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Stephanie Ratté

Stephanie Ratté
SickKids · Program in Neurosciences and Mental Health (NMH)

Ph.D.

About

29
Publications
3,111
Reads
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1,361
Citations
Introduction
Stephanie Ratté currently works at the Program in Neurosciences and Mental Health (NMH), SickKids. Stephanie does research in Neuroscience.

Publications

Publications (29)
Article
Neurons can use different aspects of their spiking to simultaneously represent (multiplex) different features of a stimulus. For example, some pyramidal neurons in primary somatosensory cortex (S1) use the rate and timing of their spikes to, respectively, encode the intensity and frequency of vibrotactile stimuli. Doing so has several requirements....
Article
Full-text available
Neurons regulate their excitability by adjusting their ion channel levels. Degeneracy - achieving equivalent outcomes (excitability) using different solutions (channel combinations) - facilitates this regulation by enabling a disruptive change in one channel to be offset by compensatory changes in other channels. But neurons must co-regulate many p...
Preprint
Full-text available
The axon initial segment (AIS) converts graded depolarization into all-or-none spikes that are transmitted by the axon to downstream neurons. Analog-to-digital transduction and digital signal transmission call for distinct spike initiation properties (filters) and those filters should, therefore, differ between the AIS and distal axon. Here we show...
Article
Full-text available
Neuropathic pain is a debilitating condition caused by the abnormal processing of somatosensory input. Synaptic inhibition in the spinal dorsal horn plays a key role in that processing. Mechanical allodynia – the misperception of light touch as painful – occurs when inhibition is compromised. Disinhibition is due primarily to chloride dysregulation...
Preprint
Full-text available
Neuropathic pain is a debilitating condition caused by the abnormal processing of somatosensory input. Synaptic inhibition in the spinal dorsal horn plays a key role in that processing. Mechanical allodynia – the misperception of light touch as painful – occurs when inhibition is compromised. Disinhibition is due primarily to chloride dysregulation...
Article
Full-text available
Multiplexing refers to the simultaneous encoding of two or more signals. Neurons have been shown to multiplex, but different stimuli require different multiplexing strategies. Whereas the frequency and amplitude of periodic stimuli can be encoded by the timing and rate of the same spikes, natural scenes, which comprise areas over which intensity va...
Article
Characterizing the cellular targets of kHz (1-10 kHz) electrical stimulation remains a pressing topic in neuromodulation because expanding interest in clinical application of kHz stimulation has surpassed mechanistic understanding. The presumed cellular targets of brain stimulation do not respond to kHz frequencies according to conventional electro...
Article
Full-text available
Continuation of spiking after a stimulus ends (i.e. persistent spiking) is thought to support working memory. Muscarinic receptor activation enables persistent spiking among synaptically isolated pyramidal neurons in anterior cingulate cortex (ACC), but a detailed characterization of that spiking is lacking and the underlying mechanisms remain uncl...
Article
Full-text available
Background: Kilohertz-frequency electric field stimulation (kEFS) applied to the spinal cord can reduce chronic pain without causing the buzzing sensation (paresthesia) associated with activation of dorsal column fibers. This suggests that high-rate spinal cord stimulation (SCS) has a mode of action distinct from conventional, parasthesia-based SC...
Chapter
The somatosensory system is responsible for processing proprioceptive, thermal, touch, and pain information from the body surface and internal tissues. The skin is in fact the largest sensory organ in the body. Braille readers demonstrate a capacity to use discriminative touch in ways most of us will never develop, yet all of us can appreciate diff...
Article
Full-text available
The cortex encodes a broad range of inputs. This breadth of operation requires sensitivity to weak inputs yet non-saturating responses to strong inputs. If individual pyramidal neurons were to have a narrow dynamic range, as previously claimed, then staggered all-or-none recruitment of those neurons would be necessary for the population to achieve...
Article
Full-text available
Neurons rely on action potentials, or spikes, to encode information. But spikes can encode different stimulus features in different neurons. We show here through simulations and experiments how neurons encode the integral or derivative of their input based on the distinct tuning properties conferred upon them by subthreshold currents. Slow-activati...
Article
Full-text available
Neural networks are more than the sum of their parts, but the properties of those parts are nonetheless important. For instance, neuronal properties affect the degree to which neurons receiving common input will spike synchronously, and whether that synchrony will propagate through the network. Stimulus-evoked synchrony can help or hinder network c...
Article
Full-text available
Correlated spiking has been widely observed, but its impact on neural coding remains controversial. Correlation arising from comodulation of rates across neurons has been shown to vary with the firing rates of individual neurons. This translates into rate and correlation being equivalently tuned to the stimulus; under those conditions, correlated s...
Article
Full-text available
Synaptic inhibition by GABA(A) receptors requires a transmembrane chloride gradient. Hyperpolarization or shunting results from outward current produced by chloride flowing down this gradient, into the cell. Chloride influx necessarily depletes the chloride gradient. Therefore, mechanisms that replenish the gradient (by reducing intracellular chlor...
Article
Prion protein (PrP) is abundant in the nervous system, but its role remains uncertain. Prion diseases depend on an aggregation of the protein that is likely to interfere with its normal function. Loss of function does not in itself cause neurodegeneration, but whether it contributes to the clinical features of the disease remains an open question....
Article
Full-text available
During wakefulness, pyramidal neurons in the intact brain are bombarded by synaptic input that causes tonic depolarization, increased membrane conductance (i.e., shunting), and noisy fluctuations in membrane potential; by comparison, pyramidal neurons in acute slices typically experience little background input. Such differences in operating condit...
Article
Prion diseases are heterogeneous in clinical presentation, suggesting that different prion diseases have distinct pathophysiological changes. To understand the pathophysiology specific to variant Creutzfeldt-Jakob Disease (vCJD), in vitro electrophysiological studies were performed in a mouse model in which human-derived vCJD prions were transmitte...
Article
Full-text available
The membrane conductance of a pyramidal neuron in vivo is substantially increased by background synaptic input. Increased membrane conductance, or shunting, does not simply reduce neuronal excitability. Recordings from hippocampal pyramidal neurons using dynamic clamp revealed that adaptation caused complete cessation of spiking in the high conduct...
Article
The epileptiform activity in the kainic acid (KA) model of epilepsy arises from complex changes in excitation and inhibition. To assess the involvement of excitatory drive onto inhibitory interneurons in this epileptiform activity, we examined changes in spontaneous and minimally evoked excitatory post-synaptic currents (sEPSCs and eEPSCs) in CA1 i...
Article
Synaptic properties and connectivity of GABAergic inhibitory interneurons are modified in CA1 hippocampus of the KA model of epilepsy (Fig. 1). These changes affect interneurons that target dendritic areas of principal cells and have important consequences for network activity and hyperexcitability. Some of these changes contribute to hyperexcitabi...
Article
Hippocampal CA1 inhibitory interneurones control the excitability and synchronization of pyramidal cells, and participate in hippocampal synaptic plasticity. Pairing theta-burst stimulation (TBS) with postsynaptic depolarization, we induced long-term potentiation (LTP) of putative single-fibre excitatory postsynaptic currents (EPSCs) in stratum ori...
Article
Full-text available
Prion protein (PrP) plays a crucial role in prion disease, but its physiological function remains unclear. Mice with gene deletions restricted to the coding region of PrP have only minor phenotypic deficits, but are resistant to prion disease. We generated double transgenic mice using the Cre-loxP system to examine the effects of PrP depletion on n...
Article
The procerebrum is believed to be important for processing olfactory information and storing olfactory memories in terrestrial pulmonate molluscs. Previous results have demonstrated that the procerebral cell population is morphologically heterogeneous. In the present study, serial sections and electron microscopy were used to investigate difference...
Article
Full-text available
The procerebrum of terrestrial molluscs is an important processing centre for olfaction. While the physiology of the procerebrum is relatively well characterized, the procerebrum's structure and organization has not been previously investigated in detail. The goal of this thesis is to better characterize the structural organization of the procerebr...
Article
Full-text available
Terrestrial snails have a highly developed sense of olfaction. Because the procerebrum has a large number of cells and is located at the entry site of the olfactory nerve into the brain, the structure is thought to have a significant role in the processing of olfactory stimuli. The morphology of the procerebral neurons in the snail Helix aspersa wa...

Projects

Projects (5)