Homeostatic plasticity

…been attributed to excitatory synaptic plasticity and the effect of inhibitory plasticity on memory capacity and recall remains underexplored. To elucidate how inhibitory plasticity affects memory capacity and recall, we compare two inhibitory plasticity rules in spiking autoassociative networks: a homeostatic plasticity rule and a rule that maintains firing rate heterogeneity. Our results

…another due to ever-present synaptic plasticity. So far, only single-layer networks of drifting assemblies have been considered. Biological neuronal assemblies are, however, thought to be distribu

Cortical excitatory (E) neurons exhibit clear tuning to stimulus features, but the tuning properties of inhibitory interneurons remain ambiguous. While inhibitory neurons are traditionally viewed as functionally and structurally untuned [1-4], recent studies indicate that parvalbumin-expressing (PV) neurons do show feature selectivity and establish co-tuned reciprocal connections with individual pyramidal neurons at a pairwise level [5-7]. Using mean-field theory and large-scale network simulations of spiking cells (Fig. 1A), we reconcile these seemingly contradictory findings by demonstrating

Olfactory sensory neurons (OSNs) detect odours at a wide range of intensities. In insects, volatile compounds are perceived by odorant receptors (ORs), which are made up of an odour-specific protein (OrX) and the ubiquitous odorant co-receptor Orco. In principle, ORs tune the sensitivity of odour detection, with some OSNs exhibiting exceptionally high sensitivity. To test whether additional mechanisms underlie odour-specific neuronal processing, we investigated synapses between OSNs and projection neurons in the antennal lobe, the first relay station of the olfactory pathway. Here, we studied

Primary cilia are sensory organelles understood to play important roles throughout development, as evidenced by the spectrum of neurodevelopmental phenotypes observed in instances of ciliary dysfunction (termed ciliopathies). Recent research indicates that in the adult brain, primary cilia may play roles in excitability, maintaining synaptic connectivity, and even form specialised synapses capable of altering the transcriptional landscape of neurons.To further understand the role of cilia in postmitotic neurons, we generated human induced pluripotent stem cell lines (hiPSCs) with NPHP1-/- and

Homeostatic regulation of sleep and wakefulness is essential for survival, but the underlying mechanisms are poorly understood. In Drosophila, a central role in sleep homeostasis is attributed to neurons projecting to the dorsal fan-shaped body (dFB), which store sleep need via their intrinsic excitability. Here, we test if and how dFB neurons incorporate this intrinsic account of sleep drive into their network activity. In vivo dFB neuron ensemble activity is rhythmic, with a peak at 0.2-1 Hz (measured via calcium imaging). The amplitude of these slow oscillations increases with sleep drive,

…Neuronal plasticity enables information storage relevant to those changes but also serves to regulate stable neuronal firing. Homeostatic plasticity mechanisms protect neurons from activity extremes that are associated with pathological conditions such as mood disorders, epilepsy, and dementia. Our aim is to assess how targeted human brain neurons and the synaptic connections between them adapt to prolonged elevation of activity. To assess plasticity, we perform whole-cell patch-clamp

…differentiation, neuronal activity, homeostatic plasticity, neuroinflammation and senescence.Understanding the endogenous mechanisms that control the level of REST is critical, if the protective expression of REST in neurodegeneration or aging were to become the focus of therapeutic approaches. Calcium is a signaling molecule that regulates neuronal activities as well as cellular processes such as autophagy leading to senescen

Cortical networks have the remarkable ability to self-assemble into dynamic regimes in which excitatory positive feedback is balanced by recurrent inhibition. This inhibition-stabilized regime is increasingly viewed as the default dynamic regime of the cortex but how it emerges in an unsupervised manner remains an open question. Theoretical work has established that four sets of weights (WE←E, WE←I, WI←E, WI←I) must obey specific relationships to produce inhibition-stabilized dynamics, but it is not known how the brain autonomously sets the values of all four weight classes to be in the suitab

Experience helps us learn the structure of the environment. Such learning can be described by statistical inference models in which environmental priors adapt to new information across time and influence future estimates. For instance, we may learn that certain colors are overrepresented in the world (e.g., I will see more greens and browns if I am in a forest), leading to cognitive biases in favor of more common environmental features. Humans display systematic biases when retaining estimates of an object's features in working memory, which may reflect learned priors of object feature values.

Change is ubiquitous in living beings. In particular, the connectome and neural representations can change. Nevertheless behaviors and memories often persist over long times. In a standard model, associative memories are represented by assemblies of strongly interconnected neurons. For faithful storage these assemblies are assumed to consist of the same neurons over time. We propose a contrasting memory model with complete temporal remodeling of assemblies, based on experimentally observed changes of synapses and neural representations. The assemblies drift freely as noisy autonomous network a

…and characterization of mechanisms of homeostatic plasticity as they relate to the control of synaptic transmission. He will then provide evidence of translation to the mammalian neuromuscular junction and central synapses, and provide tangible links to the etiology of neurological disease.

…with a "sleep phase", in which plasticity is anti-Hebb

…by learning and experience-dependent plasticity. How do our brains acheive this balance between opposing need for plasticity and stability? Over the past two decades, we and others have uncovered a family of “homeostatic” negative feedback mechanisms that are theorized to stabilize overall brain activity while allowing specific connections to be reconfigured by experience. Here I discuss recent work in which we demonstrate that individua

Neuroplasticity is a fundamental property of the nervous system that is maximal early in life, within a specific temporal window called critical period. However, it is still unclear to which extent the plastic potential of the visual cortex is retained in adulthood. We have surprisingly revealed residual ocular dominance plasticity in adult humans by showing that short-term monocular deprivation unexpectedly boosts the deprived eye (both at the perceptual and at the neural level), reflecting homeostatic plasticity. This effect is accompanied by a decrease of GABAergic inhibition in the primary

Homeostatic plasticity plays a key role in stabilizing neural network activity. But what is its role in neural information processing? We showed analytically how homeostasis changes collective dynamics and consequently information flow - depending on the input to the network. We then studied how input and homeostasis on a recurrent network of LIF neurons impacts information flow and task performance. We showed how we can tune the working point of the network, and found that, contrary to previous assumptions, there is not one optimal working point for a family of tasks, but each task may requir

…by learning and experience- dependent plasticity. There is abundant theoretical and experimental evidence that network stability is achieved through homeostatic plasticity mechanisms that adjust synaptic and neuronal properties to stabilize some measure of average activity, and this process has been extensively studied in primary visual cortex (V1), where chronic visual deprivation induces an initial drop in activity and ensemble average firing rates (FRs), but over time activity is restored