Physical principles for scalable neural recording

Simultaneously measuring the activities of all neurons in a mammalian brain at millisecond resolution is a challenge beyond the limits of existing techniques in neuroscience. Entirely new approaches may be required, motivating an analysis of the fundamental physical constraints on the problem. We outline the physical principles governing brain activity mapping using optical, electrical, magnetic resonance, and molecular modalities of neural recording. Focusing on the mouse brain, we analyze the scalability of each method, concentrating on the limitations imposed by spatiotemporal resolution, energy dissipation, and volume displacement. Based on this analysis, all existing approaches require orders of magnitude improvement in key parameters. Electrical recording is limited by the low multiplexing capacity of electrodes and their lack of intrinsic spatial resolution, optical methods are constrained by the scattering of visible light in brain tissue, magnetic resonance is hindered by the diffusion and relaxation timescales of water protons, and the implementation of molecular recording is complicated by the stochastic kinetics of enzymes. Understanding the physical limits of brain activity mapping may provide insight into opportunities for novel solutions. For example, unconventional methods for delivering electrodes may enable unprecedented numbers of recording sites, embedded optical devices could allow optical detectors to be placed within a few scattering lengths of the measured neurons, and new classes of molecularly engineered sensors might obviate cumbersome hardware architectures. We also study the physics of powering and communicating with microscale devices embedded in brain tissue and find that, while radio-frequency electromagnetic data transmission suffers from a severe power–bandwidth tradeoff, communication via infrared light or ultrasound may allow high data rates due to the possibility of spatial multiplexing. The use of embedded local recording and wireless data transmission would only be viable, however, given major improvements to the power efficiency of microelectronic devices

Roadmap on semiconductor-cell biointerfaces.

This roadmap outlines the role semiconductor-based materials play in understanding the complex biophysical dynamics at multiple length scales, as well as the design and implementation of next-generation electronic, optoelectronic, and mechanical devices for biointerfaces. The roadmap emphasizes the advantages of semiconductor building blocks in interfacing, monitoring, and manipulating the activity of biological components, and discusses the possibility of using active semiconductor-cell interfaces for discovering new signaling processes in the biological world

Complex Neuro-Cognitive Systems

Cognitive functions such as a perception, thinking and acting are based on the working of the brain, one of the most complex systems we know. The traditional scientific methodology, however, has proved to be not sufficient to understand the relation between brain and cognition. The aim of this paper is to review an alternative methodology – nonlinear dynamical analysis – and to demonstrate its benefit\ud for cognitive neuroscience in cases when the usual reductionist method fails

Life as an Explanation of the Measurement Problem

No consensus regarding the universal validity of any particular interpretation of the measurement problem has been reached so far. The problem manifests strongly in various Wigner's-friend-type experiments where different observers experience different realities measuring the same quantum system. But only classical information obeys the second law of thermodynamics and can be perceived solely at the holographic screen of the closed orientable two-dimensional manifold implied by Verlinde's and Landauer's mass-information equivalence equations. I conjecture that biological cell, as a dissipative structure, is the smallest agent capable of processing quantum information through its holographic screen and that this mechanism have been extended by natural evolution to endo- and exosemiosis in multicellular organisms, and further to language of Homo sapiens. Any external stimuli must be measured and classified by the cell in the context of classical information to provide it with an evolutionary gain. Quantum information contained in a pure quantum state cannot be classified, while incoherent mixtures of non-orthogonal quantum states are only partially classifiable. The concept of an unobservable velocity, normal to the holographic screen is introduced. It is shown that it enables to derive the Unruh acceleration as acting normal to the screen, as well as to conveniently relate de Broglie and Compton wavelengths. It follows that the perceived universe, is induced by the set of Pythagorean triples, while all its measurable features, including perceived dimensionality, are set to maximise informational diversity.Comment: This research is incomplete and partially incorrec