Pattern separation

The canonical model of the dentate gyrus (DG) of the hippocampus suggests the DG performs pattern separation, orthogonalizing similar input patterns [1, 2] aided by an approximate 5-fold expansion of the cell population relative to its entorhinal cortex inputs [3]. However, more recent experimental results challenge this standard model, suggesting the DG also supports the precise binding of objects and events to space and the integration of information across episodes [4]. Very recent studies attribute pattern separation and pattern integration to anatomically distinct parts of the DG, the sup

…DG model suggests it performs pattern separation. More recent experimental results challenge this standard model, suggesting DG function is more complex and also supports the precise binding of objects and events to space and the integration of information across episodes. Very recent studies attribute pattern separation and patte

Hippocampal granule cell (GC) models exhibit degeneracy with different ion channel parameters resulting in comparable functional behaviour [1,2]. However, it is unknown how the degenerate models are further constrained by energetic considerations and known computational functions of GCs. Here, we use Pareto optimality to investigate this question. The Pareto perspective is particularly useful for multi-objective optimisation with multiple trade-offs [3]. We assume that evolution constrains and simplifies the ion channel parameter space by favouring Pareto optimal neurons, which cannot improve

The interaction of the hippocampus and amygdala, crucial for the formation of emotional memories, may play a central role in the pathophysiology of posttraumatic stress disorder (PTSD). However, with amygdala hyperactivity regarded as a hallmark of PTSD, it is still not clear whether amygdala hyperresponsiveness before a traumatic event is a predisposing factor for the development of PTSD or is an acquired condition upon trauma. To address this question, in the current study, we explore the effect of heightened amygdala activity on anxiety and fear memory in the formation of hippocampal fear m

…deficits, particularly pertaining to pattern separation and episodic memory. The hippocampal dentate gyrus (DG) subregion is crucial for gating the flow and separating the patterns of cortical information inputs, transmitting them via DG granule cell mossy

…reflected in distinct neural activity patterns in hippocampus and entorhinal cortex. Electrophysiological work from rodents has shown that single hippocampal place cells represent different locations in different spaces – a functio

While the hippocampus is known to encode physical position through place cells, substantial evidence indicates that hippocampal neurons also respond to a variety of other non-spatial sensory information. We explore the hypothesis that these representations emerge through generic computations implemented by the hippocampus that actively learn from the statistical structure of experience. Theoretical work has shown that place cell coding arises as a special case during spatial exploration in networks trained to learn sparse, compressed representations, due to the local correlations present in th

Network models of cortex typically focus on excitatory population dynamics, relegating inhibition to a support role. However, recent studies have shown that memories can be encoded by both excitatory and inhibitory neurons (EI engrams), adding to the evidence of the functional importance of inhibitory neurons beyond mere stabilization. The functional consequence of such EI engrams is unclear, and the synaptic plasticity rules that could sustain them are unknown. Here, we explore in silico a mechanism for EI engrams storage and recall to glean possible computational benefits of such engrams ove

…separating them into non-overlapping patterns and reducing interference of stored representations. It is highly susceptible to aging-related structural and physiological changes and thought to contribute to age-related cognitive dysfunctions. In this study we examined possible age-related changes in pattern separation function and associated changes in DG cellular engrams using a contextual fear conditioning task. Young adult (3-month-old) and healthy aged (24-mo

Correct memory recall requires two cognitive processes. Pattern separation (PS) is an encoding process that enables the discrimination among similar experiences. Conversely, Pattern completion (PC) allows memory retrieval from partial information. In aging and Alzheimer’s disease (AD), the balance between PS and PC is shifted, in favor of PC over PS, inducing overgeneralization and overlapping memories. Mechanistically, PS and PC rely on the dentate gyrus (DG) and the CA3 hippocampal areas. We previously showed that the DG conditional knock-out of Vangl2 – a core Planar Cell Polarity (PCP) gen

Pattern separation and pattern completion are important functions of the hippocampal formation involving particularly the dentate gyrus (DG)-CA3 mossy fiber system. These functions allow for the differentiation of similar memories as well as a generalization of a memory trace in response to incomplete sensory inputs. The salience of hippocampus-dependent contextual fear memories is controlled by local somatostatin (SST)-positive interneurons that regulate the excitability of DG granule cells. In the current study we investigate if SST-positive interneurons contribute to fear memory specificity

Mammalian hippocampal circuits undergo extensive remodeling through adult neurogenesis. While this process has been widely studied, the specific contribution of adult-born granule cells to spatial operations in the hippocampus remains unknown. Here, we show that optogenetic activation of 4-week-old (young) adult-born granule cells in free-foraging mice produces a non-reversible reconfiguration of spatial maps in proximal CA3 while rarely evoking neural activity. Stimulation of the same neuronal cohort on subsequent days recruits CA3 neurons with increased efficacy but fails to induce further r

Aim: Decrease in adult neurogenesis has been described to correlate with Alzheimer’s disease (AD) progression, and we have previously demonstrated a causal link between Amyloid-beta oligomers (AβOs) accumulation in adult neural stem cells (NSCs) and reduced subventricular zone (SVZ) neurogenesis in AD Tg2576 mouse model at pre-symptomatic stage. Here we investigated if AβOs targeting in the dentate gyrus of AD mice, both at pre-symptomatic and symptomatic stage, can rescue adult hippocampal neurogenesis (AHN) and recover AD-related memory deficits. Methods: Using a disease modifying gene-thera

The striatum is crucial for motor control and reinforcement learning. The striatum has only 1% fast-spiking interneurons (FSI) which constitute feedforward inhibition (FFI). Therefore, striatal neurons receive a high degree of shared FFI, which makes the striatum a unique network in the brain. Here we ask, what role such high shared FFI may play in striatal function besides inducing synchrony. We found that with highly shared connectivity FSIs increase the trial-by-trial variability of striatal responses. Moreover, when the striatum is driven by correlated inputs, FSIs decorrelate the response

Neurons in the rodent hippocampus appear to encode the position of the animal in physical space during movement. Individual ``place cells'' fire in restricted sub-regions of an environment, a feature often taken as evidence that the hippocampus encodes a map of space that subserves navigation. But these same neurons exhibit complex responses to many other variables that defy explanation by position alone, and the hippocampus is known to be more broadly critical for memory formation. Here we elaborate and test a theory of hippocampal coding which produces place cells as a general consequence of

The ability to discriminate different sensory patterns by disentangling their neural representations is an important property of neural networks. While a variety of learning rules are known to be highly effective at fine-tuning synapses to achieve this, less is known about how different cell types in the brain can facilitate this process by providing architectural priors that bias the network towards sparse, selective, and discriminable representations. We studied this by simulating a neuronal network modelled on the dentate gyrus—an area characterised by sparse activity associated with patter

…expansion are that it facilitates pattern separation1 and smoo

…some of these features can facilitate pattern separation. However, these theories don’t consider the need for it to learn fast in order to control smooth and accurate movements. Here, we confront this gap. This talk w