Biology subjects

Li, C. T.

Publications and source records attributed to Li, C. T..

9 recordsLinked to original sources

bioRxiv2026

Hierarchy in neuronal representations of multiple tasks in prefrontal cortex

The ability to perform multiple tasks is one of the fundamental hallmarks of general intelligence in the brain. However, the underlying neural mechanisms remain largely unknown. We trained macaque monkeys to perform four tasks with identical spatial layouts but different cognitive demands, and recorded activities of thousands of prefrontal neurons using two-photon calcium imaging. Within the same neuronal population, we identified a multitask neural geometry composed of multiple low-dimensional subtask spaces, each encoding spatial information within a specific subtask. These subtask spaces shared a ring-like representational structure, forming a generalized spatial code across different subtasks. Task separation arose from separable bases and offsets of subtask spaces, modulated primarily by meta-task features. Thus, the neural geometry is organized by a three-level hierarchical structure: location codes are nested within subtask spaces, which are grouped as different meta-tasks. This hierarchy supported generalization across both locations and tasks, and explained monkeys error behaviors. Together, the hierarchically organized neural geometry underlies flexible multitask behavior.

neuroscience↗

bioRxiv2025

MindSight: A Bio-Inspired Neural Architecture for Visual Restoration via Cortical Electrical Stimulation

Visual impairment is a common condition worldwide, and cortical electrical stimulation is one of the approaches to aid in visual restoration. However, existing methods suffer from limited precision, flexibility, and generalization in generating the desired visual perception. In this paper, we propose a novel deep learning-based algorithm for cortical electrical stimulation, named "MindSight," aimed at enhancing the clarity and accuracy of induced visual perceptions. Our framework introduces three key innovations: (1) A differentiable biophysical model simulating cortical state transitions under electrical stimulation, enabling end-to-end training; (2) A dual-path training architecture combining neural decoding fidelity with phosphene simulation constraints; (3) An attention-guided background gated network for input filtration and, a multi-channel activation constraint to ensure the effectiveness of electrical stimulation. We validated our approach through novel experiments with macaque monkeys, demonstrating superior performance in visual perception tasks. These results highlight the potential of our approach in assisting individuals with visual impairments. Codehttps://github.com/zyj9902/MindSight

bioengineering↗

bioRxiv2025

Meta-AlignNN: A meta-learning framework for stable brain-computer interface performance across subjects, time, and tasks

Practical application of brain-computer interfaces (BCIs) requires stable mapping between neuronal activity and behavior through various behavioral contexts and for different individuals. Due to neural activity instability, BCIs require frequent recalibration to maintain robust performance. Early approaches to addressing BCI stability issues mainly focused on tackling the challenge of neural activity changes over time. However, future BCI applications involve diversified scenarios and subjects, requiring solutions that address neural variability across time, subjects, and tasks. This study proposes a meta-learning-based algorithm to achieve BCI stability, named "Meta-AlignNN." By capitalizing on the consistency of neural population dynamics, it provides a unified solution for maintaining BCI stability, robustness, and scalability across subjects, time, and tasks. Tested over two years on four tasks with three monkeys, as well as on public datasets, the approach has achieved significantly excellent performance in both offline decoding and real-time brain-control, outperforming existing methods. Our findings provides a foundation for meeting the clinical demands of longterm, efficient, and stable usability across patients and tasks, offering a compelling solution for practical BCI applications.

bioengineering↗

bioRxiv2023

Hierarchical replay of multi-regional sequential spiking associated with working memory

How does millisecond-scale neural activity mediate behaviors over seconds? We recorded brain-wide activity in mice performing an olfactory working-memory task to decipher cross-region organization of activity. Spike-correlograms revealed millisecond within- and cross-region spike couplings, more prominent among neurons encoding similar memories. Spike coupling linked neurons into motifs of chains, single loops, and nested loops, especially among hippocampal and prefrontal-cortex neurons. Direction of spike coupling and activity chains was in line with that of memory-associated activity waves. Intriguingly, activity motifs were replayed before and after task performance, and during inter-trial intervals. Motifs were hierarchically organized, with progressively increasing time constants and the number of participating neurons. Thus, hierarchically organized and replayed cross-region spiking motifs are modulated on demand during delay period to mediate perceptual working memory. One Sentence SummaryNested activity motifs of chains, single loops, and nested loops, with progressively increasing time constants and number of participating neurons, are hierarchically organized and replayed to mediate perceptual working-memory maintenance.

neuroscience↗

bioRxiv2023

Timing-dependent modulation of working memory by VTA dopamine release in medial prefrontal cortex

Dopamine significantly modulates working memory (WM)1-8, a fundamental cognitive function that maintains information during a brief delay period9-11. The temporal precision of dopaminergic modulation in WM and related neural mechanisms remain elusive. Here we unveiled the pivotal role of dopamine timing in WM performance with head-fixed mice engaged in learning an olfactory WM task. Through electrophysiology and optogenetics, we found that dopaminergic neurons in the ventral tegmental area (VTA) could encode WM information during the delay period, and manipulating dopaminergic neuronal activity bidirectionally modulated WM performance in an inverted U-shaped manner. Optogenetic manipulation of VTA activity also induced bidirectional changes in WM-related neural activity in the medial prefrontal cortex (mPFC). Imaging with a dopamine-sensitive GPCR-activation-based sensor (GRABDA)12,13 revealed transient dopamine peaks in the mPFC specifically during the early-delay period. Optogenetic stimulation of VTA-to-mPFC dopaminergic projections during the early- and late-delay period enhanced and impaired WM performance, respectively. Manipulations outside these periods or involving the nucleus accumbens had no effect. Single-unit recordings demonstrated that optogenetic excitation of VTA-to-mPFC projections could modulate mPFC neuronal activity in a manner consistent with behavioral modulation. Thus, the timing of dopamine release is critical in modulation of neuronal activity and behavior.

neuroscience↗

bioRxiv2023

Prefrontal projections modulate recurrent circuitry in insular cortex to support short-term memory

Short-term memory (STM) maintains information during a short delay period. How long-range and local connections interact to support STM encoding remains elusive. Here we tackled the problem focusing on long-range projections from medial prefrontal cortex (mPFC) to anterior agranular insular cortex (aAIC) in head-fixed mice performing an olfactory delayed-response task. Optogenetic and electrophysiological experiments revealed behavioral importance of the two regions in encoding STM information. Spike-correlogram analysis revealed strong local and cross-region functional coupling (FC) between memory neurons encoding the same information. Optogenetic suppression of mPFC-aAIC projections during the delay period reduced behavioral performance, the proportion of memory neurons and memory-specific FC within aAIC, whereas optogenetic excitation enhanced all of them. MPFC-to-aAIC projections also bidirectionally modulated efficacy of STM-information transfer, measured by contribution of FC spiking pairs to coding ability of following neurons. Thus, prefrontal projections modulate functional connectivity and coding ability of insular neurons to support short-term memory.

neuroscience↗

bioRxiv2021

Hypertonic saline and aprotinin based blockage of SARS-CoV-2 specific furin site cleavage by inhibition of nasal protease activity

SARS-CoV-2 enters into the human body mainly through the nasal epithelial cells. Cell entry of SARS-CoV-2 needs to be pre-activated by S1/S2 boundary furin motif cleavage by furin and/or relevant proteases. It is important to locally block SARS-CoV-2 S1/S2 site cleavage caused by furin and other relevant protease activity in the nasal cavity. We tested hypertonic saline and aprotinin-based blockage of SARS-CoV-2 specific furin site cleavage by furin, trypsin and nasal swab samples containing nasal proteases. Our results show that saline and aprotinin block SARS-Cov-2 specific furin site cleavage and that a saline and aprotinin combination could significantly reduce SARS-Cov-2 wild-type and P681R mutant furin site cleavage by inhibition of nasal protease activity.

pharmacology and toxicology↗

bioRxiv2021

High-throughput mapping of single-cell molecular and projection architecture of neurons by retrograde barcoded labelling

Deciphering patterns of connectivity between neurons in the brain is a critical step toward understanding brain function. Imaging-based neuroanatomical tracing identifies area-to-area or sparse neuron-to-neuron connectivity patterns, but with limited throughput. Barcode-based connectomics maps large numbers of single-neuron projections, but remains a challenge for jointly analyzing single-cell transcriptomics. Here, we established a rAAV2-retro barcode-based multiplexed tracing method that simultaneously characterizes the projectome and transcriptome at the single neuron level. We uncovered dedicated and collateral projection patterns of ventromedial prefrontal cortex (vmPFC) neurons to five downstream targets and found that projection-defined vmPFC neurons are molecularly heterogeneous. We identified transcriptional signatures of projection-specific vmPFC neurons, and verified Pou3f1 as a marker gene of neurons extending collateral branches to dorsomedial striatum and lateral hypothalamus. In summary, we have developed a new multiplexed technique whose paired connectome and gene expression data can help reveal organizational principles that form neural circuits and process information.

neuroscience↗

bioRxiv2019

Dynamic neuronal activation of a distributed cortico-basal ganglia-thalamus loop in learning a delayed sensorimotor task

The cortico-basal ganglia-thalamus (CBT) loop is important for behavior. However, the activity and learning-related modulation within the loop in behavior remain unclear. To tackle this problem, we trained mice to perform a delayed sensorimotor-transformation task and recorded single-unit activity during learning simultaneously from four regions in a CBT loop: prelimbic area (PrL), posterior premotor cortex (pM2), dorsomedial caudate/putamen (dmCP), and mediodorsal thalamus (MD). Sensory and decision related information were encoded by the neurons within the loop, with weak interaction among neurons of different coding ability. The functional interaction among regions within the loop was dynamically routed in the loop during different behavioral phases and contributed to explain decision-related neuronal activity. The neurons of PrL and dmCP exhibited learning-related reorganization in neuronal activity and more persistent coding of sensory and decision-related information. Thus, both sensory- and decision-related information are processed in a functionally interacted CBT loop that is modulated by learning.

neuroscience↗