Evidence of Top-Down Sensory Prediction in Neonates Within 2 Days of Birth Recent studies have demonstrated top-down modulation in perceptual cortices in infants as young as 6 months. However, it is unclear when and how this ability emerges given conflicting evidence available. This study investigates top-down perceptual modulation by focusing on a neural signature referred to as top-down sensory prediction, where the prediction of upcoming sensory information is exhibited in the modulation of activity in perceptual cortices. We extended a paradigm previously used to identify top-down sensory prediction in 6-month-old infants to neonates. Using functional near-infrared spectroscopy (fNIRS), we monitored occipital lobe activity in sleeping neonates held by their caregivers. The study consisted of a Learning session, where neonates were exposed to a novel auditory-visual stimulus combination (A+V+), followed by sessions presenting occasional visual stimulus omissions (A+V−). Results showed that fNIRS channels over the occipital lobe, which were active during the Learning session, also responded to the unexpected visual omissions, indicating neonatal brains’ capability for top-down sensory prediction. Experiment 2 confirmed that this response depended on learning the audiovisual association, ruling out non-specific mechanisms such as heightened arousal or an increase in the visual response when a non-specific auditory stimulus is presented. These findings offer the first evidence of top-down modulation of visual responses in neonates, suggesting this capacity exists at birth, significantly earlier than previously thought. This study suggests that top-down predictive processing is crucial for early perceptual and cognitive development.
The possibilities of conscious experience in light of the dual origin hypothesis of the neocortex According to contemporary psycho- and physiological perspectives, the brain supports our experience of the world by constantly anticipating what may happen next. In this context, limbic mesocortical areas have been proposed to play a key domain-general role in cortical processing, holding highly abstract content that may be efficiently broadcasted to virtually the whole brain, ultimately integrating interoception into a unified field of experience from the point of view of someone who has a body. Here we ground the evolutionary basis of such structural and functional organization in the hypothesis of the dual origin of the neocortex, suggesting that the addition of phylogenetically newer cortical types with modality-specific processing may have enabled the primitive polysensory role of limbic mesocortical areas to evolve into a multimodal coordinator within an ever more complex brain, favoring the possibilities of conscious experience. Moreover, two fundamental functional axes with relevance for allostasis emerge: (i) a navigation/spatial versus exchange/contact axis; and (ii) a sensing versus acting axis. The former summarizes a fundamental distinction between spatial navigation and musculoskeletal control versus close interactions in the intimate and internal spheres; the latter reflects a functional (although intimately linked) distinction between sensory and motor aspects. These axes define a conceptual bidimensional space across cortical types where virtually all cortical areas may be placed according to their functional relevance, with limbic mesocortices ultimately integrating experience across sensory-motor function and navigation-exchange. These notions have important implications for our understanding of allostasis and human experience.
Three propositions about conscious experience and their implications for theories of consciousness The aim of this paper is to make and defend three simple propositions about what can and cannot be conscious in the human brain and to elucidate their implications for research and theory on consciousness. The first proposition is that the fact that some information is conscious should be, but often is not, distinguished from the information itself. The second proposition is that, treating the brain as an information processing system, information can be conscious (or not) but processes that operate on information cannot be conscious. This is illustrated with analysis of voluntary action generation, such as making a verbal report. The third proposition is that access consciousness is just access. Adding the word “consciousness” to it makes no difference to how it operates. An information processing system exactly like the human brain but in which no information was conscious would function in exactly the same way as human brains in which some information is conscious. Conscious experience must be explained by means of a generative mechanism; no such mechanism has yet been proposed.
Effects of Novelty and Temporal Distance on Postexperience Spike Patterns of Hippocampal Place Cells Encoding Multiple Environments The hippocampus plays a crucial role in consolidating episodic memories from diverse experiences that encompass spatial, temporal, and novel information. This study analyzed the spike patterns of hippocampal place cells in the CA3 and CA1 areas of male rats that sequentially foraged in five rooms, including familiar and novel rooms, followed by a rest period. Across the five rooms, both CA3 and CA1 place cells showed overlapping spatial representations. In a postexperience rest period, both CA3 and CA1 place cells increased baseline spike rates depending on the temporal distance from when the cells had place fields. In addition, CA3 place cells that encoded novel environments showed stronger sharp-wave ripple (SWR) reactivation. Coordinated reactivation of CA1 place cell ensembles that encoded temporally distant environments was eliminated. These results suggest that, following sequential experiences in multiple environments, increases in SWR-induced spikes of hippocampal neurons more specifically process novelty-related aspects of memory, while global increases in baseline spike rates process temporal distance-related aspects.
Predicting human decision-making across task conditions via individuality transfer Predicting an individual’s behavior in one task condition based on their behavior in a different condition is a key challenge in modeling individual decision-making tendencies. We propose a novel framework that addresses this challenge by leveraging neural networks and introducing a concept we term the ‘individual latent representation’. This representation, extracted from behavior in a ‘source’ task condition via an encoder network, captures an individual’s unique decision-making tendencies. A decoder network then utilizes this representation to generate the weights of a task-specific neural network (a ‘task solver’), which predicts the individual’s behavior in a ‘target’ task condition. We demonstrate the effectiveness of our approach in two distinct decision-making tasks: a value-guided task and a perceptual task. Our framework offers a robust and generalizable approach for parameterizing individual variability, providing a promising pathway toward computational modeling at the individual level—replicating individuals in silico.
Distinct contributions of hippocampal pathways in learning regularities and exceptions revealed by functional footprints Fundamental aspects of learning are theorized to be supported by hippocampal pathways: The monosynaptic pathway (MSP) extracts regularities, whereas the trisynaptic pathway (TSP) rapidly encodes exceptional items. Yet, the empirical evidence for the dynamic involvement of MSP and TSP in learning remains unresolved. We leveraged diffusion-weighted imaging to estimate the endpoints of MSP- and TSP-related white matter structures (i.e., footprints) within hippocampal subfields and the entorhinal cortex. We then measured the activation of pathway-specific footprints with functional MRI while participants learned novel concepts defined by regularities and exceptions. The functional footprint method revealed links between MSP-related footprint activation and regularity encoding early in learning and TSP-related footprint activation and exception encoding late in learning. These findings provide empirical evidence that learning concept regularities and exceptions is preferentially supported by hippocampal pathways. The pathway footprint approach provides insights into the functional dynamics of the human hippocampus, translating theoretical and computational work into empirically testable questions in humans.
Does the Experience of Remembering Differentially Influence the Factual Accuracy of Recognition, and Confidence in Its Accuracy? Remembering is typically viewed as unreliable and prone to errors, whereas highly confident recognition memory is often believed to be highly reliable and associated with high recognition accuracy. We evaluated these beliefs using memory for photographs of natural scenes in two studies: recognition memory to examine picture similarity effects in a 2-alternative forced-choice measure, and source memory to examine picture-location associations with a continuous retrieval accuracy measure. Additionally, we assessed the experience of remembering and its influence on judgments of confidence and memory accuracy. High confidence remembering was associated with high accuracy when perceptually or mnemonically similar lures were presented in the item recognition task. However, an association between high confidence and high accuracy was also seen in the absence of remembering for mnemonically similar lures. The confidence-accuracy inversion in the picture similarity task is speculated due to confidently (mis)remembering a similar picture stored in memory. Based on analyses of participant and trial level data, in both studies memory quality was strongly associated with confidence. Importantly, remembering moderated the association between recognition accuracy and confidence judgments, differentially influencing confidence more than it influenced accuracy. Memory quality moderated the association between source accuracy and confidence, the relationship being stronger for images remembered vividly. Our findings have implications for accounts of vividness, confidence, episodic memory, and eyewitness testimony. High confidence recognition may not in all cases reliably imply high accuracy. Highly vivid memories, confidently recollected, may not always be factually accurate.
Brain metabolomics in an insect pollinator: impacts of CO2 and cold-induced anaesthesia alone and in combination with neonicotinoid exposure Characterizing the effect of pesticides on pollinators is essential in the strive to protect biodiversity while maintaining efficient food production. Metabolomics offers detailed insight into the physiological response to pesticides. The impact of pre-dissection and dissection methodology on the metabolic response remains largely unknown, as does their possible effect on the measured metabolic response to pesticide exposure. Three different pre-dissection treatments were evaluated in Eristalis tenax: carbon dioxide, ice or no anaesthesia. Brain dissections were conducted at room temperature or on ice. Flies were also orally exposed to a high dose of the neonicotinoid insecticide acetamiprid (4 μg per fly) in sucrose or sucrose alone. Brains were homogenized, and metabolites extracted and analysed by gas chromatography/mass spectrometry. Pre-dissection and dissection conditions affected metabolites linked to oxidative stress, energy production and cold response. Acetamiprid exposure elicited consistent metabolic responses across all immobilization methods, including significant alterations in glutamate metabolism. Alterations in brain metabolism in response to acetamiprid were largely conserved across various pre-dissection methods, allowing for flexibility in methodology to address experimental constraints. Whether the subtle differences observed would compromise studies of lower doses of acetamiprid or other pesticides requires further validation.