How does sequence learning reshape item representations? We found that the brain incorporates high-level successor representations even outside the sequence task. This process is supported by slow-wave sleep. Great work by Xianhui He and the team!
New preprint: How sleep ripples reactivate human neurons to support memory
We show that neurons tuned to later remembered memories are preferentially reactivated during sleep ripples, linking the replay of individual neurons to successful memory consolidation.
Sleep ripples drive single-neuron reactivation for human memory consolidation
https://www.biorxiv.org/content/10.64898/2026.03.27.714528v1.abstract
Rodent studies identified hippocampal ripples as a core mechanism of memory consolidation and neuronal replay, and human imaging revealed macroscopic patterns of offline reactivation. But the cellular basis of human memory consolidation remains unknown.
Using rare intracranial recordings, we simultaneously measured single-neuron activity and intracranial EEG during wakefulness and sleep, allowing us to identify ripples and ripple-locked neuronal firing in the human brain.
We found that human ripples robustly drive neuronal firing, with sleep ripples eliciting stronger activation than wake ripples.
How is this reactivation linked to behaviour? We constructed a memory task around neurons that responded to specific stimuli used during learning. This allowed us to compare ripple-triggered reactivation across neurons responding to remembered versus forgotten stimuli.
We discovered that neurons tuned to items that were later remembered fired more strongly during ripples than neurons coding for forgotten items. This memory-linked reactivation was selectively observed during sleep.
Preprint: Semantic Tuning of Single Neurons in the Human Medial Temporal Lobe
How do human neurons encode meaning? In this work, led by Katharina Karkowski, we recorded hundreds of human MTL neurons to study semantic coding in the human brain:
https://www.biorxiv.org/content/10.1101/2025.10.21.682935v1
The discovery of concept cells sparked debate about binary vs distributed coding. Here, we developed a closed-loop algorithm that adaptively presents images semantically related to response-eliciting stimuli to explore the semantic tuning of MTL neurons.
Neuronal tuning curves are core coding principles in neuroscience (e.g., in vision and audition). They can vary in width and steepness. Using semantic embeddings and standardised image sets (THINGS), we presented items at controlled semantic distances to map the local semantic vicinity.
Human MTL neurons exhibit semantic tuning, with graded responses that follow narrow and steep tuning curves (steepest in hippocampus). Neurons preferentially respond to semantically related stimuli, and their firing rates correlate with semantic similarity to preferred stimuli.
This example amygdala neuron responds to several food- and drink-related items but not to unrelated items (such as the bus).
New Paper on single-neuron representations of odours in the human brain published in Nature
Link to the paper:
https://www.nature.com/articles/s41467-023-38190-5
We recorded single-neuron activity in the human olfactory cortex and medial temporal lobe to study how neurons encode odor identity and valence, and contribute to odor identification and cross-modal integration.
Neurons in the piriform cortex, amygdala, hippocampus, and entorhinal cortex modulate their activity based on odors presented, and they respond stronger to actual odors than odorless controls. Population activity in these regions accurately predicts odor identity.
Repeated odor presentations reduce neuronal responses, showing repetition suppression and habituation. Notably, piriform neurons show a marked first-trial effect, responding significantly stronger to the first than the second presentation of the same odor.
Our recordings show how specific brain regions contribute to distinct aspects of odor processing, with amygdala neurons adjusting their firing based on personal odor preference, and hippocampal activity predicting participants’ ability to correctly identify odors.
Presenting images matching each odor revealed explicit coding of visual information in the olfactory cortex, with individual neurons exhibiting chemosensory conceptual coding, e.g., in the form of a neuron responding to the smell, image, and written name of a banana.
A big thanks to everyone who contributed to this project.
Pope Francis invites representatives of the Chocó and of CASA HOGAR for a private audience to the Vatican
New preprint on intrinsic neural timescales in humans during wakefulness and sleep
In this research work we use the spiking activity of neurons in the human brain to estimate the timescales of information processing during different states of vigilance.
Charity Concert for CASA HOGAR
After our plans for the benefit concert were thwarted by the COVID-19 pandemic, I am excited to announce the new date for the concert:
Saturday August 27th 08:00 pm at the Cologne Philharmonic Hall.
Find more information here:
Visiting Scholar at the Staresina Memory Lab at the University of Oxford
I am thrilled to start working in the Memory and Sleep Lab of Prof. Staresina at Oxford University. We will explore the mechanisms underlying memory consolidation using single unit recordings from the Medial Temporal Lobe (MTL) in humans.
New Method Paper on Single Unit Recordings
In this paper we present possible solution to the problem that neural spikes are sometimes detected multiple times in human extracellular single unit recordings.
Frontotemporal Regulation of Subjective Value to Suppress Impulsivity in Intertemporal Choices
New paper on the neural basis of delay discounting using MEG and eye tracking.
How do we value rewards if we have to wait for them?
And do we act differently if we decide for ourselves or for our best friend?
Find out in the paper below: