New types of polymeric membranes with molecular recognition sites for L-phenylalanine (L-Phe), 6-amino-1-propyluracil (APU), atrazine, and sialic acid have been prepared using the molecular imprinting approach. The membrane synthesis includes radical polymerization of ethylene glycol dimethacrylate (EDMA) and functional monomers in the presence of a template. Several compoundss-(diethylamino)ethyl methacrylate (DEAEM), methacrylic acid (MAA), allylamine (AA), and (4-vinylphenyl)boronic acidswere as functional monomers, which are able to form covalent, ionic, or hydrogen bonds with the corresponding templates. Template specific conductometric sensors, based on these polymers, were constructed and studied. An opposite response of covalently versus noncovalently imprinted membranes was demonstrated and discussed in detail. Sensors based on these materials could detect the target molecules at concentrations of 1-50 µM in solution. The high specificity and stability of these imprinted membranes render them promising alternatives to enzymes, antibodies, and other natural receptors usually used in sensor technology.

The development of modern neuroscience tools is critical for deciphering brain circuit organization and function. An important aspect for technical development is to enhance each technique's advantages and compensate for limitations. We developed a high-precision and fast functional mapping technique in brain slices that incorporates the spatial precision of activation that can be achieved by laser-scanning photostimulation with rapid and high-temporal resolution assessment of evoked network activity that can be achieved by voltage-sensitive dye imaging. Unlike combination of whole cell recordings with photostimulation for mapping local circuit inputs to individually recorded neurons, this innovation is a new photostimulation-based technique to map cortical circuit output and functional connections at the level of neuronal populations. Here we report on this novel technique in detail and show its effective applications in mapping functional connections and circuit dynamics in mouse primary visual cortex and hippocampus. Given that this innovation enables rapid mapping and precise evaluation of cortical organization and function, it can have broad impacts in the field of cortical circuitry.

Levi, R., P. Varona, Y. I. Arshavsky, M. I. Rabinovich, and A. I. Selverston. Dual sensory-motor function for a molluskan statocyst network. J Neurophysiol 91: 336 -345, 2004. First published September 24, 2003 10.1152/jn.00753.2003. In mollusks, statocyst receptor cells (SRCs) interact with each other forming a neural network; their activity is determined by both the animal's orientation in the gravitational field and multimodal inputs. These two facts suggest that the function of the statocysts is not limited to sensing the animal's orientation. We studied the role of the statocysts in the organization of search motion during hunting behavior in the marine mollusk, Clione limacina. When hunting, Clione swims along a complex trajectory including numerous twists and turns confined within a definite space. Search-like behavior could be evoked pharmacologically by physostigmine; application of physostigmine to the isolated CNS produced "fictive search behavior" monitored by recordings from wing and tail nerves. Both in behavioral and in vitro experiments, we found that the statocysts are necessary for search behavior. The motor program typical of searching could not be produced after removing the statocysts. Simultaneous recordings from single SRCs and motor nerves showed that there was a correlation between the SRCs activity and search episodes. This correlation occurred even though the preparation was fixed and, therefore the sensory stimulus was constant. The excitation of individual SRCs could in some cases precede the beginning of search episodes. A biologically based model showed that, theoretically, the hunting search motor program could be generated by the statocyst receptor network due to its intrinsic dynamics. The results presented support for the idea that the statocysts are actively involved in the production of the motor program underlying search movements during hunting behavior.

Levi R, Akanyeti O, Ballo A, Liao JC. Frequency response properties of primary afferent neurons in the posterior lateral line system of larval zebrafish. J Neurophysiol 113: 657-668, 2015. First published October 29, 2014 doi:10.1152/jn.00414.2014.-The ability of fishes to detect water flow with the neuromasts of their lateral line system depends on the physiology of afferent neurons as well as the hydrodynamic environment. Using larval zebrafish (Danio rerio), we measured the basic response properties of primary afferent neurons to mechanical deflections of individual superficial neuromasts. We used two types of stimulation protocols. First, we used sine wave stimulation to characterize the response properties of the afferent neurons. The average frequency-response curve was flat across stimulation frequencies between 0 and 100 Hz, matching the filtering properties of a displacement detector. Spike rate increased asymptotically with frequency, and phase locking was maximal between 10 and 60 Hz. Second, we used pulse train stimulation to analyze the maximum spike rate capabilities. We found that afferent neurons could generate up to 80 spikes/s and could follow a pulse train stimulation rate of up to 40 pulses/s in a reliable and precise manner. Both sine wave and pulse stimulation protocols indicate that an afferent neuron can maintain their evoked activity for longer durations at low stimulation frequencies than at high frequencies. We found one type of afferent neuron based on spontaneous activity patterns and discovered a correlation between the level of spontaneous and evoked activity. Overall, our results establish the baseline response properties of lateral line primary afferent neurons in larval zebrafish, which is a crucial step in understanding how vertebrate mechanoreceptive systems sense and subsequently process information from the environment. afferent neuron; lateral line; zebrafish; electrophysiology; frequency response; pulse stimulus

Sensory input plays a major role in controlling motor responses during most behavioral tasks. The vestibular organs in the marine mollusk Clione, the statocysts, react to the external environment and continuously adjust the tail and wing motor neurons to keep the animal oriented vertically. However, we suggested previously that during hunting behavior, the intrinsic dynamics of the statocyst network produce a spatiotemporal pattern that may control the motor system independently of environmental cues. Once the response is triggered externally, the collective activation of the statocyst neurons produces a complex sequential signal. In the behavioral context of hunting, such network dynamics may be the main determinant of an intricate spatial behavior. Here, we show that (1) during fictive hunting, the population activity of the statocyst receptors is correlated positively with wing and tail motor output suggesting causality, (2) that fictive hunting can be evoked by electrical stimulation of the statocyst network, and (3) that removal of even a few individual statocyst receptors critically changes the fictive hunting motor pattern. These results indicate that the intrinsic dynamics of a sensory network, even without its normal cues, can organize a motor program vital for the survival of the animal.

In a recent paper Prinz et al. (Nature Neurosci. 7, 1345-52 (2004) have addressed the fundamental question, whether neural systems are built with a fixed blueprint of tightly controlled parameters or in a way in which properties can vary largely from one individual to another, using a database modeling approach. In this article we examine the main conclusion that neural circuits indeed are built with largely varying parameters in light of our own experimental and modeling observations. We critically discuss the experimental and theoretical evidence including the general adequacy of database approaches for questions of this kind and come to the conclusion that the last word for this fundamental question has not yet been spoken.

Cockroaches respond to the approach of a predator by turning away and then running. Three bilateral pairs of giant interneurons are involved in determining the direction of the sensory stimulus and setting the turn direction. Each of these six interneurons has a different directional response to wind stimuli. We have tested whether these six cells use a winner-take-all mechanism to perform this directional determination: that is, each of these cells suppressing the motor response that each of the other cells promotes. Such a mechanism is found in similar behaviors of some other animals. By adding spikes to identified giant interneurons through intracellular stimulation during the sensory-induced behavior and analyzing the resulting directional leg movements, we find that a winner-take-all is not used in this system. Rather, directional determination appears to be based on collaborative calculation of direction by the giant interneurons as a group.

The idea of closed-loop interaction in in vitro and in vivo electrophysiology has been successfully implemented in the dynamic clamp concept strongly impacting the research of membrane and synaptic properties of neurons. In this paper we show that this concept can be easily generalized to build other kinds of closed-loop protocols beyond (or in addition to) electrical stimulation and recording in neurophysiology and behavioral studies for neuroethology. In particular, we illustrate three different examples of goal-driven real-time closed-loop interactions with drug microinjectors, mechanical devices and video event driven stimulation. Modern activity-dependent stimulation protocols can be used to reveal dynamics (otherwise hidden under traditional stimulation techniques), achieve control of natural and pathological states, induce learning, bridge between disparate levels of analysis and for a further automation of experiments. We argue that closed-loop interaction calls for novel real time analysis, prediction and control tools and a new perspective for designing stimulus-response experiments, which can have a large impact in neuroscience research.