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Those glands contain more mucous cells and many gastrin-secreting enteroendocrine cells symptoms tonsillitis cheap synthroid 75 mcg without a prescription. The wall of the stomach consists of the mucosa (epithelium symptoms 3 days before period buy cheap synthroid 100mcg, lamina propria medications ending in pam buy synthroid 75mcg with amex, and muscularis mucosa) medicine zetia purchase 125mcg synthroid amex, submucosa, muscularis externa, and serosa (B) lined by a mesothelium. The exit of chloride through the open channels is followed by the passage of sodium and water. The result can be dehydration, which can be offset by intravenous feeding or oral rehydration therapy. A number of pancreatic secretions are released into the pancreatic duct system as zymogens (inactive precursors). Enterokinase, a brush border enterocyte enzyme, converts trypsinogen to trypsin (answer a). Trypsin and enterokinase are responsible for the activation of chymotrypsinogen, proelastase, and procarboxypeptidase A and B to their active forms: chymotrypsin, elastase, and carboxypeptidase A and B. The patient in the scenario is suffering from lactase deficiency which often has an adult onset since lactase activity decreases after childhood. The absence of lactase or reduced lactase activity results in passage of undigested lactose into the colon. Colonic bacteria carry out fermentation of the lactose to organic acids and hydrogen. The bloating, cramping, and abdominal pain are due to the breakdown of lactose and production of the hydrogen gas. The 340 Anatomy, Histology, and Cell Biology microvilli are also the site of the glucose/galactose transporter (answers b and c). However, the glucose/galactose transporter is not the site of the deficiency in lactose intolerance. Other brush border enzymes include the other monosaccharidases and enterokinase, which is important for cleavage of pancreatic zymogens. Digestion of lipids occurs through the action of bile (from the liver and bile duct) and lipase (from the pancreas). Bile serves to emulsify the lipid to form micelles, whereas lipase breaks down the lipid from triglycerides to fatty acids, glycerol, and monoglycerides (answers d and e). Those three breakdown products diffuse freely across the microvilli to enter the apical portion of the enterocyte by passive diffusion. Those two types of molecules form the coverings of the triglyceride cores of the chylomicra. The chylomicra are released at the basolateral membranes by exocytosis into the lacteals. From the lacteals, the chylomicra travel into the cisterna chyli and eventually into the venous system by way of the thoracic duct. Digestion of fat occurs to a greater extent in the duodenum and jejunum than in the ileum. Sugars are broken down by amylase in the oral cavity, with continued digestion by brush border monosaccharidases. Proteins are broken down by pepsinogen in the stomach with continued breakdown in the small intestine by the enzymes of the pancreatic juice. The products of protein digestion are amino acids that are actively transported by transporters also located in the brush border. The adrenal cortex influences the secretion of the adrenal medulla by means of which of the following? Secretion of aldosterone into the intra-adrenal circulation Secretion of glucocorticoids into the intra-adrenal circulation Autonomic neural connections Secretion of monoamine oxidase into the portal circulation Secretion of androgens into the intrarenal circulation 224. In the presence of this tumor, which of the following symptoms would most likely be observed? During the physical examination of a newborn child, it is observed that the genitalia are female, but masculinized. She has lost 22 lb since her last office visit 9 months ago and indicates that she has not changed her diet. To which of the following would you expect to detect autoantibodies within this organ? Which of the following cells or parts of the pituitary are derived embryologically from neuroectoderm? A tumor in the specific region denoted by the asterisks will most likely cause which of the following? Diabetes Hypoglycemia Elevated blood pressure Decreased blood pressure Increased bone resorption 346 Anatomy, Histology, and Cell Biology 231. The low-magnification micrograph (A) and is from the same organ as the highmagnification micrograph (B). A 30-year-old woman presents with chronic fatigue that has worsened during the past months. She has muscle weakness and describes a loss of appetite with a 15-lb weight loss since her last visit. She admits to having "no appetite and eating less," but "craves salty foods" when she is able to eat. The darkening of her skin is most visible in her skin folds and at her elbows, knees and knuckles. She describes being "irritable and depressed" and has had very irregular menstrual periods over the 6 months, which she attributes to early menopause. Hypertrophy of zone A only Hypertrophy of zones A, B, and C only Hypotrophy of zones A, B, and C only Hypotrophy of zones A, B, C, and D only Hypertrophy of zones A and B only 348 Anatomy, Histology, and Cell Biology 232. The region labeled C is not a good candidate for transplantation compared with other endocrine glands for which of the following reasons? More severe rejection of neurally related tissue occurs compared with other endocrine organs b. Its hormonal source is unavailable after its axonal connections to the hypothalamus are disrupted c. The vascular wall of the superior hypophyseal arteries is unique Endocrine Glands 349 233. A 45-year-old woman, who works as a corporate executive, presents with the primary complaint of "always being tired. She is continuously turning the thermostats in the house and work to higher temperatures, to the dismay of family members and coworkers, respectively. She also complains that her skin is very dry; use of lotions and creams have not helped the dryness. A biopsy of the organ shown in question 227 indicates dense lymphocytic infiltration with germinal centers throughout the parenchyma. T3 is bound to thyroid-hormone binding proteins the liver and kidney convert T4 to T3 peripherally T3 and T4 are regulated by two different anterior pituitary hormones Thyrotrophs produce T3 T4 and T3 immunoassays cross-react in immunoassays Endocrine Glands Answers 223. Glucocorticoids synthesized in the zona fasciculata of the adrenal are released into the sinusoids and enter the medulla (answers a and e). The adrenal gland is not usually considered a classic portal system although there are similarities. Monoamine oxidase is a mitochondrial enzyme that regulates the storage of catecholamines in peripheral sympathetic nerve endings (answers c and d). The adrenal cortex is derived from mesoderm and the adrenal medulla from neural crest. The blood supply to the adrenal is derived from three adrenal arteries: (1) the superior adrenal (suprarenal) from the inferior phrenic, (2) the middle adrenal from the aorta, and (3) the inferior adrenal from the renal artery. These are seizure-like catecholamineinduced attacks that include headache, profuse sweating, palpitations, and overall anxiety. Pheochromocytoma is a common tumor of the adrenal medulla that leads to an excess of norepinephrine, which causes hypertension and hyperglycemia. Vasoconstriction of arterioles occurs in conjunction with the increased blood pressure. The pinealocytes secrete melatonin in response to the light-dark cycle and influence the rhythmicity of other endocrine organs. The pineal contains two main cell types: pinealocytes and neuroglia [the latter appear to be modified astrocytes 350 Endocrine Glands Answers 351 (answer c)].
The hobo element within the generator may recombine with any hobo insertion within the genome treatment yeast buy 75 mcg synthroid fast delivery. The recombination then deletes any gene(s) between the hobo insertion and the generator insertion points including one of the flanking markers medicine rising appalachia lyrics buy synthroid 200 mcg cheap, W or Y medicine lake discount synthroid 25 mcg line, depending on the orientation of the generator construct in the chromosome medications kidney damage buy generic synthroid 200mcg on-line. The deletion of the W wild type allele produces white eye in the males and the loss of Y results in yellow body color. Also a series of nested deletions can be obtained and the function of the unknown deleted genes can be annotated by the phenotype of the deletion animals. Deletion Mapping: Used in Drosophila and plants on the basis of pseudo-dominance, i. Wild type was restored by recombination only between non-overlapping deletions and the crosses with the long deletion indicated that the mutation and the short deletion were both within the range of the long deletion. Deletion mapping Demethylation 487 Phage T4 rll Long Deletion X Recombination + + Shorter Deletion X Recombinant Wild-Type Strand Mutant X Strand binding to Notch in cis inhibits Notch signaling. Dll4-specific antibody signaling deregulates angiogenesis and inhibits tumor growth (Ridgway J et al 2006 Nature [Lond] 444:1083). Demecolcine (N-Deacetyl-N-methylcolchicine): Demecolcine depolymerizes microtubules and causes mitotic arrest at metaphase without significant effects on other cellular processes. Frontotemporal dementia is a heterogeneous disease involving human chromosome 3, 9 and 17 and it is characterized by apathy, restlessness, lack of judgment, mutism and dystonia. Demethylation: It may take place by demethylase enzymes or by base excision repair. Deletions may be generated by molecular biology techniques using restriction endonucleases and extension of the gaps by exonuclease. Since the restriction enzymes nick at specific locations, they can be used for site-directed deletions. After removing the single strands left behind, nested sets of deletions of various lengths are obtained. Bal 31 Delila: A database manager program for selection of nucleic acid sequences in a library. Demethylation has significance for developmental controls in which methylation may turn off genes and demethylation may restore activity. In Arabidopsis mutation in the recessive gene ddm1 may reduce the level of methylated cytosine by 70% and the demethylated condition is transmitted also through meiosis (Kakutani T et al 1999 Genetics 151:831). The animal spermatozoa are heavily methylated but rapidly dimethylated after fertilization. In animals, the methylated state is reset in the new generation (Meyer W et al 2000 Nature [Lond] 403:501). De novo methylation is essential for embryogenesis and gametogenesis of mice (Okano M et al 1999 Cell 99:247). Demic Diffusion: Geographic expansion of a small deme into a large area resulting in demographic growth. Demography: the study of changes in the human populations by migration, birth, mortality, marriages, health, occupations, education, etc. De Novo Synthesis: the formation of molecules through synthesis from (simple) precursors rather than by cannibalization (recycling) of more complex processes of salvage. Adhesive forces between complementary strands of 20, 16 and 12 base pairs was found to be 1. The complex of monomers has the potential to hybridize with complementary oligonucleotides at the open single strands. Dendrimers have been used as synthetic gene delivery vehicles for in vivo gene therapy. After delivering a special signal the dendrimer may self-destruct leaving the passenger molecule. Dendrite: A relatively short branch of neurons that receives information from other nerve cells. Although dendritic cells chew to pieces most of antigens presented to T cells, some antigens are presented intact to B cells (Bergtold A et al 2005 Immunity 23:503) (see. They travel from the peripheral tissues to the lymphoid organs and promote immunity. Myeloid type dendritic cells may stimulate T lymphocytes whereas the lymphoid dendritic cells may have the opposite effect. Fusion of human dendritic cells with breast carcinoma cells activates cytotoxic T cells against the tumors. Dendritic cells can detect pathogens directly or sense the products of infection such as heat shock proteins or uric acid crystals. Oligodendrocyte Dendrogram: A chart showing relationship among entities in a form resembling branches of a tree. The transduced mosquitos cannot support the replication and thus do not transmit the virus. It is made of Ficoll-400 (a non-ionic synthetic sucrose polymer), polyvinylpyrrolidone (an insoluble material removing phenolic impurities) and bovine serum albumin at a concentration of 2. Densitometry: Optical detection of increased or decreased amounts of a substance in a solution or in solid medium. Density Gradient Centrifugation: the separation of subcellular organelles or macromolecules on the basis of their density (see. Among cellular organelles nuclei sediment fastest, then chloroplasts and mitochondria occupy the highest position in the centrifuge tube. For the separation of organelles either sucrose or percoll (polyvinylpyrrolidone-coated silica) are used most commonly. Density gradient centrifugation Density Labeling: By growing cells first in dense (heavy isotope) medium. Depression 491 Dentin Dysplasia: In dentin dysplasia the pulp is absent or poorly developed, the root canal is frequently empty and/or enlarged, and the bluish teeth is spontaneously lost. Dentinogenesis Imperfecta: the dominant condition is encoded in human chromosome 4q21. Denver Classification: this classification of human chromosomes in 1960, arranged the chromosomes into 7 groups (A to G) on the basis of decreasing length and arm ratio. Dependovirus: Dependovirus replicates only in the presence of a co-infecting helper virus. It is frequently associated with glucocorticoid over-production that may lead to hippocampal atrophy. The therapy may involve serotonin re-uptake inhibitor drugs, such as Prosac (fluoxetine). Low activity of serotoenergic neurotransmission results in depression (dysphoria) whereas high activity causes euphoria. Preliminary results indicate that in treatment-resistant depression the subgenual cingulate brain region (the cingulate gyrus is just above the middle of the corpus callosum; see diagram) is metabolically over-active. Some mentally ill persons suffering from severe depression contributed a great deal to human culture like Vincent van Gogh the great Dutch painter. The highly acclaimed and yet often rejected great Austrian composer and performer Robert A. Schumann suffered from periodic despair among periods of great achievement and spent the last two and half years of his life in a mental asylum. Depression Derivative: Mathematically, it is a function f of a function f whose value at any point x1 in the domain of f (see formula) if such limit exists (see. Dermatan Sulfate: Glucosaminoglucan; repeating units of disaccharides, generally acetyl-galactosamines linked to an iuduronic acid. Dermatoglyphics: the examination of dermal ridges and creases on fingers, toes, palms and soles for the purpose of identification, diagnosis and forensic investigations. Dermatome: the cell layer that generates the mesenschymal connective layer of skin. The procollagen peptidase that cleaves a peptide from the N-terminus of the chains is defective causing disorganized, poor fiber formation resulting in extreme brittleness of the hide. At such sites the depurination rate is several-fold higher than in other areas of the genome.
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A simple rule for axon outgrowth and synaptic competition generates realistic connection lengths and filling fractions medications kosher for passover buy synthroid 25 mcg with amex. Effects of surgical levels of propofol and sevoflurane anesthesia on cerebral blood flow in healthy subjects studied with positron emission tomography symptoms torn rotator cuff proven 200mcg synthroid. Evaluating causal relations in neural systems: Granger causality 4 medications at walmart order 100mcg synthroid with visa, directed transfer function and statistical assessment of signifi cance medicine x stanford order synthroid 125mcg on-line. The pervasiveness of lIf scaling in speech reflects the metastable basis of cognition. Toward a complementary neuroscience: Metastable coordina tion dynamics of the brain. Activity and functional connectivity of inferior frontal cortex associated with response conflict. Keep your options open: An information-based driving principle for sensorimotor systems. Directionality in the history of life: Diffusion from the left wall or repeated scaling of the right? An investigation of functional and ana tomical connectivity using magnetic resonance imaging. A framework for the stochastic generation of large scale neuronal networks with realistic neuron morphologies. Global relationship between anatomical connectivity and activ ity propagation in the cerebral cortex. Mul timodal characterisation of cortical areas by multivariate analyses of receptor binding and connectivity data. Network participation indices: Characterizing component roles for information processing in neural networks. Online retrieval, processing, and visualization of primate connectivity data from the CoCoMac database. Disturbed structural connectivity in schizophrenia-Primary factor in pathology or epiphenomenon? The cytoarchitectonic structure of the cerebral cortex of Ateles: A critical examination of architectonic studies. Edge of chaos and prediction of computational performance for neural microcircuit models. The role of anterior cingulate cortex in working memory is shaped by functional connectivity. Synchronized activity in prefrontal cortex during anticipation of visuomotor processing. Widespread functional disconnectivity in schizophrenia with resting-state functional magnetic resonance imaging. Intracortical connectivity of pyramidal and stellate cells: Esti mates of synaptic densities and coupling symmetry. Long-range temporal correlations and scaling behavior in human brain oscillations. Stimulus induced change in long-range temporal correlations and scaling behaviour of sensorimotor oscillations. Transgenic strategies for com binatorial expression of fluorescent proteins in the nervous system. The intrinsic electrophysiological properties of mammalian neurons: Insights into central system function. Spontaneous events outline the realm of possible sensory responses in neocortical popUlations. Real-time computing without stable states: A new framework for neural computation based on perturbations. Modeling stability in neuron and network function: the role of activity in homeostasis. Structural equation modeling and its application to network analysis in functional brain imaging. Changes in limbic and prefrontal functional interactions in a working memory task for faces. Differential functional connectiv ity of prefrontal and medial temporal cortices during episodic memory retrieval. Functional connectivity of the medial tem poral lobe relates to learning and awareness. Increased brain signal variability accompanies lower behavioral variability in development. Large-scale neurocognitive networks and distributed processing for attention, language, and memory. Array tomography: A new tool for imaging the molecular architecture and ultrastructure of neural circuits. Response to Comment on "Network motifs: Simple building blocks of complex networks" and "Superfamilies of evolved and designed networks. Long-term relation ships between synaptic tenacity, synaptic remodeling, and network activity. Nonrandom connectivity of the epileptic dentate gyrus predicts a major role for neuronal hubs in seizures. Human primary auditory cortex: Cytoarchitectonic subdivisions and mapping into a spatial refer ence system. Interhemispheric correla tions of slow spontaneous neuronal fluctuations revealed in human sensory cortex. Time domains for spatial network development generate multiple-cluster small-world networks. Functional imaging with cellular reso lution reveals precise micro-architecture in visual cortex. Efficient network reconstruction from dynamical cascades identi fies small-world topology of neuronal avalanches. Uncovering the overlapping community struc ture of complex networks in nature and society. Towards ultra-high reso lution fibre tract mapping of the human brain-registration of polarized light images and reorientation of fibre vectors. Transcranial magnetic stimulation in cognitive neuroscience-Virtual lesion, chronometry, and functional connectivity. Maturation of white matter in the human brain: A review of magnetic resonance studies. Correlation of variability in structure with variability in synaptic connections of an identified interneuron in locusts. Mapping the Brain and Its Functions: Integrating Enabling Technologies into Neuroscience Research. DeveJopemental changes in visual object recognition between 1 8 and 24 months of age. Contribution of exploratory methods to the investigation of extended large-scale brain networks in functional M R I: Methodologies, results, and chal lenges. Avalanche dynamics of human brain oscillations: Relation to critical branching processes and temporal correlations. Failure to deactivate in the prefrontal cortex in schizophrenia: Dysfunction of the default mode network? Dynamic properties of network motifs contribute to biological network organization. Dynamic synchronization and chaos in an associative neural network with multiple active memories. Variability in locations of areas 9 and 46 and relationship to the Talairach coordinate system. Predictive coding in the visual cortex: A functional interpreta tion of some extra-classical receptive-field effects. Visuomotor integration is associated with zero time-lag synchronization among cortical areas. Examining the volume efficiency of the cortical architecture in a multi-processor network model. Neurophysiological architecture of functional magnetic resonance images of human brain. Whole Brain Emulation: A Roadmap, Technical Report #2008-3, Future of Humanity Institute, Oxford University.
However symptoms 3 dpo buy synthroid 200 mcg with mastercard, structural connections are not the only means by which neurons can causally affect the activity of other neurons treatment 1st degree heart block discount synthroid 200mcg overnight delivery. Another way in which neural states can cause other neural states is through the environment treatment shingles buy cheap synthroid 50 mcg on-line, as a result of bodily movement that causes changes in sensory inputs symptoms 9dp5dt discount 75 mcg synthroid mastercard. Historically, this point formed a key rationale for the cybernetic approach to brain function. Norbert Wiener noted that cybernetics must take into account the "circular processes, emerging from the nervous system into the muscles, and re-entering the nervous system through the sense organs" (Wiener, 1 948, p. Ross Ashby emphasized that organism and environment must be treated as a single system, and that "the dividing line [. Humberto Maturana and Francisco Varela extended the idea in a different direction, describing the brain as a "closed system in which neuronal activity always leads to neuronal activ ity," either through a network of interacting neurons or through linkages between sensors and effectors that extend through the environment. Environmental interactions thus further expand the available repertoire of functional brain networks. Much of this book has been devoted to the link between the topology of structural brain networks and the dynamic patterns of functional and effective connectivity they generate. To give a full account of these struc ture-function linkages, it does not suffice to focus only on the structure and physiology of the nervous system. The physiology of the organism as a whole profoundly affects brain structure and function. Examples for physiological links between brain and body are the metabolic coupling of neural tissue with surrounding glial cells and the cerebral vasculature, the circadian regulation of brain and behavior, and the actions of hor mones on neural circuits. In addition to these powerful physiological couplings between brain and body, the important roles of body and environment in shaping the statistics of neural events cannot be ignored. Sensors relay information about exogenous signals that perturb network states of the brain, and network activity triggers effectors, resulting in bodily movement and the repositioning of sensors. Hence, the body forms a dynamic interface between brain and environment, enabling neural activity to generate actions that in turn lead to new sensory inputs. In this final chapter, I will argue that brain-body-environment interac tions can have profound effects on brain networks on both slow and fast time scales. These interactions are essential for natural sensing and mul timodal perception, and they are integral components of cognitive and social development. Brain-body-environment interactions can be con ceptualized as an extension of functional connectivity beyond the bound aries of the physical nervous system. Approaches from dynamical system and information theory provide a 307 Brain and Body A I i " Cognitive. Thc brain is divided into several components primarily conccrned with sensory, cognitive, and motor function, as well as information related to the internal state of the organism. Embodi ment, Intel ligence, and Morphology Complex behavior can arise from even the simplest of processing mecha nisms, provided these mechanisms are expressed in relation to an exter nal environment. Moving, turning and pausing, avoiding pebbles and seaweed, traveling over and across uneven surfaces, its path is anything but straight. However, this complexity is not a result of complex internal processing on the part of the ant. Rather, the complexity emerges from the interaction of the ant with its environment, the irregularities of the terrain and the abundance of obstacles. The apparent complexity of its behavior over time is largely a reflection of the complexity of the environment in which it finds itself. While the agents are extremely simple in their internal construction, once they are put into a "natural environment," often surprising patterns of behavior can arise. Complex behavior is the result of their interaction, not the end product or readout of centralized control. The coupling between brain, body, and environment has become a cornerstone of the theoretical framework of "embodied cognition. In both examples shown here a single sensor is connected to a single motor (driving a wheel), but the arrangement of the connections differs. In one case the vehicle will turn away from a light source while in the other it will approach it. Most theories of embodied cognition incorporate the notion that coher ent, coordinated, or intelligent behavior results from the dynamic inter actions between brain, body, and environment (Chiel and Beer, 1997; Pfeifer and Scheier, 1999;! Cognition does not occur all in the head-instead it stretches beyond the boundaries of the nervous system. Andy Clark has made a compelling argument that the minds of highly evolved cognitive agents extend into their environments and include tools, symbols, and other artifacts that serve as external substrates for representing, structuring, and performing mental operations (Clark, 2008). If this view of cognition as extending into body and world is correct, then cognition is not "brain bound" but depends on a web of interactions involving both neural and nonneural elements. The networks of the brain fundamentally build on this extended web that binds together perception and action and that grounds internal neural states in the external physical world. Turning away from the prevailing paradigm of centralized control, Rodney Brooks argued that "coherent intelligence can emerge from independent subprocesses interacting in the world" (Brooks, 1991, p. Hence, the design of intelligent systems requires working with "complete agents," fully embodied systems that are autonomous in their actions and are situated and embedded in an environment. Brooks envisioned a modular rather than serial organi zation for the internal control architecture, in which each module has access to sensory input and motor output, and where coordinated behav ior emerges from the interaction of these modules meditated by both brain and body, situated in the real world. Variations of decentralized control have been successfully implemented in robot models of various types of movement and locomotion (walking, running, crawling, etc. Many of the robot models employed in this work were directly inspired by specific biological systems (Pfeifer et aI. One such model involved the construction of a humanoid robot equipped with sensors and effectors for real-world sensorimotor activity, and a modular control system for vision and sound, balance and posture, recognition and motor control (Brooks et aI. What all these models and robots have in common is that they act autonomously in the real world. Building such systems is extraordinarily revealing about the relations between neural control and bodily action, the role of material properties and movements of sensors in delivering useful information, and the dependency of cogni tive processes on sensorimotor interactions. They are subject to physical laws that govern the function of their control architectures as well as their bodies. They act on their environment and, through their actions, generate sensory inputs. Their brains and bodies form a single dynamical system with attractor states that are configured partly through interactions with the environment. Finally, their body joins in the task of information processing by performing functions that otherwise would 311 B rain and Body have to be performed by the brain. This last property, which Pfeifer refers to as "morphological computation," is illustrated in figure 1 4. As a result, its movements appear sluggish, stiff, and unbiological, and its algorithms are slow to adapt to changes in terrain, surface properties, physical load, or energy supply. In contrast, animals exploit not only neural control but also the physical and material properties of their bodies to achieve stable and adaptive motion. The compliant "hardware" of arms and legs, their sensor-rich muscles, tendons, and joints, participate in the dynamics of movement and promote stability and flexibility. This aspect of morpho logical computation can also be exploited by mechanical agents or robots that incorporate elastic joints, flexible materials, and a control architec ture that models body and brain as an integrated dynamical system. To achieve flexible control, such a system naturally exploits the processing capacities of brain networks (and thus of brain morphology) as well as the material properties of the body and its coupling to the physical world. As Rolf Pfeifer has argued, intelligence is not only a function of neural processing or, more generally, of a set of clever control algorithms. Intelligence depends not only on the architecture of the brain but on the architecture of brain and body-brain and body evolve together. Recall that morpho logical considerations, not of the body but of the brain itself, were a major focus of an earlier chapter (chapter 7). Not only is the physical structure of the brain inseparable from that of the body and its sensorimotor repertoire, its dynamics and functional networks are continually modulated by interactions with the environ ment. Before we turn to an emerging theoretical framework for body brain interactions that builds on information theory and complex networks, let us examine how some of the neural mechanisms that under lie sensory processes, multimodal perception, cognitive development, and social interactions relate to embodied cognition. From Natural Sensing to Social Interactions Sensation and perception result from motion and action within the physi cal world. Instead, they actively explore their environments, and their motor activity gener ates and selects sensory inputs (Ahissar and Arieli, 2001; Kleinfeld et aI. Active movement o f receptor arrays i n visual, auditory, and tactile systems creates variations in spatiotemporal pat terns of stimulus energy, enhances spatial and temporal detail, and pre vents receptor adaptation.
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