scholarly journals Anechoic aquarium for ultrasonic neural telemetry

2000 ◽  
Vol 355 (1401) ◽  
pp. 1305-1308 ◽  
Author(s):  
Allen F. Mensinger ◽  
Max Deffienbaugh
Keyword(s):  
Acoustic Signal ◽  
Water Surface ◽  
Neural Mechanisms ◽  
Natural Habitats ◽  
Free Swimming ◽  
Opsanus Tau ◽  
Signal Discrimination ◽  
Viiith Nerve ◽  
Multipath Environment ◽  
To Receive

An acoustic neural telemetry tag has been developed for recording from free–swimming aquatic animals. Microwire electrodes were implanted into the VIIIth nerve of the toadfish, Opsanus tau , and interfaced to the subdermally implanted tag. The telemetry tag frequency modulates the neural signal, converting it into a varying frequency, which is amplified and transmitted acoustically (centre frequency of 90 kHz and a 20 kHz bandwidth). This acoustic signal is detected by a receiver hydrophone, and the receiver reconstructs the full neural waveform from the acoustic signal. However, due to the multipath environment in the experimental aquarium, the acoustic signal is quickly degraded as the hydrophone is moved away from the source. In order to receive the signal independent of fish position, an anechoic aquarium was designed. Streams of microbubbles ( ca. 70 μm diameter) were generated to produce a curtain of sound–absorptive material along the walls and water surface of the aquarium. Microbubble generation significantly reduced the multipath artefacts, and allowed signal discrimination independent of fish and hydrophone position. The anechoic aquarium will allow the recording of neural activity from freeswimming fishes in quasi–natural habitats, thus allowing better understanding of the neural mechanisms of behaviour.

Imaginative Reinforcement Learning: Computational Principles and Neural Mechanisms

2017 ◽  
Vol 29 (12) ◽  
pp. 2103-2113 ◽  
Author(s):  
Samuel J. Gershman ◽  
Jimmy Zhou ◽  
Cody Kommers
Keyword(s):  
Decision Making ◽  
Reinforcement Learning ◽  
Internal Model ◽  
Learning Model ◽  
Neural Mechanisms ◽  
Sequential Decision Making ◽  
Sequential Decision ◽  
The Impact ◽  
To Receive ◽  
Reinforcement Learning Model

Imagination enables us not only to transcend reality but also to learn about it. In the context of reinforcement learning, an agent can rationally update its value estimates by simulating an internal model of the environment, provided that the model is accurate. In a series of sequential decision-making experiments, we investigated the impact of imaginative simulation on subsequent decisions. We found that imagination can cause people to pursue imagined paths, even when these paths are suboptimal. This bias is systematically related to participants' optimism about how much reward they expect to receive along imagined paths; providing feedback strongly attenuates the effect. The imagination effect can be captured by a reinforcement learning model that includes a bonus added onto imagined rewards. Using fMRI, we show that a network of regions associated with valuation is predictive of the imagination effect. These results suggest that imagination, although a powerful tool for learning, is also susceptible to motivational biases.

Host-finding in Trichobilharzia ocellata cercariae: swimming and attachment to the host

Parasitology ◽  
1988 ◽  
Vol 96 (3) ◽  
pp. 493-505 ◽  
Author(s):  
W. Feiler ◽  
W. Haas
Keyword(s):  
Energy Saving ◽  
Temperature Difference ◽  
Water Surface ◽  
Host Finding ◽  
Swimming Behaviour ◽  
Chemical Components ◽  
Maximal Response ◽  
Free Swimming ◽  
Trichobilharzia Ocellata ◽  
Selection Of

SUMMARYThe cercaria of Trichobilharzia ocellata finds and identifies its duck host with a seriesof different behavioural phases. Dispersal and selection of the water surface as microhabitat is achieved by an intermittent swimming behaviour, which is governed by the interplay of passive dropping with forward and backward swimming movements and includes a positive phototactic and a geonegative orientation. Then the cercariae tend to cling to the water surface in an energy-saving resting position. A movement towards the duck feet as the site of entry occurs when shadows evoke forward swimming movements, which are directed away from the source of light, i.e. normally downwards. Forward swimming movements are also stimulated by touch, but only in free-swimming cercariae and not when these are in the resting position. Attachments occur only when a substrate is touched during forward swimming movements. Attachments are stimulated by warm substrates (1 °C temperature difference triggers a nearly maximal response) and by chemical components of duck-foot skin, and the readiness to attach is increased when the forward swimming movement is started by shadow stimuli.

scholarly journals The Chemoautotrophically Based Movile Cave Groundwater Ecosystem, a Hotspot of Subterranean Biodiversity

Diversity ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 128
Author(s):  
Traian Brad ◽  
Sanda Iepure ◽  
Serban M. Sarbu
Keyword(s):  
Primary Productivity ◽  
Water Surface ◽  
Energy Input ◽  
Free Swimming ◽  
Invertebrate Species ◽  
Microbial Biofilms ◽  
Oxidation Of Hydrogen ◽  
Aquatic Food ◽  
Movile Cave

Movile Cave hosts one of the world’s most diverse subsurface invertebrate communities. In the absence of matter and energy input from the surface, this ecosystem relies entirely on in situ primary productivity by chemoautotrophic microorganisms. The energy source for these microorganisms is the oxidation of hydrogen sulfide provided continuously from the deep thermomineral aquifer, alongside methane, and ammonium. The microbial biofilms that cover the water surface, the cave walls, and the sediments, along with the free-swimming microorganisms, represent the food that protists, rotifers, nematodes, gastropods, and crustacean rely on. Voracious water-scorpions, leeches, and planarians form the peak of the aquatic food web in Movile Cave. The terrestrial community is even more diverse. It is composed of various species of worms, isopods, pseudoscorpions, spiders, centipedes, millipedes, springtails, diplurans, and beetles. An updated list of invertebrate species thriving in Movile Cave is provided herein. With 53 invertebrate species (21 aquatic and 32 terrestrial), of which 38 are endemic for this unusual, but fascinating environment, Movile Cave is the first known chemosynthesis-based groundwater ecosystem. Therefore, Movile Cave deserves stringent attention and protection.

scholarly journals A neural pathway controlling motivation to exert effort

2018 ◽  
Vol 115 (22) ◽  
pp. 5792-5797 ◽  
Author(s):  
Christophe D. Proulx ◽  
Sage Aronson ◽  
Djordje Milivojevic ◽  
Cris Molina ◽  
Alan Loi ◽  
...  
Keyword(s):  
Dopaminergic Neurons ◽  
Neural Mechanisms ◽  
Neural Pathway ◽  
Motor Tasks ◽  
Lateral Habenula ◽  
Negative Valence ◽  
Tegmental Nucleus ◽  
Rostromedial Tegmental Nucleus ◽  
Hedonic Property ◽  
To Receive

The neural mechanisms conferring reduced motivation, as observed in depressed individuals, is poorly understood. Here, we examine in rodents if reduced motivation to exert effort is controlled by transmission from the lateral habenula (LHb), a nucleus overactive in depressed-like states, to the rostromedial tegmental nucleus (RMTg), a nucleus that inhibits dopaminergic neurons. In an aversive test wherein immobility indicates loss of effort, LHb→RMTg transmission increased during transitions into immobility, driving LHb→RMTg increased immobility, and inhibiting LHb→RMTg produced the opposite effects. In an appetitive test, driving LHb→RMTg reduced the effort exerted to receive a reward, without affecting the reward’s hedonic property. Notably, LHb→RMTg stimulation only affected specific aspects of these motor tasks, did not affect all motor tasks, and promoted avoidance, indicating that LHb→RMTg activity does not generally reduce movement but appears to carry a negative valence that reduces effort. These results indicate that LHb→RMTg activity controls the motivation to exert effort and may contribute to the reduced motivation in depression.

Neural Recordings From the Lateral Line in Free-Swimming Toadfish, Opsanus tau

2003 ◽  
Vol 205 (2) ◽  
pp. 216-218 ◽  
Author(s):  
L. M. Palmer ◽  
B. A. Giuffrida ◽  
A. F. Mensinger
Keyword(s):  
Lateral Line ◽  
Free Swimming ◽  
Neural Recordings ◽  
Opsanus Tau

Development of an acoustic telemetry tag for monitoring electromyograms in free-swimming fish

1999 ◽  
Vol 202 (19) ◽  
pp. 2693-2699
Author(s):  
H. Dewar ◽  
M. Deffenbaugh ◽  
G. Thurmond ◽  
K. Lashkari ◽  
B.A. Block
Keyword(s):  
Marine Fish ◽  
Acoustic Signal ◽  
Acoustic Telemetry ◽  
Yellowfin Tuna ◽  
Squalus Acanthias ◽  
Spiny Dogfish ◽  
Thunnus Albacares ◽  
Free Swimming ◽  
Absolute Value ◽  
Zero Crossings

We report the development of an acoustic telemetry tag used to monitor electromyograms (EMGs) remotely from free-swimming marine fish. The device described amplifies and filters the EMG and then converts the electrical waveform into a frequency-modulated acoustic signal that is transmitted through water. The signal is then received, demodulated and recorded by the receiving system. The EMG tag described has been tested on a range of species, including toadfish Opsanus τ, spiny dogfish Squalus acanthias, yellowfin tuna Thunnus albacares and eastern Pacific bonito Sarda chiliensis, in different tank environments. In certain tanks the fidelity with which the system replicates the EMG is sufficient to quantify accurately the onset, offset, duration, the integrated area under the absolute value of the signal and the number of signal zero crossings. This EMG tag will expand the scope of questions that can be addressed about the behavior and physiology of free-swimming fish.

Chronic Recording of Regenerating VIIIth Nerve Axons With a Sieve Electrode

2000 ◽  
Vol 83 (1) ◽  
pp. 611-615 ◽  
Author(s):  
Allen F. Mensinger ◽  
David J. Anderson ◽  
Christopher J. Buchko ◽  
Michael A. Johnson ◽  
David C. Martin ◽  
...  
Keyword(s):  
Nervous System ◽  
Neural Activity ◽  
Silicon Substrate ◽  
Single Unit ◽  
Genetically Engineered ◽  
High Fidelity ◽  
Prosthetic Devices ◽  
Chronic Recording ◽  
Opsanus Tau ◽  
Viiith Nerve

A micromachined silicon substrate sieve electrode was implanted within transected toadfish ( Opsanus tau) otolith nerves. High fidelity, single unit neural activity was recorded from seven alert and unrestrained fish 30 to 60 days after implantation. Fibrous coatings of genetically engineered bioactive protein polymers and nerve guide tubes increased the number of axons regenerating through the electrode pores when compared with controls. Sieve electrodes have potential as permanent interfaces to the nervous system and to bridge missing connections between severed or damaged nerves and muscles. Recorded impulses might also be amplified and used to control prosthetic devices.

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