The role of the hippocampus in object discrimination based on visual features.

The role of rodent hippocampus has been intensively studied in different cognitive tasks. However, its role in discrimination of objects remains controversial due to conflicting findings. We tested whether the number and type of features available for the identification of objects might affect the strategy (hippocampal-independent vs. hippocampal-dependent) that rats adopt to solve object discrimination tasks. We trained rats to discriminate 2D visual objects presented on a computer screen. The objects were defined either by their shape only or by multiple-features (a combination of filling pattern and brightness in addition to the shape). Our data showed that objects displayed as simple geometric shapes are not discriminated by trained rats after their hippocampi had been bilaterally inactivated by the GABAA-agonist muscimol. On the other hand, objects containing a specific combination of non-geometric features in addition to the shape are discriminated even without the hippocampus. Our results suggest that the involvement of the hippocampus in visual object discrimination depends on the abundance of object's features.

Perception of direct vs. averted gaze in portrait paintings: An fMRI and eye-tracking study.

In this study, we use separate eye-tracking measurements and functional magnetic resonance imaging to investigate the neuronal and behavioral response to painted portraits with direct versus averted gaze. We further explored modulatory effects of several painting characteristics (premodern vs modern period, influence of style and pictorial context). In the fMRI experiment, we show that the direct versus averted gaze elicited increased activation in lingual and inferior occipital and the fusiform face area, as well as in several areas involved in attentional and social cognitive processes, especially the theory of mind: angular gyrus/temporo-parietal junction, inferior frontal gyrus and dorsolateral prefrontal cortex. The additional eye-tracking experiment showed that participants spent more time viewing the portrait's eyes and mouth when the portrait's gaze was directed towards the observer. These results suggest that static and, in some cases, highly stylized depictions of human beings in artistic portraits elicit brain activation commensurate with the experience of being observed by a watchful intelligent being. They thus involve observers in implicit inferences of the painted subject's mental states and emotions. We further confirm the substantial influence of representational medium on brain activity.

Spatial decisions and cognitive strategies of monkeys and humans based on abstract spatial stimuli in rotation test.

We showed previously that macaque monkeys (Macaca mulatta) could orient in real space using abstract visual stimuli presented on a computer screen. They made correct choices according to both spatial stimuli (designed as an abstract representation of a real space) and nonspatial stimuli (pictures lacking any inner configuration information). However, we suggested that there were differences in processing spatial and nonspatial stimuli. In the present experiment we show that monkeys could also use as a cue abstract spatial stimuli rotated with respect to the real response space. We studied the ability of monkeys to decode abstract spatial information provided in one spatial frame (computer screen) and to perform spatial choices in another spatial frame (touch panel separated from the screen). We analyzed how the monkeys were affected by the type of training, whether they perceived the stimuli as "spatial" or "nonspatial," and which cues they used to decode them. We compared humans to monkeys in a similar test to find out which cognitive strategy they used and whether they perceive spatial stimuli in the same way. We demonstrated that there were two possible strategies to solve the task, simple "fitting" ignoring rotations and "remapping," when the stimulus was represented as an "abstract space" per se.

Selective impairment of timing in a NMDA hypofunction animal model of psychosis.

Schizophrenia is severe neuropsychiatric disease, which is commonly accompanied not only by positive or negative symptoms, but also by cognitive impairment. To study neuronal mechanisms underlying cognitive distortions and mechanisms underlying schizophrenia, animal pharmacological models of cognitive symptoms are commonly used. Between various cognitive impairments in schizophrenia patients, disturbed time perception has often been reported. Here, we examined temporal and spatial cognition in a modified Carousel maze task in the animal model of schizophrenia induced by non-competitive NMDA-receptor antagonists MK-801. Male Long-Evans rats (n = 18) first learned to avoid the aversive sector on a rotating arena in both dark and light intervals. We verified that during dark, rats used temporal cues, while during light they relied predominantly on spatial cues. We demonstrated that the timing strategy depends on the stable rotation speed of the arena and on the repositioning clues such as aversive stimuli. During testing (both in light and dark intervals), half of the rats received MK-801 and the control half received saline solution. We observed dose-dependent disruptions of both temporal and spatial cognition. Namely, both doses of MK-801 (0.1 and 0.12 mg/kg) significantly impaired timing strategy in the dark and increased locomotor activity. MK-801 dose 0.1 mg/kg, but not 0.12, also impaired spatial avoidance strategy in light. We found that the timing strategy is more sensitive to NMDA antagonist MK-801 than the spatial strategy. To conclude, a modified version of the Carousel maze is a useful and sensitive tool for detecting timing impairments in the MK-801 induced rodent model of schizophrenia.

Inter-individual differences in laboratory rats as revealed by three behavioural tasks.

Stable inter-individual differences in behaviour and personality have been studied for several decades now. The aim of this study was to test the repeatability of behaviour of the Long Evans strain of laboratory rats in order to assess their inter-individual differences. Male laboratory rats (n = 36) were tested in a series of tasks (Open field test, Elevated plus maze test, and modified T-maze test) repeated over time to assess their personality traits. To evaluate the temporal stability of the behaviour, we calculated repeatability estimates of the examined traits. We also checked for a link in behavioural traits across these experiments, which would suggest the existence of a behavioural syndrome. We found stable inter-individual differences in behaviour. Interestingly, no link emerged between the tasks we studied and therefore we did not find support for a behavioural syndrome. The lack of behavioural correlations between these experiments suggests that the results derived from these tasks should be interpreted carefully, as these experiments may measure various behavioural axes. Moreover, the animals habituate to the apparatus. Consequently, behaviour in the Open field test and Elevated plus maze test is not fully consistent and repeatable across subsequent trials.

What is the future for immersive virtual reality in memory rehabilitation? A systematic review.

BACKGROUND: A growing interest in non-pharmacological approaches aimed at cognitive rehabilitation and cognitive enhancement pointed towards the application of new technologies. The complex virtual reality (VR) presented using immersive devices has been considered a promising approach. OBJECTIVE: The article provides a systematic review of studies aimed at the efficacy of VR-based rehabilitation. First, we shortly summarize literature relevant to the role of immersion in memory assessment and rehabilitation. METHODS: We searched Web of Science, ScienceDirect, and PubMed with the search terms "memory rehabilitation", "virtual reality", "memory deficit". Only original studies investigating the efficacy of complex three-dimensional VR in rehabilitation and reporting specific memory output measures were included. RESULTS: We identified 412 citations, of which 21 met our inclusion criteria. We calculated appropriate effect sizes for 10 studies including control groups and providing descriptive data. The effect sizes range from large to small, or no effect of memory rehabilitation was present, depending on the control condition applied. Summarized studies with missing control groups point out to potential positive effects of VR but do not allow any generalization. CONCLUSIONS: Even though there are some theoretical advantages of immersive VE over non-immersive technology, there is not enough evidence yet to draw any conclusions.

Is short-term memory capacity (7±2) really predicted by theta to gamma cycle length ratio?

Several studies suggest that EEG parameters, reflecting top-down processes in the brain, may predict cognitive performance, e.g. short-term memory (STM) capacity. According to Lisman and Idiart's model, STM capacity is predicted by theta and gamma EEG waves and their ratio. This model suggests that the more periods of gamma band waves fit into one period of theta band waves, the more information can be stored. We replicated the study by Kaminski et al. (2011), which recorded spontaneous EEG activity and measured verbal STM capacity with a modified digit span task from the Wechsler battery. Our study included more subjects and two EEG recording sessions. We discuss the possible limits of EEG correlates of STM capacity as EEG parameters were not stable across the two measurements and no correlation was found between the theta/gamma ratio and performance in the digit span task.

Validation of the Human-Animal Interaction Scale (HAIS) in Czech Language.

Human-Animal interaction (HAI) refers to any contact between humans and animals. Despite the lack of standardized measures of evaluation, one possible tool is the Human Animal Interaction Scale (HAIS). This study aimed to evaluate it in Czech language and to verify its use in clinical settings. One group of participants included 85 non-clinical volunteers; the second included 22 clinical participants, who were hospitalized in a long-term inpatient department All participants filled out the HAIS, the Companion Animal Bonding Scale (CABS) and the Companion Animal Semantic Differential (CASD). The Czech HAIS achieved similarly good psychometric properties as the original scale. The Cronbach's alpha showed strong internal consistency (α = 0.920) in the sample of volunteers, but low internal consistency (α = 0.656) in the group of clinical participants. In non-clinical volunteers, all scales and subscales correlated mutually at the p < 0.01 level. In the group of clinical participants, the CABS did not show significant correlations with other scales and subscales, nor was there a correlation of total HAIS score with the perceived rapport with animals. The findings of this study suggest that the Czech HAIS may be an effective tool for evaluating HAI with non-clinical contingents, however careful modification is suggested before clinical use. One reason for this is the difficulty in conducting some activities assessed by the scale in a clinical practice or hospital setting.

Spontaneous color preferences in rhesus monkeys: What is the advantage of primate trichromacy?

Color perception and color signaling play an important role in various aspects of animal behavior. However, in mammals, trichromatic vision characterized by three retinal photopigments tuned to peak short, middle and long wavelengths is limited only to some primate species. In Old and New World primates a second photopigment has appeared repeatedly during phylogeny, allowing red colors to be distinguished from yellows and greens. Several hypotheses aspire to explain the adaptive benefits of trichromatic vision for primates. The predominant one is foraging adaptation for facilitation visual detection of fruits or young leaves. Alternative explanations are based on the function of red color in aposematic signaling or its role in socio-sexual communication. We tested spontaneous color preference in macaque monkeys (Macaca mulatta) for both food and non-food objects in a laboratory environment. We hypothesized that preference for or avoidance of red color together with the context of such behavior may help us to understand what the adaptive advantage leading to a rapid expansion of a gene for a second pigment in the long-wavelength region was. We found neither preference nor avoidance toward red color in non-food objects, but we found a significant preference for red color in food; therefore, we suggest that the results support the foraging hypothesis in macaque monkeys.

Fusiform Activity Distinguishes Between Subjects With Low and High Xenophobic Attitudes Toward Refugees.

This study analyzes how people's attitudes to the European refugee crisis (ERC) correspond to selected psychological state and trait measures and impact the neural processing of media images of refugees. From a large pool of respondents, who filled in an online xenophobia questionnaire, we selected two groups (total N = 38) with the same socio-demographic background, but with opposite attitudes toward refugees. We found that a negative attitude toward refugees (high xenophobia - HX) was associated with a significantly higher conscientiousness score and with a higher trait aggression and hostility, but there was no group effect connected with empathy, fear, and anxiety measures. At the neural level we found that brain activity during the presentation of ERC stimuli is affected by xenophobic attitudes-with more xenophobic subjects exhibiting a higher BOLD response in the left fusiform gyrus. However, while the fMRI results demonstrate increased attention and vigilance toward ERC-related stimuli in the HX group, they do not show differentiated patterns of brain activity associated with perception of dehumanized outgroup.

Mapping the Scene and Object Processing Networks by Intracranial EEG.

Human perception and cognition are based predominantly on visual information processing. Much of the information regarding neuronal correlates of visual processing has been derived from functional imaging studies, which have identified a variety of brain areas contributing to visual analysis, recognition, and processing of objects and scenes. However, only two of these areas, namely the parahippocampal place area (PPA) and the lateral occipital complex (LOC), were verified and further characterized by intracranial electroencephalogram (iEEG). iEEG is a unique measurement technique that samples a local neuronal population with high temporal and anatomical resolution. In the present study, we aimed to expand on previous reports and examine brain activity for selectivity of scenes and objects in the broadband high-gamma frequency range (50-150 Hz). We collected iEEG data from 27 epileptic patients while they watched a series of images, containing objects and scenes, and we identified 375 bipolar channels responding to at least one of these two categories. Using K-means clustering, we delineated their brain localization. In addition to the two areas described previously, we detected significant responses in two other scene-selective areas, not yet reported by any electrophysiological studies; namely the occipital place area (OPA) and the retrosplenial complex. Moreover, using iEEG we revealed a much broader network underlying visual processing than that described to date, using specialized functional imaging experimental designs. Here, we report the selective brain areas for scene processing include the posterior collateral sulcus and the anterior temporal region, which were already shown to be related to scene novelty and landmark naming. The object-selective responses appeared in the parietal, frontal, and temporal regions connected with tool use and object recognition. The temporal analyses specified the time course of the category selectivity through the dorsal and ventral visual streams. The receiver operating characteristic analyses identified the PPA and the fusiform portion of the LOC as being the most selective for scenes and objects, respectively. Our findings represent a valuable overview of visual processing selectivity for scenes and objects based on iEEG analyses and thus, contribute to a better understanding of visual processing in the human brain.

Reactions to novel objects in monkeys: what does it mean to be neophobic?

Animals' reactions to novel objects vary not only with zoological taxa and their ecology but also in the types of presented stimuli, the context, and individual characteristics. Behavioral reactions can vary from extremely neophobic (avoiding novel objects) to extremely neophilic (intense exploration of novel objects); most often, a mixture of these behavioral patterns appears. In primates, reactions toward novel objects vary according to species, age, sex, population, and the types of objects. Most experiments in this field have used a free exploration design with food or non-food objects. Here, we tested the reactions of captive male rhesus macaques using various stimuli, motivation levels, rewards, and time limits. We found that the monkeys explored and manipulated novel objects in various contexts, with little evidence of a neophobic response; however, environment, types of stimuli, and other parameters of the test can significantly affect monkeys' reactions.

Spatial choices of macaque monkeys based on the visual representation of the response space: rotation of the stimuli.

In earlier experiments we have demonstrated that macaque monkeys (Macaca mulatta) are able to use abstract visual stimuli presented on a computer screen to make spatial choices in the real environment. In those experiments a touch board ("response space") was directly connected to the computer screen ("virtual space"). The goal of the present experiment was to find out whether macaque monkeys are able: (1) To make spatial choices in a response space which is completely separated from the screen where the stimuli (designed as representation of the response space) are presented. (2) To make spatial choices based on visual stimuli representing the configuration of the response space which are rotated with respect to this response space. The monkeys were trained to choose one of the nine "touch holes" on a transparent touch panel situated beside a computer monitor on which the visual stimuli were presented. The visual stimuli were designed as an abstract representation of the response space: the rewarded position was shown as a bright circle situated at a certain position in the rectangle representing the contours of the touch panel. At first, the monkeys were trained with non-rotated spatial stimuli. After this initial training, the visual stimuli were gradually rotated by 20 degrees in each step. In the last phase, the stimulus was suddenly rotated in the opposite direction by 60 degrees in one step. The results of the experiment suggest that the monkeys are able to use successfully abstract stimuli from one spatial frame for spatial choices in another frame. Effective use of the stimuli after their rotation suggested that the monkeys perceived the stimuli as a representation of the configuration of the touch holes in the real space, not only as different geometrical patterns without configuration information.

Could Prolonged Usage of GPS Navigation Implemented in Augmented Reality Smart Glasses Affect Hippocampal Functional Connectivity?

BACKGROUND: Augmented reality (AR) glasses with GPS navigation represent the rapidly evolving technology which spares (and externalizes) navigational capacities. Regarding the expected everyday usage of this device, its impact on neuroplastic brain changes and navigation abilities should be evaluated. AIMS: This study aimed to assess possible changes in functional connectivity (FC) of hippocampus and other brain regions involved in spatial navigation. METHODS: Thirty-three healthy participants completed two resting state functional magnetic resonance imaging (rsfMRI) measurements at the baseline and after 3 months. For this period, the experimental group (n = 17) has had used AR device (Vuzix M100) with incorporated GPS guidance system during navigation in real world. Participants from the control group (n = 16) have not used any GPS device while navigating during walking. The rsfMRI FC of right and left hippocampi was analyzed using a seed-driven approach. Virtual city task was used to test navigational abilities both before and after the usage of AR device. RESULTS: We identified strong functional coupling of right and left hippocampi at the baseline (p < 0.05, FDR corrected). Mild changes in bilateral hippocampal FC (p < 0.05, FDR uncorrected) were observed in both assessed groups mainly between the bilateral hippocampi and between each hippocampus and temporal regions and cerebellum. However, the experimental group showed FC decrease after three months of using GPS navigation implemented in AR glasses in contrast to FC increase in the control group without such intervention. Importantly, no effect of intervention on navigational abilities was observed. DISCUSSION: Our observation supports the assumption that externalization of spatial navigation to technological device (GPS in AR glasses) can decrease the functional coupling between hippocampus and associated brain regions. Considering some limitations of the present study, further studies should elucidate the mechanism of the observed changes and their impact on cognitive abilities.

Scopolamine disrupts place navigation in rats and humans: a translational validation of the Hidden Goal Task in the Morris water maze and a real maze for humans.

RATIONALE: Development of new drugs for treatment of Alzheimer's disease (AD) requires valid paradigms for testing their efficacy and sensitive tests validated in translational research. OBJECTIVES: We present validation of a place-navigation task, a Hidden Goal Task (HGT) based on the Morris water maze (MWM), in comparable animal and human protocols. METHODS: We used scopolamine to model cognitive dysfunction similar to that seen in AD and donepezil, a symptomatic medication for AD, to assess its potential reversible effect on this scopolamine-induced cognitive dysfunction. We tested the effects of scopolamine and the combination of scopolamine and donepezil on place navigation and compared their effects in human and rat versions of the HGT. Place navigation testing consisted of 4 sessions of HGT performed at baseline, 2, 4, and 8 h after dosing in humans or 1, 2.5, and 5 h in rats. RESULTS: Scopolamine worsened performance in both animals and humans. In the animal experiment, co-administration of donepezil alleviated the negative effect of scopolamine. In the human experiment, subjects co-administered with scopolamine and donepezil performed similarly to subjects on placebo and scopolamine, indicating a partial ameliorative effect of donepezil. CONCLUSIONS: In the task based on the MWM, scopolamine impaired place navigation, while co-administration of donepezil alleviated this effect in comparable animal and human protocols. Using scopolamine and donepezil to challenge place navigation testing can be studied concurrently in animals and humans and may be a valid and reliable model for translational research, as well as for preclinical and clinical phases of drug trials.

Spatial choices of macaque monkeys based on abstract visual stimuli.

Our study investigates whether macaque monkeys (Macaca mulatta) are able to make spatial choices in a real space according to abstract visual stimuli presented on a computer screen. We tested whether there was a difference in the processing of stimuli reflecting the configuration of a response space ("spatial stimuli") and stimuli of simple geometrical patterns lacking implicit spatial information. We trained two monkeys to choose one of nine touch-holes on a transparent panel attached to a computer monitor according to one of four visual stimuli successively displayed on the screen. The first monkey followed the visual stimuli designed as a representation of the response space ("configurations"), the second monkey observed geometrical patterns or pictures without information about the response space. In the first phase the position or the size of the stimuli varied but the shapes remained the same. In the second phase we changed the stimuli - "configurations" represented the response space in a similar way as in the previous phase, but marked different touch-holes - the patterns were changed entirely. The comparison of these two monkeys using different stimuli was expected to reveal potential differences between pattern discrimination and using configuration information included in the stimuli. The results of this experiment showed that both monkeys were able to use visual stimuli in phase 1 effectively (independently on their position on the screen), but only the monkey that obtained configuration information learnt an effective strategy after the change of stimuli in phase 2.

Spatial choices of rats based on abstract visual information: Pattern- or configuration-discrimination?

Animals demonstrate their ability to represent a geometric configuration of their environment and to use this information for spatial decisions in their response space in many situations. In presented experiment, we examined the ability of rats to interpret a configuration of abstract visual stimuli to make spatial decisions in a real response space. We tested whether they are able to interpret spatial configuration of abstract stimuli or whether they perceive such visual stimuli simply as geometric patterns associated to particular spatial choices. The rats were tested in a Skinner box with four nosing holes in the transparent front wall through which a computer screen was visible. According to the visual stimuli on the screen, the rats should choose the appropriate nosing hole to obtain a reward. We compared two groups of rats: the first group was exposed to the visual stimuli designed as a representation of the response space: the position of rewarded nosing hole was shown in relation to other nosing holes. The second group was exposed to one of four geometric patterns associated to one of the four nosing holes but without any implicit information about the response space. The results suggested that rats using the stimuli with information about configuration were significantly more successful than rats trained to respond to visual stimuli unrelated to the geometry of the environment.

Spatial decisions in rats based on the geometry of computer-generated patterns.

Animals often demonstrate the ability to use the geometric configuration of multiple landmarks for orientation in the environment. We developed a new behavioral task using a computer screen for presentation of visual stimuli allowing the rats to make navigational decisions in real space according to the geometric configuration of external virtual patterns (designed as a possible representation of this space). The rats were placed in a Skinner box with four nosing holes in the transparent front wall through which the computer screen was visible. They were trained in successive phases: first the visual stimulus displayed on the screen directly marked the rewarded nosing hole, then the displayed stimuli were reduced in size or displaced, thus disconnected from the response space. The results suggested that rats were able to use the geometric configuration of stimuli presented on the computer screen for navigational decisions in real space.

MK-801 and memantine act differently on short-term memory tested with different time-intervals in the Morris water maze test.

N-methyl-d-aspartate receptors (NMDARs) play a crucial role in spatial memory formation. In neuropharmacological studies their functioning strongly depends on testing conditions and the dosage of NMDAR antagonists. The aim of this study was to assess the immediate effects of NMDAR block by (+)MK-801 or memantine on short-term allothetic memory. Memory was tested in a working memory version of the Morris water maze test. In our version of the test, rats underwent one day of training with 8 trials, and then three experimental days when rats were injected intraperitoneally with low- 5 (MeL), high - 20 (MeH) mg/kg memantine, 0.1mg/kg MK-801 or 1ml/kg saline (SAL) 30min before testing, for three consecutive days. On each experimental day there was just one acquisition and one test trial, with an inter-trial interval of 5 or 15min. During training the hidden platform was relocated after each trial and during the experiment after each day. The follow-up effect was assessed on day 9. Intact rats improved their spatial memory across the one training day. With a 5min interval MeH rats had longer latency then all rats during retrieval. With a 15min interval the MeH rats presented worse working memory measured as retrieval minus acquisition trial for path than SAL and MeL and for latency than MeL rats. MK-801 rats had longer latency than SAL during retrieval. Thus, the high dose of memantine, contrary to low dose of MK-801 disrupts short-term memory independent on the time interval between acquisition and retrieval. This shows that short-term memory tested in a working memory version of water maze is sensitive to several parameters: i.e., NMDA receptor antagonist type, dosage and the time interval between learning and testing.