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Chapter 17 - The Thalamus in Attention
- from Section 7: - Cognition
- Edited by Michael M. Halassa, Massachusetts Institute of Technology
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- Book:
- The Thalamus
- Published online:
- 12 August 2022
- Print publication:
- 01 September 2022, pp 324-339
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Summary
Selective attention is a cognitive process that enables the preferential routing of behaviorally relevant information through the brain.The associated large-scale network includes regions in all major lobes as well as subcortical structures such as the thalamus. There is mounting evidence that the visual thalamus–the lateral geniculate nucleus (LGN), thalamic reticular nucleus (TRN), and pulvinar–plays an important functional role in this process. The LGN has been traditionally viewed to be a relay of retinal information to the cortex. However, it has been shown that neural gain is amplified in LGN neurons, possibly in pathway-specific ways and via TRN-regulated inhibitory control, to amplify neural representations in the focus of attention at the expense of those that are unattended, thereby boosting attention-related information and filtering unwanted distracter information at the earliest possible processing stage of the visual pathway. The pulvinar is the largest nucleus of the primate thalamus and is almost exclusively interconnected with the cortex. Its function has remained elusive for many decades. Recent evidence suggests at least two functions that may be interdependent. First, pulvinar influences on the cortex are necessary to enable regular cortical function so that information can be processed from one area to the next. Second, the pulvinar coordinates information processing across the cortical attention network by synchronizing local population activity, thereby optimizing information transfer. Taken together, emerging views suggest roles for the LGN–TRN circuit as the gatekeeper and for the pulvinar as the timekeeper of the cortex.
6 - How to anesthetize mouse lemurs
- from Part II - Methods for studying captive and wild cheirogaleids
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- By Sabine B.R. Kästner, University of Veterinary Medicine Hannover, Germany, Julia Tünsmeyer, University of Veterinary Medicine Hannover, Germany, Alexandra F. Schütter, University of Veterinary Medicine Hannover, Germany
- Edited by Shawn M. Lehman, University of Toronto, Ute Radespiel, Elke Zimmermann
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- Book:
- The Dwarf and Mouse Lemurs of Madagascar
- Published online:
- 05 March 2016
- Print publication:
- 07 April 2016, pp 135-160
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Summary
Introduction
Mouse and dwarf lemurs are the smallest primate species. They may be used in a variety of scientific projects under field or laboratory conditions. Despite trap capture and the small size of mouse and dwarf lemurs, for successful performance of some procedures animals need to be anesthetized (Glander, 2013). In particular, the very small size of mouse lemurs with a body mass of 20–100 g and a body length of 5–13 cm (Louis et al., 2008) requires special considerations for anesthesia and might limit the use of standard veterinary anesthesia equipment and techniques in the field.
To choose the best anesthetic method for a project, different factors such as drugs and available equipment, type, invasiveness and duration of procedure, possible interaction of drugs with measured parameters, and the experience of the scientist should be considered. In the face of modern imaging methods and the use of mouse lemurs as a research model of human disease, more prolonged anesthetics and sensitive monitoring of vital parameters, ventilation, and oxygenation becomes necessary to maintain physiological conditions.
Therefore, the purpose of the current article was to discuss general considerations for anesthesia in an animal of the size of mouse lemurs relating to equipment, and the properties and effects of anesthetic drugs. In addition, a review of published drug doses and drug combinations used for various procedures in mouse lemurs is included.
Material and methods
Publications concerning anesthesia techniques in mouse and dwarf lemurs were found by searching “Pubmed” of the United States National Library of Medicine, “Veterinary Science” of CAB International and Web of Science. These databases were searched for the following words or terms: “mouse lemur,” “dwarf lemur,” “Microcebus,” “Cheirogaleus”, alone or in combination with the word “an*esthesia.”
The search covered the period from 1959 to January 2014. Articles were scrutinized for description of immobilization or anesthesia techniques. Relevant articles were selected manually. Abstracts of conference proceedings were included only when material and methods and results were clearly stated.
Results
Vital parameters
Regardless of which anesthetic technique is used, knowledge of basic physiological variables of the species of interest, such as heart rate, respiratory rate, and body temperature, is useful to successfully monitor the animals' response (respiratory and cardiovascular depression) to anesthesia. Based on the influence of drugs, handling or capture stress and activity state, these values can vary considerably.
4 - Cortical mechanisms of visuospatial attention in humans and monkeys
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- By Sabine Kastner, Department of Psychology Center for the Study of Brain, Mind & behavior Princeton University Green Hall (3-N-1E) Princeton, NJ 08544-1010, Peter De Weerd, Laboratory of Perception & Actions Department of Psychology (Room 518) University of Arizona 1503 E. University Blvd. PO Box 210068 Tucson, AZ 85721, Leslie G. Ungerleider, Chief Laboratory of Brain and Cognition National Institute of Mental Health Building 10, Room 4C104 10 Center Drive, MSC 1148 Bethesda, MD 20892-1366
- Edited by James R. Pomerantz, Rice University, Houston
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- Book:
- Topics in Integrative Neuroscience
- Published online:
- 08 August 2009
- Print publication:
- 21 February 2008, pp 77-118
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Summary
Introduction
In everyday life, the scenes we view are typically cluttered with many different objects. However, the capacity of the visual system to process information about multiple objects at any given moment in time is limited (Broadbent, 1958; Neisser, 1967; Schneider & Shiffrin, 1977; Tsotsos, 1990). This limited processing capacity can be exemplified in a simple experiment. If subjects are presented with two different objects and asked to identify two different attributes at the same time (e.g., color of one and orientation of the other), the subjects' performance is worse than if the task had been performed with only a single object (Duncan, 1980, 1984; Treisman, 1969). Hence, multiple objects present at the same time in the visual field compete for neural representation due to limited processing resources.
How can the competition among multiple objects be resolved? One way is by bottom-up, stimulus-driven processes. For example, in Figure 4.1A, the vertical line among the multiple distracter lines is effortlessly and quickly detected because of its salience in the display, which biases the competition in favor of the vertical line. Stimulus salience depends on various factors, including simple feature properties such as line orientation or color of the stimulus (Treisman & Gelade, 1980; Treisman & Gormican, 1988), perceptual grouping of stimulus features by Gestalt principles (Driver & Baylis, 1989; Duncan, 1984; Lavie & Driver, 1996; Prinzmetal, 1981), and the dissimilarity between the stimulus and nearby distracter stimuli (Duncan & Humphreys, 1989, 1992; Nothdurft, 1993).
Neuronal responses to orientation and motion contrast in cat striate cortex
- SABINE KASTNER, HANS-CHRISTOPH NOTHDURFT, IVAN N. PIGAREV
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- Journal:
- Visual Neuroscience / Volume 16 / Issue 3 / May 1999
- Published online by Cambridge University Press:
- 01 May 1999, pp. 587-600
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Responses of striate neurons to line textures were investigated in anesthetized and paralyzed adult cats. Light bars centered over the excitatory receptive field (RF) were presented with different texture surrounds composed of many similar bars. In two test series, responses of 169 neurons to textures with orientation contrast (surrounding bars orthogonal to the center bar) or motion contrast (surrounding bars moving opposite to the center bar) were compared to the responses to the corresponding uniform texture conditions (all lines parallel, coherent motion) and to the center bar alone. In the majority of neurons center bar responses were suppressed by the texture surrounds. Two main effects were found. Some neurons were generally suppressed by either texture surround. Other neurons were less suppressed by texture displaying orientation or motion (i.e. feature) contrast than by the respective uniform texture, so that their responses to orientation or motion contrast appeared to be relatively enhanced (preference for feature contrast). General suppression was obtained in 33% of neurons tested for orientation and in 19% of neurons tested for motion. Preference for orientation or motion contrast was obtained in 22% and 34% of the neurons, respectively, and was also seen in the mean response of the population. One hundred nineteen neurons were studied in both orientation and motion tests. General suppression was correlated across the orientation and motion dimension, but not preference for feature contrast. We also distinguished modulatory effects from end-zones and flanks using butterfly-configured texture patterns. Both regions contributed to the generally suppressive effects. Preference for orientation or motion contrast was not generated from either end-zones or flanks exclusively. Neurons with preference for feature contrast may form the physiological basis of the perceptual saliency of pop-out elements in line textures. If so, pop-out of motion and pop-out of orientation would be encoded in different pools of neurons at the level of striate cortex.