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PubMed1984

Effect of alpha adrenergic agonists and blockers on Purkinje fiber transmembrane potentials and automaticity in the dog.

Previous studies have shown that alpha adrenergic stimulation can reduce the automaticity of canine Purkinje fibers. In the present study, our interest was to determine whether this is an alpha-1 or alpha-2 adrenergic action. We used standard microelectrode techniques to study the effects of the alpha agonists, phenylephrine and clonidine, and the alpha antagonists, prazosin and yohimbine, on phenylephrine-induced decreases in automaticity. Prazosin and yohimbine, 1 X 10(-5) M, alone, significantly reduced the amplitude and upstroke velocity (Vmax) of stimulated action potentials. In addition, yohimbine, 1 X 10(-5) M, accelerated and prazosin, 1 X 10(-5) M, attenuated repolarization. Prazosin, 1 X 10(-5) M, and yohimbine greater than or equal to 1 X 10(-7) M, alone, decreased automaticity. Phenylephrine, 5 X 10(-8) M, alone, significantly increased the cycle length of automatic Purkinje fibers. The effects of phenylephrine on automaticity were blocked by prazosin but not by yohimbine. Clonidine, alone, 1 X 10(-6) and 1 X 10(-5) M, significantly reduced automaticity, an effect that was not blocked by yohimbine or prazosin. Clonidine, 1 X 10(-6) and 1 X 10(-5) M, also significantly reduced Vmax and prolonged action potential duration of driven Purkinje fibers, an action consistent with direct membrane effects. These experiments suggest that the negative chronotropic effects of phenylephrine on Purkinje fiber automaticity are mediated by alpha-1 adrenergic receptors.

Adrenergic alpha-Agonists↗
PubMedDate not supplied

[Automatic information processing, the frontal system and blunted affect. From clinical dimensions to cognitive processes toward a psychobiological explanation of temperament].

Several theorists have drawn a distinction between automatic and attentional or controlled processing. Hasher and Zacks (1979), were the very first to argue that effortful processes are reduced under conditions of stress including depression. They suggested that, in these conditions, no such deficit occurs in automatic processing. Then, Weingartner and co-workers provided some experiments which seemed to support such an interpretation of the cognitive dysfunction in depressed patients. However, some recent data do not fit with this well admitted theoretical framework. The purpose of our article is to try to clarify this issue both from a theoretical and from a methodological point of view. First, we make a critical review of the most recent results in three fields of experimentation related to the "automatic versus controlled" topic: 1) The classical neuropsychology of memory which manipulates the level of effort required to perform the tasks. Confusion arises when theories at the process level are tested with reference to data collected at the task level. The transparency assumption could be false: Impairment in an effort-demanding task could be due to a defect in automatic processes and it is possible to hypothesize that the more automatic processes are deficient, the more controlled processes are saturated and the effort demanding task impaired. The emergence of controlled processes could depend on the level of automaticity and the regulation of automatic processes could be determinant for the ability of the subject to make associations. 2) The recent studies on implicit memory in depression.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1996

Automatic garage door openers: hazard for children.

OBJECTIVES: Despite significant advances in automatic garage door opener design, automatic garage door openers continue to severely injure or kill children. In this investigation, we sought to determine the frequency and circumstances of accidents that have caused severe injury or death to children. We also tried to develop a means by which homeowners can evaluate their door openers. METHODS: We present the histories of three children severely injured or killed by automatic garage door openers. We reviewed national data of similar accidents primarily published by the US Product Safety Commission and Underwriters Laboratories. Also, we evaluated 50 automatic door openers for safety of operation. The reversing mechanisms of door openers were tested using a cardiopulmonary resuscitation mannequin, a roll of paper towels, and a block of wood. RESULTS: In the United States, at least 85 children have had permanent brain injury or have died since 1974 as a result of accidents involving automatic door openers. A review of circumstances of the accidents illustrates that accidents are caused both by use of the openers by children and by faults in design. Most accidents have occurred when children have found access to the activation devices and have been entrapped under closing doors that failed to reverse. However, in one case, an adult activated the opener and left the premises before the door completely closed. Our evaluation of 50 garage door openers showed that although 88% percent reversed when encountering a block of wood, 40% failed to reverse when coming down on a supine, child-sized cardiopulmonary resuscitation mannequin. CONCLUSIONS: Automatic garage door openers pose a serious risk of severe injury or death to children. It is probable that many doors would not reverse if they came down on a young child. Therefore, we have devised a way for homeowners to test their door openers that closely mimics our evaluations using the mannequin by using a large roll of paper towels. If the door fails to reverse using this test, we suggest that homeowners disconnect their openers and operate the doors manually until the openers are serviced or replace their automatic openers with one that meets the latest Underwriters Laboratory standards. We also have other recommendations regarding the safe operation of the doors, including improving the safety standards for openers in apartment complexes. Compliance with these recommendations should reduce the number of injuries to children caused by garage door openers.

Accidents, Home↗
PubMed1997

Clinical validation of automatic quantitative defect size in rest technetium-99m-sestamibi myocardial perfusion SPECT.

UNLABELLED: We examined the relationships of automatic quantitative perfusion defect size and defect severity to rest left ventricular ejection fraction and semiquantitative visual sestamibi defect size in rest 99mTc-sestamibi SPECT in 40 consecutive patients with a history of myocardial infarction more than 30 days prior to testing. The purpose of this investigation was to validate the use of automatic quantitative rest sestamibi SPECT as a clinical measure of assessing relative infarction size. METHODS: All patients received 20-30 mCi of 99mTc-sestamibi followed by SPECT imaging. Quantitative defect analysis used previously developed resting normal limits and an automatic version of a commercially available quantitative program (CEqual). Semiquantitative visual defect interpretation used a 20 segment/scan and five-point scoring analysis. First-pass (FP) radionuclide ventriculography (RVG) and gated sestamibi perfusion SPECT were each performed in 31 patients. RESULTS: LVEF assessed by FP RVG was 37% +/- 15% (range 14%-62%) and 37% +/- 16% (range 12%-63%) by gated perfusion SPECT with high linear correlation (r = 0.96, n = 22) between the two methods. Myocardial perfusion defect size was 24% +/- 15% of LV (range 0%-50%) and defect severity was 1103 +/- 864 (range 0 to 2825) by automatic quantitative rest sestamibi. Perfusion defect size and defect severity both had close correlations with LVEF by FP RVG (r = -0.78, r = -0.86) and by gated perfusion SPECT (r = -0.75, r = -0.79). High linear correlations were observed between quantitative defect size and summed visual score of segments with score > or = 2 (r = 0.82) and the number of visually abnormal segments (r = 0.77), as well as between defect severity and visual summed rest score (r = 0.86) and the number of visually abnormal segments (r = 0.76). CONCLUSION: Quantitation of rest sestamibi SPECT defect extent and severity using automatic CEqual correlates well with rest LVEF and with semiquantitative expert visual analysis. Results of this study define a strong relationship between measurements of 99mTc-sestamibi perfusion defect as measured by an automatic software program and global left ventricular function. The automatic quantitative program appears to be a useful measure of assessing infarct size in patients with remote myocardial infarction.

Adult↗
PubMed2001

Test of a potential link between analytic and nonanalytic category learning and automatic, effortful processing.

The link between automatic and effortful processing and nonanalytic and analytic category learning was evaluated in a sample of 29 college undergraduates using declarative memory, semantic category search, and pseudoword categorization tasks. Automatic and effortful processing measures were hypothesized to be associated with nonanalytic and analytic categorization, respectively. Results suggested that contrary to prediction strong criterion-attribute (analytic) responding on the pseudoword categorization task was associated with strong automatic, implicit memory encoding of frequency-of-occurrence information. Data are discussed in terms of the possibility that criterion-attribute category knowledge, once established, may be expressed with few attentional resources. The data indicate that attention resource requirements, even for the same stimuli and task, vary depending on the category rule system utilized. Also, the automaticity emerging from familiarity with analytic category exemplars is very different from the automaticity arising from extensive practice on a semantic category search task. The data do not support any simple mapping of analytic and nonanalytic forms of category learning onto the automatic and effortful processing dichotomy and challenge simple models of brain asymmetries for such procedures.

Adult↗
PubMed2000

Habits as knowledge structures: automaticity in goal-directed behavior.

This study tested the idea of habits as a form of goal-directed automatic behavior. Expanding on the idea that habits are mentally represented as associations between goals and actions, it was proposed that goals are capable of activating the habitual action. More specific, when habits are established (e.g., frequent cycling to the university), the very activation of the goal to act (e.g., having to attend lectures at the university) automatically evokes the habitual response (e.g., bicycle). Indeed, it was tested and confirmed that, when behavior is habitual, behavioral responses are activated automatically. In addition, the results of 3 experiments indicated that (a) the automaticity in habits is conditional on the presence of an active goal (cf. goal-dependent automaticity; J. A. Bargh, 1989), supporting the idea that habits are mentally represented as goal-action links, and (b) the formation of implementation intentions (i.e., the creation of a strong mental link between a goal and action) may simulate goal-directed automaticity in habits.

Adult↗
PubMed2006

Autobiographical memories prompted by automatic thoughts in panic disorder and social phobia.

This study examined the retrieval of autobiographical memories when prompted by automatic thoughts that were representative of maladaptive schema content specific to 2 anxiety disorders. Participants with panic disorder (n = 20), those with social phobia (n = 22) and non-anxious participants (n = 20) indicated the first specific memory that came to mind when cued with panic-related, social phobia-related and control automatic thoughts. Panic participants retrieved memories cued with panic disorder-related automatic thoughts more quickly than social phobic and non-anxious participants, and social phobic participants retrieved memories cued with social phobia-related automatic thoughts more quickly than non-anxious participants. Relative to non-anxious participants, participants in both patient groups retrieved more anxious/worried memories when cued with automatic thoughts related to their diagnosis and more fearful memories when cued with either type of diagnosis-related automatic thought. Results indicate that panic and social phobic participants were characterized by general threat-relevant autobiographical memory biases.

Adult↗
PubMed2004

Consistent mapping and automatic visual search: comparing persons with and without intellectual disability.

BACKGROUND: Merrill et al. (1996) reported that persons with intellectual disability (ID) were slower at learning a visual search task to automaticity relative to persons of the same age without ID. For persons without ID, automaticity develops most rapidly under conditions in which a response is always the same for a particular stimulus. This study was designed to investigate whether persons with and without ID are differentially sensitive to the influence of consistently mapped versus inconsistently mapped stimulus responses. METHODS: The primary manipulation was the consistency between a particular stimulus and the response to that stimulus in a visual search task. Sixteen participants with ID and 16 without ID searched displays of two, three, or four pictured objects to determine if a target was present. For half of the participants, the targets were always targets. For the other half, the targets became nontargets on 25% of the trials. RESULTS: Analyses focused on changes in response times associated with set size. Because automaticity allows for parallel processing, the elimination of significant effects of set size was taken as an index of the development of automaticity. Results indicated that inconsistent mapping significantly slowed the development of automaticity for the participants without ID but not for the participants with ID. DISCUSSION: Results were discussed in terms of the role of inhibition processes in the development of automatic search and detection. The effectiveness of inhibition processes was compromised by the consistency manipulation. The effect of the consistency manipulation was greater for the participants without ID because they were presumed to be using inhibition processes more effectively during practice than did the participants with ID.

Adolescent↗
PubMed1995

Automatisms with preserved responsiveness: a lateralizing sign in psychomotor seizures.

This is a report of a 1-year prospective study to investigate how often automatisms occur with preserved responsiveness in psychomotor seizures. Responsiveness is usually impaired or lost when automatisms occur during psychomotor seizures. However, there are several anecdotal reports in the literature of patients who have automatisms with preserved responsiveness (APRs). We evaluated 123 patients with temporal lobe epilepsy (57 patients [46%] left-sided, 48 patients [39%] right-sided, and 18 patients [15%] bitemporal) with video/EEG monitoring, testing responsiveness by asking the patient to respond verbally and to follow motor commands. Seven patients (5.6%) had preserved responsiveness in the presence of prominent automatisms (lip smacking, swallowing). In 15 seizures, the responsiveness was adequately tested (3.6 questions per period of automatism). Average seizure duration was 71.6 +/- 14.8 seconds (range, 45 to 100 seconds). Average duration of automatisms was 59.5 +/- 13.5 seconds (range, 40 to 80 seconds). Ictal EEG was localized over the right temporal area in nine seizures, over the right hemisphere in five, and was nonlocalizable in one seizure. APRs never occurred in left-sided psychomotor seizures and occurred in 10% of the right temporal cases. In conclusion, APRs reliably lateralized to the right side in temporal lobe epilepsy.

Adult↗
PubMed2004

Multiple rapid automatic naming measures of cognition: normal performance and effects of aging.

Rapid automatic naming tasks are clinical tools for probing brain functions that underlie normal cognition. To compare performance for various stimuli in normal subjects and assess the effect of aging, we administered six single-dimension stimuli (color, form, number, letter, animal, and object) and five dual-dimension stimuli (color-form, color-number, color-letter, color-animal, and color-object) to 144 normal volunteers who ranged in age from 15 to 85 years. Rapid automatic naming times for letters and numbers were significantly less than for forms, animals, and objects. Rapid automatic naming times for color-number and color-letter stimuli were significantly less than for color-form, color-animal, or color-object stimuli. Age correlated significantly with rapid automatic naming time for each single-dimension stimulus and for color-form, color-number, color-animal, and color-object stimuli. Linear regression showed that rapid automatic naming times increased with age for aggregated color stimuli, aggregated single-dimension stimuli, and aggregated dual-dimension stimuli. This age effect persisted in subgroups less than 60 years of age and greater than 60 years of age. We conclude that normal performance time is dependent on the task, with letter and number stimuli eliciting most rapid responses, and that most rapid automatic naming times increase with age.

Adolescent↗
PubMed2006

Automatic retrieval in directed forgetting.

In two experiments, we investigated the role of automatic retrieval in directed forgetting, using a stem completion test. In each experiment, we compared the performance of an implicit group, a process dissociation procedure (PDP) group, and a group given a speeded response task. The response times of the speeded response group on the stem completion task replicated earlier data in suggesting that this group adopted a purely automatic retrieval strategy. Experiment 1 revealed a directed-forgetting effect on automatic retrieval with the item method, but Experiment 2 revealed no directed-forgetting effect on automatic retrieval with the list method, consistent with the lack of implicit effects with the list method throughout the literature. Both experiments showed lower automatic estimates for the PDP group than for the implicit and speeded response groups, which did not differ. The data are consistent with either a selective rehearsal or an inhibition account of directed forgetting with the list method. The comparison of methods for assessing automatic retrieval is consistent with earlier evidence suggesting that subjects may adopt a generate/recognize strategy when given direct retrieval instructions.

Automatism↗
PubMed2002

Automatism: comparison of common law and civil law approaches--a search for the optimal.

This article reviews common and civil law approaches to automatism with discussion of legal definitions and the conditions in which automatism occurs. The common law approach to sane (exogenous) and insane (endogenous) automatism is examined. Despite a change in the law, which obviates mandatory incarceration for all persons found not guilty on the basis of insane automatism, the stigma of insanity remains. A number of Continental jurisdictions, though, have adopted an approach divorced from judgmental labels, whereby acts, which result from automatism, are classified under the rubric of unconsciousness. The article draws upon this approach, analyses alternatives to insane automatism and proposes instead an analysis by reference to "cognitive dysfunction", thereby removing all reference to the concept of insanity.

Automatism↗
PubMed2001

Fully automatic anatomical, pathological, and functional segmentation from CT scans for hepatic surgery.

OBJECTIVE: To improve the planning of hepatic surgery, we have developed a fully automatic anatomical, pathological, and functional segmentation of the liver derived from a spiral CT scan. MATERIALS AND METHODS: From a 2 mm-thick enhanced spiral CT scan, the first stage automatically delineates skin, bones, lungs, kidneys, and spleen by combining the use of thresholding, mathematical morphology, and distance maps. Next, a reference 3D model is immersed in the image and automatically deformed to the liver contours. Then an automatic Gaussian fitting on the imaging histogram estimates the intensities of parenchyma, vessels, and lesions. This first result is next improved through an original topological and geometrical analysis, providing an automatic delineation of lesions and veins. Finally, a topological and geometrical analysis based on medical knowledge provides hepatic functional information that is invisible in medical imaging: portal vein labeling and hepatic anatomical segmentation according to the Couinaud classification. RESULTS: Clinical validation performed on more than 30 patients shows that delineation of anatomical structures by this method is often more sensitive and more specific than manual delineation by a radiologist. CONCLUSION: This study describes the methodology used to create the automatic segmentation of the liver with delineation of important anatomical, pathological, and functional structures from a routine CT scan. Using the methods proposed in this study, we have confirmed the accuracy and utility of the creation of a 3D liver model compared with the conventional reading of the CT scan by a radiologist. This work may allow improved preoperative planning of hepatic surgery by more precisely delineating liver pathology and its relationship to normal hepatic structures. In the future, this data may be integrated with computer-assisted surgery and thus represents a first step towards the development of an augmented-reality surgical system.

Humans↗
PubMed2001

Development of a resonator with automatic tuning and coupling capability to minimize sample motion noise for in vivo EPR spectroscopy.

EPR spectroscopy has been applied to measure free radicals in vivo; however, respiratory, cardiac, and other movements of living animals are a major source of noise and spectral distortion. Sample motions result in changes in resonator frequency, Q, and coupling. These instabilities limit the applications that can be performed and the quality of data that can be obtained. Therefore, it is of great importance to develop resonators with automatic tuning and automatic coupling capability. We report the development of automatic tuning and automatic coupling provisions for a 750-MHz transversely oriented electric field reentrant resonator using two electronically tunable high Q hyperabrupt varactor diodes and feedback loops. In both moving phantoms and living mice, these automatic coupling control and automatic tuning control provisions resulted in an 8- to 10-fold increase in signal-to-noise ratio.

Animals↗
PubMed1995

Clinical evaluation of a method for automatic detection and removal of artifacts in auditory evoked potential monitoring.

OBJECTIVE: The objective of our study was to evaluate the method for detection and removal of artifacts in evoked potential monitoring described earlier by Cluitmans and colleagues in a clinical setting. METHODS: The method for detection and removal of artifacts by Cluitmans and colleagues is based on the assumption that a sweep of the recorded electroencephalogram (EEG) signal contains artifacts if one or more variables derived from the signal deviates strongly from the normal range of values. Once these normal ranges are defined, all future EEG recordings that are recorded under comparable circumstances can be automatically evaluated for artifacts by tracking when one or more signal variables falls outside the normal range. To assess the performance of this method in a clinical setting, recordings from a learning set were visually evaluated for artifacts. From the empirical distribution functions of the signal variables, the thresholds for automatic detection of artifacts were determined. The auditory evoked potential (AEP) waveforms resulting after automatic screening were compared with the waveforms obtained after visual evaluation of the raw signal combined with manual exclusion of signal periods containing artifacts. RESULTS: The quality of the resulting waveform was improved by our method of automatic detection and removal of artifacts in 97% of partly contaminated recordings. In only 2% of the recordings, automatic screening slightly degraded the resulting waveform. CONCLUSIONS: We conclude that the described method of automatic detection and removal of artifacts in AEP recordings effectively improves the quality of the resulting AEP waveform, without excessive rejection of artifact-free signal periods. The signal variables used in this method seem appropriate for distinguishing artifact-free signal periods from periods containing artifacts for the types of artifact that were studied.

Algorithms↗
PubMed2006

Fully automatic diagnostic system for early- and late-onset mild Alzheimer's disease using FDG PET and 3D-SSP.

PURPOSE: The purpose of this study was to design a fully automatic computer-assisted diagnostic system for early- and late-onset mild Alzheimer's disease (AD). METHODS: Glucose metabolic images were obtained from mild AD patients and normal controls using positron emission tomography (PET) and( 18)F-fluorodeoxyglucose (FDG). Two groups of 20 mild AD patients with different ages of onset were examined. A fully automatic diagnostic system using the statistical brain mapping method was established from the early-onset (EO) and late-onset (LO) groups, with mean ages of 59.1 and 70.9 years and mean MMSE scores of 23.3 and 22.8, respectively. Aged-matched normal subjects were used as controls. We compared the diagnostic performance of visual inspection of conventional axial FDG PET images by experts and beginners with that of our fully automatic diagnostic system in another 15 EO and 15 LO AD patients (mean age 58.4 and 71.7, mean MMSE 23.6 and 23.1, respectively) and 30 age-matched normal controls. A receiver operating characteristic (ROC) analysis was performed to compare data. RESULTS: The diagnostic performance of the automatic diagnostic system was comparable with that of visual inspection by experts. The area under the ROC curve for the automatic diagnostic system was 0.967 for EO AD patients and 0.878 for LO AD patients. The mean area under the ROC curve for visual inspection by experts was 0.863 and 0.881 for the EO and LO AD patients, respectively. The mean area under the ROC curve for visual inspection by beginners was 0.828 and 0.717, respectively. CONCLUSION: The fully automatic diagnostic system for EO and LO AD was able to perform at a similar diagnostic level to visual inspection of conventional axial images by experts.

Age of Onset↗
PubMed2001

Automatic bolus tracking in monophasic spiral CT of the liver: liver-to-lesion conspicuity.

The aim of this study was to evaluate the value of automatic bolus tracking for monophasic spiral CT of the liver and to assess the liver-to-lesion conspicuity in comparison with time-delay examinations. In 40 patients scheduled for therapy control of known hypovascular hepatic metastases a monophasic spiral CT was completed either with time delay of 65 s (n = 20) or with automatic bolus tracking in the liver parenchyma (n = 20). Examinations were performed with 120 ml of contrast material and a flow rate of 3.0 ml/s. For automatic bolus tracking a parenchymal enhancement threshold of 40 HU was used. Contrast enhancement in the liver parenchyma and in liver lesions was obtained by means of regions of interest (ROI). Mean parenchymal enhancement was not significantly different between time delay and bolus-tracking group. In 4 of 20 patients in the bolus-tracking group the threshold level of 40 HU was not reached. With automatic bolus tracking a significantly higher liver-to-lesion density difference was observed (P < 0.0001). Automatic bolus tracking allows a better liver-to-lesion conspicuity in monophasic spiral CT. Contrary to recent studies, a significantly higher parenchymal enhancement was not found using automatic bolus tracking.

Adult↗
PubMed2004

Induced automaticity in isolated rat atrial cells by incorporation of a stretch-activated conductance.

Stretch of the atrium and sympathetic activity have been implicated as substrates for atrial fibrillation. We investigate how a model of stretch in combination with sympathetic stimulation can induce automaticity in atrial cells. We adapted our coupling clamp circuit so that a model ionic current that represents stretch-activated channels (SACs) was injected into an isolated rat atrial cell in real time. This current was calculated as ISAC= GSAC (Vm-ESAC), where GSAC and ESAC are the conductance and reversal potential of SACs and Vm is the cell's membrane potential. Repetitive automaticity was induced by a sufficiently large GSAC and this critical value of GSAC was decreased by exposure to isoproterenol. The critical value of GSAC decreased from 0.63+/-0.05 nS (mean+/-SE) in control to 0.40+/-0.07 nS in isoproterenol (P<0.05). Additionally, after exposure to isoproterenol, automaticity continued after GSAC was no longer applied and was accompanied by delayed after-depolarizations. In three cells, repetitive automaticity could not be induced at any value of GSAC. Exposure to 10 nM isoproterenol converted these cells to cells with repetitive automaticity in response to GSAC. We conclude that automaticity can be induced in isolated rat atrial cells by application of a model of SACs. Exposure to isoproterenol enhances this effect.

Action Potentials↗