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David Hunter Hubel (1926–2013) and Torsten Nils Wiesel (b. 1924)
Published in Andrew P. Wickens, Key Thinkers in Neuroscience, 2018
Soon after this work was finished, Hubel and Wiesel moved to Harvard (1959) where they would continue their research until the late 1970s. Their collaboration soon resulted in another classic paper, this time published in 1962, which Hubel and Wiesel described as their “magnum opus”. The most important theme in this article was the distinction between simple and complex cells. Simple cells were essentially the same as those described in their first paper. But complex cells, while still responsive to edges, had greater latitude in their “preferred direction”. That is, the edge tended to elicit a brisk response if it fell anywhere within the neuron’s receptive field. Furthermore, complex cells were sensitive to movement – often responding with sustained firing to any motion over large regions of the receptive field, compared to a very narrow boundary separating the excitatory and inhibitory regions for simple cells that preferred stationary input. Later, in 1965, Hubel and Wiesel reported a third type of cell, hypercomplex, which responded best to a line of limited length that had to fall within the confines of the receptive field. There was also an anatomical location for the cells types. Simple cells were found exclusively in layer 4 of the visual cortex (this layer receives input from eye and lateral geniculate nucleus), whereas complex and hypercomplex cells were found in layers 1 to 3 and 5 to 6.
Chapter 4 Cancer in different areas of the body and mind
Published in Lawrence Goldie, Jane Desmarais, Psychotherapy and the Treatment of Cancer Patients, 2013
Lawrence Goldie, Jane Desmarais
Because of their different consequences, a distinction can be made between the cancers that are ‘solid’, developing from tissues and structures that are solid (such as the lungs, liver, breast and bone), and ‘cancers’ of the ‘glandular’ components of the body, which produce blood, lymph or other secretions. The latter do not obtrude into consciousness until there has been a considerable disruption of normal processes and the individual feels ill or when an unusual change is detected, a new lump, for example. An overproduction of lymphocytes, for example, interferes with the production of other cells needed for defence against infection and blood loss and deposits of lymphocytes produce blockages and swellings in different parts. The effect of this kind of cancer is generalised in the body. Some forms develop rapidly, but the cancer cells, being primitive simple cells, are therefore more vulnerable to cell destroyers — chemical toxins and X-rays — and can be eliminated and the condition cured. Other forms are slow growing but more resistant to treatment and this is because the cancer cells are less primitive, more mature, and are more like normal tissue cells.
Feedback Connections: Splitting the Arrow
Published in Jon H. Kaas, Christine E. Collins, The Primate Visual System, 2003
Another study24 used a slightly different paradigm, involving drug manipulation rather than inactivation. Simultaneous recordings were carried out of paired neurons in MT and V1, while drugs were applied focally in MT to create local changes in the neuronal responsivity to MT-customized stimuli. The advantage of this procedure is that spontaneous activity remains intact, and there is accordingly less drastic modification of the network circuitry. For 79 cells showing effects in area V1 during drug iontophoresis in MT, 60 (76%) showed changes in response magnitude to a texture stimulus. Magnitude was significantly increased for 29 cells, and decreased for 31. Shifts in response magnitude were not laminar specific, but were cell-type specific. For non-orientation-tuned cells, 75% exhibited opposite polarity changes to the paired MT cell responses, consistent with a suppressive effect. For orientation-tuned cells (simple and complex), 64% showed the same polarity changes, although the proportion was higher for simple cells (82%). The result can be interpreted as a facilitatory effect on most simple cells (Reference 24 and H. Jones, personal communication).
Advancing human in vitro pulmonary disease models in preclinical research: opportunities for lung-on-chips
Published in Expert Opinion on Drug Delivery, 2020
Arbel Artzy-Schnirman, Claus-Michael Lehr, Josué Sznitman
Not unlike the challenges faced with in vivo animal models, though, the relevance and success of lung-on-chip models will lie in their validity to mirror major hallmarks of respiratory conditions, including foremost chronic progressive and irreversible changes in the lungs. Such endeavors are extremely challenging, in particular when etiological factors (e.g. occupational exposure, cigarette smoke) and natural history of the disease are poorly understood (e.g. COPD, IPF) or conversely in the absence of unique molecular signatures (e.g. acute respiratory distress syndrome ARDS). Nevertheless, and in contrast to human tissue in vivo, the relatively simple cell composition of such platforms offers advantages. The use of primary (and immune) cells originating from different donors holds the potential to explore disease diversity across populations, toward personalized medicine applications, and as such a path toward understanding basic mechanisms of disease initiation. As a final remark, we briefly recall that in vitro studies should be distinguished between investigations aimed at determining underlying mechanisms of injury or disease and those focused on the mechanisms of resolution, in particular when concerned with therapeutic action. In the latter case, one open research avenue with lung-on-chips lies, for example, in administering target therapeutics in the hope of observing symptoms returning to normal conditions following the elicitation of a disease state.
Comparing membrane and spacer biofouling by Gram-negative Pseudomonas aeruginosa and Gram-positive Anoxybacillus sp. in forward osmosis
Published in Biofouling, 2019
Anne Bogler, Douglas Rice, Francois Perreault, Edo Bar-Zeev
Biofilms that form in wastewater facilities are often found to be site-specific and to constitute a highly diverse community (Al Ashhab et al. 2014; Vanysacker et al. 2014; Zhang et al. 2014). Although most strains on FO membranes have been found to be Gram-negative, Gram-positive strains have also been observed (Qiu and Ting 2013; Zhang et al. 2014; Ding et al. 2016). Gram-positive bacteria (eg Anoxybacillus sp.) have a simple cell wall structure surrounding the cytoplasmic membrane, primarily composed of a thick (20–80 nm) peptidoglycan layer (Madigan et al. 2012). Conversely, Gram-negative bacteria (eg Pseudomonas aeruginosa) have a complex outer cell structure comprising a thin (2–3 nm) peptidoglycan layer sandwiched between two phospholipid bilayer membranes (Madigan et al. 2012). Apart from phospholipids, the outer membrane also contains lipopolysaccharides, where the long polysaccharide chains are on the outer surface of the cell (Madigan et al. 2012). The surface properties of bacteria resulting from these outer cell structures control adhesion of cells onto surfaces, often via hydrophobic or hydrophilic interactions (Neu 1996).
The enigmatic nature of the triggering receptor expressed in myeloid cells -1 (TLT- 1)
Published in Platelets, 2021
Siobhan Branfield, A. Valance Washington
Receptors are important targets for the pharmacological manipulation of cellular functions and disease. Even though platelets are considered, by many, as simple cells because of their lack of a nucleus, their functions are very complex. Platelets probe our vasculature, identify breaches, and restore vessel integrity [1,2]. In recent years, the role of platelets beyond hemostasis has taken center stage, especially in the field of innate immunology, where they have been shown to be key determinates in disease severity and outcomes [1,3]. As such, understanding the pathways that are regulated by platelet receptors is paramount, if we are to be able to manipulate the diseases in which their function is key.