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PubMed1996

A template-matching pandemonium recognizes unconstrained handwritten characters with high accuracy.

Psychological data suggest that internal representations such as mental images can be used as templates in visual pattern recognition. But computational studies suggest that traditional template matching is insufficient for high-accuracy recognition of real-life patterns such as handwritten characters. Here we explore a model for visual pattern recognition that combines a template-matching and a feature-analysis approach: Character classification is based on weighted evidence from a number of analyzers (demons), each of which computes the degree of match between the input character and a stored template (a copy of a previously presented character). The template-matching pandemonium was trained to recognize totally unconstrained handwritten digits. With a mean of 37 templates per type of digit, the system has attained a recognition rate of 95.3%, which falls short of human performance by only 2%-3%.

Algorithms↗
PubMed1996

Memory for words and novel visual patterns: repetition, recognition, and encoding effects in the event-related brain potential.

Event-related potentials (ERPs) were recorded during initial study and recognition of words and novel visual patterns. Words and patterns yielded similar recognition results that discriminated correctly recognized old items from correct new items, incorrect old items, and incorrect new items. The study phase data included a number of dissociations between words and patterns. Occasional repeated items yielded faster reaction times for both stimulus types but a late positive ERP repetition effect for words only. The study phase data differentiated words that would later be recognized versus unrecognized, but the patterns did not yield a similar encoding effect. Moreover, the study phase positivity contingent on subsequent recognition was restricted to words that received a positive semantic judgment during study. The functional relationships among the repetition, recognition, and encoding effects are discussed.

Adult↗
PubMed1998

Electric source localization adds evidence for task-specific CNVs.

This study was an attempt to replicate recent magnetoencephalographic (MEG) findings on human task-specific CNV sources (Basile et al., Electroencephalography and Clinical Neurophysiology 90, 1994, 157-165) by means of a spatio-temporal electric source localization method (Scherg and von Cramon, Electroencephalography and Clinical Neurophysiology 62, 1985, 32-44; Scherg and von Cramon, Electroencephalography and Clinical Neurophysiology 65, 1986, 344-360; Scherg and Berg, Brain Electric Source Analysis Handbook, Version 2). The previous MEG results showed CNV sources in the prefrontal cortex of the two hemispheres for two tasks used, namely visual pattern recognition and visual spatial recognition tasks. In the right hemisphere, the sources were more anterior and inferior for the spatial recognition task than for the pattern recognition task. In the present study we obtained CNVs in five subjects during two tasks identical to the MEG study. The elicited electric potentials were modeled with four spatio-temporal dipoles for each task, three of which accounted for the visual evoked response and one that accounted for the CNV. For all subjects the dipole explaining the CNV was always localized in the frontal region of the head, however, the dipole obtained during the visual spatial recognition task was more anterior than the one obtained during the pattern recognition task. Thus, task-specific CNV sources were again observed, although the stable model consisted of only one dipole located close to the midline instead of one dipole in each hemisphere. This was a major difference in the CNV sources between the previous MEG and the present electric source analysis results. We discuss the possible basis for the difference between the two methods used to study slow brain activity that is believed to originate from extended cortical patches.

Journal Article↗
PubMed1985

Internal representations and operations in the visual comparison of transformed patterns: effects of pattern point-inversion, position symmetry, and separation.

A scheme for visual pattern recognition is described. It is supposed, amongst other things, that patterns are internally represented by the visual system in terms of local features, spatial-order relations between local features, and global spatial relations specifying approximate pattern position with respect to the point of fixation. It is further supposed that there are two distinct types of internal operation that may be applied to the components of internal representations in the process of pattern comparison: typically a discrete spatial-order-reversal operation and a continuous position-shift operation. Some general predictions of the scheme are tested against data obtained in an experiment using random-dot patterns that were subjected to rigid transformations and presented at various locations along the horizontal meridian. Patterns were presented sequentially, in pairs, to subjects in a "same-different" comparison task. Pattern pairs were to be responded to as "same" if they were identical or related by point-inversion (planar rotation through 180 degrees) or responded to as "different". Extending earlier findings, the present results showed that "same"-detection performance for identical and point-inverted patterns depended differentially on the distance between the patterns and the symmetry of the pattern positions about the point of fixation in a manner consistent with the predictions of the scheme.

Adult↗
PubMed1975

An interactive computer program for studying fetal electroencephalograms.

Fetal electroencephalogram (FEEG), recorded during labor, produces very large volumes of data for visual interpretation. An established terminology, developed for the interpretation of neonatal electroencephalogram, has been found to be useful for visual pattern recognition of FEEG. A program, which identifies FEEG patterns within ten second epochs and provides direct comparison between visual and programmed analysis, has been developed using an interactive computer system. This program provides 85-90 percent consistency with visual interpretation.

Brain↗
PubMed1977

Effect of emotional stress on recognition of visual patterns.

The object of the study was to observe the changes in efficiency of perceptive activity of man (recognition of visual patterns against a background of noises) throughout an increase in emotional stress caused by a forthcoming parachuete jump. A moderate degree of emotional stress can improve performance efficiency and decrease the number of the subject's errors. Later an impairment of differentation of similar signals was seen and an increase in the number of "false alarm" errors along with a decrease in the number of omissions to reactions signals. The neurophysiological basis of such changes in perceptive activity consists in a transition from conditional behaviour to reaction through mechanisms of Ukhtomsky's dominant focus.

Aerospace Medicine↗
PubMed1998

Serial report and item recognition of novel visual patterns.

Previous studies of memory for novel visual patterns have reported how item recognition varies across serial positions, but have neglected serial order memory. In Expts 1 and 2 participants reported the order in which short series of novel patterns had been presented. The results showed markedly bowed serial position curves similar to those reported for sequences of verbal items or spatial locations. Concurrent articulation reduced performance in the serial report task relative to the memory task alone (Expt 2) or concurrent tapping (Expt 3) suggesting that a verbal component was involved. When two-alternative forced choice tests were used to test memory for the configuration of each pattern in the series, no primacy or recency was found (Expt 4). In Expt 5 the presentation of a series of five items was followed at random by either a serial report or the two-choice item recognition task. The serial position curves for the two tasks remained different, suggesting that encoding strategies were not responsible. The results show that bowed serial position curves are found when judgments of serial order are required, even when phonological coding is discouraged, whereas memory for item descriptions is independent of serial position. The implications for current conceptualizations of short-term memory are discussed.

Analysis of Variance↗
PubMed2002

Teaching residents humanistic skills in a colposcopy clinic.

OBJECTIVE: The aim of this project is to add formal training and evaluation of humanistic skills for residents in a colposcopy clinic. Medical education of residents in office procedures has generally focused on proficiency in a particular technical skill and acquisition of clinical knowledge regarding management options. The literature supports assessing pattern recognition with visual images and observing a specific number of procedures to achieve proficiency. Little attention has been given to training residents to demonstrate sensitivity during procedures. However, we believe this is a key element, as the procedure involves anxious patients who are fearful of cancer and fearful of pain in their most private body parts. Further, women who have painful or unpleasant colposcopy procedures are less likely to follow up for further evaluation of treatment and may be at higher risk to develop cervical cancer. DESCRIPTION: Colposcopy training for gynecology residents, family medicine residents, medical students, and emergency room sexual assault nurses is provided at a colposcopy clinic that performs more than 400 procedures per year. The majority of women are referred for colposcopy from outside clinics, and more than one third are non-English-speaking. We have added to our traditional didactics and case instruction curriculum a session dedicated to training residents in humanistic skills related to performing colposcopy. Topics of discussion include (1) how to ask sensitive questions regarding risk factors for cervical dysplasia, (2) how to explain the procedure and obtain consent, especially with non-English-speaking women, (3) how to educate patients about human papilloma virus (HPV) and prevention of cervical cancer, (4) how to speak to the patient and the attending physician during the procedure to reduce rather than increase anxiety, (5) how to provide comfort measures during colposcopy (e.g., using a warm speculum, using local anesthesia, hiding instruments from patient view), and (6) how to review findings during and after procedures. The discussion includes errors that previous residents have made and approaches that create effective, culturally sensitive role models. The training session participants are given feedback regarding statements or actions that may make patients anxious or less comfortable during and following clinical procedures. Residents are evaluated at the end of each rotation by faculty who rate their technical skills, visual pattern recognition, knowledge on the subject, and humanistic qualities. DISCUSSION: The training session participants have responded favorably to feedback about observed interactions with patients during procedures. Indications are that this training may improve the quality of care given by providers during colposcopy and other sensitive procedures. To document the curriculum's effect on patient satisfaction and care, we plan to pilot the use of a patient survey regarding physicians' humanistic qualities.

Colposcopy↗
PubMed1977

Anatomical and neurobehavioral investigations concerning the thalamo-cortical organization of the rat's visual system.

The organization of thalamic afferents to the rat's visual cortex was investigated autoradiographically and through the retrograde transport of horseradish peroxidase (HRP) following infections into striate and peristriate cortex. The results revealed that Nucleus lateralis posterior (NLP) projects to a large peristriate cortical field that includes areas 18A, 7, and the anterior portion of area 18, and to a circumscribed temporal area corresponding to Krieg's ('46a,b) area 20. The dorsal lateral geniculate nucleus (LGNd) was shown to project to two spatially discontinuous cortical areas. The largest geniculate receiving area is partially coextensive with Krieg's area 17, but an extension of this projection posterior and medial to the striate cortex was found. In addition, a geniculate projection to a restricted field located in the lateral peristriate cortex was identified. Concurrent investigations were designed to assess the pattern discrimination abilities of rats prepared with striate cortical ablations, lesions in NLP and combined striate-cortical and thalamic ablations. Comparison of these animals with normal control subjects revealed that the striate cortex in the rat (as in the cat [Doty, '71; Sprague et al., '77] and the tree shrew [Killackey and Diamond, '71; Ware et al., '74]) is not necessary for successful pattern discrimination, and that the geniculo-striate and NLP-extra-striate projection systems are both involved in mediating the visual discriminative abilities of the rat. The results add species generality to the concept that the central connections to the visual cortex are characterized by parallel-conducting thalamic channels and contribute to the growing number of demonstrations that the extra-striate cortex and associated thalamic cell groups contribute significantly to the process of visual-pattern recognition.

Afferent Pathways↗
PubMed1981

Modelling the visual cortex with "Modulo system" concept.

"Modulo system" is a general information extracting and processing network for modelling the nervous system. Its essential features are briefly summarized. The concept is applied to visual pattern recognition. The input is a two-dimensional picture of an object. The network extracts the contours, the line-segments, the lines of different directions, and the vertices of different numbers of lines, in successive functional layers. Afterwards, it recognized the simplest known pattern which has the actually extracted features. Uncertainty, association, and tolerance are also concerned. The network is detailed for the classification of of three-dimensional geometrical objects.

Form Perception↗
PubMed2003

Diazepam produces disinhibitory cognitive effects in male volunteers.

RATIONALE: Diazepam has well known amnestic and sedative effects but effects on fronto-executive function remain largely uninvestigated, especially on neuropsychologically validated tests of risk taking and orbitofrontal cortex function. OBJECTIVES: We aimed to determine the impact of diazepam on a variety of executive tasks. METHODS: The effects of 5, 10 and 20 mg of diazepam on a battery of neuropsychological tests were investigated using a randomised, double blind, placebo-controlled design. Seventy-five adult men were recruited. The Rogers et al. (1999b) test of risk-taking was given along with tasks from the CANTAB battery. RESULTS: Diazepam impaired performance on the Tower of London test of planning, without influencing visual pattern recognition memory. Subjects who had taken diazepam made more risky choices on the risk-taking task. On two speeded reaction time tasks diazepam impaired discrimination sensitivity and increased the bias to respond. CONCLUSIONS: In contrast to the well-known sedative effects of diazepam, we demonstrate disinhibitory effects on two speeded reaction time tasks. Our results show that diazepam can impair performance on reaction time tasks both by impairing sensitivity and by increasing the bias to respond. Furthermore diazepam impaired performance on tests of planning and risky decision making that depend predominantly on dorsolateral and orbitofrontal regions of the prefrontal cortex, respectively.

Adult↗
PubMed2006

A neuropsychological comparison of obsessive-compulsive disorder and trichotillomania.

BACKGROUND: Obsessive-compulsive disorder (OCD) and trichotillomania (compulsive hair-pulling) share overlapping co-morbidity, familial transmission, and phenomenology. However, the extent to which these disorders share a common cognitive phenotype has yet to be elucidated using patients without confounding co-morbidities. AIM: To compare neurocognitive functioning in co-morbidity-free patients with OCD and trichotillomania, focusing on domains of learning and memory, executive function, affective processing, reflection-impulsivity and decision-making. METHOD: Twenty patients with OCD, 20 patients with trichotillomania, and 20 matched controls undertook neuropsychological assessment after meeting stringent inclusion criteria. RESULTS: Groups were matched for age, education, verbal IQ, and gender. The OCD and trichotillomania groups were impaired on spatial working memory. Only OCD patients showed additional impairments on executive planning and visual pattern recognition memory, and missed more responses to sad target words than other groups on an affective go/no-go task. Furthermore, OCD patients failed to modulate their behaviour between conditions on the reflection-impulsivity test, suggestive of cognitive inflexibility. Both clinical groups showed intact decision-making and probabilistic reversal learning. CONCLUSIONS: OCD and trichotillomania shared overlapping spatial working memory problems, but neuropsychological dysfunction in OCD spanned additional domains that were intact in trichotillomania. Findings are discussed in relation to likely fronto-striatal neural substrates and future research directions.

Adult↗
PubMed2001

Automated detection of tracé alternant during sleep in healthy full-term neonates using discrete wavelet transform.

OBJECTIVE: To develop an automated procedure for scoring neonatal sleep states using signal processing which are based on visual pattern recognition techniques. METHODS: We are developing an automated computer system to study relationships among multiple non-cerebral physiologic measures and brain activity in newborn infants, and are evaluating the usefulness of a number of different time-frequency domain transforms as potential diagnostic tools. RESULTS: Wavelet transforms yield excellent results in the detection of all twenty tracé alternant quiet sleep segments for 6 full-term healthy infants. CONCLUSIONS: We suggest that this method will be useful for the automated detection of neonatal sleep states, and may help delineate when sleep cycle disturbances occur on either an environmental or disease basis. More accurate physiologic descriptions of neonatal state may improve the clinician's ability to assess functional brain organization for a given post-conceptional age as well as document functional brain maturation at progressively older corrected ages.

Algorithms↗
PubMed2006

Distinct memory traces for two visual features in the Drosophila brain.

The fly Drosophila melanogaster can discriminate and remember visual landmarks. It analyses selected parts of its visual environment according to a small number of pattern parameters such as size, colour or contour orientation, and stores particular parameter values. Like humans, flies recognize patterns independently of the retinal position during acquisition of the pattern (translation invariance). Here we show that the central-most part of the fly brain, the fan-shaped body, contains parts of a network mediating visual pattern recognition. We have identified short-term memory traces of two pattern parameters--elevation in the panorama and contour orientation. These can be localized to two groups of neurons extending branches as parallel, horizontal strata in the fan-shaped body. The central location of this memory store is well suited to mediate translational invariance.

Adenylyl Cyclases↗