Incidental temporal binding in rats: A novel behavioral task.

We designed a behavioral task called One-Trial Trace Escape Reaction (OTTER), in which rats incidentally associate two temporally discontinuous stimuli: a neutral acoustic cue (CS) with an aversive stimulus (US) which occurs two seconds later (CS-2s-US sequence). Rats are first habituated to two similar environmental contexts (A and B), each consisting of an interconnected dark and light chamber. Next, rats experience the CS-2s-US sequence in the dark chamber of one of the contexts (either A or B); the US is terminated immediately after a rat escapes into the light chamber. The CS-2s-US sequence is presented only once to ensure the incidental acquisition of the association. The recall is tested 24 h later when rats are presented with only the CS in the alternate context (B or A), and their behavioral response is observed. Our results show that 59% of the rats responded to the CS by escaping to the light chamber, although they experienced only one CS-2s-US pairing. The OTTER task offers a flexible high throughput tool to study memory acquired incidentally after a single experience. Incidental one-trial acquisition of association between temporally discontinuous events may be one of the essential components of episodic memory formation.

Cognitive Remediation in Virtual Environments for Patients with Schizophrenia and Major Depressive Disorder: A Feasibility Study.

Standard approaches to cognitive remediation can suffer from limited skill transferability to patients' life. Complex virtual environments (VEs) enable us to create ecologically valid remediation scenarios while preserving laboratory conditions. Nevertheless, the feasibility and efficacy of these programs in psychiatric patients are still unknown. Our aim was to compare the feasibility and efficacy of a novel rehabilitation program, designed in complex VEs, with standard paper-pencil treatment in patients with schizophrenia and major depressive disorder. We recruited 35 participants to complete a VE rehabilitation program and standard treatment in a crossover pilot study. Twenty-eight participants completed at least one program, 22 were diagnosed with schizophrenia and 6 with major depressive disorder. Participant's performance in the representative VE training task significantly improved in terms of maximum achieved difficulty (p ≤ 0.001), speed (p < 0.001) and efficacy (p ≤ 0.001) but not in item performance measure. Neither the standard treatment nor the VE program led to improvement in standardized cognitive measures. Participants perceived both programs as enjoyable and beneficial. The refusal rate was higher in the VE program (8.6%) than in the standard treatment (0%). But in general, the VE program was well-accepted by the psychiatric patients and it required minimal involvement of the clinician due to automatic difficulty level adjustment and performance recording. However, the VE program did not prove to be effective in improving cognitive performance in the standardized measures.

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.

Path integration in large-scale space and with novel geometries: Comparing vector addition and encoding-error models.

Path integration is thought to rely on vestibular and proprioceptive cues yet most studies in humans involve primarily visual input, providing limited insight into their respective contributions. We developed a paradigm involving walking in an omnidirectional treadmill in which participants were guided on two sides of a triangle and then found their back way to origin. In Experiment 1, we tested a range of different triangle types while keeping the distance of the unguided side constant to determine the influence of spatial geometry. Participants overshot the angle they needed to turn and undershot the distance they needed to walk, with no consistent effect of triangle type. In Experiment 2, we manipulated distance while keeping angle constant to determine how path integration operated over both shorter and longer distances. Participants underestimated the distance they needed to walk to the origin, with error increasing as a function of the walked distance. To attempt to account for our findings, we developed configural-based computational models involving vector addition, the second of which included terms for the influence of past trials on the current one. We compared against a previously developed configural model of human path integration, the Encoding-Error model. We found that the vector addition models captured the tendency of participants to under-encode guided sides of the triangles and an influence of past trials on current trials. Together, our findings expand our understanding of body-based contributions to human path integration, further suggesting the value of vector addition models in understanding these important components of human navigation.

How Much of What We Learn in Virtual Reality Transfers to Real-World Navigation?

Past studies suggest that learning a spatial environment by navigating on a desktop computer can lead to significant acquisition of spatial knowledge, although typically less than navigating in the real world. Exactly how this might differ when learning in immersive virtual interfaces that offer a rich set of multisensory cues remains to be fully explored. In this study, participants learned a campus building environment by navigating (1) the real-world version, (2) an immersive version involving an omnidirectional treadmill and head-mounted display, or (3) a version navigated on a desktop computer with a mouse and a keyboard. Participants first navigated the building in one of the three different interfaces and, afterward, navigated the real-world building to assess information transfer. To determine how well they learned the spatial layout, we measured path length, visitation errors, and pointing errors. Both virtual conditions resulted in significant learning and transfer to the real world, suggesting their efficacy in mimicking some aspects of real-world navigation. Overall, real-world navigation outperformed both immersive and desktop navigation, effects particularly pronounced early in learning. This was also suggested in a second experiment involving transfer from the real world to immersive virtual reality (VR). Analysis of effect sizes of going from virtual conditions to the real world suggested a slight advantage for immersive VR compared to desktop in terms of transfer, although at the cost of increased likelihood of dropout. Our findings suggest that virtual navigation results in significant learning, regardless of the interface, with immersive VR providing some advantage when transferring to the real world.

Virtual microscope interface to high resolution histological images.

The Hypertext Atlas of Dermatopathology, the Atlas of Fetal and Neonatal Pathology and Hypertext Atlas of Pathology (this one in Czech only) are available at http://www.muni.cz/atlases. These atlases offer many clinical, macroscopic and microscopic images, together with short introductory texts. Most of the images are annotated and arrows pointing to the important parts of the image can be activated.The Virtual Microscope interface is used for the access to the histological images obtained in high resolution using automated microscope and image stitching, possibly in more focusing planes. Parts of the image prepared in advance are downloaded on demand to save the memory of the user's computer. The virtual microscope is programmed in JavaScript only, works in Firefox/Mozilla and MSIE browsers without need to install any additional software.