The human ability to perceive vivid memories as if they "float" before our eyes, even in the absence of actual visual stimuli, captivates the imagination. To determine the neural substrates underlying visual memories, we investigated the neuronal representation of working memory content in the primary visual cortex of monkeys. Our study revealed that neurons exhibit unique responses to different memory contents, using firing patterns distinct from those observed during the perception of external visual stimuli. Moreover, this neuronal representation evolves with alterations in the recalled content and extends beyond the retinotopic areas typically reserved for processing external visual input. These discoveries shed light on the visual encoding of memories and indicate avenues for understanding the remarkable power of the mind's eye.
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http://dx.doi.org/10.1126/sciadv.adk3953 | DOI Listing |
Int J Mol Sci
January 2025
Botulinum Research Center, Institute of Advanced Sciences, Dartmouth, MA 02747, USA.
Botulinum toxin (BoNT), the most potent substance known to humans, likely evolved not to kill but to serve other biological purposes. While its use in cosmetic applications is well known, its medical utility has become increasingly significant due to the intricacies of its structure and function. The toxin's structural complexity enables it to target specific cellular processes with remarkable precision, making it an invaluable tool in both basic and applied biomedical research.
View Article and Find Full Text PDFElife
January 2025
National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India.
Co-active or temporally ordered neural ensembles are a signature of salient sensory, motor, and cognitive events. Local convergence of such patterned activity as synaptic clusters on dendrites could help single neurons harness the potential of dendritic nonlinearities to decode neural activity patterns. We combined theory and simulations to assess the likelihood of whether projections from neural ensembles could converge onto synaptic clusters even in networks with random connectivity.
View Article and Find Full Text PDFSci Adv
January 2025
Lee Kong Chian School of Medicine, Nanyang Technological University, 11 Mandalay Road, Singapore 308232, Singapore.
Reward prediction errors (RPEs) quantify the difference between expected and actual rewards, serving to refine future actions. Although reinforcement learning (RL) provides ample theoretical evidence suggesting that the long-term accumulation of these error signals improves learning efficiency, it remains unclear whether the brain uses similar mechanisms. To explore this, we constructed RL-based theoretical models and used multiregional two-photon calcium imaging in the mouse dorsal cortex.
View Article and Find Full Text PDFJ Comput Neurosci
January 2025
Program in Neuroscience, Indiana University Bloomington, Bloomington, IN, USA.
Hippocampal representations of space and time seem to share a common coding scheme characterized by neurons with bell-shaped tuning curves called place and time cells. The properties of the tuning curves are consistent with Weber's law, such that, in the absence of visual inputs, width scales with the peak time for time cells and with distance for place cells. Building on earlier computational work, we examined how neurons with such properties can emerge through self-supervised learning.
View Article and Find Full Text PDFJ Neurosci
January 2025
Oregon Hearing Research Center, Oregon Health and Science University, Portland, OR 97239, USA
In everyday hearing, listeners face the challenge of understanding behaviorally relevant foreground stimuli (speech, vocalizations) in complex backgrounds (environmental, mechanical noise). Prior studies have shown that high-order areas of human auditory cortex (AC) pre-attentively form an enhanced representation of foreground stimuli in the presence of background noise. This enhancement requires identifying and grouping the features that comprise the background so they can be removed from the foreground representation.
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