Cerebral cortex
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The somatic marker hypothesis provides a systems-level neuroanatomical and cognitive framework for decision making and the influence on it by emotion. The key idea of this hypothesis is that decision making is a process that is influenced by marker signals that arise in bioregulatory processes, including those that express themselves in emotions and feelings. This influence can occur at multiple levels of operation, some of which occur consciously and some of which occur non-consciously. ⋯ Decision making is not mediated by the orbitofrontal cortex alone, but arises from large-scale systems that include other cortical and subcortical components. Such structures include the amygdala, the somatosensory/insular cortices and the peripheral nervous system. Here we focus only on the role of the orbitofrontal cortex in decision making and emotional processing, and the relationship between emotion, decision making and other cognitive functions of the frontal lobe, namely working memory.
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Biography Historical Article
The Cortical Scholar Award: Peyman Golshani.
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The cerebral cortex and thalamus constitute a unified oscillatory machine displaying different spontaneous rhythms that are dependent on the behavioral state of vigilance. In vivo multi-site recordings from a variety of neocortical areas and related thalamic nuclei in cat, including dual simultaneous intracellular recordings, demonstrate that corticofugal volleys are effective in synchronizing fast (20-50 Hz) and low-frequency (< 15 Hz) oscillations in thalamocortical networks, characterizing activated and de-afferented states. (i) Fast spontaneous oscillations depend on the depolarization of thalamic and cortical cells and appear in a sustained manner during waking and REM sleep. Corticothalamic neurons, discharging high-frequency (400 Hz) spike-bursts at 30-40 Hz, are good candidates to synchronize fast oscillations in reentrant thalamocortical loops. ⋯ These inputs also control the shape of spindles, and favor the long-range synchronization and nearly simultaneous appearance of spindles. (iii) The cortical control of thalamic activity is also demonstrated in spike-wave-seizures developing from sleep patterns. More than half of thalamocortical neurons are silent during spike-wave seizures, being tonically hyperpolarized, and display IPSPs (closely related to the paroxysmal depolarizing shifts of cortical cells) that are determined by the pattern of activities in thalamic reticular cells. All these data congruently show the power of cortical control upon thalamic oscillators.
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One feature of the cerebral cortex circuitry is the complex network of fibers which links its different functional regions. Our knowledge of the specific relationships between neurons which form these pathways is limited. The cortico-cortical connections between primary somatosensory cortex (SI) and primary motor cortext (MI) were the focus of the study. ⋯ This aspect of the connection may exemplify a unique feature of the cortical circuit which helps to define its functional role. The significance of these results in defining cortical function is that the particular cortical circuit described may provide an anatomical substrate for the modulation of motor cortex activity by integrated signals from the sensory cortex. The synaptic relationships of neurons in this pathway may be characteristic of i
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Prenatal exposure to cocaine has the potential to modify normal brain development and result in behavioral dysfunction. We used a new animal model in which cocaine was administered intravenously during prenatal development in pregnant rabbits twice daily at low dosages. Analysis of brain development focused on two areas of the cerebral cortex, anterior cingulate and primary visual, in which dopamine afferents, a target of cocaine, are differentially distributed. ⋯ The data indicate that prenatal exposure to cocaine can lead to specific alterations of neuronal growth that are long lasting. The lack of dendritic changes in visual cortex suggests that the drug does not modify development of cortical regions uniformly. This study also provides a new focus on the anterior cingulate cortex as a site in which aberrant structure-function relationships following prenatal cocaine exposure should be examined in both animal models and clinically.