Tactile spatial resolution. II. Neural representation of Bars, edges, and gratings in monkey primary afferents.
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Afferent Pathways↗
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Photovoice ethics: perspectives from Flint Photovoice.
Photovoice is a participatory health promotion strategy in which people use cameras to document their health and work realities. As participants engage in a group process of critical reflection, they may advocate for change in their communities by using the power of their images and stories to communicate with policy makers. In public health initiatives from China to California, community people have used photovoice to carry out participatory needs assessment, conduct participatory evaluation, and reach policy makers to improve community health. This article begins to address ethical issues raised by the use of photovoice: the potential for invasion of privacy and how that may be prevented; issues in recruitment, representation, participation, and advocacy; and specific methodological techniques that should be used to minimize participants' risks and to maximize benefits. The authors describe lessons learned from the large-scale Flint Photovoice involving youth, adults, and policy makers.
Commerce↗
The neuropsychology of spatial cognition in the rat.
This article provides a review of the neural mechanisms of spatial cognition in the rat. A survey of the literature shows that the rat has spatial capabilities that can be explained only if one assumes that it possesses a representation of some features of the environment. The scope of such a representation may, however, be more limited than what is implied by the hypothesis of a bird's-eye view of the environment. The best documented spatial ability of the rat is illustrated by its efficiency in performing the water maze navigation task. A review of recent neurobiological data collected while a rat was performing this task suggests that several brain structures make unique contributions to spatial navigation. In particular, the hippocampal formation and the associative (posterior) parietal cortex seem to handle different aspects of navigation and to be differentially involved in the various stages of spatial memory formation. Electrophysiological data support the hypothesis that the hippocampal formation is concerned with rapidly building associative memories of spatial relationships within the environment. In contrast, the associative parietal cortex might be involved in more abstract spatial processing, resulting in a metric representation of spatial information collected during movements.
Animals↗
Is semantic priming due to association strength or feature overlap? A microanalytic review.
In a recent meta-analysis, Lucas (2000) concluded that there is strong evidence of an overall pure semantic priming effect but no evidence of priming based purely on association. In the present review, I critically examine the individual studies claiming evidence of featural and associative relations in semantic memory. The most important conclusion is that automatic priming appears to be due to both association strength and feature overlap. Mediated associates provide the strongest evidence of automatic associative priming, whereas functional associates, synonyms, and antonyms instead support priming based on feature overlap. In contrast, automatic priming does not occur for category coordinates or perceptually similar items, at least when presented in the visual modality. The status of other relations, such as collocates, episodic relatives, and script relations, is unclear and requires further experimentation. Implications for current models of semantic representation and priming are discussed.
Attention↗
Unitary classification in a comparison task.
Sequential effects were used to diagnose whether elements in a two-object comparison task are represented as a perceptual unit or separately. The presence of sequential effects and absence of influences of individual elements on the subsequent trial in a successive comparison task favor the hypothesis that the elements in a pair are represented as a unit, and that a response is made to the perceptual unit. The patterns of response times on same and different trials differed in several ways; these suggested that the quality of the representations of same and different trials may differ.
Adult↗
Relationship of perceived stimulus structure and intelligence: further tests of a separability hypothesis.
The representation of objects by moderately and mildly mentally retarded subjects was determined using a classification task in which triads of objects were presented that placed classification by overall similarity relations and classification by shared dimensional relations in conflict. Results indicate that a separability hypothesis of normal perceptual development (Kemler, 1982; Shepp, Burns, & McDonough, 1980; Smith, 1979; Smith & Kemler, 1977) can be extended to retarded populations. Representation as unitary wholistic objects dominated among moderately retarded subjects, and with increasing intelligence, the representation of objects as component separable dimensions began to emerge.
Adolescent↗
MegaPlantTF: a machine learning framework for comprehensive identification and classification of plant transcription factors.
MOTIVATION: Understanding the role of transcription factors (TFs) in plants is essential for the study of gene regulation and various biological processes. However, both TF detection and classification remain challenging due to the great diversity and complexity of these proteins. Conventional approaches, such as BLAST, often suffer from high computational complexity and limited performance on less common TF families. RESULTS: We introduce MegaPlantTF, the first comprehensive machine learning and deep learning framework for the prediction (TF versus non-TF) and classification (family-level) of plant TFs. Our method employs k-mer-based protein representations and a two-stage architecture combining a deep feed-forward neural network with a stacking ensemble classifier. To ensure robust performance assessment, we report micro-, macro-, and weighted-average performance metrics, providing a holistic evaluation of both frequent and underrepresented TF families. Additionally, we employ threshold-based evaluation to calibrate confidence in TF detection. The results show that MegaPlantTF achieves strong accuracy and precision, particularly with a k-mer size of 3 and a classification threshold of 0.5, and maintains stable performance even under stringent thresholds. In addition to the standard cross-validation tests, a use case study on Sorghum bicolor confirms that our method performs strongly in the genome-wide analysis, making it highly suitable for large-scale TF identification and classification tasks. MegaPlantTF represents a novel contribution by integrating k-mer encoding, binary family-specific classifiers, and a two-stage stacking ensemble into a unified, reproducible framework for large-scale plant TF identification and classification. AVAILABILITY AND IMPLEMENTATION: MegaPlantTF is freely accessible through a public web server available at https://bioinformatics.um6p.ma/MegaPlantTF. The complete source code, including pretrained models and example datasets, is available at https://github.com/Bioinformatics-UM6P/MegaPlantTF.
Transcription Factors↗
Audiovisual speech facilitates voice learning.
In this research, we investigated the effects of voice and face information on the perceptual learning of talkers and on long-term memory for spoken words. In the first phase, listeners were trained over several days to identify voices from words presented auditorily or audiovisually. The training data showed that visual information about speakers enhanced voice learning, revealing cross-modal connections in talker processing akin to those observed in speech processing. In the second phase, the listeners completed an auditory or audiovisual word recognition memory test in which equal numbers of words were spoken by familiar and unfamiliar talkers. The data showed that words presented by familiar talkers were more likely to be retrieved from episodic memory, regardless of modality. Together, these findings provide new information about the representational code underlying familiar talker recognition and the role of stimulus familiarity in episodic word recognition.
Auditory Perception↗
Conservation of spatial memory function in the pallial forebrain of reptiles and ray-finned fishes.
The hippocampus of mammals and birds is critical for spatial memory. Neuroanatomical evidence indicates that the medial cortex (MC) of reptiles and the lateral pallium (LP) of ray-finned fishes could be homologous to the hippocampus of mammals and birds. In this work, we studied the effects of lesions to the MC of turtles and to the LP of goldfish in spatial memory. Lesioned animals were trained in place, and cue maze tasks and crucial probe and transfer tests were performed. In experiment 1, MC-lesioned turtles in the place task failed to locate the goal during trials in which new start positions were used, whereas sham animals navigated directly to the goal independently of start location. In contrast, no deficit was observed in cue learning. In experiment 2, LP lesion produced a dramatic impairment in goldfish trained in the place task, whereas medial and dorsal pallium lesions did not decrease accuracy. In addition, none of these pallial lesions produced deficits in cue learning. These results indicate that lesions to the MC of turtles and to the LP of goldfish, like hippocampal lesions in mammals and birds, selectively impair map-like memory representations of the environmental space. Thus, the forebrain structures of reptiles and teleost fish neuroanatomically equivalent to the mammalian and avian hippocampus also share a central role in spatial cognition. Present results suggest that the presence of a hippocampus-dependent spatial memory system is a primitive feature of the vertebrate forebrain that has been conserved through evolution.
Animals↗
Learning from technical documents: the role of intermodal referring expressions.
OBJECTIVE: We investigated the impact of two types of intermodal referring expressions on efficiency of instructions for use. BACKGROUND: User manuals for software or technical devices such as a video recording system frequently combine verbal instructions and illustrations. Much research has shown that the presence of an illustration has a beneficial effect on learning. The present study focuses on a factor that modulates this beneficial effect. The combination of text and an illustration can be effective only if the user integrates the information coming from these two media. This integration depends largely on the intermodal referential expressions, the function of which is to mark explicitly the relations between the text and the illustration. METHOD: In an experiment (N = 104), we compared the effectiveness of two intermodal referring expressions often used in procedural texts: indexes (numbers introduced in the illustrations and in the instructions to establish cross-references) and icons (visual representations of the components of the device, which are inserted in the verbal instructions). RESULTS: The icons condition led to the most efficient use of the device. CONCLUSION: This experiment shows that learning from multimedia documents depends on the possibility of effectively connecting the verbal instructions to the illustration. APPLICATION: Taking into account the ergonomic properties of the cross-media referring expressions should allow text designers to improve the effectiveness of technical documents.
Belgium↗
Dopamine, uncertainty and TD learning.
Substantial evidence suggests that the phasic activities of dopaminergic neurons in the primate midbrain represent a temporal difference (TD) error in predictions of future reward, with increases above and decreases below baseline consequent on positive and negative prediction errors, respectively. However, dopamine cells have very low baseline activity, which implies that the representation of these two sorts of error is asymmetric. We explore the implications of this seemingly innocuous asymmetry for the interpretation of dopaminergic firing patterns in experiments with probabilistic rewards which bring about persistent prediction errors. In particular, we show that when averaging the non-stationary prediction errors across trials, a ramping in the activity of the dopamine neurons should be apparent, whose magnitude is dependent on the learning rate. This exact phenomenon was observed in a recent experiment, though being interpreted there in antipodal terms as a within-trial encoding of uncertainty.
Journal Article↗
Anterograde and retrograde memory for object discriminations and places in rats with perirhinal cortex lesions.
Three experiments examined the effects of perirhinal cortex lesions on rats' retrograde and anterograde memory for object-discriminations and water-maze place-memory problems. In Experiment 1, rats learned two object-discriminations - the first was learned 2 weeks before surgery and the second 24 h before surgery. Rats with perirhinal cortex lesions displayed mildly impaired retention of both object discriminations, with no evidence of a temporal gradient. They also learned a new discrimination at a normal rate, but were impaired on a retention test 24 h later. In Experiment 2, rats learned two water-maze place problems, conducted in different rooms - the first was learned 4 weeks before surgery and the second during the week immediately before surgery. Rats with perirhinal cortex lesions displayed deficits on the early retention trials of both place problems, but they quickly relearned both problems. In Experiment 3, rats with perirhinal cortex lesions learned a new place problem at a normal rate and performed as well as control rats on a retention test 3 weeks later. Although some of the results are consistent with the conclusion that perirhinal damage disrupts storage or retrieval of place information acquired before surgery, additional considerations suggest instead a role for perirhinal cortex in the representation of nonspatial information that makes a useful but nonessential contribution to water-maze performance.
Amnesia, Anterograde↗
Dissociable effects of the implicit and explicit memory systems on learning control of reaching.
Adaptive control of reaching depends on internal models that associate states in which the limb experienced a force perturbation with motor commands that can compensate for it. Limb state can be sensed via both vision and proprioception. However, adaptation of reaching in novel dynamics results in generalization in the intrinsic coordinates of the limb, suggesting that the proprioceptive states in which the limb was perturbed dominate representation of limb state. To test this hypothesis, we considered a task where position of the hand during a reach was correlated with patterns of force perturbation. This correlation could be sensed via vision, proprioception, or both. As predicted, when the correlations could be sensed only via proprioception, learning was significantly better as compared to when the correlations could only be sensed through vision. We found that learning with visual correlations resulted in subjects who could verbally describe the patterns of perturbations but this awareness was never observed in subjects who learned the task with only proprioceptive correlations. We manipulated the relative values of the visual and proprioceptive parameters and found that the probability of becoming aware strongly depended on the correlations that subjects could visually observe. In all conditions, aware subjects demonstrated a small but significant advantage in their ability to adapt their motor commands. Proprioceptive correlations produced an internal model that strongly influenced reaching performance yet did not lead to awareness. Visual correlations strongly increased the probability of becoming aware, yet had a much smaller but still significant effect on reaching performance. Therefore, practice resulted in acquisition of both implicit and explicit internal models.
Adaptation, Psychological↗
Pathology in the new medical curriculum: what has replaced the subject courses?
In line with the UK General Medical Council recommendations, the traditional, taught curriculum at Liverpool was replaced from 1996 by a new one using problem-based learning (PBL) as its principal method of information transfer. There is integration of clinical and preclinical studies, coupled with a reduction in the factual knowledge content and the disappearance of identifiable separate subject courses. Learning is now student-centred. This requires a new approach to the acquisition of pathology knowledge. 1. Pathology is included in all relevant PBL case scenarios by pathology representation on module planning and review committees. 2. Special study modules (SSMs) allow students to observe the practice of pathology including surgical and autopsy work, carry out a detailed study and write a dissertation. Career selectives are provided for individual students in the final year. 3. Clinicopathological (CPC) teaching meetings are held, with the discussion of case examples, clinicians and students contributing. 4. Assessments include the input of appropriate pathology content, integrated with other subjects. 5. A pathology teaching website is provided, containing images, notes, self-assessment questions, handouts, timetables and information. Although the 1996 intake have not yet completed their studies, the results of in-course assessments have been encouraging. The response to the pathology SSMs has been very positive, and the level of presentations and dissertations reached is of a high standard. With the disappearance of a separate subject course in pathology, the subject is being learned by other routes, and the students will complete their undergraduate course with a sound basis for proceeding with their further studies.
Curriculum↗
Event-related FMRI study of context processing in dorsolateral prefrontal cortex of patients with schizophrenia.
Context processing is conceptualized as an executive function involved in voluntary, complex actions such as overcoming automatic responses. The present study tested the hypothesis that context-processing deficits in patients with schizophrenia are associated with a dysfunction of left dorsolateral prefrontal cortex (DLPFC). Using event-related functional magnetic resonance imaging (fMRI), 17 controls and 17 medicated patients performed a version of the AX task in which a learned, automatic response had to be inhibited. In controls, left DLPFC activity increased when preparing to overcome an automatic response, whereas patients with schizophrenia showed no differential activation. In controls, context processing appeared to be associated with the differential representation of cues associated with the need to provide top-down support for overcoming automatic responses. This mechanism appeared to be impaired in patients with schizophrenia.
Adult↗
The interplay between perceptual organization and categorization in the representation of complex visual patterns by young infants.
The relation between perceptual organization and categorization processes in 3- and 4-month-olds was explored. The question was whether an invariant part abstracted during category learning could interfere with Gestalt organizational processes. A 2003 study by Quinn and Schyns had reported that an initial category familiarization experience in which infants were presented with visual patterns consisting of a pacman shape and a complex polygon could interfere with infants' subsequent good continuation-based parsing of a circle from visual patterns consisting of a circle and a complex polygon. However, an alternative noninterference explanation for the results was possible because the pacman had been presented with greater frequency and duration than had the circle. The current study repeated Quinn and Schyns's procedure but provided an equivalent number of familiarization trials and duration of study time for the infants to process the pacman during initial familiarization and the circle during subsequent familiarization. The results replicated the previous findings of Quinn and Schyns. The data are consistent with the interference account and suggest that a cognitive system of adaptable feature creation can take precedence over organizational principles with which a perceptual system comes pre-equipped.
Cognition↗
Serial learning with a wild card by pigeons (Columba livia): effect of list length.
Pigeons (Columba livia) learned 3-, 4- or 5-item lists prior to subset and wild card tests. On the latter, a novel item replaced 1 of the list items. Pigeons who learned 3-item lists responded accurately on all subset pairs (AB, BC, and AC) and on all types of 3-item wild card trials (WBC, AWC, & ABW). Pigeons who learned 4- and 5-item lists responded at chance levels of accuracy on all subsets that did not contain a start or an end item (BC, BD, & CD, respectively, on 4- and 5-item subset tests). On wild card trials, they exceeded chance levels of performance only when the wild card replaced the last item (ABCW & ABCDW trials). Monkeys (Cebus apella) trained to produce a 5-item list perform accurately on all subsets and wild cards. (M. R. D'Amato & M. Colombo, 1988, 1989). These differences provide strong evidence that pigeons and monkeys form qualitatively different representations of lists containing four or more items.
Animals↗
Automatic classification of HITS into artifacts or solid or gaseous emboli by a wavelet representation combined with dual-gate TCD.
BACKGROUND AND PURPOSE: Transcranial Doppler (TCD) can detect high-intensity transient signals (HITS) in the cerebral circulation. HITS may correspond to artifacts or solid or gaseous emboli. The aim of this study was to develop an offline automated Doppler system allowing the classification of HITS. METHODS: We studied 600 HITS in vivo, including 200 artifacts from normal subjects, 200 solid emboli from patients with symptomatic internal carotid artery stenosis, and 200 gaseous emboli in stroke patients with patent foramen ovale. The study was 2-fold, each part involving 300 HITS (100 of each type). The first 300 HITS (learning set) were used to construct an automated classification algorithm. The remaining 300 HITS (validation set) were used to check the validity of this algorithm. To classify HITS, we combined dual-gate TCD with a wavelet representation and compared it with the current "gold standard," the human experts. RESULTS: A combination of the peak frequency of HITS and the time delay makes it possible to separate artifacts from emboli. On the validation set, we achieved a sensitivity of 97%, a specificity of 98%, a positive predictive value (PPV) of 99%, and a negative predictive value (NPV) of 94%. To distinguish between solid and gaseous emboli, where positive refers now to the solid emboli, we used the peak frequency, the relative power, and the envelope symmetry of HITS. On the validation set, we achieved a sensitivity of 89%, a specificity of 86%, a conditional PPV of 89%, and a conditional NPV of 89%. CONCLUSIONS: An automated wavelet representation combined with dual-gate TCD can reliably reject artifacts from emboli. From a clinical standpoint, however, this approach has only a fair accuracy in differentiating between solid and gaseous emboli.
Adult↗