IFIBYNE   05513
INSTITUTO DE FISIOLOGIA, BIOLOGIA MOLECULAR Y NEUROCIENCIAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Motion Vision in crabs: behavioral, anatomical and neurophysiological accounts.
Autor/es:
DANIEL TOMSIC
Lugar:
Suecia
Reunión:
Conferencia; International Congress on Invertebrate Vision; 2008
Institución organizadora:
Universidad de Lund
Resumen:
Motion vision in crabs: behavioral, anatomical and neurophysiological accounts Daniel Tomsic Laboratorio de Neurobiología de la Memoria. Dpto. Fisiología Biología Molecular y Celular. Universidad de Buenos Aires. IFIBYNE-CONICET. Argentina tomsic@fbmc.fcen.uba.ar Despite crustaceans represent a mayor phylogenetic group that has conquered most ecological niches, studies of their visual system are scarce. Semiterrestrial grapsid crabs are highly visual animals in which the processing of visual information can be conveniently studied. The size and robustness of these animals, as well as the accessibility to the optic neuropils allow stable intracellular recording to be taken from the intact animal. Moreover, after hours of recording the animal remains healthy and can be tested in behavioral experiments. For many years we have been studying the visual learning and memory abilities of the crab Chasmagnathus and, few years ago, we began to investigate the general organization and neural elements of the optic lobe in this animal. In this talk I will summarize the main findings from our studies combining behavioral, electrophysiological and morphological approaches. I will shown that: a) Giant tangential neurons from the lobula (LGs: lobula giants), which integrate multimodal information, undergo learning-induced changes that support long-term visual memories. Thus, I will argue that the lobula of crabs, and perhaps of insects too, is not simply a visual processing neuropil but also possesses features that are often ascribed to “higher centers”. b) The group of the LGs is composed of at least four different cell classes, all of which project to the midbrain. LGs respond to object rather than to flow field motion, which lead us to hypothesise that flow field would be analyzed by the tangential neurons from a lobula plate-like neuropil that has recently been described in Chasmagnathus. The presence of a lobula plate neuropil in Crustacea with functions similar to those carried out by this neuropil in insects, would be an important piece of evidence in the debate on the phylogenetic relationship among crustaceans and between malacostracans and insects. c) Among the LG classes so far identified, three are composed by few or even a single element and possess panoramic receptive fields. The fourth class is composed of 14 elements with smaller receptive fields, which are homogeneously distributed across the retinotopic mosaic of the lobula. This cell assembly appears to be suitable for assessing the location and direction of object motion across the entire panorama. d) Using computer generated stimuli and a walking simulator device that allows precise measurements of the latency, direction, speed of run, etc., we study the crab’s escape response to a variety of looming stimuli. We found that the speed of run is finely controlled by continuous visual feedback. Two identified LG classes respond to looming stimuli by increasing their rate of firing in a way that closely matches the dynamic of each particular image expansion. Results indicate that these neurons encode information about object approach and convey such information downstream to determine the speed of escape run. with functions similar to those carried out by this neuropil in insects, would be an important piece of evidence in the debate on the phylogenetic relationship among crustaceans and between malacostracans and insects. c) Among the LG classes so far identified, three are composed by few or even a single element and possess panoramic receptive fields. The fourth class is composed of 14 elements with smaller receptive fields, which are homogeneously distributed across the retinotopic mosaic of the lobula. This cell assembly appears to be suitable for assessing the location and direction of object motion across the entire panorama. d) Using computer generated stimuli and a walking simulator device that allows precise measurements of the latency, direction, speed of run, etc., we study the crab’s escape response to a variety of looming stimuli. We found that the speed of run is finely controlled by continuous visual feedback. Two identified LG classes respond to looming stimuli by increasing their rate of firing in a way that closely matches the dynamic of each particular image expansion. Results indicate that these neurons encode information about object approach and convey such information downstream to determine the speed of escape run. with functions similar to those carried out by this neuropil in insects, would be an important piece of evidence in the debate on the phylogenetic relationship among crustaceans and between malacostracans and insects. c) Among the LG classes so far identified, three are composed by few or even a single element and possess panoramic receptive fields. The fourth class is composed of 14 elements with smaller receptive fields, which are homogeneously distributed across the retinotopic mosaic of the lobula. This cell assembly appears to be suitable for assessing the location and direction of object motion across the entire panorama. d) Using computer generated stimuli and a walking simulator device that allows precise measurements of the latency, direction, speed of run, etc., we study the crab’s escape response to a variety of looming stimuli. We found that the speed of run is finely controlled by continuous visual feedback. Two identified LG classes respond to looming stimuli by increasing their rate of firing in a way that closely matches the dynamic of each particular image expansion. Results indicate that these neurons encode information about object approach and convey such information downstream to determine the speed of escape run. began to investigate the general organization and neural elements of the optic lobe in this animal. In this talk I will summarize the main findings from our studies combining behavioral, electrophysiological and morphological approaches. I will shown that: a) Giant tangential neurons from the lobula (LGs: lobula giants), which integrate multimodal information, undergo learning-induced changes that support long-term visual memories. Thus, I will argue that the lobula of crabs, and perhaps of insects too, is not simply a visual processing neuropil but also possesses features that are often ascribed to “higher centers”. b) The group of the LGs is composed of at least four different cell classes, all of which project to the midbrain. LGs respond to object rather than to flow field motion, which lead us to hypothesise that flow field would be analyzed by the tangential neurons from a lobula plate-like neuropil that has recently been described in Chasmagnathus. The presence of a lobula plate neuropil in Crustacea with functions similar to those carried out by this neuropil in insects, would be an important piece of evidence in the debate on the phylogenetic relationship among crustaceans and between malacostracans and insects. c) Among the LG classes so far identified, three are composed by few or even a single element and possess panoramic receptive fields. The fourth class is composed of 14 elements with smaller receptive fields, which are homogeneously distributed across the retinotopic mosaic of the lobula. This cell assembly appears to be suitable for assessing the location and direction of object motion across the entire panorama. d) Using computer generated stimuli and a walking simulator device that allows precise measurements of the latency, direction, speed of run, etc., we study the crab’s escape response to a variety of looming stimuli. We found that the speed of run is finely controlled by continuous visual feedback. Two identified LG classes respond to looming stimuli by increasing their rate of firing in a way that closely matches the dynamic of each particular image expansion. Results indicate that these neurons encode information about object approach and convey such information downstream to determine the speed of escape run. with functions similar to those carried out by this neuropil in insects, would be an important piece of evidence in the debate on the phylogenetic relationship among crustaceans and between malacostracans and insects. c) Among the LG classes so far identified, three are composed by few or even a single element and possess panoramic receptive fields. The fourth class is composed of 14 elements with smaller receptive fields, which are homogeneously distributed across the retinotopic mosaic of the lobula. This cell assembly appears to be suitable for assessing the location and direction of object motion across the entire panorama. d) Using computer generated stimuli and a walking simulator device that allows precise measurements of the latency, direction, speed of run, etc., we study the crab’s escape response to a variety of looming stimuli. We found that the speed of run is finely controlled by continuous visual feedback. Two identified LG classes respond to looming stimuli by increasing their rate of firing in a way that closely matches the dynamic of each particular image expansion. Results indicate that these neurons encode information about object approach and convey such information downstream to determine the speed of escape run. with functions similar to those carried out by this neuropil in insects, would be an important piece of evidence in the debate on the phylogenetic relationship among crustaceans and between malacostracans and insects. c) Among the LG classes so far identified, three are composed by few or even a single element and possess panoramic receptive fields. The fourth class is composed of 14 elements with smaller receptive fields, which are homogeneously distributed across the retinotopic mosaic of the lobula. This cell assembly appears to be suitable for assessing the location and direction of object motion across the entire panorama. d) Using computer generated stimuli and a walking simulator device that allows precise measurements of the latency, direction, speed of run, etc., we study the crab’s escape response to a variety of looming stimuli. We found that the speed of run is finely controlled by continuous visual feedback. Two identified LG classes respond to looming stimuli by increasing their rate of firing in a way that closely matches the dynamic of each particular image expansion. Results indicate that these neurons encode information about object approach and convey such information downstream to determine the speed of escape run. began to investigate the general organization and neural elements of the optic lobe in this animal. In this talk I will summarize the main findings from our studies combining behavioral, electrophysiological and morphological approaches. I will shown that: a) Giant tangential neurons from the lobula (LGs: lobula giants), which integrate multimodal information, undergo learning-induced changes that support long-term visual memories. Thus, I will argue that the lobula of crabs, and perhaps of insects too, is not simply a visual processing neuropil but also possesses features that are often ascribed to “higher centers”. b) The group of the LGs is composed of at least four different cell classes, all of which project to the midbrain. LGs respond to object rather than to flow field motion, which lead us to hypothesise that flow field would be analyzed by the tangential neurons from a lobula plate-like neuropil that has recently been described in Chasmagnathus. The presence of a lobula plate neuropil in Crustacea with functions similar to those carried out by this neuropil in insects, would be an important piece of evidence in the debate on the phylogenetic relationship among crustaceans and between malacostracans and insects. c) Among the LG classes so far identified, three are composed by few or even a single element and possess panoramic receptive fields. The fourth class is composed of 14 elements with smaller receptive fields, which are homogeneously distributed across the retinotopic mosaic of the lobula. This cell assembly appears to be suitable for assessing the location and direction of object motion across the entire panorama. d) Using computer generated stimuli and a walking simulator device that allows precise measurements of the latency, direction, speed of run, etc., we study the crab’s escape response to a variety of looming stimuli. We found that the speed of run is finely controlled by continuous visual feedback. Two identified LG classes respond to looming stimuli by increasing their rate of firing in a way that closely matches the dynamic of each particular image expansion. Results indicate that these neurons encode information about object approach and convey such information downstream to determine the speed of escape run. with functions similar to those carried out by this neuropil in insects, would be an important piece of evidence in the debate on the phylogenetic relationship among crustaceans and between malacostracans and insects. c) Among the LG classes so far identified, three are composed by few or even a single element and possess panoramic receptive fields. The fourth class is composed of 14 elements with smaller receptive fields, which are homogeneously distributed across the retinotopic mosaic of the lobula. This cell assembly appears to be suitable for assessing the location and direction of object motion across the entire panorama. d) Using computer generated stimuli and a walking simulator device that allows precise measurements of the latency, direction, speed of run, etc., we study the crab’s escape response to a variety of looming stimuli. We found that the speed of run is finely controlled by continuous visual feedback. Two identified LG classes respond to looming stimuli by increasing their rate of firing in a way that closely matches the dynamic of each particular image expansion. Results indicate that these neurons encode information about object approach and convey such information downstream to determine the speed of escape run. with functions similar to those carried out by this neuropil in insects, would be an important piece of evidence in the debate on the phylogenetic relationship among crustaceans and between malacostracans and insects. c) Among the LG classes so far identified, three are composed by few or even a single element and possess panoramic receptive fields. The fourth class is composed of 14 elements with smaller receptive fields, which are homogeneously distributed across the retinotopic mosaic of the lobula. This cell assembly appears to be suitable for assessing the location and direction of object motion across the entire panorama. d) Using computer generated stimuli and a walking simulator device that allows precise measurements of the latency, direction, speed of run, etc., we study the crab’s escape response to a variety of looming stimuli. We found that the speed of run is finely controlled by continuous visual feedback. Two identified LG classes respond to looming stimuli by increasing their rate of firing in a way that closely matches the dynamic of each particular image expansion. Results indicate that these neurons encode information about object approach and convey such information downstream to determine the speed of escape run. Chasmagnathus and, few years ago, we began to investigate the general organization and neural elements of the optic lobe in this animal. In this talk I will summarize the main findings from our studies combining behavioral, electrophysiological and morphological approaches. I will shown that: a) Giant tangential neurons from the lobula (LGs: lobula giants), which integrate multimodal information, undergo learning-induced changes that support long-term visual memories. Thus, I will argue that the lobula of crabs, and perhaps of insects too, is not simply a visual processing neuropil but also possesses features that are often ascribed to “higher centers”. b) The group of the LGs is composed of at least four different cell classes, all of which project to the midbrain. LGs respond to object rather than to flow field motion, which lead us to hypothesise that flow field would be analyzed by the tangential neurons from a lobula plate-like neuropil that has recently been described in Chasmagnathus. The presence of a lobula plate neuropil in Crustacea with functions similar to those carried out by this neuropil in insects, would be an important piece of evidence in the debate on the phylogenetic relationship among crustaceans and between malacostracans and insects. c) Among the LG classes so far identified, three are composed by few or even a single element and possess panoramic receptive fields. The fourth class is composed of 14 elements with smaller receptive fields, which are homogeneously distributed across the retinotopic mosaic of the lobula. This cell assembly appears to be suitable for assessing the location and direction of object motion across the entire panorama. d) Using computer generated stimuli and a walking simulator device that allows precise measurements of the latency, direction, speed of run, etc., we study the crab’s escape response to a variety of looming stimuli. We found that the speed of run is finely controlled by continuous visual feedback. Two identified LG classes respond to looming stimuli by increasing their rate of firing in a way that closely matches the dynamic of each particular image expansion. Results indicate that these neurons encode information about object approach and convey such information downstream to determine the speed of escape run. with functions similar to those carried out by this neuropil in insects, would be an important piece of evidence in the debate on the phylogenetic relationship among crustaceans and between malacostracans and insects. c) Among the LG classes so far identified, three are composed by few or even a single element and possess panoramic receptive fields. The fourth class is composed of 14 elements with smaller receptive fields, which are homogeneously distributed across the retinotopic mosaic of the lobula. This cell assembly appears to be suitable for assessing the location and direction of object motion across the entire panorama. d) Using computer generated stimuli and a walking simulator device that allows precise measurements of the latency, direction, speed of run, etc., we study the crab’s escape response to a variety of looming stimuli. We found that the speed of run is finely controlled by continuous visual feedback. Two identified LG classes respond to looming stimuli by increasing their rate of firing in a way that closely matches the dynamic of each particular image expansion. Results indicate that these neurons encode information about object approach and convey such information downstream to determine the speed of escape run. with functions similar to those carried out by this neuropil in insects, would be an important piece of evidence in the debate on the phylogenetic relationship among crustaceans and between malacostracans and insects. c) Among the LG classes so far identified, three are composed by few or even a single element and possess panoramic receptive fields. The fourth class is composed of 14 elements with smaller receptive fields, which are homogeneously distributed across the retinotopic mosaic of the lobula. This cell assembly appears to be suitable for assessing the location and direction of object motion across the entire panorama. d) Using computer generated stimuli and a walking simulator device that allows precise measurements of the latency, direction, speed of run, etc., we study the crab’s escape response to a variety of looming stimuli. We found that the speed of run is finely controlled by continuous visual feedback. Two identified LG classes respond to looming stimuli by increasing their rate of firing in a way that closely matches the dynamic of each particular image expansion. Results indicate that these neurons encode information about object approach and convey such information downstream to determine the speed of escape run. Chasmagnathus. The presence of a lobula plate neuropil in Crustacea with functions similar to those carried out by this neuropil in insects, would be an important piece of evidence in the debate on the phylogenetic relationship among crustaceans and between malacostracans and insects. c) Among the LG classes so far identified, three are composed by few or even a single element and possess panoramic receptive fields. The fourth class is composed of 14 elements with smaller receptive fields, which are homogeneously distributed across the retinotopic mosaic of the lobula. This cell assembly appears to be suitable for assessing the location and direction of object motion across the entire panorama. d) Using computer generated stimuli and a walking simulator device that allows precise measurements of the latency, direction, speed of run, etc., we study the crab’s escape response to a variety of looming stimuli. We found that the speed of run is finely controlled by continuous visual feedback. Two identified LG classes respond to looming stimuli by increasing their rate of firing in a way that closely matches the dynamic of each particular image expansion. Results indicate that these neurons encode information about object approach and convey such information downstream to determine the speed of escape run.