The University of Lethbridge is a publicly funded comprehensive academic and research university, founded in the liberal education tradition, located in Lethbridge, Alberta, Canada, with two other urban campuses in Calgary and Edmonton. The main building sits among the coulees on the west side of the Oldman River.The U of L is a member of the Alberta Rural Development Network. Wikipedia.
Luczak A.,University of Lethbridge |
McNaughton B.L.,University of Lethbridge |
McNaughton B.L.,University of California at Irvine |
Harris K.D.,University College London
Nature Reviews Neuroscience | Year: 2015
Cortical circuits work through the generation of coordinated, large-scale activity patterns. In sensory systems, the onset of a discrete stimulus usually evokes a temporally organized packet of population activity lasting â 1/450-200 ms. The structure of these packets is partially stereotypical, and variation in the exact timing and number of spikes within a packet conveys information about the identity of the stimulus. Similar packets also occur during ongoing stimuli and spontaneously. We suggest that such packets constitute the basic building blocks of cortical coding. © 2015 Macmillan Publishers Limited. All rights reserved.
Agency: European Commission | Branch: FP7 | Program: CP | Phase: ICT-2011.9.11 | Award Amount: 9.20M | Year: 2013
Most cognitive functions are based on computations that take place in the cerebral cortex, composed of a larger number of areas, each with a complex anatomical structure, with neurons of different types and in different layers interacting according to a precise scheme. The anatomical organization of cortical areas is similar, with some modulation according to its sensory, motor or associative function. Several areas have a columnar organization, but in all areas a similar vertical organization of cortical modules is repeated, suggesting that the same fundamental computation scheme is carried out. Despite the large amount of available data, this processing capability of the cortical module is still poorly understood. Two key technological advances to explore cortical computation have been ensemble electrophysiology, the use of multiple electrodes to record groups of neurons, and optogenetics. However, the optogenetic tools are still critically lacking in layer and cell-type specificity, and the recording techniques still do not attain the yields necessary to properly characterize the cortical microcircuit. To overcome these limitations, we propose a new probe that dramatically increases the density of electrodes providing an unprecedented view of currents in the extracellular medium. This will be complemented with an optical stimulator, capable of activating excitatory and inhibitory channelrhodopsins with a 100 m resolution. We will take full advantage of the rich data that can be obtained with these new devices by producing new strategies for signal classification, to locate cells in cortical layers and assign them to a cell type based on the spatiotemporal fingerprint generated at each action potential. We will analyze cortical function at multiple scales in a number of contexts, from memory formation, to ongoing processing during decision making, and to sensorimotor integration for actions, advancing our understanding of cortical representations.
Sparks F.T.,University of Lethbridge
Neurobiology of learning and memory | Year: 2013
There are still basic uncertainties concerning the role of the hippocampus (HPC) in maintaining long-term context memories. All experiments examining the effects of extensive HPC damage on context memory for a single learning episode find that damage soon after learning results in robust retrograde amnesia. Some experiments find that if the learning-to-damage interval is extended, remote context memories are spared. In contrast, other experiments fail to find spared remote context memory. One possible explanation for inconsistency might be the potency of the context memory conditioning procedure, as the experiments showing spared remote memory used a greater number of context-shock pairings, likely creating a stronger context fear memory. We designed an experiment to directly test the question: does increasing the number of context-shock pairings result in sparing of remote context memory after HPC damage? Six independent groups of rats received either 3 or 12 context-shock pairings during a single conditioning session and then either received extensive HPC damage or Control surgery at 1-week, 2-months, or 4-months after conditioning. 10 days after surgery rats were tested for memory of the shock context. Consistent with all relevant studies, HPC damage at the shortest training-surgery interval produced robust retrograde amnesia for both 3- and 12-shock groups whereas the Control rats expressed significantly high levels of memory. At the longer training-surgery interval, HPC damage produced similarly robust retrograde amnesia in the rats in both the 3- and 12-shock groups. These results clearly demonstrate that increasing the number of context-shock pairings within a single learning session does not change the dependence of the memory on the HPC. Current evidence from our group on retrograde amnesia has now shown that partial damage, dorsal vs. ventral damage, discrete cue+context conditioning, time after training, and number of context-shock pairings do not affect HPC dependence of context fear memories. When taken together, the evidence strongly supports a permanent role of the HPC in context memory. Copyright © 2013 Elsevier Inc. All rights reserved.
Euston D.R.,University of Lethbridge |
Gruber A.J.,University of Lethbridge |
McNaughton B.L.,University of Lethbridge
Neuron | Year: 2012
Some have claimed that the medial prefrontal cortex (mPFC) mediates decision making. Others suggest mPFC is selectively involved in the retrieval of remote long-term memory. Yet others suggests mPFC supports memory and consolidation on time scales ranging from seconds to days. How can all these roles be reconciled? We propose that the function of the mPFC is to learn associations between context, locations, events, and corresponding adaptive responses, particularly emotional responses. Thus, the ubiquitous involvement of mPFC in both memory and decision making may be due to the fact that almost all such tasks entail the ability to recall the best action or emotional response to specific events in a particular place and time. An interaction between multiple memory systems may explain the changing importance of mPFC to different types of memories over time. In particular, mPFC likely relies on the hippocampus to support rapid learning and memory consolidation.
Sutherland R.J.,University of Lethbridge |
Lehmann H.,Trent University
Current Opinion in Neurobiology | Year: 2011
We discuss very recent experiments with rodents addressing the idea that long-term memories initially depending on the hippocampus, over a prolonged period, become independent of it. No unambiguous recent evidence exists to substantiate that this occurs. Most experiments find that recent and remote memories are equally affected by hippocampus damage. Nearly all experiments that report spared remote memories suffer from two problems: retrieval could be based upon substantial regions of spared hippocampus and recent memory is tested at intervals that are of the same order of magnitude as cellular consolidation. Accordingly, we point the way beyond systems consolidation theories, both the Standard Model of Consolidation and the Multiple Trace Theory, and propose a simpler multiple storage site hypothesis. On this view, with event reiterations, different memory representations are independently established in multiple networks. Many detailed memories always depend on the hippocampus; the others may be established and maintained independently. © 2011 Elsevier Ltd.
Johnson K.R.D.,University of Lethbridge |
Hayes P.G.,University of Lethbridge
Chemical Society Reviews | Year: 2013
Cyclometalative C-H bond activation is a process that is commonly encountered in the field of organometallic chemistry. In rare earth and actinide complexes, ligand cyclometalation is most prevalent in highly reactive alkyl and hydrido species. Numerous factors promote ligand cyclometalation and influence the rate at which it occurs. This tutorial review discusses key issues relevant to ligand cyclometalation in rare earth and actinide complexes, including kinetic and mechanistic considerations. A variety of examples is presented for a wide range of ligand types and metals, the scope of which is intended to include routine cases, while also highlighting exceptional cyclometalation reactions that lead to unusual bonding modes. The reaction chemistry of cyclometalated rare earth and actinide complexes with various small molecule substrates (e.g. phenol, anilines, triethylammonium salts, alkynes, olefins, hydrogen and hydrocarbons) is also outlined. This journal is © The Royal Society of Chemistry.
Henzi S.P.,University of Lethbridge
Philosophical transactions of the Royal Society of London. Series B, Biological sciences | Year: 2013
Primate social life and behaviour is contingent on a number of levels: phylogenetic, functional and proximate. Although this contingency is recognized by socioecological theory, variability in behaviour is still commonly viewed as 'noise' around a central tendency, rather than as a source of information. An alternative view is that selection has acted on social reaction norms that encompass demographic variation both between and within populations and demes. Here, using data from vervet monkeys (Chlorocebus aethiops pygerythrus), we illustrate how this alternative approach can provide a more nuanced account of social structure and its relation to contingent events at the ecological and demographic levels. Female vervets in our South African study population live in large groups, where they experience demographic stress and increased levels of feeding competition relative to an East African population in Amboseli, Kenya. Females in the South African population did not respond to this stress by intensifying competition for high-value grooming partners to help alleviate the effects of this stress, did not show the expected rank-related patterns of grooming, nor did they show any spatial association with their preferred grooming partners. Increased group size therefore resulted in a reorganization of female social engagement that was both qualitatively and quantitatively different to that seen elsewhere, and suggests that female vervets possess the flexibility to shift to alternative patterns of social engagement in response to contingent ecological and demographic conditions.
University of Lethbridge | Date: 2015-07-24
The disclosure provides an apparatus and method for assessing brain plasticity by measuring electrical brain biomarkers, for example, with a near real-time analysis of electrical brain biomarkers, where an increase or decrease in at least one biomarker is indicative of a state of brain plasticity in response to a stimulus or treatment. Brain plasticity can be measured with or without an added stimuli, for example, to determine the best time for learning. Also provided is a method for treating a neurological disease or trauma by applying an electrical or drug stimulus to a patient, where the stimulus is increased or decreased depending on the changes of electrical brain biomarker of the patient. This treatment can occur in near real-time, so a course of treatment can be tailored immediately to a patients needs.
University of Alberta and University of Lethbridge | Date: 2015-02-05
The disclosure provides methods for the treatment of skin disorders through the use of minimally invasive terahertz radiation. The method includes exposing skin cells to terahertz radiation in amount sufficient to modulate gene expression in the skin cells. The modulation of gene expression then results in a reduction of the disease state or aspects thereof in the exposed skin cells.
Rasmussen J.B.,University of Lethbridge
Journal of Animal Ecology | Year: 2010
1.This paper outlines a gradient-based model that can be used for isotopic signature source partitioning, even if source signatures are not distinct, as long as their spatial gradients differ. A model of this type is applied to the partitioning of autochthonous vs. allochthonous contribution to stream invertebrate d13C signatures, which has often been confounded by overlap in source signatures. 2. δ13C signatures of inorganic carbon and most autochthonous production exhibit pronounced gradients along rivers, being depleted relative to terrestrial signatures in upstream reaches, and enriched downstream. Terrestrial detritus, by contrast, exhibits no gradient. Thus terrestrial food consumption reduces downstream signature slopes in proportion to the amount of terrestrial food consumed. 3. The gradient-based mixing model produces estimates of the proportion of terrestrial consumption (pT) from signature slopes of consumers; pT estimates for invertebrate primary consumers were: herbivore/grazers (0·15)