Morphological identification of prey-selective neurons in the grass frog's optic tectum

Ewert, Jörg-Peter; Matsumoto, Nobuyoshi; Schwippert, Wolfgang W.

doi:10.1007/bf00497442

Cited by 34 publications

(24 citation statements)

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“…Postmetamorphic prey-naive common toads (the tadpoles are vegetarian) raised in the laboratory from the egg exhibit prey-catching patterns immediately after their transition to terrestrial life, although precise acts are subject to maturation (Ewert 1985;Traud 1983). The "standard" prey-catching sequence o,a,f,s can be regarded as a series of stimulus-response cycles (Figure 1).…”

Section: Releasing Mechanismsmentioning

confidence: 99%

“…In the present study, the term recognition (comparison with stored image) will refer to a genetically determined "information store"; consider a prey-naive toad raised in a homogeneous visual environment. At the completion of metamorphosis, such an animal responds preferentially to particular visual stimuli with motor patterns related to prey-catching; we hence infer that this is based on comparing the incoming signal with a "prey image" that has emerged and been established in the toad's visual system during its evolutionary history (Ewert 1985;Traud 1983). More generally, visual pattern recognition is defined here as the assignment of space time-dependent contrast distributions (features) from the visual environment to innate or learned categories that have behavioral significance ("invariants" or "universals").…”

Section: How Are Objects Sorted Into Categories?mentioning

confidence: 99%

“…The question of whether central visual maps ( Figure 7) and related structures are involved in various kinds of visual behavior can be investigated by the 2DG method. Figure 8 shows that prey-catching in response to a wormlike moving stripe (W), predator avoidance in response to a moving large square (S), and no motor response to an antiwormlike moving stripe (A) are associated with different patterns of increase and decrease in 2DG uptake in various brain structures (Finkenstadt et al 1985;; see also Ewert 1985). In view of the distinct releasing properties of the W-, S-, and A-stimuli, the following suggestions can be made: If the uptake of 14 C-labeled 2DG in a given brain area is different in S-and Wexperiments ( 14 C S ¥= 14 C W ), a correlation with preycatching or predator avoidance, respectively, can be inferred (e.g., see thalamic pretectal lateral posteroventral [Lpv] nucleus); if, in addition, 14 C A ¥• l 4 C w , the structure under investigation may also be involved in stimulus-feature analysis (e.g., see optic tectum [OT], thalamic pretectal lateral posterodorsal [Lpd] nucleus).…”

Section: Regional Distribution Of Brain Activitymentioning

confidence: 99%

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Neuroethology of releasing mechanisms: Prey-catching in toads

1987

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Abstract“Sign stimuli” elicit specific patterns of behavior when an organism's motivation is appropriate. In the toad, visually released prey-catching involves orienting toward the prey, approaching, fixating, and snapping. For these action patterns to be selected and released, the prey must be recognized and localized in space. Toads discriminate prey from nonprey by certain spatiotemporal stimulus features. The stimulus-response relations are mediated by innate releasing mechanisms (RMs) with recognition properties partly modifiable by experience. Striato-pretecto-tectal connectivity determines the RM's recognition and localization properties, whereas medialpallio-thalamo-tectal circuitry makes the system sensitive to changes in internal state and to prior history of exposure to stimuli. RMs encode the diverse stimulus conditions referring to the same prey object through different combinations of “specialized” tectal neurons, involving cells selectively tuned to prey features. The prey-selective neurons express the outcome of information processing in functional units consisting of interconnected cells. Excitatory and inhibitory interactions among feature-sensitive tectal and pretectal neurons specify the perceptual operations involved in distinguishing the prey from its background, selecting its features, and discriminating it from predators. Other connections indicate stimulus location. The results of these analyses are transmitted by specialized neurons projecting from the tectum to bulbar/spinal motor systems, providing a sensorimotor interface. Specific combinations of such projective neurons – mediating feature- and space-related messages – form “command releasing systems” that activate corresponding motor pattern generators for appropriate prey-catching action patterns.

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Section: Releasing Mechanismsmentioning

confidence: 99%

Section: How Are Objects Sorted Into Categories?mentioning

confidence: 99%

Section: Regional Distribution Of Brain Activitymentioning

confidence: 99%

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Neuroethology of releasing mechanisms: Prey-catching in toads

1987

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“…Being analogous to mammalian superior colliculus, it has been a subject of electrophysiological, morphological and behavioral studies [1][2][3][4][5][6][7][8][9][10] . The optic tectum is composed of 9 layers numbered from 9 (superficial layer) to 1 (periventricular layer) [11,12] .…”

Section: Introductionmentioning

confidence: 99%

Intracellular and current source density analysis of pretectal input to the optic tectum of the frog

Kang

et al. 2010

Neurosci. Bull.

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Objective Electrophysiological examination of the ipsilateral pretectotectal projection has proved that pretectal cells elicit strong suppressive responses to the ipsilateral tectum. However, the neural mechanisms underlying the contralateral pretectotectal prejection are still obscure. The present study aimed to examine the synaptic nature of pretectal nuclei and contralateral tectal cells, and to demonstrate the spatiotemporal pattern of neuronal activity in the 2 main brain structures.Methods Intracellular recording and current source density (CSD) analysis were used to test the complexity of neuronal mechanism of pretectotectal information transfer. Results The pretectal stimulation elicited only one type of response on the contralateral tectum, the inhibitory postsynaptic potential (IPSP). The majority of contra-induced IPSPs were assumed to be polysynaptically driven. In the CSD analysis, only one sink with short latency was observed in each profile. The ipsilateral projection produced a prominent monosynaptic sink in layer 8 of tectum. Recipient neurons were located in layers 6 and 7 of tectum. The result confirmed former findings from ipsilateral intracellular recordings. Conclusion These results suggest the following neuronal circuit: afferents from the pretectal nuclei broadly inhibit both tectal neuron, and since no second sink occurs in tectal layers, the pretectotectal excitatory afferents probably do not extend over the whole tectum, but are within limited state. The results of intracellular recording and CSD analysis further provide evidence of how pretectal afferent activity flows within the tectal laminae.

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“…Tectal responses under apomorphine (APO). (After[159]; all figures reprinted with kind permission of Springer Science and Business Media.) Representative examples.…”

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confidence: 99%

Modulation of visual perception and action by forebrain structures and their interactions in amphibians

Ewert

Schwippert

Neurotransmitter Interactions and Cognitive Function

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Nervous systems of lower animals appraised simple prove to be relatively complexDo amphibians "know" while humans "learn"?Towards the middle of the last century, many ethologists suggested that behaviors displayed among so-called "lower" invertebrates or vertebrates -such as some crustaceans or amphibians, respectively -are predominantly innate and rigid in their performance (e.g., [1]). Moreover, responses to behaviorally significant sign stimuli should proceed reflex-like, for example, the lobster's tailflip-reflex in response to a threatening stimulus (e.g., [2]) and the toad's snap-reflex in response to a prey stimulus (e.g., [3]). In detail it was assumed, that a sign [key] stimulus activates an innate releasing mechanism (IRM), that -much like a safe is unlocked by a keyreleases the corresponding action pattern (e.g., [4,5]). According to the IRM concept, (re-)cognition and motor skills are innate. Neurophysiologically, the concept of IRM suggests an inborn sensorimotor interface that translates perception into action: recognizing ("detecting") the sign stimulus at its afferent input-side and activating ("commanding") the corresponding motor system at the efferent output-side. Hence, the concepts of "feature detector" and "command neuron" were born (e.g., [6,7]). Theoretically, the simplest innate releasing mechanism would consist of a command neuron, CN, operating in a chain like: sign-stimulus → CN → motor pattern generator → behavior In this case, the commanding neuron should be a cell specifically tuned to the feature of the sign stimulus, and the axon of that neuron should have access to the motor pattern generating network.Meanwhile, the concepts of command neuron and innate releasing mechanism were revisited and revised from many points of view (e.g., [8][9][10][11][12][13]). First of all, appetitive and consummative behavioral responses both in so-called lower and higher animals depend on state-dependent modulatory influences (referring to motivation

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Morphological identification of prey-selective neurons in the grass frog's optic tectum

Cited by 34 publications

References 5 publications

Neuroethology of releasing mechanisms: Prey-catching in toads

Neuroethology of releasing mechanisms: Prey-catching in toads

Intracellular and current source density analysis of pretectal input to the optic tectum of the frog

Modulation of visual perception and action by forebrain structures and their interactions in amphibians

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