Search

Neurons and glia represent the fundamental building blocks orchestrating nervous systems. Their properties are determined by a highly complex cellular and molecular machinery that is subject to continued activity-dependent modification. Indeed, activity of the nervous system involves a constant reciprocal interplay between genes, the encoded proteins, and the resulting cellular activity patterns and neural circuitry that governs behavior. Individual cells are only grains of sand within the huge and highly structured nervous systems. This chapter briefly investigates principle cellular and molecular mechanisms underlying the cellular dynamics of the nervous system. It serves as a general introduction to the chapters following where individual mechanisms are elucidated in detail regarding specific physiological or pathophysiological processes.

Investigations of human laterality suggest motor preference is not arbitrary, but rather represents an evolutionary bias stemming from the asymmetric organization of underlying neural function for skilled action. The most prominent manifestation of lateralized motor behavior in humans is right-handedness. While human right-handedness provides a highly reliable marker for the brain organization of left hemisphere language function, the causal evolutionary link between the two remains highly controversial. Once considered a unique hallmark of human evolution, structural neuroanatomical investigations have now revealed homologous asymmetric language regions (larger left hemisphere) in great apes, providing evidence for a common mechanism underlying communication processes in humans and apes. However, whether this translates into a handedness bias in great apes remains highly controversial. This chapter discusses the unique characteristics of human and non-human primate handedness within an evolutionary framework and explores new manual laterality findings, celebrating the emergence of multimodal, quantitative methodologies aimed at bridging the gap between studies of brain and behavior.

To calculate the experimental data of indexes with computer through the multi-objective decision-making, and then to make the comprehensive evaluation of effects of different Chinese Medicines combined with Bone Mesenchymal Stem Cells(BMSCs) transplantation on cerebral ischemia rats based on analytic hierarchy process(AHP). BMSCs were implanted via rats carotid artery. Rats general neural function, cerebral infarction size and brain water ratio were detected and weights of indexes were calculate by using AHP. Weight of Rhubarb aglycone was the largest in 1 w groups. In 2 w groups, Naomaitong was the largest. In 4 w groups, Rhubarb aglycone and Naomaitong combined with BMSCs transplantation were larger. It was indicated that It was feasible to make a comprehensive evaluation of effects through comparing weight indexes of experimental data by using AHP, and the combination of Chinese medicines and BMSCs transplantation showed more significant effects following the prolongation of BMSCs transplantation.

Public debate about electronic implants for the restoration or modulation of disturbed neural function has controversial aspects and it is loaded with baseless expectations and probably unwarranted fears.

Dyslexia has been studied from many angles. Researchers have obtained seemingly contradictory results and created widely varying theories and treatments. A complete understanding of dyslexia requires recognition of neurological and psychological components and their interaction, and could therefore benefit from a complex systems approach. This paper surveys and synthesizes results from many theoretical, experimental, and clinical approaches to dyslexia, including Galaburda, Davis, Geiger, and Merzenich. The magnocellular hypothesis combined with the Davis theory of “triggers” appear to explain nearly every experimental result, observation, and successful treatment of which the author is aware. Dyslexia can be understood as an accretion of simple symptoms in multiple sensory modalities, each symptom having the same neurological basis; each individual has a different combination of symptoms, and the symptoms are created and maintained through mental/psychological interaction with the individual’s efforts to perform. There is strong observational evidence, confirmed by pilot studies carried out by the author, that the symptoms can change momentarily. Although such rapid change is not recognized by many dyslexia researchers, it has been demonstrated with PET scans in the case of stuttering; this finding is crucial to a full understanding of the interaction between neural function and mental state. The recognition of the diversity of symptoms, their common neurological basis, and their extreme plasticity in response to high-level mental state, may help to focus research and to develop increasingly effective and rapid treatments.

The nervous system is designed to produce behavior, and so behavioral analysis is the ultimate assay of neural function. In this chapter we provide an overview of the behavior of rodents. We also provide references for testing details. Most of the behavioral methodology comes from research on rats, but the ethograms of rodents are similar enough to allow for generalization of the methods, if not many aspects of behavior, to other species. The testing method can be conceive of as having a number of stages, sequentially involving the description of: (I) general appearance, (II) sensorimotor behavior, (III) immobility and its reflexes, (IV) locomotion, (V) skilled movement, (VI) species-specific behaviors, and (VII) learning. For convenience, tables summarizing each class of behaviors are given in the relevant sections that follow.

There is considerable evidence that changes in common electrophysiologic recordings, such as those of sensory evoked potentials, do not provide reliable information about changes in intracranial pressure (ICP). Several studies in animals (Bothe et al., 1993) as well as in human (Konasiewicz et al., 1994; Moulton et al., 1994) have shown that changes in sensory evoked potentials (somatosensory evoked potentials (SSEP), brainstem auditory evoked potentials (BAEP), or visual evoked potentials (VEP) are poorly correlated with changes (elevation) in ICP. Some studies, in which sensory evoked potentials were recorded simultaneously with ICP, have shown that sometimes an elevated ICP does not affect neural function but sometimes it is accompanied by changes in sensory evoked potentials, thus an indication of altered neural function. Only when an elevated ICP affects neural function as a result of ischemia or other forms of injury to neural tissue (perhaps deformation of brain tissue) are there consistent changes in specific evoked potentials (Moulton et al., 1994). There is experimental evidence that changes in sensory evoked potentials are closely related to changes (decrease) in arteriovenous oxygen content (AVDO2) (Moulton et al., 1994), which is a sign of a decrease in cerebral oxygenation. Thus an elevated ICP does not seem to play a direct role in the deterioration of neural function.

Hyperosmolar agents are often administered to obtain a rapid decrease in elevated intracranial pressure (ICP). Numerous workers have reported the effects of glycerol but little is known about its actions on cerebral circulation in the area of peritumoral edema and neural function. This study was undertaken to elucidate the effect of glycerol on regional cerebral blood flow (rCBF) and neural function in patients with intracranial space occupying lesions.

Since the classical studies of Lorente de No (1947) on peripheral nerves numerous investigations have been devoted to the effects of carbon dioxide on other neural structures and functions (Speckmann and Caspers 1974; Caspers et al. 1987). One general aspect in the variety of specific results obtained in these studies is that the actions of CO2 turn out to be partly excitatory, partly depressive in nature. The following presentation focuses on this particular problem. In a first section some examples of different CO2 effects on EEG waves as well as on the membrane potential and discharge frequency of single neurons are described. A fmal section then deals with the mechanisms possibly involved in generating opposite responses.

This review seeks to focus attention on the potential complexity of the information conveyed by the release of chemicals during the synaptic or secretory activity of neurons. The importance of peptides in the control of neural function is underscored by the growing research in four different areas: (a) co-localization of peptides with classical neurotransmitters (Lundberg and Hokfelt 1983; Lloyd et al. 1987); (b) demonstration of peptidergic neurons in all parts of the central nervous systems of vertebrate and invertebrate species by immunohistochemical and biochemical approaches (e.g., Swanson and Sawchenko 1983; Siwicki et al. 1987; Kaldany et al. 1985); (c) cases of classical neurosecretory cells (e.g., those of the vertebrate hypothalamus, Swanson and Kuypers 1980) which do not have their processes restricted to neurohemal organs (e.g., the neurohypophysis), but participate in widespread interactions within the central nervous system; and (d) a spectrum of activities ranging from neurotransmitter to neurohormonal processes and their involvement in complex behaviors (Koob and Bloom 1982). Further, in all known instances, those neurons known to secrete peptides as either the major or a co-localized product never secrete a single peptide, but rather a mixture of peptides.

In head-injury patients, vasogenic edema results from damage to cerebral cortical vessels, which permits the extravasation of plasma ultrafiltrate into the surrounding extracellular space. Although the electrophysiological effects of white matter edema have been studied [3, 6, 8], it remains unclear whether the exudation of plasma into the cerebral cortex results in any direct impairment of cortical function. The present experiment was carried out to study the effects of cortical edema and ischemia on cortical neural activity. The air-exposure edema used does not induce direct cortical injury comparable to that caused by cold injury or brain compression. Effects of a high dose of steroid on cortical neural function were also investigated.

Models for neural function have suggested new ways of designing special-purpose processors. These electronic neural networks mix analog and digital processing. For some applications neural networks may have speed advantages over conventional architectures. This paper provides an introduction to electronic neural computing and describes circuit implementations.

Alzheimer’s disease appears to be associated with the loss of the cholinergic innervation to cortical and limbic areas of the brain. In attempting to produce an in vitro model for studying Alzheimer’s disease, therefore, one feature must be the presence of a deficit in cholinergic neuronal function.

For the last century and a half, the cerebellum (CB) has been known as the part of the brain that performs the most lucid global function: motor coordination (cf. classical treatises by Flourens, 1842; Sherrington, 1906; Holmes, 1939: Dow and Moruzzi, 1958; or recent review in Towe and Luschei, 1981). Experimentalists have also been enticed by the ”crystalline” elegance of the microarchitecture of this remarkable neuronal circuitry (cf. pioneering studies by Purkinje, 1837; Golgi, 1874; Ramon y Cajal, 1911; and modern analyses by Palkovits et al., 1972; Oscarsson, 1973; Palay and ChanPalay, 1974; Voogd and Bigare, 1980; and Hillman this volume). As a result, the CB has been studied by now in more detail than virtually any other part of the brain (cf. reviews in Eccles et al., 1967; Llinas, 1969a, 1981; Palay and Chan-Palay, 1982). Based on these pillars of general and detailed knowledge, attempts have also been made to erect a structure in order to show how knowledge of the functioning may be built into an understanding of neural function (cf. reviews in Szentagothai, 1968; Pellionisz, 1979a; Llinas and Simpson, 1981; Ito, 1984). Such understanding may ultimately be utilized in medicine (Mann, 1981; Dichgans this volume, Gilman this volume), as well as in novel applications, eg. in the construction of brain-like machines (Albus, 1981; Marr, 1982; Loeb, 1983; Pellionisz, 1983b).

The concept of a “chemode”, a device to deliver medications to specific areas of the brain is an old one. Such a system would make control of neural function possible through the application of specific chemicals in a precise fashion to a limited region. This concept has now become a practical reality for use in man by the development of programmable implanted drug pumps. Coupled with catheter systems and stereotaxic placement, the neural environment can be changed in virtually any region. The initial neurosurgical application of this device took place three years ago, when a Medtronic pump was used to deliver morphine into the lumbar subarachnoid space to relieve cancer pain (Penn et al. 1984). The diffusion of morphine into the dorsal cord from the cerebral spinal fluid provided complete pain control without the undesirable central side effects. The dose could be precisely adjusted to the patient’s needs.

Potential intelligence and actual intellective ability are not quite the same. Intellective ability falls short of intellective potential for a number of reasons. When we analyze the data of Figures 1, 2, and 3, we need to determine whether we can make inferences about the aging of potential intellect. It is one thing to say that a measured ability of intellective function declines with age. It is quite another thing to say that potential intelligence or capacity declines. The latter insists upon, or at least strongly suggests, an age change in neural function; the former may or may not be based upon such a change. Again, Wechsler was very clear in his evaluation. He wrote, “We have advanced the hypothesis that the decline of mental ability with age is part of the general organic process which constitutes the universal phenomenon of senescence...” (1958, p. 205).

Through the substance of the core of the brain stem runs a continuous column of neurons and fibers known as the reticular formation. This system bridges the gap, both spatially and phylogenetically, between spinal reflexive levels and the great telencephalic tissue masses (cerebral cortices) which apparently represent the most mature expression of neural function. Compared to the latter, the reticular core is archaic both historically and histologically. However, despite the absence of a rigorously stated structural theme and an axial location, sheltered from direct contact with any primary sensory input, the system is now known to exert a remarkable range of control upon the neuraxis and upon the organism as a whole. These functions include: determination of operational modes; gating of all sensory influx; participation at all levels of cortical function, including read out for cortical differentiative and comparative processes; gain manipulation of motor output; multilevel control over most visceral functions; and the active manipulation of a spectrum of states of consciousness from deep coma to maximal vigilance. This panoramic range of activities suggests that the reticular core serves a keystone role in brain function and combines, perhaps in larval form, the prototype of every neural process. If so, it should serve as a convenient paradigm upon which brain system models may be shaped.