structure has strong persistence against to time lapse. Implications of these findings are discussed in relation to the partial reinforcement delayed extinction effect which shows persistent extinction performance after regularly alternating schedules.

Evidence for synchronous activation of neurons located in different layers of primary somatosensory cortex.

Although many studies have examined the columnar organization of primary somatosensory (SI) cortex, the functional relationship among neurons in different layers remains unclear. To understand how activity is coordinated among different cortical layers, the present investigation tested the hypothesis that the initial part of a peripheral stimulus produces a serial pattern of laminar activation in SI cortex. Extracellular discharges of 334 histologically recovered neurons were recorded from the medial bank of the coronal sulcus in nine anesthetized cats during electrical or cutaneous stimulation of the distal forelimb. Mean responses during the initial 50-msec period following stimulus onset were largest in layers IIIb or IV for both types of stimulation, but laminar differences in the magnitude of onset responses were not statistically significant. Among 175 neurons with responses exceeding 0.5 spikes per stimulus, electrical stimulation consistently produced shorter response latencies than mechanical indentation in the extragranular (II, IIIa, V, VI), but not in the middle (IIIb, IV), cortical layers. The average minimum latencies for different cortical layers ranged from 7.4 to 10.1 msec for responses to electrical stimulation and from 10.3 to 11.6 msec for responses to mechanical indentations, but these laminar differences were not statistically significant. In some experiments, neurons in different layers of a cortical column were recorded simultaneously with dual-electrode assemblies; among 37 neuron pairs in which both neurons responded with more than 0.5 spikes per stimulus, response latencies were similar, even though the neurons were separated by several hundred microns. Cross-correlation analysis of the onset responses for neurons recorded simultaneously from different layers also indicated that many cells throughout a cortical column were activated nearly simultaneously by the initial phase of a peripheral stimulus. Results from the present study are compared with previous reports examining laminar patterns of activation.

The impact of motor responses on serial-pattern learning.

Subjects are able to learn even very complex serial patterns in serial-reaction-time tasks. The investigation of the learning processes behind this phenomenon has yielded contradictory results. Some studies have come to the conclusion the subjects had learned the sequence of stimuli. Other studies have assumed that the sequence of responses had been learned or a combination of both stimuli and responses. The present experiments stress the impact of motor responses on serial-pattern learning. The subjects had to respond to serial targets that were presented within a matrix of distractors. The position of each target could be predicted from the identity and position of the previous target. If the subjects were to learn this pattern, they would be able to speed up the search for the target and give faster responses. The results indicated that the relation between the target identity and the position of the next target was acquired much better by those subjects who had to respond to each target with a special motor response. If the same response was required for the relevant targets, knowledge of the rule was somewhat fragmentary. To explain these results, mechanisms of motor learning and motor planning are discussed. It is assumed that learning of the rules occurs if the position changes appear to be effects of different motor responses.

The dynamics of Prägnanz.

There is quite wide-spread agreement about the relevance of pattern Prägnanz (Koffka, 1935) with respect to the human interpretation of visual patterns. There is less agreement about whether pattern Prägnanz is based solely on pattern information (static) or also on the history of the perceiver (dynamic). In Van Leeuwen and Van den Hof (1991), experimental data concerning serial patterns are presented within the framework of the dynamic-network approach initiated by Buffart (1986, 1987). These experimental data are claimed to give evidence against the static-coding approach initiated by Leeuwenberg (1969, 1971). In the present paper, however, I show first that Buffart's theoretical basis is incorrect, and that in fact Leeuwenberg's static-coding approach is the basis for the dynamic-network approach. Second, I show that those experimental data rather give evidence in favor of the static-coding approach, by using those same data for a test of the most recent static-coding model (Van der Helm & Leeuwenberg, 1991; Van der Helm, Van Lier, & Leeuwenberg, 1992). Finally, I propose a reconciliation between the two approaches, in the sense that the dynamic-network model could be shaped in such a way that it yields a simulation, and maybe even an enrichment, of the static-coding model.

Serial pattern learning after head injury

Nonverbal serial pattern learning in patients with traumatic brain injury was examined using a serial reaction time task developed by Nissen and Bullemer (1987). During four blocks of pattern acquisition trials, subjects responded to asterisks appearing in repetitions of a 10-element spatial sequence. An indirect measure of pattern learning was obtained by comparing response times in the fourth pattern acquisition block with response times in a fifth block where asterisks occurred in random sequence. A direct measure of pattern memory was provided by accuracy scores in a final pattern generation block in which subjects predicted the spatial sequence of asterisks. Prior research with this task has shown that individuals from several special populations--including the normal elderly, Korsakoff's syndrome patients, and Alzheimer's patients--show intact performance on the indirect measure of pattern learning, but are impaired on the direct measure. In contrast to these earlier findings, the results of this study showed that mild to moderately severe traumatic brain injury does not cause a marked disruption in the ability to learn and remember serial pattern information. There was evidence that the amount of practice required to learn the serial pattern increases after moderately severe head injury; however, the ability to use pattern memory to enhance prediction accuracy appears to be normal.