Flexible couplings: diffusing neuromodulators and adaptive robotics

Recent years have seen the discovery of freely diffusing gaseous neurotransmitters, such as nitric oxide (NO), in biological nervous systems. A type of artificial neural network (ANN) inspired by such gaseous signaling, the GasNet, has previously been shown to be more evolvable than traditional ANNs when used as an artificial nervous system in an evolutionary robotics setting, where evolvability means consistent speed to very good solutions¿here, appropriate sensorimotor behavior-generating systems. We present two new versions of the GasNet, which take further inspiration from the properties of neuronal gaseous signaling. The plexus model is inspired by the extraordinary NO-producing cortical plexus structure of neural fibers and the properties of the diffusing NO signal it generates. The receptor model is inspired by the mediating action of neurotransmitter receptors. Both models are shown to significantly further improve evolvability. We describe a series of analyses suggesting that the reasons for the increase in evolvability are related to the flexible loose coupling of distinct signaling mechanisms, one ¿chemical¿ and one ¿electrical.

Neutral coding - A report based on an NRP work session

Neural coding by impulses and trains on single and multiple channels, and representation of information in nonimpulse carrier

Evidence for Information Processing in the Brain

Many cognitive and neuroscientists attempt to assign biological functions to brain structures. To achieve this end, scientists perform experiments that relate the physical properties of brain structures to organism-level abilities, behaviors, and environmental stimuli. Researchers make use of various measuring instruments and methodological techniques to obtain this kind of relational evidence, ranging from single-unit electrophysiology and optogenetics to whole brain functional MRI. Each experiment is intended to identify brain function. However, seemingly independent of experimental evidence, many cognitive scientists, neuroscientists, and philosophers of science assume that the brain processes information as a scientific fact. In this work we analyze categories of relational evidence and find that although physical features of specific brain areas selectively covary with external stimuli and abilities, and that the brain shows reliable causal organization, there is no direct evidence supporting the claim that information processing is a natural function of the brain. We conclude that the belief in brain information processing adds little to the science of cognitive science and functions primarily as a metaphor for efficient communication of neuroscientific data

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 323)

This bibliography lists 125 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during April, 1989. Subject coverage includes; aerospace medicine and psychology, life support systems and controlled environments, safety equipment exobiology and extraterrestrial life, and flight crew behavior and performance

Experimental approaches to understanding the role of protein phosphorylation in the regulation of neuronal function

Studies by Earl Sutherland and his colleagues on hormonal regulation of the breakdown of glycogen in liver resulted in the discovery that the first step in the action of many hormones is to increase the synthesis of cAMP by activating adenylate cyclase (Raft et al 1957, Sutherland & Rall 1958, Robison et al 1968). It was later established that cAMP exerts its effects by stimulating protein kinases that catalyze the phosphorylation of specific functional proteins and thereby regulate their activity (Walsh et al 1968, Kuo & Greengard 1969, Krebs & Beavo 1979). The discovery that the brain contains a high concentration of cAMP-dependent protein kinase led to the proposal that protein phosphorylation might play an important role in regulation of neuronal properties by neurotransmitters and neurohormones (Miyamoto et al 1969). In particular, it seemed that protein phosphorylation, which usually takes place on a time scale of hundreds of milliseconds or longer, might be a mechanism underlying relatively long-lasting changes in neuronal properties such as "slow" changes in post-synaptic potentials (McAfee & Greengard 1972), changes in the rate of transmitter synthesis (Morgenroth et al 1975), or changes in gene expression (Klein & Berg 1970). The biochemists and neurobiologists who took up the study of brain protein phosphorylation hoped to gain insight into some of the mechanisms underlying changes in neuronal excitability and synaptic efficacy and also, perhaps, into processes that govern the development of various neuronal types during the formation of the nervous system. This line of research was bolstered by the findings that the brain contains not only high concentrations of protein kinases, but also protein phosphatases, adenylate cyclase, and phosphodiesterase (Greengard 1976), and also by the discovery that several neurotransmitters stimulate the synthesis of second messengers such as cyclic AMP and cyclic GMP by binding to specific receptors on the surfaces of neurons (for reviews see Nathanson 1977, Greengard 1981)

Aerospace Medicine and Biology: A continuing bibliography with indexes (supplement 290)

This bibliography lists 125 reports, articles and other documents introduced into the NASA scientific and technical information system in October 1986

What can developmental disorders tell us about the neurocomputational constraints that shape development? the case of Williams syndrome

The uneven cognitive phenotype in the adult outcome of Williams syndrome has led some researchers to make strong claims about the modularity of the brain and the purported genetically determined, innate specification of cognitive modules. Such arguments have particularly been marshaled with respect to language. We challenge this direct generalization from adult phenotypic outcomes to genetic specification and consider instead how genetic disorders provide clues to the constraints on plasticity that shape the outcome of development. We specifically examine behavioral studies, brain imaging, and computational modeling of language in Williams syndrome but contend that our theoretical arguments apply equally to other cognitive domains and other developmental disorders. While acknowledging that selective deficits in normal adult patients might justify claims about cognitive modularity, we question whether similar, seemingly selective deficits found in genetic disorders can be used to argue that such cognitive modules are prespecified in infant brains. Cognitive modules are, in our view, the outcome of development, not its starting point. We note that most work on genetic disorders ignores one vital factor, the actual process of ontogenetic development, and argue that it is vital to view genetic disorders as proceeding under different neurocomputational constraints, not as demonstrations of static modularity

The role of the cerebellum in unconsciuos and conscious processing of emotions: a review

Studies from the past three decades have demonstrated that there is cerebellar involvement in the emotional domain. Emotional processing in humans requires both unconscious and conscious mechanisms. A significant amount of evidence indicates that the cerebellum is one of the cerebral structures that subserve emotional processing, although conflicting data have been reported on its function in unconscious and conscious mechanisms. This review discusses the available clinical, neuroimaging and neurophysiological data on this issue. We also propose a model in which the cerebellum acts as a mediator between the internal state and external environment for the unconscious and conscious levels of emotional processing