Flexibility of functional neuronal assemblies supports human memory

Umbach, Gray; Tan, Ryan; Jacobs, Joshua; Pfeiffer, Brad E.; Lega, Bradley

doi:10.1038/s41467-022-33587-0

Cited by 14 publications

(11 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Neural coding is unlikely to be fully explained by pairwise interactions alone. Recent work in humans 27 suggested that groups of neurons that have significant co-firing tendencies can be categorized into cell assemblies whose expression is linked to episodic memory performance. We next evaluated whether integrated neural assemblies were detectable in our data and whether co-rippling across multiple electrodes facilitates their expression.…”

Section: Co-rippling Modulates the Expression Of Neuronal Assemblies ...mentioning

confidence: 99%

“…We next evaluated whether integrated neural assemblies were detectable in our data and whether co-rippling across multiple electrodes facilitates their expression. We detected cell assemblies during NREM and waking according to previously described methods 27,28 . We divided neural spike trains from NREM and waking into 100 ms bins (roughly the duration of a ripple event) and normalized the binned firing rates for each neuron across the recording session.…”

Section: Co-rippling Modulates the Expression Of Neuronal Assemblies ...mentioning

confidence: 99%

See 1 more Smart Citation

Co-occurring ripple oscillations facilitate neuronal interactions between cortical locations in humans

Verzhbinsky,

Rubin,

Kajfez

et al. 2023

Preprint

View full text Add to dashboard Cite

Synchronous bursts of high frequency oscillations ("ripples") are hypothesized to contribute to binding by facilitating integration of neuronal firing across cortical locations. We tested this hypothesis using local field-potentials and single-unit firing from four 96-channel microelectrode arrays in supragranular cortex of 3 patients. Neurons in co-rippling locations showed increased short-latency co-firing, prediction of each-other's firing, and co-participation in neural assemblies. Effects were similar for putative pyramidal and interneurons, during NREM sleep and waking, in temporal and Rolandic cortices, and at distances up to 16mm. Increased co-prediction during co-ripples was maintained when firing-rate changes were equated, and were strongly modulated by ripple phase. Co-ripple enhanced prediction is reciprocal, synergistic with local upstates, and enhanced when multiple sites co-ripple. Together, these results support the hypothesis that trans-cortical co-ripples increase the integration of neuronal firing of neurons in different cortical locations, and do so in part through phase-modulation.

show abstract

Section: Co-rippling Modulates the Expression Of Neuronal Assemblies ...mentioning

confidence: 99%

Section: Co-rippling Modulates the Expression Of Neuronal Assemblies ...mentioning

confidence: 99%

Co-occurring ripple oscillations facilitate neuronal interactions between cortical locations in humans

Verzhbinsky,

Rubin,

Kajfez

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…For example, neurons that share common input [46] or targets [47] are more likely to form recurrent connections amongst themselves. Additionally, there is strong evidence that groups of highly interconnected neurons (neuronal assemblies) share common functions within recurrent networks [31, 48, 49]. Moreover, evidence has accumulated [50, 51] that different neurons type (excitatory and inhibitory subtypes) follow distinct spatial connectivity patterns, which have implications for neural computation.…”

Section: Discussionmentioning

confidence: 99%

Structural influences on synaptic plasticity: the role of presynaptic connectivity in the emergence of E/I co-tuning

Giannakakis

Vinogradov

Buendía

et al. 2023

Preprint

View full text Add to dashboard Cite

Experimental studies have shown that in cortical neurons, excitatory and inhibitory incoming currents are strongly correlated, which is hypothesized to be essential for efficient computations. Additionally, cortical neurons exhibit strong preference to particular stimuli, which combined with the co-variability of excitatory and inhibitory inputs indicates a detailed co-tuning of the corresponding populations. Such co-tuning is hypothesized to emerge during development in a self-organized manner. Indeed, theoretical studies have demonstrated that a combination of plasticity rules could lead to the emergence of E/I co-tuning in neurons driven by low noise signals from feedforward connections. However, cortical signals are very noisy and originate in highly recurrent networks, which raises a question on the ability of known plasticity mechanisms to self-organize co-tuned connectivity. We demonstrate that high noise levels combined with random recurrence destroy co-tuning. However, we demonstrate that introducing structure in the connectivity patterns of the recurrent E/ I network, the recurrence does not hinder but enhances the formation of the co-tuned selectivity. We employ a combination of analytical methods and simulation-based inference to uncover constraints on the recurrent connectivity that allow E/I co-tuning to emerge. We find that stronger excitatory connectivity within similarly tuned neurons, combined with more homogeneous inhibitory connectivity enhances the ability of plasticity to produce co-tuning in an upstream population. Our results suggest that structured recurrent connectivity controls information propagation and can enhance the ability of synaptic plasticity to learn input-output relationships in higher brain areas.

show abstract

“…Previous investigations found drift in the lateral temporal context contributed to successful recall of related items ( El-Kalliny et al, 2019 ). Gamma oscillations also coordinate contextually relevant neuronal assemblies ( Umbach et al, 2022 ). Our results build on this finding by characterizing drift in gamma oscillations and further describing how gamma activity is associated with context.…”

Section: Discussionmentioning

confidence: 99%

Episodic boundaries affect neural features of representational drift in humans

Kulkarni,

Lega

2023

Preprint

Self Cite

View full text Add to dashboard Cite

A core feature of episodic memory is representational drift, the gradual change in aggregate oscillatory features that supports temporal association of memory items. However, models of drift overlook the role of episodic boundaries, which indicate a shift from prior to current context states. Our study focuses on the impact of task boundaries on representational drift in the parietal and temporal lobes in 99 subjects during a free recall task. Using intracranial EEG recordings, we show boundary representations reset gamma band drift in the medial parietal lobe, selectively enhancing the recall of early list (primacy) items. Conversely, the lateral temporal cortex shows increased drift for recalled items but lacked sensitivity to task boundaries. Our results suggest regional sensitivity to varied contextual features: the lateral temporal cortex uses drift to differentiate items, while the medial parietal lobe uses drift-resets to associate items with the current context. We propose drift represents relational information tailored to a region’s sensitivity to unique contextual elements. Our findings offer a mechanism to integrate models of temporal association by drift with event segmentation by episodic boundaries.

show abstract

Flexibility of functional neuronal assemblies supports human memory

Cited by 14 publications

References 43 publications

Co-occurring ripple oscillations facilitate neuronal interactions between cortical locations in humans

Co-occurring ripple oscillations facilitate neuronal interactions between cortical locations in humans

Structural influences on synaptic plasticity: the role of presynaptic connectivity in the emergence of E/I co-tuning

Episodic boundaries affect neural features of representational drift in humans

Contact Info

Product

Resources

About