Evidence for Long-Timescale Patterns of Synaptic Inputs in CA1 of Awake Behaving Mice

Toward the unknown: consciousness and pain

Studies of consciousness are hindered by the complexity of the brain, but it is possible to study the consciousness of a sensation, namely pain. Three systems are necessary to experience pain: the somatosensory system conveys information about an injury to the thalamus where an awareness of the injury but not the painfulness emerges. The thalamus distributes the information to the affective system, which modulates the intensity of the pain, and to the cognitive system that imparts attention to the pain. Imaging of patients in pain and those experiencing placebo and hypnosis-induced analgesia shows that two essential cortical circuits for pain and attention are located within the anterior cingulate cortex. The circuits are activated when a high-frequency input results in the development of a long-term potentiation (LTP) at synapses on the apical dendrites of pyramidal neurons. The LTP acts via α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptors, and an anterior cingulate cortex-specific type-1 adenylate cyclase is necessary for both the LTP and the pain. The apical dendrites form an extensive network such that the input from serious injuries results in the emergence of a local field potential. Using mouse models, I propose experiments designed to test the hypothesis that the local field potential is necessary and sufficient for the consciousness of pain.

In Vivo Whole-Cell Patch-Clamp Methods: Recent Technical Progress and Future Perspectives

Brain functions are fundamental for the survival of organisms, and they are supported by neural circuits consisting of a variety of neurons. To investigate the function of neurons at the single-cell level, researchers often use whole-cell patch-clamp recording techniques. These techniques enable us to record membrane potentials (including action potentials) of individual neurons of not only anesthetized but also actively behaving animals. This whole-cell recording method enables us to reveal how neuronal activities support brain function at the single-cell level. In this review, we introduce previous studies using in vivo patch-clamp recording techniques and recent findings primarily regarding neuronal activities in the hippocampus for behavioral function. We further discuss how we can bridge the gap between electrophysiology and biochemistry.

Advances in the automation of whole-cell patch clamp technology

Electrophysiology is the study of neural activity in the form of local field potentials, current flow through ion channels, calcium spikes, back propagating action potentials and somatic action potentials, all measurable on a millisecond timescale. Despite great progress in imaging technologies and sensor proteins, none of the currently available tools allow imaging of neural activity on a millisecond timescale and beyond the first few hundreds of microns inside the brain. The patch clamp technique has been an invaluable tool since its inception several decades ago and has generated a wealth of knowledge about the nature of voltage- and ligand-gated ion channels, sub-threshold and supra-threshold activity, and characteristics of action potentials related to higher order functions. Many techniques that evolve to be standardized tools in the biological sciences go through a period of transformation in which they become, at least to some degree, automated, in order to improve reproducibility, throughput and standardization. The patch clamp technique is currently undergoing this transition, and in this review, we will discuss various aspects of this transition, covering advances in automated patch clamp technology both in vitro and in vivo.