Brain-robot interaction (BRI) empowers individuals to control (semi-)automated machines through brain activity, either passively or actively. In the past decade, BRI systems have advanced significantly, primarily leveraging electroencephalogram (EEG) signals. This article presents an up-to-date review of 87 curated studies published between 2018 and 2023, identifying the research landscape of EEG-based BRI systems. The review consolidates methodologies, interaction modes, application contexts, system evaluation, existing challenges, and future directions in this domain. Based on our analysis, we propose a BRI system model comprising three entities: Brain, Robot, and Interaction, depicting their internal relationships. We especially examine interaction modes between human brains and robots, an aspect not yet fully explored. Within this model, we scrutinize and classify current research, extract insights, highlight challenges, and offer recommendations for future studies. Our findings provide a structured design space for human-robot interaction (HRI), informing the development of more efficient BRI frameworks.

Human olfactory perception is understudied in the whole spectrum of neuroscience, from computational to system neuroscience. In this study, we explore the hierarchy underlying human olfactory perception by embedding perceptual data in the hyperbolic space. Previous research emphasizes the significance of hyperbolic geometry in gaining insights into the neural encoding of natural odorants. This is due to the exponential growth of the hyperbolic space, that makes it appropriate to encode hierarchical data. We employ a contrastive learning approach over the Poincare ball in order to embed olfactory perceptual data in a hyperbolic space. The results indicate the emergence of a hierarchical representation in the hyperbolic space, which could have implications for understanding the structure of the olfactory perceptual space in the brain. Our finding suggests that the human brain may encode olfactory perceptions in a hierarchical manner, where higher odor perceptual certainty correlates with deeper levels in the hierarchical representation.

The human brain encodes stimuli from the environment into representations that form a sensory perception of the world. Despite recent advances in understanding visual and auditory perception, olfactory perception remains an under-explored topic in the machine learning community due to the lack of large-scale datasets annotated with labels of human olfactory perception. In this work, we ask the question of whether pre-trained transformer models of chemical structures encode representations that are aligned with human olfactory perception, i.e., can transformers smell like humans? We demonstrate that representations encoded from transformers pre-trained on general chemical structures are highly aligned with human olfactory perception. We use multiple datasets and different types of perceptual representations to show that the representations encoded by transformer models are able to predict: (i) labels associated with odorants provided by experts; (ii) continuous ratings provided by human participants with respect to pre-defined descriptors; and (iii) similarity ratings between odorants provided by human participants. Finally, we evaluate the extent to which this alignment is associated with physicochemical features of odorants known to be relevant for olfactory decoding.

Capturing informative electroencephalogram (EEG) signals is a challenging task due to the presence of noise (e.g., due to human movement). In extreme cases, data recordings from specific electrodes (channels) can become corrupted and entirely devoid of information. Motivated by recent work on deep-learning-based approaches for EEG signal denoising, we present the first benchmark study on the performance of EEG signal denoising methods in the presence of corrupted channels. We design our study considering a wide variety of datasets, models, and evaluation tasks. Our results highlight the need for assessing the performance of EEG deep-learning models across a broad suite of datasets, as provided by our benchmark.

Most wearable robots such as exoskeletons and prostheses can operate with dexterity, while wearers do not perceive them as part of their bodies. In this perspective, we contend that integrating environmental, physiological, and physical information through multi-modal fusion, incorporating human-in-the-loop control, utilizing neuromuscular interface, employing flexible electronics, and acquiring and processing human-robot information with biomechatronic chips, should all be leveraged towards building the next generation of wearable robots. These technologies could improve the embodiment of wearable robots. With optimizations in mechanical structure and clinical training, the next generation of wearable robots should better facilitate human motor and sensory reconstruction and enhancement.

Retrieval of mental images from measured brain activity may facilitate communication, especially when verbal or muscular communication is impossible or inefficient. The existing work focuses mostly on retrieving the observed visual stimulus while our interest is on retrieving the imagined mental image. We present a closed-loop BCI framework to retrieve mental images of human faces. We utilize EEG signals as binary feedback to determine the relevance of an image to the target mental image. We employ the feedback to traverse the latent space of a generative model to propose new images closer to the actual target image. We evaluate the proposed framework on 13 volunteers. Unlike previous studies, we do not restrict the possible attributes of the resulting images to predefined semantic classes. Subjective and objective tests validate the ability of our model to retrieve face images similar to the actual target mental images.