Topic: 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

Sex hormones are powerful neuromodulators of learning and memory. In rodents and nonhuman primates estrogen and progesterone influence the central 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

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

Working memory (WM) is a fundamental human cognitive capacity that allows us to maintain and manipulate information stored for a short period of time in an active form. Thanks to a unique opportunity to record activity of neurons in humans during epilepsy monitoring we could test neuronal mechanisms of this cognitive capacity. We showed that firing 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

Since the identification of concept cells nearly two decades ago [1], the semantic invariance 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

A prominent theory proposes that maintaining sequential information in memory is reflected in ordered firing of neurons at different phases of theta oscillations (1). One study has recently challenged this view using single-unit and LFP recordings 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

Humans can infer never-experienced global relational structures (e.g., "A>D”) by observing and integrating multiple local relations (e.g., "A>B", "B>C", “C>D”). This capability for “transitive 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