Recognition Memory for Colored and Black-and-White Scenes in Normal and Color Deficient Observers (Dichromats)

Color deficient (dichromat) and normal observers’ recognition memory for colored and black-and-white natural scenes was evaluated through several parameters: the rate of recognition, discrimination (A’), response bias (B”D), response confidence, and the proportion of conscious recollections (Remember responses) among hits. At the encoding phase, 36 images of natural scenes were each presented for 1 sec. Half of the images were shown in color and half in black-and-white. At the recognition phase, these 36 pictures were intermixed with 36 new images. The participants’ task was to indicate whether an image had been presented or not at the encoding phase, to rate their level of confidence in his her/his response, and in the case of a positive response, to classify the response as a Remember, a Know or a Guess response. Results indicated that accuracy, response discrimination, response bias and confidence ratings were higher for colored than for black-and-white images; this advantage for colored images was similar in both groups of participants. Rates of Remember responses were not higher for colored images than for black-and-white ones, whatever the group. However, interestingly, Remember responses were significantly more often based on color information for colored than for black-and-white images in normal observers only, not in dichromats.     

Enhanced Memory for Scenes Presented at Behaviorally Relevant Points in Time

The ability to remember a briefly presented scene depends on a number of factors, such as its saliency, novelty, degree of threat, or behavioral relevance to a task. Here, however, we show that the encoding of a scene into memory may depend not only on what the scene contains but also when it occurs. Participants performed an attentionally demanding target detection task at fixation while also viewing a rapid sequence of full-field photographs of urban and natural scenes. Participants were then tested on whether they recognized a specific scene from the previous sequence. We found that scenes were recognized reliably only when presented concurrently with a target at fixation. This is evidence of a mechanism where traces of a visual scene are automatically encoded into memory at behaviorally relevant points in time regardless of the spatial focus of attention.     

Falling Out of Time: Enhanced Memory for Scenes Presented at Behaviorally Irrelevant Points in Time in Posttraumatic Stress Disorder (PTSD)

Spontaneous encoding of the visual environment depends on the behavioral relevance of the task performed simultaneously. If participants identify target letters or auditory tones while viewing a series of briefly presented natural and urban scenes, they demonstrate effective scene recognition only when a target, but not a behaviorally irrelevant distractor, appears together with the scene. Here, we show that individuals with posttraumatic stress disorder (PTSD), who witnessed the red sludge disaster in Hungary, show the opposite pattern of performance: enhanced recognition of scenes presented together with distractors and deficient recognition of scenes presented with targets. The recognition of trauma-related and neutral scenes was not different in individuals with PTSD. We found a positive correlation between memory for scenes presented with auditory distractors and re-experiencing symptoms (memory intrusions and flashbacks). These results suggest that abnormal encoding of visual scenes at behaviorally irrelevant events might be associated with intrusive experiences by disrupting the flow of time.     

Memory of Location and Site Recognition in the Ant Formica uralensis (Hymenoptera: Formicidae)

Spatial recognition cues used in site fidelity in the ant Formica uralensis Ruzsky were studied using outdoor and laboratory arenas. Ant workers visiting symmetrically spaced feeders were colour-marked corresponding to the initial feeder visited during sampling. The effect of manipulating environmental cues on the mean 'spatial specialization' of the population was measured. Site recognition appears to be based on visual landmark/canopy cues. However, ants maintained some fidelity when shielded from these cues, suggesting the involvement of additional cues. When ridding our experimental device of olfactory deposits and shielding visual cues, site fidelity was lost. Idiothetic and/or geomagnetic cues are thought to provide spatial references to visual or olfactory landmarks. Altering nest position relative to the arena and changing the geomagnetic field within the arena in our study, however, did nothing to the site fidelity of visually deprived and non-deprived foragers.
We conclude that site fidelity is developed in a visually structured environment but supplemented by an olfactory backup system that is probably based on discrete home range markings rather than radial odour trails. We demonstrate furthermore that the visual component involved in site location can be stored in the memory of individual F. uralensis foragers during a 6-month hibernation period.     

Color-Vision Mechanisms in the Peripheral Retinas of Normal and Dichromatic Observers

It is possible that so-called normal trichromatic vision occurs only between the central blue-blind fixation area and about 30° peripherally. Beyond about 30° vision has been alleged to become dichromatic (red-green blind), and beyond about 60°, monochromatic. Hence every form of color blindness may characterize various zones of the normal retina. We have studied mechanisms of peripheral color vision, mainly by measuring the spectral sensitivities of the blue-, green-, and red-sensitive systems, isolated by differential color adaptation. In normal observers the sensitivity of the blue-mechanism falls off about 2 log units by 80° out. The green- and red-sensitive systems decline only about 0.7 log unit over the same range. Protanopes, deuteranopes, and tritanopes exhibit comparable changes. We have not found any color mechanism present centrally to be wholly lost peripherally. Nor, for dichromats, have we found any mechanism missing centrally to be present peripherally. Whatever evidences of peripheral color blindness have been observed appear to involve other mechanisms than failure of receptors, probably including some fusion of neural pathways from receptors to centers.     

Examining Event-Related Potential (ERP) Correlates of Decision Bias in Recognition Memory Judgments

Memory judgments can be based on accurate memory information or on decision bias (the tendency to report that an event is part of episodic memory when one is in fact unsure). Event related potentials (ERP) correlates are important research tools for elucidating the dynamics underlying memory judgments but so far have been established only for investigations of accurate old/new discrimination. To identify the ERP correlates of bias, and observe how these interact with ERP correlates of memory, we conducted three experiments that manipulated decision bias within participants via instructions during recognition memory tests while their ERPs were recorded. In Experiment 1, the bias manipulation was performed between blocks of trials (automatized bias) and compared to trial-by-trial shifts of bias in accord with an external cue (flexibly controlled bias). In Experiment 2, the bias manipulation was performed at two different levels of accurate old/new discrimination as the memory strength of old (studied) items was varied. In Experiment 3, the bias manipulation was added to another, bottom-up driven manipulation of bias induced via familiarity. In the first two Experiments, and in the low familiarity condition of Experiment 3, we found evidence of an early frontocentral ERP component at 320 ms poststimulus (the FN320) that was sensitive to the manipulation of bias via instruction, with more negative amplitudes indexing more liberal bias. By contrast, later during the trial (500–700 ms poststimulus), bias effects interacted with old/new effects across all three experiments. Results suggest that the decision criterion is typically activated early during recognition memory trials, and is integrated with retrieved memory signals and task-specific processing demands later during the trial. More generally, the findings demonstrate how ERPs can help to specify the dynamics of recognition memory processes under top-down and bottom-up controlled retrieval conditions.     

哺乳期棕色田鼠对配偶的识别记忆

观察了分娩后哺乳雌性棕色田鼠（Microtus mandarinus）与配偶分离7d、14d、21d后对配偶与陌生雄鼠的行为反应。结果发现,在频次和持续时间上,与配偶分离7d、14d、21d的雌鼠对配偶的攻击行为显著低于陌生雄鼠（P〈0．05）;对配偶的嗅闻及友善行为显著高于陌生雄鼠（P〈0．05）。处于哺乳前、中、后期不同阶段的雌鼠对陌生雄鼠攻击水平没有显著性差异（P〉0．05）。这些结果说明,在整个哺乳期,雌鼠能够识别配偶,对配偶的记忆不因分离时间的增加而减弱,而且对陌生鼠的攻击水平不会因哺乳阶段的变化而变化,维持高水平的攻击可能与其较强的母性行为有关。     

Mice with Deficient BK Channel Function Show Impaired Prepulse Inhibition and Spatial Learning,but Normal Working and Spatial Reference Memory

Genetic variations in the large-conductance, voltage- and calcium activated potassium channels (BK channels) have been recently implicated in mental retardation, autism and schizophrenia which all come along with severe cognitive impairments. In the present study we investigate the effects of functional BK channel deletion on cognition using a genetic mouse model with a knock-out of the gene for the pore forming α-subunit of the channel. We tested the F1 generation of a hybrid SV129/C57BL6 mouse line in which the slo1 gene was deleted in both parent strains.We first evaluated hearing and motor function to establish the suitability of this model for cognitive testing. Auditory brain stem responses to click stimuli showed no threshold differences between knockout mice and their wild-type littermates. Despite of muscular tremor, reduced grip force, and impaired gait, knockout mice exhibited normal locomotion. These findings allowed for testing of sensorimotor gating using the acoustic startle reflex, as well as of working memory, spatial learning and memory in the Y-maze and the Morris water maze, respectively.Prepulse inhibition on the first day of testing was normal, but the knockout mice did not improve over the days of testing as their wild-type littermates did. Spontaneous alternation in the y-maze was normal as well, suggesting that the BK channel knock-out does not impair working memory. In the Morris water maze knock-out mice showed significantly slower acquisition of the task, but normal memory once the task was learned. Thus, we propose a crucial role of the BK channels in learning, but not in memory storage or recollection.     

Niche Divergence Among Sex and Age Classes in Black-and-White Snub-nosed Monkeys (Rhinopithecus bieti)

A wide range of dimorphic species exhibit intraspecific differences in feeding ecology and habitat use; however, studies comparing resource partitioning between males and females and between age groups occur mainly at the community and species level. We here classified the main habitat of black-and-white snub-nosed monkeys (Rhinopithecus bieti) –fir tree crown– into six microhabitats; examined the lichen-load of the microhabitats; and investigated the microhabitat use of age–sex groups within one-male units (OMUs: an adult male, several females, and juveniles) of R. bieti using instantaneous scanning sampling methods to test whether there is resource niche partitioning in social units of this sexually dimorphic primate in a reserve in Yunnan, China. Our results showed that adult females and juveniles often foraged in the outer layer of the fir tree crown, whereas adult males often foraged in the inner layer, closer to the trunk where food abundance was highest. Adult females and juveniles, however, both shifted microhabitat-use patterns to the inner layer of the fir tree crown when the adult male was absent from the tree. We suggested that the preference for and benefit of the central layer of fir tree crown lies in food availability, but that adult male competitively excluded group members. Microhabitat segregation may serve to maximize the fitness of the group members by reducing intragroup competition, while also increasing interindividual distance, thereby reducing the possible effects of scramble competition.     

Functional Analysis of Aggression in a Black-and-White Ruffed Lemur (Varecia variegata variegata)

A functional analysis was conducted to assess the antecedent and reinforcing conditions underlying aggressive behavior in a female lemur in captivity. Results showed that her aggression was primarily the result of human attention. A replacement behavior-training program was introduced, and the lemur's aggression was successfully eliminated. These results demonstrate the utility of using functional assessment and analyses in zoos with captive wild nonhuman animals.     

Metforminium Decavanadate (MetfDeca) Treatment Ameliorates Hippocampal Neurodegeneration and Recognition Memory in a Metabolic Syndrome Model

Neurochemical Research - The consumption of foods rich in carbohydrates, saturated fat, and sodium, accompanied by a sedentary routine, are factors that contribute to the progress of metabolic...     

Comfort Behavior of Black-and-White (Varecia variegata variegata) and Red (Varecia variegata rubra) Ruffed Lemurs (Primates,Lemuridae)

Biology Bulletin - Abstract—Knowledge of grooming makes it possible to characterize the intragroup social connections of lemurs and accurately form groups in captivity. The results of this...     

Using an Improved SIFT Algorithm and Fuzzy Closed-Loop Control Strategy for Object Recognition in Cluttered Scenes

Partial occlusions, large pose variations, and extreme ambient illumination conditions generally cause the performance degradation of object recognition systems. Therefore, this paper presents a novel approach for fast and robust object recognition in cluttered scenes based on an improved scale invariant feature transform (SIFT) algorithm and a fuzzy closed-loop control method. First, a fast SIFT algorithm is proposed by classifying SIFT features into several clusters based on several attributes computed from the sub-orientation histogram (SOH), in the feature matching phase only features that share nearly the same corresponding attributes are compared. Second, a feature matching step is performed following a prioritized order based on the scale factor, which is calculated between the object image and the target object image, guaranteeing robust feature matching. Finally, a fuzzy closed-loop control strategy is applied to increase the accuracy of the object recognition and is essential for autonomous object manipulation process. Compared to the original SIFT algorithm for object recognition, the result of the proposed method shows that the number of SIFT features extracted from an object has a significant increase, and the computing speed of the object recognition processes increases by more than 40%. The experimental results confirmed that the proposed method performs effectively and accurately in cluttered scenes.