The responses of peripheral and central mechanosensory lateral line units of weakly electric fish to moving objects

1993 ◽  
Vol 172 (1) ◽  
pp. 115-128 ◽  
Author(s):  
H. Bleckmann ◽  
R. Zelick
Keyword(s):  
Lateral Line ◽  
Electric Fish ◽  
Moving Objects ◽  
Weakly Electric Fish ◽  
Weakly Electric

Global Electrosensory Oscillations Enhance Directional Responses of Midbrain Neurons in Eigenmannia

2006 ◽  
Vol 96 (5) ◽  
pp. 2319-2326 ◽  
Author(s):  
J. U. Ramcharitar ◽  
E. W. Tan ◽  
E. S. Fortune
Keyword(s):  
Electric Fish ◽  
Moving Objects ◽  
Synaptic Depression ◽  
Weakly Electric Fish ◽  
Directional Selectivity ◽  
Short Term ◽  
Midbrain Neurons ◽  
Transmission Of Information ◽  
Jamming Avoidance ◽  
Weakly Electric

Eigenmannia, a genus of weakly electric fish, exhibits a specialized behavior known as the jamming avoidance response (JAR). The JAR results in a categorical difference between Eigenmannia that are in groups of conspecifics and those that are alone. Fish in groups exhibit the JAR behavior and thereby experience ongoing, global synchronous 20- to 50-Hz electrosensory oscillations, whereas solitary fish do not. Although previous work has shown that these ongoing signals do not significantly degrade electrosensory behavior, these oscillations nevertheless elicit short-term synaptic depression in midbrain circuits. Because short-term synaptic depression can have profound effects on the transmission of information through synapses, we examined the differences in intracellularly recorded responses of midbrain neurons in awake, behaving fish to moving electrosensory images under electrosensory conditions that mimic solitary fish and fish in groups. In solitary conditions, moving objects elicited Gaussian or sinusoidal postsynaptic potentials (PSPs) that commonly exhibited preferential responses to a direction of motion. Surprisingly, when the same stimulus was presented in the presence of the global oscillations, directional selectivity was increased in all neurons tested. The magnitudes of the differences in PSP amplitude for preferred and nonpreferred directions were correlated with a measure of short-term synaptic depression in both conditions. The electrosensory consequences of the JAR appear to result in an enhancement of the representation of direction of motion in midbrain neurons. The data also support a role for short-term synaptic depression in the generation and modulation of directional responses.

Inhibition Evoked From Primary Afferents in the Electrosensory Lateral Line Lobe of the Weakly Electric Fish (Apteronotus leptorhynchus)

1998 ◽  
Vol 80 (6) ◽  
pp. 3173-3196 ◽  
Author(s):  
Neil J. Berman ◽  
Leonard Maler
Keyword(s):  
Lateral Line ◽  
Granule Cell ◽  
Electric Fish ◽  
Inhibitory Response ◽  
Primary Afferents ◽  
Weakly Electric Fish ◽  
Apteronotus Leptorhynchus ◽  
Primary Afferent ◽  
Weakly Electric ◽  
Stimulation Of

Berman, Neil J. and Leonard Maler. Inhibition evoked from primary afferents in the electrosensory lateral line lobe of the weakly electric fish ( Apteronotus leptorhynchus). J. Neurophysiol. 80: 3173–3196, 1998. The responses of two types of projection neurons of the electrosensory lateral line lobe, basilar (BP) and nonbasilar (NBP) pyramidal cells, to stimulation of primary electrosensory afferents were determined in the weakly electric fish, Apteronotus leptorhynchus. Using dyes to identify cell type, the response of NBP cells to stimulation of primary afferents was inhibitory, whereas the response of BP cells was excitation followed by inhibition. γ-Aminobutyric acid (GABA) applications produced biphasic (depolarization then hyperpolarization) responses in most cells. GABAA antagonists blocked the depolarizing effect of GABA and reduced the hyperpolarizing effect. The GABAB antagonists weakly antagonized the hyperpolarizing effect. The early depolarization had a larger increase in cell conductance than the late hyperpolarization. The conductance changes were voltage dependent, increasing with depolarization. In both cell types, baclofen produced a slow small hyperpolarization and reduced the inhibitory postsynaptic potentials (IPSPs) evoked by primary afferent stimulation. Tetanic stimulation of primary afferents at physiological rates (100–200 Hz) produced strongly summating compound IPSPs (∼500-ms duration) in NBP cells, which were usually sensitive to GABAA but not GABAB antagonists; in some cells there remained a slow IPSP that was unaffected by GABAB antagonists. BP cells responded with excitatory or mixed excitatory + inhibitory responses. The inhibitory response had both a fast (∼30 ms, GABAA) and long-lasting slow phase (∼800 ms, mostly blocked by GABAA antagonists). In some cells there was a GABAA antagonist-insensitive slow IPSP (∼500 ms) that was sensitive to GABAB antagonists. Application of glutamate ionotropic receptor antagonists blocked the inhibitory response of NBP cells to primary afferent stimulation and the excitatory response of BP cells but enhanced the BP cell slow IPSP; this remaining slow IPSP was reduced by GABAB antagonists. Unit recordings in the granule cell layer and computer simulations of pyramidal cell inhibition suggested that the duration of the slow GABAA inhibition reflects the prolonged firing of GABAergic granule cell interneurons to primary afferent input. Correlation of the results with known GABAergic circuitry in the electrosensory lobe suggests that the GABAergic type 2 granule cell input to both pyramidal cell types is via GABAA receptors. The properties of the GC2 GABAA input are well suited to their putative role in gain control, regulation of phasicness, and coincidence detection. The slow GABAB IPSP evoked in BP cells is likely due to ovoid cell input to their basal dendrites.

Receptive field properties of neurons in the electrosensory lateral line lobe of the weakly electric fish, Gnathonemus petersii

2008 ◽  
Vol 194 (12) ◽  
pp. 1063-1075 ◽  
Author(s):  
Michael G. Metzen ◽  
Jacob Engelmann ◽  
João Bacelo ◽  
Kirsty Grant ◽  
Gerhard von der Emde
Keyword(s):  
Receptive Field ◽  
Lateral Line ◽  
Electric Fish ◽  
Weakly Electric Fish ◽  
Receptive Field Properties ◽  
Weakly Electric ◽  
Gnathonemus Petersii

Logarithmic time course of sensory adaptation in electrosensory afferent nerve fibers in a weakly electric fish

1996 ◽  
Vol 76 (3) ◽  
pp. 2020-2032 ◽  
Author(s):  
Z. Xu ◽  
J. R. Payne ◽  
M. E. Nelson
Keyword(s):  
Firing Rate ◽  
Lateral Line ◽  
Time Course ◽  
Electric Fish ◽  
Weakly Electric Fish ◽  
Sensory Adaptation ◽  
Adaptation Time ◽  
Firing Rates ◽  
P Type ◽  
Weakly Electric

1. We recorded single unit activity from individual primary electrosensory afferent axons in the posterior branch of the anterior lateral line nerve of gymnotid weakly electric fish, Apteronotus leptorhynchus. We analyzed the responses of P-type (probability-coding) afferent fibers to externally applied amplitude step changes in the quasi-sinusoidal transdermal potential established by the fish's own electric organ discharge (EOD). 2. In response to AM step increases in transdermal potential, the firing rate of P-type afferents exhibited an abrupt increase followed by an initially rapid and subsequently more gradual decay back toward the baseline level. Afferent responses continued to adapt slowly throughout the duration of prolonged step stimuli lasting > 100 s. The time course of sensory adaptation was similar for all units tested. 3. We introduce a new functional form for describing the time course of sensory adaptation in which the change in firing rate delta r decays logarithmically with time: delta r(t) = A/[B In (t) + 1]. This logarithmic form accurately describes the adaptation time course of P-type afferents over five decades in time, from milliseconds to hundreds of seconds, with only two free parameters. Using a nonlinear least-squares fitting technique, we obtained a mean value of the parameter B, which characterizes the adaptation time course, of 0.149 +/- 0.028 (mean +/- SD, n = 49). 4. We compare logarithmic fits with traditional multiexponential and power law forms and demonstrate that the logarithmic form yields a better characterization of P-type afferent responses. This analysis helps explain the variability in previously reported adaptation time constants, which have ranged from 0.2 to 3.4 s, in gymnotid P-type afferents. 5. We tested the linearity of P-type afferent responses using positive and negative AM steps of varying amplitudes. Aside from nonlinearities associated with rectification (firing rates cannot be negative) and saturation (firing rates cannot exceed the EOD frequency), we found that P-type afferent responses scaled linearly with stimulus amplitude. 6. Based on the observed linearity, we predict the frequency domain response characteristics of P-type afferents and find that the predicted gain and phase are in good agreement with experimental measurements using sinusoidal AM stimuli over a range of AM frequencies from 1 to 100 Hz. Thus the logarithmic parameterization of the step appears to accurately capture the response dynamics of P-type afferents over a wide range of behaviorally relevant AM frequencies. 7. We conclude that the temporal filtering properties of pyramidal cells in the medullary electrosensory nucleus, the electrosensory lateral line lobe (ELL), need to be reevaluated in light of the logarithmic adaptation time course in the periphery, and we discuss implications for the role of P-type afferents in driving a feedback gain control mechanism that regulated ELL pyramidal cell responsiveness.

Sign in / Sign up

Export Citation Format

Share Document