Medial temporal lobe

The human medial temporal lobe contains neurons that respond selectively to the semantic contents of a presented stimulus. These "concept cells" may respond to very different pictures of a given person and even to their written or spoken name. Their response latency is far longer than necessary for object recognition, they follow subjective, conscious perception, and they are found in brain regions that are crucial for declarative memory formation. It has thus been hypothesized that they may represent the semantic "building blocks" of episodic memories. In this talk I will present data from

The centre of memory is the medial temporal lobe (MTL) and especially the hippocampus. In our research, a more flexible brain-inspired computational microcircuit of the CA1 region of the mammalian hippocampus was upgraded and used to examine how information retrieval could be affected under different conditions. Six models (1-6) were created by modulating different excitatory and inhibitory pathways. The results showed that the increase in the strength of the feedforward excitation was the most effective way to recall memories. In other words, that allows the system to access stored memories m

…of single neurons in the human medial temporal lobe has been extensively investigated [2, 3]. Such investigations typically consist of an initial screening to identify semantically-tuned neurons and a subsequent follow-up experiment which uses the identified stimulus-response pairings to address a particular question. While often examined in the service of other scientific investigations, the initial screenings have rarely been the sole focus of investigation [4]. Given the challenges endemic to human

…from epilepsy patients in the human medial temporal lobe (MTL, 2). In addition to predicting a specific temporal relationship between spiking and theta oscillations related to temporal order, the theory also assumes that 1. gamma-frequency activity encodes stimulus-relevant information that is maintained within memory and temporally aligned to spikin

…resting state networks (RSNs) and the medial temporal lobe (MTL) is the parahippocampal cortex (PHC), where abnormal activity has been reported in depressed patients and suicide attempters. Alterations in neuronal mitochondrial function may contribute to depression and suicidal behavior, however, little is known about the underlying molecular level changes in relevant structures. Specifically, expressional changes related to suicide have not been reported in the PHC. Here, we c

…of single-neuron activity in the medial temporal lobe relative to the local theta rhythm. 18 epilepsy patients participated in the task and contributed to 27 experimental sessions. We extracted single-neuron action potentials fro

…inference” (TI) depends on the medial temporal lobe (MTL). But the mechanisms by which the MTL performs TI remain poorly understood. Previous work suggested that “concept cells” (CCs), which are neurons that selectively respond to preferred concepts (e.g. “A”), might contribute to relational learning and potentially TI by widening their tuning to new concepts that co-occurred with initially r

Physical Exercise (PE) is widely acknowledged for its positive impact on cognition and specifically on short-term memory. However, the precise neurophysiological mechanisms of performance improvements are unclear. We developed an MEG-compatible pedal exercises – mimicking walking – to explore PE’s impact on working memory (WM). In simultaneous MEG/EEG recordings participants carried out an N-back task with varying WM loads across blocks and either rested or walked during 2-min-breaks between blocks. PE improved target detection, heightened EEG-spindle activity. MEG ripples (80-150Hz) displayed

…Different medial temporal lobe structures including the hippocampus have been highly implicated to play a major role in novelty detection. In this project, we aim to understand how CA1 of the hippocampus encodes novelty and familiarity signals induced by unimodal and multimodal sensory stimuli and what are the processes that mediate the transition between novelty and familiarity. We plan to use a multisensory cue delivery

…neural timescales, a measure of temporal autocorrelation, which reflect functional significance for cognition, changes in gene expression, and modulations in brain disorders. To date, however, less is known about the regional distribution of neural timescales at the whole-brain level during sleep in humans, where the need fo

…of the hippocampal complex and medial temporal lobe (MTL) areas. These areas however are not sufficient by themselves to support most episodic memory functions. Instead, MTL areas are embedded as a central hub into a more distributed cortical network that supports both the storing, consolidation and subsequent reactivation of memories. Recently emerging evidence however indicates that cortical areas like posterior parietal regions and prefrontal areas contribute more to the processes than previousl

…in auditory cortex and in the medial temporal lobe. In a verbal WM task, 9 epilepsy patients heard strings of letters during encoding and then mentally replayed them during WM maintenance. In each trial, the string consisted of different letter items. While patients performed the task, we recorded from hippocampus, amygdala and ent

The medial temporal lobe (MTL) is important for mnemonic processes, navigation and social cognition. At the basis of all these cognitive processes lies the integration of a multitude of stimuli and their classification into conceptual groups. Neurons in human MTL indeed show concept-specific activity profiles in that they fire specifically for pictures presenting concepts of animals, landscapes, faces, concept relations and their grade of novelty. How such representations are organized during moving scenes, where different concepts are presented simultaneously, has so far received little atten

…Oscillatory power in the medial temporal lobe of a seated observer is sensitive to the spatial location of a watched moving other individual (Stangl et al., 2020). The hippocampus also encodes predictions about when a moving target will hit a boundary on a 2D display (Polti et al., 2021). Using a 2D display and joystick, monkey dorsal anterior cingulate cortex activity predicts a moving target’s future location. (Yoo et al., 2021). However, it remains untested whether the encoding syst

…nervous system across a range of spatiotemporal scales. Yet, their influence on the structural and functional architecture of the human brain is largely unknown. Here, I highlight findings from a series of dense-sampling neuroimaging studies from my laboratory designed to probe the dynamic interplay between the nervous and endocrine systems. Individuals underwent brain imaging and venipuncture every 12-24 hours for 30 consecutive days. These procedu

…non-spatial information processing in medial temporal lobe (MTL) regions including hippocampus [1,2,3]. A prominent theory suggests that neural activity at different phases of theta oscillations encodes the serial order of items within short-term memory [4]. Based on recordings of spiking activity and local field potentials (LFPs) of epilepsy patients performing a multi-item sequential memory task, we show phase-dependent spiking during the delay, with preferred phases that were related to stimulus position within the s

We learn different rules that can switch depending on context. When the rule depends on context, the context is important to learn to differentiate the rewarded choice in different contexts. While it has previously been shown that the reinstatement of context guides decisions for reward, it is less clear how or whether context-based reactivation guides the efficient learning of reward and context associations. We hypothesize that representations of the context are used to guide learning of associations between context and reward. We test whether this context is retrieved from memory circuits p

Decades of research have shown that temporal encoding context is a powerful organizing principle in memory. When remembering lists of words, subjects tend to recall items together that were presented in nearby list positions (“temporal clustering”). The retrieved context framework explains these results by assuming that new memories are stored along with a slowly changing context representation, which cues similar memories at retrieval. Outside of the laboratory, our experiences unfold over both time and space, raising the question of how spatial context affects memory organization. Studies us

…rate of image selective neurons in Medial Temporal Lobe persists through maintenance periods of working memory task. This activity was behaviorally relevant and formed attractors in its state-space. Furthermore, we showed that firing rate of those n