Transfer of Visual Motion Information via Graded Synapses Operates Linearly in the Natural Activity Range

Kurtz, Rafael; Warzecha, Anne-Kathrin; Egelhaaf, Martin

doi:10.1523/jneurosci.21-17-06957.2001

Cited by 46 publications

(81 citation statements)

References 49 publications

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“…First, calcium mediates different processes within neurons. Therefore, even though calcium concentration correlates well with total spiking activity (Svoboda et al, 1997;Charpak et al, 2001;Kurtz et al, 2001;Galizia and Kimmerle, 2004), this correlation is not perfect. Most importantly, the polarity of input and output of the recorded neurons is unclear, because calcium is involved both in presynaptic and postsynaptic processes.…”

Section: Discussionmentioning

confidence: 93%

Olfactory Information Processing in theDrosophilaAntennal Lobe: Anything Goes?

Silbering¹,

Okada²,

Ito³

et al. 2008

J. Neurosci.

119

131

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When an animal smells an odor, olfactory sensory neurons generate an activity pattern across olfactory glomeruli of the first sensory neuropil, the insect antennal lobe or the vertebrate olfactory bulb. Here, several networks of local neurons interact with sensory neurons and with output neurons-insect projection neurons, or vertebrate mitral/tufted cells. The extent and form of information processing taking place in these local networks has been subject of controversy. To investigate the role of local neurons in odor information processing we have used the calcium sensor G-CaMP to perform in vivo recordings of odor-evoked spatiotemporal activity patterns in five genetically defined neuron populations of the antennal lobe of Drosophila melanogaster: three distinct populations of local neurons (two GABAergic and one cholinergic), as well as sensory neurons and projection neurons. Odor-specific and concentration dependent spatiotemporal response patterns varied among neuron populations. Activity transfer differed along the olfactory pathway for different glomerulus-odor combinations: we found cases of profile broadening and of linear and complex transfer. Moreover, the discriminability between the odors also varied across neuron populations and was maximal in projection neurons. Discriminatory power increased with higher odor concentrations over a wide dynamic range, but decreased at the highest concentration. These results show the complexity and diversity of odor information processing mechanisms across olfactory glomeruli in the fly antennal lobe.

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Section: Discussionmentioning

confidence: 93%

Olfactory Information Processing in theDrosophilaAntennal Lobe: Anything Goes?

Silbering¹,

Okada²,

Ito³

et al. 2008

J. Neurosci.

119

131

View full text Add to dashboard Cite

show abstract

“…In contrast, at rod photoreceptor terminals, there is a linear relationship between the magnitude of I Ca and exocytosis . Evidence for linear or nearly linear relationships between I Ca and release has also emerged from studies of insect photoreceptors, olfactory nerve terminals, mature hair cells and neuroendocrine cells (Engisch and Nowycky, 1996;Kurtz et al, 2001;Murphy et al, 2004;Johnson et al, 2004a, b).…”

Section: Linearity Between Ca 2+ Influx and Exocytosis: Mechanistic Imentioning

confidence: 98%

Synaptic transmission at retinal ribbon synapses

Heidelberger

Thoreson

Witkovsky

2005

Progress in Retinal and Eye Research

209

231

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The molecular organization of ribbon synapses in photoreceptors and ON bipolar cells is reviewed in relation to the process of neurotransmitter release. The interactions between ribbon synapseassociated proteins, synaptic vesicle fusion machinery and the voltage-gated calcium channels that gate transmitter release at ribbon synapses are discussed in relation to the process of synaptic vesicle exocytosis. We describe structural and mechanistic specializations that permit the ON bipolar cell to release transmitter at a much higher rate than the photoreceptor does, under in vivo conditions. We also consider the modulation of exocytosis at photoreceptor synapses, with an emphasis on the regulation of calcium channels.

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“…presynaptic neuron, whereas both the presynaptic Ca 2+ concentration and the postsynaptic spike rate decrease only slightly below their resting levels. Thus, apart from this rectification, motion information is transmitted largely undistorted to the contralateral visual system [42] with a functional consequence that the synaptic transfer does not affect the dependence of the motion signals on the stimulus parameters, such as the velocity of motion.…”

Section: Combining Information On Optic Flow From Both Eyesmentioning

confidence: 99%

“…Electrophysiological and optical recording data reproduced from Ref. [42], cell reconstructions shown in (a) reproduced from Refs [13,29].…”

Section: Evaluation Of Behaviourally Generated Optic Flowmentioning

confidence: 99%

Neural encoding of behaviourally relevant visual-motion information in the fly

Egelhaaf

Kern

Krapp

et al. 2002

Trends in Neurosciences

150

109

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The goal of neuroethology is to explain behaviour in terms of the activity of nerve cells and their interactions. This can only be achieved if the experimental animal can be analysed at different levels ranging from behaviour to individual neurons. Cellular mechanisms underlying processing of neuronal information are frequently analysed using in vitro preparations where artificial stimulation replaces the natural sensory input. Although such studies provide fascinating insights into the complex computational abilities of neurons [1], the results may not be extrapolated easily to in vivo conditions, where the range of response amplitudes of neurons and their temporal activity patterns may differ considerably from artificially induced activity. In systems such as the retina of the horseshoe crab [5,6], it is now feasible to analyse the neuronal representation of visual input as it is experienced during behaviour (reviewed in Refs [7,8]). Until now, however, in most systems the underlying neuronal mechanisms have been difficult to unravel.In the fly it is possible to employ both quantitative behavioural approaches as well as in vivo electrophysiological and imaging methods to analyse how behaviourally relevant visual input is processed [9][10][11][12][13][14][15][16][17][18][19][20]. Although the latter techniques are mainly employed in the blowfly, which is relatively big, they are complemented by studies of the smaller fruitfly, Drosophila, where a broad range of genetic approaches can be applied to dissect the visual system in an increasingly specific way [21,22].We review recent progress on the encoding of optic-flow information in the blowfly. Optic flow is an important source of information about self-motion and the three-dimensional layout of the environment, not only for flies but for most moving animals including humans (Box 1, [4,[23][24][25]). Flies exploit optic flow to guide their locomotion [13] and to control compensatory head movements [26], and understanding the computational principles underlying optic-flow processing in flies could provide insights into visual-motion analysis in general.Information processing in visual systems is constrained by the spatial and temporal characteristics of the sensory input and by the biophysical properties of the neuronal circuits. Hence, to understand how visual systems encode behaviourally relevant information, we need to know about both the computational capabilities of the nervous system and the natural conditions under which animals normally operate. By combining behavioural, neurophysiological and computational approaches, it is now possible in the fly to assess adaptations that process visual-motion information under the constraints of its natural input. It is concluded that neuronal operating ranges and coding strategies appear to be closely matched to the inputs the animal encounters under behaviourally relevant conditions.

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Transfer of Visual Motion Information via Graded Synapses Operates Linearly in the Natural Activity Range

Cited by 46 publications

References 49 publications

Olfactory Information Processing in theDrosophilaAntennal Lobe: Anything Goes?

Olfactory Information Processing in theDrosophilaAntennal Lobe: Anything Goes?

Synaptic transmission at retinal ribbon synapses

Neural encoding of behaviourally relevant visual-motion information in the fly

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