Electric fish measure distance in the dark

Article Abstract:

Animals can use both non-visual and visual cues to assess distance. Active electrolocation is the method employed by weakly electric fish, which produce electric signals to detect and analyze objects. The fish were not thought to be able to use distance discrimination since they would have to tackle ambiguities arising when objects are of unknown sizes and materials. A study of these fish shows that they can usually assess distance accurately, no matter what the material, size and shape of the object.

Analysis, Ichthyological research, Ichthyology, Depth perception

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The analytical bend of the leech

Article Abstract:

Leeches bend away from point of contact in response to a touch on their skin. They have four sensory neurons (P neurons) in each body segment, representing the site of the touch stimulus. Lewis and Kristan have identified the touch locations that prompt the maximum activity from each of the P neurons. The P-cell-interneuron circuit is designed to compute projections of motor force vectors along the desired bend direction.

Observations, Perceptual-motor processes, Leeches

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Synaptic plasticity in a cerebellum-like structure depends on temporal order

Article Abstract:

The electrosensory lobe of the mormyrid electric fish 'Gnathonemus petersii' is found to be used as adaptive sensory processors. In this cerebellum-like organ, unpredicted inputs are derived by subtracting generated sensory input from actual sensory input. The plasticity of parallel fibre synapses exhibit characteristics such as reversibility, anti-hebbian potentials and dependence on pre- and post-synaptic events.

Fishes, Animal anatomy

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