Co-Planar Stereotaxic Atlas of the Human Brain—3-Dimensional Proportional System: An Approach to Cerebral Imaging, J. Talairach, P. Tournoux. Georg Thieme Verlag, New York (1988), 122 pp., 130 figs. DM 268

Functional neuroimaging studies have started unravelling unexpected functional attributes for the posteromedial portion of the parietal lobe, the precuneus. This cortical area has traditionally received little attention, mainly because of its hidden location and the virtual absence of focal lesion studies. However, recent functional imaging findings in healthy subjects suggest a central role for the precuneus in a wide spectrum of highly integrated tasks, including visuo-spatial imagery, episodic memory retrieval and self-processing operations, namely first-person perspective taking and an experience of agency. Furthermore, precuneus and surrounding posteromedial areas are amongst the brain structures displaying the highest resting metabolic rates (hot spots) and are characterized by transient decreases in the tonic activity during engagement in non-self-referential goal-directed actions (default mode of brain function). Therefore, it has recently been proposed that precuneus is involved in the interwoven network of the neural correlates of self-consciousness, engaged in self-related mental representations during rest. This hypothesis is consistent with the selective hypometabolism in the posteromedial cortex reported in a wide range of altered conscious states, such as sleep, drug-induced anaesthesia and vegetative states. This review summarizes the current knowledge about the macroscopic and microscopic anatomy of precuneus, together with its wide-spread connectivity with both cortical and subcortical structures, as shown by connectional and neurophysiological findings in non-human primates, and links these notions with the multifaceted spectrum of its behavioural correlates. By means of a critical analysis of precuneus activation patterns in response to different mental tasks, this paper provides a useful conceptual framework for matching the functional imaging findings with the specific role(s) played by this structure in the higher-order cognitive functions in which it has been implicated. Specifically, activation patterns appear to converge with anatomical and connectivity data in providing preliminary evidence for a functional subdivision within the precuneus into an anterior region, involved in self-centred mental imagery strategies, and a posterior region, subserving successful episodic memory retrieval.

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The precuneus: a review of its functional anatomy and behavioural correlates.

Brains, it has recently been argued, are essentially prediction machines. They are bundles of cells that support perception and action by constantly attempting to match incoming sensory inputs with top-down expectations or predictions. This is achieved using a hierarchical generative model that aims to minimize prediction error within a bidirectional cascade of cortical processing. Such accounts offer a unifying model of perception and action, illuminate the functional role of attention, and may neatly capture the special contribution of cortical processing to adaptive success. This target article critically examines this "hierarchical prediction machine" approach, concluding that it offers the best clue yet to the shape of a unified science of mind and action. Sections 1 and 2 lay out the key elements and implications of the approach. Section 3 explores a variety of pitfalls and challenges, spanning the evidential, the methodological, and the more properly conceptual. The paper ends (sections 4 and 5) by asking how such approaches might impact our more general vision of mind, experience, and agency.

/pdf/whatever-next-predictive-brains-situated-agents-and-the-epj56cs868.pdf

Whatever next? Predictive brains, situated agents, and the future of cognitive science

Let's read! We will often find out this sentence everywhere. When still being a kid, mom used to order us to always read, so did the teacher. Some books are fully read in a week and we need the obligation to support reading. What about now? Do you still love reading? Is reading only for you who have obligation? Absolutely not! We here offer you a new book enPDFd the perception of the visual world to read.

The Perception of the Visual World. By James J. Gibson. U.S.A.: Houghton Mifflin Company, 1950 (George Allen & Unwin, Ltd., London). Price 35s.

https://sites.oxy.edu/clint/physio/article/dorsalandventralstreamsaframeworkforunderstandingaspectsofthefunctionalanatomyoflanguage.pdf

Dorsal and ventral streams: a framework for understanding aspects of the functional anatomy of language.

Increasing evidence has implicated the cerebellum in providing forward models of motor plants predicting the sensory consequences of actions Assuming that cerebellar input to the cerebral cortex contributes to the cerebro-cortical processing by adding forward model signals, we would expect to find projections emphasising motor and sensory cortical areas However, this expectation is only partially met by studies of cerebello–cerebral connections Here we show that by electrically stimulating the cerebellar output and imaging responses with functional magnetic resonance imaging, evoked blood oxygen level-dependant activity is observed not only in the classical cerebellar projection target, the primary motor cortex, but also in a number of additional areas in insular, parietal and occipital cortex, including sensory cortical representations Further probing of the responses reveals a projection system that has been optimized to mediate fast and temporarily precise information In conclusion, both the topography of the stimulation effects and its emphasis on temporal precision are in full accordance with the concept of cerebellar forward model information modulating cerebro-cortical processing The cerebellum has important roles in motor control and sensory perception Sultan and colleagues use electrical stimulation and functional magnetic resonance imaging to reveal that the cerebellum provides inputs to specialized cortical regions of the brain that modulate cerebro-cortical processing

/pdf/unravelling-cerebellar-pathways-with-high-temporal-precision-3gu7ac62ya.pdf

Unravelling cerebellar pathways with high temporal precision targeting motor and extensive sensory and parietal networks

Gain Modulation: A Major Computational Principle of the Central Nervous System

An overview of current thinking in parietal lobe functions. The text is divided into five sections dealing with the areas of functional anatomy and specific contributions of the parietal lobes to eye movements; reaching and grasping; attention and perception; and the representation of space. It includes recent findings that emphasize their general implications for an understanding of the role of parietal lobe processing. The book aims to unite neurophysiological and neuropsychological approaches. It reviews work based on monkeys and on the study of patients with parietal lobe lesions. The interrelationship of the two is discussed.

Parietal Lobe Contributions to Orientation in 3D Space

The analysis of a peripheral visual location can be improved in two ways: either by orienting one's gaze (usually by making a foveating saccade) or by 'covertly' shifting one's attention to the peripheral location without making an eye movement. The premotor theory of attention holds that saccades and spatial shifts of attention share a common functional module with a distinct neuronal basis. Using single-unit recording from the brains of trained rhesus monkeys, we investigated whether the superior colliculus, the major subcortical center for the control of saccades, is part of this shared network for attention and saccades. Here we show that a distinct type of neuron in the intermediate layer of the superior colliculus, the visuomotor neuron, which is known to be centrally involved in the preparation of saccades, is also active during covert shifts of attention.

/pdf/neuron-specific-contribution-of-the-superior-colliculus-to-395jar58ly.pdf

Neuron-specific contribution of the superior colliculus to overt and covert shifts of attention.

We studied the effects of small lesions of the oculomotor vermis of the cerebellar cortex on the ability of monkeys to execute and adapt saccadic eye movements. For saccades in one horizontal direction, the lesions led to an initial gross hypometria and a permanent abolition of the capacity for rapid adaptation. Mean saccade amplitude recovered from the initial hypometria, although variability remained high. A series of hundreds of repetitive saccades in the same direction resulted in gradual decrement of amplitude. Saccades in other directions were less strongly affected by the lesions. We suggest the following. (1) The cerebellar cortex is constantly recalibrating the saccadic system, thus compensating for rapid biomechanical changes such as might be caused by muscle fatigue. (2) A mechanism capable of slow recovery from dysmetria is revealed despite the permanent absence of rapid adaptation.

https://www.jneurosci.org/content/jneuro/19/24/10931.full.pdf

Peter Thier

Papers

Unravelling cerebellar pathways with high temporal precision targeting motor and extensive sensory and parietal networks

Gain Modulation: A Major Computational Principle of the Central Nervous System

Parietal Lobe Contributions to Orientation in 3D Space

Neuron-specific contribution of the superior colliculus to overt and covert shifts of attention.

Saccadic Dysmetria and Adaptation after Lesions of the Cerebellar Cortex