Multiplexed Subspaces Route Neural Activity Across Brain-wide Networks

MacDowell, Camden J.; Libby, Alexandra; Jahn, Caroline I.; Tafazoli, Sina; Buschman, Timothy J.

doi:10.1101/2023.02.08.527772

Cited by 5 publications

(5 citation statements)

References 58 publications

(121 reference statements)

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“…Additionally, we measured the three properties of hierarchy in all brain regions, yet a smaller subset of latent features or brain regions likely mediates directed connectivity (Cai et al, 2021; Taghia et al, 2018; Vidaurre et al, 2018). While we averaged across the top 5% of values in each data epoch to compute the hierarchical properties, we would ideally apply a more principled method for reducing dimensionality and noise, such as reduced rank regression (MacDowell et al, 2023).…”

Section: Discussionmentioning

confidence: 99%

LSD flattens the hierarchy of directed information flow in fast whole-brain dynamics

Shinozuka,

Tewarie,

Luppi

et al. 2024

Preprint

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Psychedelics are serotonergic drugs that profoundly alter consciousness, yet their neural mechanisms are not fully understood. A popular theory, RElaxed Beliefs Under pSychedelics (REBUS), posits that psychedelics flatten the hierarchy of information flow in the brain. Here, we investigate hierarchy based on the imbalance between sending and receiving brain signals, as determined by directed functional connectivity. We measure directed functional hierarchy in a magnetoencephalography (MEG) dataset of 16 healthy human participants who were administered a psychedelic dose (75 micrograms, intravenous) of lysergic acid diethylamide (LSD) under four different conditions. LSD diminishes the asymmetry of directed connectivity when averaged across time. Additionally, we demonstrate that machine learning classifiers distinguish between LSD and placebo more accurately when trained on one of our hierarchy metrics than when trained on traditional measures of functional connectivity. Taken together, these results indicate that LSD weakens the hierarchy of directed connectivity in the brain by increasing the balance between senders and receivers of neural signals.

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Section: Discussionmentioning

confidence: 99%

LSD flattens the hierarchy of directed information flow in fast whole-brain dynamics

Shinozuka,

Tewarie,

Luppi

et al. 2024

Preprint

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Section: Shared Representations Were Sequentially Engaged During a Taskmentioning

confidence: 99%

“…So far, our results suggest the representation of both sensory inputs and motor responses were shared across tasks. In this framework, performing a task requires selectively transforming representations from one subspace to another to support each task 18 . Consistent with this, there was a sequential representation of the stimulus color in the shared color subspace followed by the response in the shared motor subspace during the C1 task (Fig.…”

Section: Introductionmentioning

confidence: 99%

Building compositional tasks with shared neural subspaces

Tafazoli,

Bouchacourt,

Ardalan

et al. 2024

Preprint

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Cognition is remarkably flexible; we are able to rapidly learn and perform many different tasks. Theoretical modeling has shown artificial neural networks trained to perform multiple tasks will re-use representations and computational components across tasks. By composing tasks from these sub-components, an agent can flexibly switch between tasks and rapidly learn new tasks. Yet, whether such compositionality is found in the brain is unknown. Here, we show the same subspaces of neural activity represent task-relevant information across multiple tasks, with each task compositionally combining these subspaces in a task-specific manner. We trained monkeys to switch between three compositionally related tasks. Neural recordings found task-relevant information about stimulus features and motor actions were represented in subspaces of neural activity that were shared across tasks. When monkeys performed a task, neural representations in the relevant shared sensory subspace were transformed to the relevant shared motor subspace. Subspaces were flexibly engaged as monkeys discovered the task in effect; their internal belief about the current task predicted the strength of representations in task-relevant subspaces. In sum, our findings suggest that the brain can flexibly perform multiple tasks by compositionally combining task-relevant neural representations across tasks.

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“…To understand how brain areas communicate, we need to explain how the neuronal populations in each site interact to allow the transmission of behaviorally-relevant spiking patterns 9,10 . In the neocortex, different areas can interact through a communication subspace [11][12][13][14][15][16][17][18] , a specific region in the state-space (where each dimension corresponds to the activity of a single neuron) of a local population that enables communication. In simpler words, communication occurs through local co-activity patterns that maximize the correlation between two areas.…”

Section: Introductionmentioning

confidence: 99%

Communication subspace dynamics of the canonical olfactory pathway

González,

Torterolo,

Bolding

et al. 2024

Preprint

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Understanding how different brain areas communicate is crucial for elucidating the mechanisms underlying cognition. A possible way for neural populations to interact is through a communication subspace, a specific region in the state-space enabling the transmission of behaviorally-relevant spiking patterns. In the olfactory system, it remains unclear if different populations employ such a mechanism. Our study reveals that neuronal ensembles in the main olfactory pathway (olfactory bulb to olfactory cortex) interact through a communication subspace, which is driven by nasal respiration and allows feedforward and feedback transmission to occur segregated along the sniffing cycle. Moreover, our results demonstrate that subspace communication depends causally on the activity of both areas, is hindered during anesthesia, and transmits a low-dimensional representation of odor.

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Multiplexed Subspaces Route Neural Activity Across Brain-wide Networks

Cited by 5 publications

References 58 publications

LSD flattens the hierarchy of directed information flow in fast whole-brain dynamics

LSD flattens the hierarchy of directed information flow in fast whole-brain dynamics

Building compositional tasks with shared neural subspaces

Communication subspace dynamics of the canonical olfactory pathway

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