Information Capacity of Vesicle Release in Neuro-Spike Communication

© 1997-2012 IEEE. Information transmission in the nervous system is performed through the propagation of spikes among neurons, which is done by vesicle release to chemical synapses. Understanding the fundamentals of this communication can lead to the implementation of bio-inspired nanoscale communication paradigms. In this letter, we utilize a realistic pool-based model for vesicle release and replenishment in hippocampal pyramidal neurons and evaluate the capacity of information transmission in this process by modeling it as a binary channel with memory. Then, we derive a recurrence relation for the number of available vesicles, which is used to find successful bit transmission probabilities and mutual information between input and output. Finally, we evaluate the spiking probability that maximizes mutual information and derive the capacity of the channel

Detecting and Estimating Signals over Noisy and Unreliable Synapses: Information-Theoretic Analysis

The temporal precision with which neurons respond to synaptic inputs has a direct bearing on the nature of the neural code. A characterization of the neuronal noise sources associated with different sub-cellular components (synapse, dendrite, soma, axon, and so on) is needed to understand the relationship between noise and information transfer. Here we study the effect of the unreliable, probabilistic nature of synaptic transmission on information transfer in the absence of interaction among presynaptic inputs. We derive theoretical lower bounds on the capacity of a simple model of a cortical synapse under two different paradigms. In signal estimation, the signal is assumed to be encoded in the mean firing rate of the presynaptic neuron, and the objective is to estimate the continuous input signal from the postsynaptic voltage. In signal detection, the input is binary, and the presence or absence of a presynaptic action potential is to be detected from the postsynaptic voltage. The efficacy of information transfer in synaptic transmission is characterized by deriving optimal strategies under these two paradigms. On the basis of parameter values derived from neocortex, we find that single cortical synapses cannot transmit information reliably, but redundancy obtained using a small number of multiple synapses leads to a significant improvement in the information capacity of synaptic transmission

The spontaneous formation of stereotypes via cumulative cultural evolution

All people share knowledge of cultural stereotypes of social groups—but what are the origins of these stereotypes? We examined whether stereotypes form spontaneously as information is repeatedly passed from person to person. As information about novel social targets was passed down a chain of individuals, what initially began as a set of random associations evolved into a system that was simplified and categorically structured. Over time, novel stereotypes emerged that not only were increasingly learnable but also allowed generalizations to be made about previously unseen social targets. By illuminating how cognitive and social factors influence how stereotypes form and change, these findings show how stereotypes might naturally evolve or be manipulated

Energy-efficient coding with discrete stochastic events

We investigate the energy efficiency of signaling mechanisms that transfer information by means of discrete stochastic events, such as the opening or closing of an ion channel. Using a simple model for the generation of graded electrical signals by sodium and potassium channels, we find optimum numbers of channels that maximize energy efficiency. The optima depend on several factors: the relative magnitudes of the signaling cost (current flow through channels), the fixed cost of maintaining the system, the reliability of the input, additional sources of noise, and the relative costs of upstream and downstream mechanisms. We also analyze how the statistics of input signals influence energy efficiency. We find that energy-efficient signal ensembles favor a bimodal distribution of channel activations and contain only a very small fraction of large inputs when energy is scarce. We conclude that when energy use is a significant constraint, trade-offs between information transfer and energy can strongly influence the number of signaling molecules and synapses used by neurons and the manner in which these mechanisms represent information

Delusion, Proper Function, and Justification

Among psychiatric conditions, delusions have received significant attention in the philosophical literature. This is partly due to the fact that many delusions are bizarre, and their contents interesting in and of themselves. But the disproportionate attention is also due to the notion that by studying what happens when perception, cognition, and belief go wrong, we can better understand what happens when these go right. In this paper, I attend to delusions for the second reason—by evaluating the epistemology of delusions, we can better understand the epistemology of ordinary belief. More specifically, given recent advancements in our understanding of how delusions are formed, the epistemology of delusions motivates a proper functionalist account of the justification of belief. Proper functionalist accounts of the justification of belief hold that whether a belief is justified is partly determined by whether the system that produces the belief is functioning properly. Whatever pathology is responsible for delusion formation, restoring it to its proper function resolves the epistemic condition, an effect which motivates proper functionalism

The Informational Model of Consciousness: Mechanisms of Embodiment/Disembodiment of Information

It was shown recently that information is the central concept which it is to be considered to understand consciousness and its properties. Arguing that consciousness is a consequence of the operational activity of the informational system of the human body, it was shown that this system is composed by seven informational components, reflected in consciousness by corresponding cognitive centers. It was argued also that consciousness can be connected to the environment not only by the common senses, but also by a special connection pole to the bipolar properties of the universe, allowing to explain the associated phenomena of the near-death experiences and other special phenomena. Starting from the characteristics of this model, defined as the Informational Model of Consciousness and to complete the info-communication panorama, in this paper it is analyzed the info-connectivity of the informational system with the body itself. The brain areas where the activity of each informational component are identified, and a definition of consciousness in terms of information is proposed. As the electrical connectivity by means of the nervous system was already proved, allowing the application of the analysis and developing tools of the information science, a particular attention is paid to the non-electrical mechanisms implied in the internal communication. For this, it is shown that the key mechanisms consists in embodiment/disembodiment processes of information during the inter and intra communication of the cells. This process can be modeled also by means of, and in correlation with specific concepts of the science and technology of information, referred to network communication structures, and is represented by epigenetic mechanisms, allowing the acquired trait transmission to the offspring generation. From the perspective of the informational model of consciousness, the human organism appears therefore as a dynamic reactive informational system, actuating in correlation with matter for adaptation, by embodiment/disembodiment processes of information

The Silent Voice of Those Who are no Longer: Transgenerational Transmission of Information from the Perspective of the Informational Model of Consciousness

The “nature or nurture” problem concerning the debate on the innate features with respect to the acquired ones is approached in terms of information, from the perspective of the Informational Model of Consciousness. This model reveals seven distinct informational systems reflected in consciousness as informational centers, i.e. memory (Iknow-Ik), decisional info-operational center (Iwant-Iw), emotions (Ilove-Il), metabolic operations (Iam-Ia), genetic transmission (Icreate-Ic), genetic info-generation (Icreated-Icd) and the anti-entropic center (Ibelieve-Ib). Ib is a life-assisting beneficial center, because it is opposed to the entropic action of matter, eliminating or reducing the uncertainty characteristic of unknown possibilities to certainty, and inducing in this way the trust and confidence in own actions. The pro and contra arguments of the “nature or nurture” are shortly presented, noting the large range of divergent opinions and concepts on the approached problem. It is shown that the information concept acting both as informal and matter-related information, specifically referred to the embodiment/ disembodiment mechanisms for the transmission of information during the epigenetic processes, can coherently approach and explain the transgenerational transmission of the traits acquired during the life span of the predecessors. The concepts of tendency, affinity, propensity, predisposition, aptitude, vocation and talent, specific for inheritable properties described by Icd are discussed, pointing out the large pallet and variety of such concepts describing the evidences detected by external observers on the inherited behaviors, and that of self-perceived by the implicated individual, as a silent voice of whose are no longer. The external manifestation of such inherited features and traits depends on practice, because the characteristic operation of the nervous system and of epigenetic processes is based on repetition and/or intensive practice, but these are permanently guided by the silent voice of those who are no longer, with various signal intensities

Neurotoxicity

Neurotoxicity refers to the direct or indirect effect of chemicals that disrupt the nervous system of humans or animals. Numerous chemicals can produce neurotoxic diseases in humans, and many more are used as experimental tools to disturb or damage the nervous system of animals. Some act directly on neural cells, others interfere with metabolic processes on which the nervous system is especially dependent. Some disrupt neural function, others induce maldevelopment or damage to the adult nervous system. Perturbations may appear and disappear rapidly, evolve slowly over days or weeks and regress over months or years, or cause permanent deficits. Neurotoxicity is usually self-limiting after exposure ceases and rarely progressive in the absence of continued exposure, although there may be a significant delay between exposure and manifestation of neurotoxic effects