-
Ehud Ahissar.
Temporal-to Rate-Code Conversion by Neuronal Phase-Locked Loops.
Neural Computation,
10:597-650,
1998.
Keywords: neuroscience,
neuronal coding.
| Abstract: Peripheral sensory activity follows the temporal structure of input signals. Central sensory processing uses also rate coding, and motor outputs appear to be primarily encoded by rate. I propose here a simple, efficient structure, converting temporal coding to rate coding by neuronal phase-locked loops (PLL). The simplest form of a PLL includes a phase detector (that is, a neuronal-plausible version of an ideal coincidence detector) and a controllable local oscillator that are connected in a negative feedback loop. The phase detector compares the firing times of the local oscillator and the input and provides an output whose firing rate is monotonically related to the time difference. The output rate is fed back to the local oscillator and forces it to phase-lock to the input. Every temporal interval at the input is associated with a specific pair of output rate and time difference values; the higher the output rate, the further the local oscillator is driven from its intrinsic frequency. Sequences of input intervals, which by definition encode input information, are thus represented by sequences of firing rates at the PLL's output. The most plausible implementation of PLL circuits is by thalamocortical loops in which populations of thalamic "relay" neurons function as phase detectors that compare the timings of cortical oscillators and sensory signals. The output in this case is encoded by the thalamic population rate. This article presents and analyzes the algorithmic and the implementation levels of the proposed PLL model and describes the implementation of the PLL model to the primate tactile system. |
| Comments: Le système moteur utilise principalement du rate coding, alors qu'une grande partie de l'info sensorielle est en time coding, donc il faut un read-out de l'un vers l'autre. Le papier est essentiellement technique. |
@Article{ahis_98,
author = {Ahissar, Ehud},
title = {Temporal-to Rate-Code Conversion by Neuronal Phase-Locked Loops},
journal = {Neural Computation},
year = {1998},
volume = {10},
pages = {597-650},
comments = {Le système moteur utilise principalement du rate coding, alors qu'une grande partie de l'info sensorielle est en time coding, donc il faut un read-out de l'un vers l'autre. Le papier est essentiellement technique.},
keywords = {neuroscience, neuronal coding},
rating = {C},
url = {http://www.weizmann.ac.il/neurobiology/labs/ahissar/pdf/NeCo0498.pdf},
abstract = {Peripheral sensory activity follows the temporal structure of input signals. Central sensory processing uses also rate coding, and motor outputs appear to be primarily encoded by rate. I propose here a simple, efficient structure, converting temporal coding to rate coding by neuronal phase-locked loops (PLL). The simplest form of a PLL includes a phase detector (that is, a neuronal-plausible version of an ideal coincidence detector) and a controllable local oscillator that are connected in a negative feedback loop. The phase detector compares the firing times of the local oscillator and the input and provides an output whose firing rate is monotonically related to the time difference. The output rate is fed back to the local oscillator and forces it to phase-lock to the input. Every temporal interval at the input is associated with a specific pair of output rate and time difference values; the higher the output rate, the further the local oscillator is driven from its intrinsic frequency. Sequences of input intervals, which by definition encode input information, are thus represented by sequences of firing rates at the PLL's output. The most plausible implementation of PLL circuits is by thalamocortical loops in which populations of thalamic "relay" neurons function as phase detectors that compare the timings of cortical oscillators and sensory signals. The output in this case is encoded by the thalamic population rate. This article presents and analyzes the algorithmic and the implementation levels of the proposed PLL model and describes the implementation of the PLL model to the primate tactile system.}
}
-
P. Bach-y-Rita,
K. Kaczmarek,
M. Tyler,
and J. Garcia-Lara.
Form perception with a 49-point electrotactile stimulus array on the tongue.
Journal of Rehabilitation Research Development,
35:427-430,
1998.
Keywords: sensory substitution.
| Abstract: Form perception with the tongue was studied with a 49-point electrotactile array. Five sighted adult human subjects (3M/2F) each received 4 blocks of 12 tactile patterns, approximations of circles, squares, and vertex-up equilateral triangles, sized to 4×4, 5×5, 6×6, and 7×7 electrode arrays. Perception with electrical stimulation of the tongue is better than with fingertip electrotactile stimulation, and the tongue requires 3\% (5-15 V) of the voltage. The mean current for tongue subjects was 1.612 mA. Tongue shape recognition performance across all sizes was 79.8\%. The approximate dimensions of the electrotactile array and the dimensions of compartments built into dental retainers have been determined. The goal is to develop a practical, cosmetically acceptable, wireless system for blind persons, with a miniature TV camera, microelectronics, and FM transmitter built into a pair of glasses, and the electrotactile array in a dental orthodontic retainer. |
@Article{bach_kacz_tyle_garc_98,
author = {Bach-y-Rita, P. and Kaczmarek, K. and Tyler, M. and Garcia-Lara, J.},
title = {Form perception with a 49-point electrotactile stimulus array on the tongue},
journal = {Journal of Rehabilitation Research Development},
year = {1998},
volume = {35},
pages = {427-430},
url = {http://www.vard.org/jour/98/35/4/bachr354.htm},
abstract = {Form perception with the tongue was studied with a 49-point electrotactile array. Five sighted adult human subjects (3M/2F) each received 4 blocks of 12 tactile patterns, approximations of circles, squares, and vertex-up equilateral triangles, sized to 4×4, 5×5, 6×6, and 7×7 electrode arrays. Perception with electrical stimulation of the tongue is better than with fingertip electrotactile stimulation, and the tongue requires 3\% (5-15 V) of the voltage. The mean current for tongue subjects was 1.612 mA. Tongue shape recognition performance across all sizes was 79.8\%. The approximate dimensions of the electrotactile array and the dimensions of compartments built into dental retainers have been determined. The goal is to develop a practical, cosmetically acceptable, wireless system for blind persons, with a miniature TV camera, microelectronics, and FM transmitter built into a pair of glasses, and the electrotactile array in a dental orthodontic retainer.},
rating = {C},
keywords = {sensory substitution}
}
-
Ned Block and Robert Stalnaker.
Conceptual analysis, dualism and the explanatory gap.
The Philosophical Review,
1998.
Keywords: philosophy of mind,
dualism,
explanatory gap.
| Comments: explication bien formulée de l'origine et des enjeux de la brèche explicative |
@Article{bloc_stal_98,
author = {Block, Ned and Stalnaker, Robert},
title = {Conceptual analysis, dualism and the explanatory gap},
journal = {The Philosophical Review},
year = {1998},
keywords = {philosophy of mind, dualism, explanatory gap},
comments = {explication bien formulée de l'origine et des enjeux de la brèche explicative},
rating = {C},
url = {http://www.nyu.edu/gsas/dept/philo/faculty/block/papers/ExplanatoryGap.html}
}
-
Nicolas Brunel and Jean-Pierre Nadal.
Mutual information, Fisher information and population coding.
Neural Computation,
10(7):1731-1757,
1998.
Keywords: information theory,
neural networks,
population coding.
| Abstract: In the context of parameter estimation and model selection, it is only quite recently that a direct linkbetween the Fisher informationandinformationtheoretic quantities has been exhibited.We give an interpretation of this link within the standard framework of information theory.We show that in the context of population coding, the mutual information between the activity of a large array of neurons and a stimulus to which the neurons are tuned is naturally related to the Fisher information. In the light of this result, we consider the optimization of the tuning curves parameters in the case of neurons responding to a stimulus represented by an angular variable. |
| Comments: L'argument : s'il existe un estimateur Crao-optimal d'un stimulus à partir d'une population de neurone, alors l'information mutuelle entre le stimulus et la population est supérieure à une quantité $I_{Fisher}$ calculée à partir de l'information de Fisher. |
@Article{brun_nada_98,
author = {Brunel, Nicolas and Nadal, Jean-Pierre},
title = {Mutual information, Fisher information and population coding},
journal = {Neural Computation},
year = {1998},
volume = {10},
number = {7},
pages = {1731-1757},
abstract = {In the context of parameter estimation and model selection, it is only quite recently that a direct linkbetween the Fisher informationandinformationtheoretic quantities has been exhibited.We give an interpretation of this link within the standard framework of information theory.We show that in the context of population coding, the mutual information between the activity of a large array of neurons and a stimulus to which the neurons are tuned is naturally related to the Fisher information. In the light of this result, we consider the optimization of the tuning curves parameters in the case of neurons responding to a stimulus represented by an angular variable.},
comments = {L'argument : s'il existe un estimateur Crao-optimal d'un stimulus à partir d'une population de neurone, alors l'information mutuelle entre le stimulus et la population est supérieure à une quantité $I_{Fisher}$ calculée à partir de l'information de Fisher.},
rating = {C},
keywords = {information theory, neural networks, population coding},
url = {http://citeseer.ist.psu.edu/379407.html}
}
-
David J. Chalmers.
On the Search for the Neural Correlate of Consciousnes.
Toward a Science of Consciousness II,
1998.
Keywords: philosophy,
neuroscience,
NCC.
| Abstract: I'm going to talk about one aspect of the role that neuroscience plays in the search for a theory of consciousness. Whether or not neuroscience can solve all the problems of consciousness singlehandedly, there is no question that it has a major role to play. We've seen at this conference that there's a vast amount of progress in neurobiological research, and that much of it is clearly bearing on the problems of consciousness. But the conceptual foundations of this sort of research are only beginning to be laid. So I will look at some of the things that are going on from a philosopher's perspective and will see if there's anything helpful to say about these foundations. |
@ARTICLE{chal_98,
AUTHOR = {Chalmers, David J.},
TITLE = {On the Search for the Neural Correlate of Consciousnes},
JOURNAL = {Toward a Science of Consciousness II},
YEAR = {1998},
publisher = {MIT Press},
url = {http://www.u.arizona.edu/~chalmers/papers/ncc.html},
keywords = {philosophy, neuroscience, NCC},
rating = {B},
abstract = {I'm going to talk about one aspect of the role that neuroscience plays in the search for a theory of consciousness. Whether or not neuroscience can solve all the problems of consciousness singlehandedly, there is no question that it has a major role to play. We've seen at this conference that there's a vast amount of progress in neurobiological research, and that much of it is clearly bearing on the problems of consciousness. But the conceptual foundations of this sort of research are only beginning to be laid. So I will look at some of the things that are going on from a philosopher's perspective and will see if there's anything helpful to say about these foundations.}
}
-
Imre Csiszar.
The Method of Types.
EEETIT: IEEE Transactions on Information Theory,
44(6):2505-2523,
1998.
Keywords: mathematics,
statistics,
information theory.
| Abstract: The method of types is one of the key technical tools in Shannon Theory, and this tool is valuable also in other fields. In this paper, some key applications will be presented in sufficient detail enabling an interested nonspecialist to gain a working knowledge of the method, and a wide selection of further applications will be surveyed. These range from hypothesis testing and large deviations theory through error exponents for discrete memoryless channels and capacity of arbitrarily varying channels to multiuser problems. While the method of types is suitable primarily for discrete memoryless models, its extensions to certain models with memory will also be discussed. |
| Comments: technique, mais magistral. |
@Article{csis_98,
author = {Csiszar, Imre},
title = {The Method of Types},
journal = {EEETIT: IEEE Transactions on Information Theory},
year = {1998},
volume = {44},
number = {6},
pages = {2505-2523},
comments = {technique, mais magistral.},
keywords = {mathematics, statistics, information theory},
rating = {B},
url = {http://citeseer.ist.psu.edu/csiszar98method.html},
abstract = {The method of types is one of the key technical tools in Shannon Theory, and this tool is valuable also in other fields. In this paper, some key applications will be presented in sufficient detail enabling an interested nonspecialist to gain a working knowledge of the method, and a wide selection of further applications will be surveyed. These range from hypothesis testing and large deviations theory through error exponents for discrete memoryless channels and capacity of arbitrarily varying channels to multiuser problems. While the method of types is suitable primarily for discrete memoryless models, its extensions to certain models with memory will also be discussed.}
}
-
Vittorio Gallese and Alvin Goldman.
Mirror neurons and the simulation theory of mind-reading.
Trends in Cognitive Sciences,
2(12),
1998.
Keywords: neuroscience,
mirror neurons.
| Abstract: A new class of visuomotor neuron has been recently discovered in the monkey s premotor cortex: mirror neurons. These neurons respond both when a particular action is performed by the recorded monkey and when the same action, performed by another individual, is observed. Mirror neurons appear to form a cortical system matching observation and execution of goal-related motor actions. Experimental evidence suggests that a similar matching system also exists in humans. What might be the functional role of this matching system? One possible function is to enable an organism to detect certain mental states of observed conspecifics. This function might be part of, or a precursor to, a more general mind-reading ability. Two different accounts of mindreading have been suggested. According to theory theory , mental states are represented as inferred posits of a naive theory. According to simulation theory , other people s mental states are represented by adopting their perspective: by tracking or matching their states with resonant states of one s own. The activity of mirror neurons, and the fact that observers undergo motor facilitation in the same muscular groups as those utilized by target agents, are findings that accord well with simulation theory but would not be predicted by theory theory. |
@Article{gall_gold_98,
author = {Gallese, Vittorio and Goldman, Alvin},
title = {Mirror neurons and the simulation theory of mind-reading},
journal = {Trends in Cognitive Sciences},
year = {1998},
volume = {2},
number = {12},
url = {http://www.unipr.it/%7Egallese/Gallese-Goldman%201998.pdf},
abstract = {A new class of visuomotor neuron has been recently discovered in the monkey s premotor cortex: mirror neurons. These neurons respond both when a particular action is performed by the recorded monkey and when the same action, performed by another individual, is observed. Mirror neurons appear to form a cortical system matching observation and execution of goal-related motor actions. Experimental evidence suggests that a similar matching system also exists in humans. What might be the functional role of this matching system? One possible function is to enable an organism to detect certain mental states of observed conspecifics. This function might be part of, or a precursor to, a more general mind-reading ability. Two different accounts of mindreading have been suggested. According to theory theory , mental states are represented as inferred posits of a naive theory. According to simulation theory , other people s mental states are represented by adopting their perspective: by tracking or matching their states with resonant states of one s own. The activity of mirror neurons, and the fact that observers undergo motor facilitation in the same muscular groups as those utilized by target agents, are findings that accord well with simulation theory but would not be predicted by theory theory.},
keywords = {neuroscience, mirror neurons},
rating = {B}
}
-
Paul L. Gribble,
David J. Ostry,
Vittorio Sanguineti,
and Rafael Laboissiere.
Are complex control signals required for human arm movement?.
Journal of Neurophysiology,
79:1409-1424,
1998.
Keywords: neuroscience,
motor control,
minimum variance,
feedback,
physiolology.
| Abstract: It has been proposed that the control signals underlying voluntary human arm movement have a "complex" nonmonotonic time-varying form, and a number of empirical findings have been offered in support of this idea. In this paper, we address three such findings using a model of two-joint arm motion based on the lambda version of the equilibrium-point hypothesis. The model includes six one- and two-joint muscles, reflexes, modeled control signals, muscle properties, and limb dynamics. First, we address the claim that "complex" equilibrium trajectories are required to account for nonmonotonic joint impedance patterns observed during multijoint movement. Using constant-rate shifts in the neurally specified equilibrium of the limb and constant cocontraction commands, we obtain patterns of predicted joint stiffness during simulated multijoint movements that match the nonmonotonic patterns reported empirically. We then use the algorithm proposed by Gomi and Kawato to compute a hypothetical equilibrium trajectory from simulated stiffness, viscosity, and limb kinematics. Like that reported by Gomi and Kawato, the resulting trajectory was nonmonotonic, first leading then lagging the position of the limb. Second, we address the claim that high levels of stiffness are required to generate rapid single-joint movements when simple equilibrium shifts are used. We compare empirical measurements of stiffness during rapid single-joint movements with the predicted stiffness of movements generated using constant-rate equilibrium shifts and constant cocontraction commands. Single-joint movements are simulated at a number of speeds, and the procedure used by Bennett to estimate stiffness is followed. We show that when the magnitude of the cocontraction command is scaled in proportion to movement speed, simulated joint stiffness varies with movement speed in a manner comparable with that reported by Bennett. Third, we address the related claim that nonmonotonic equilibrium shifts are required to generate rapid single-joint movements. Using constant-rate equilibrium shifts and constant cocontraction commands, rapid single-joint movements are simulated in the presence of external torques. We use the procedure reported by Latash and Gottlieb to compute hypothetical equilibrium trajectories from simulated torque and angle measurements during movement. As in Latash and Gottlieb, a nonmonotonic function is obtained even though the control signals used in the simulations are constant-rate changes in the equilibrium position of the limb. Differences between the "simple" equilibrium trajectory proposed in the present paper and those that are derived from the procedures used by Gomi and Kawato and Latash and Gottlieb arise from their use of simplified models of force generation. |
| Comments: L'argument général: la dynamique du système musculaire, quand on la regarde sérieusement sans la simplifier à mauvais essient, est compatible avec l'utilisation d'un modèle lambda simple. Le modèle lambda est le modèle le plus trivial: le recrutement des neurones moteurs déterminerait la longueur à vide des muscles, permettant un controle de la config. d'équilibre. Procedure d'estimation des paramètres intéressante: pour un mouvement donné, petites perturbations extérieures et matching. |
@Article{grib_98,
author = {Gribble, Paul L. and Ostry, David J. and Sanguineti, Vittorio and Laboissiere, Rafael},
title = {Are complex control signals required for human arm movement?},
journal = {Journal of Neurophysiology},
year = {1998},
volume = {79},
pages = {1409-1424},
comments = {L'argument général: la dynamique du système musculaire, quand on la regarde sérieusement sans la simplifier à mauvais essient, est compatible avec l'utilisation d'un modèle lambda simple. Le modèle lambda est le modèle le plus trivial: le recrutement des neurones moteurs déterminerait la longueur à vide des muscles, permettant un controle de la config. d'équilibre. Procedure d'estimation des paramètres intéressante: pour un mouvement donné, petites perturbations extérieures et matching.},
keywords = {neuroscience, motor control, minimum variance, feedback, physiolology},
rating = {C},
url = {http://www.lira.dist.unige.it/teaching/ROBOTICA/docs/gribble.ostry.sanguineti.laboissiere.1998.pdf},
abstract = {It has been proposed that the control signals underlying voluntary human arm movement have a "complex" nonmonotonic time-varying form, and a number of empirical findings have been offered in support of this idea. In this paper, we address three such findings using a model of two-joint arm motion based on the lambda version of the equilibrium-point hypothesis. The model includes six one- and two-joint muscles, reflexes, modeled control signals, muscle properties, and limb dynamics. First, we address the claim that "complex" equilibrium trajectories are required to account for nonmonotonic joint impedance patterns observed during multijoint movement. Using constant-rate shifts in the neurally specified equilibrium of the limb and constant cocontraction commands, we obtain patterns of predicted joint stiffness during simulated multijoint movements that match the nonmonotonic patterns reported empirically. We then use the algorithm proposed by Gomi and Kawato to compute a hypothetical equilibrium trajectory from simulated stiffness, viscosity, and limb kinematics. Like that reported by Gomi and Kawato, the resulting trajectory was nonmonotonic, first leading then lagging the position of the limb. Second, we address the claim that high levels of stiffness are required to generate rapid single-joint movements when simple equilibrium shifts are used. We compare empirical measurements of stiffness during rapid single-joint movements with the predicted stiffness of movements generated using constant-rate equilibrium shifts and constant cocontraction commands. Single-joint movements are simulated at a number of speeds, and the procedure used by Bennett to estimate stiffness is followed. We show that when the magnitude of the cocontraction command is scaled in proportion to movement speed, simulated joint stiffness varies with movement speed in a manner comparable with that reported by Bennett. Third, we address the related claim that nonmonotonic equilibrium shifts are required to generate rapid single-joint movements. Using constant-rate equilibrium shifts and constant cocontraction commands, rapid single-joint movements are simulated in the presence of external torques. We use the procedure reported by Latash and Gottlieb to compute hypothetical equilibrium trajectories from simulated torque and angle measurements during movement. As in Latash and Gottlieb, a nonmonotonic function is obtained even though the control signals used in the simulations are constant-rate changes in the equilibrium position of the limb. Differences between the "simple" equilibrium trajectory proposed in the present paper and those that are derived from the procedures used by Gomi and Kawato and Latash and Gottlieb arise from their use of simplified models of force generation.}
}
-
Christopher M. Harris and Daniel M. Wolpert.
Signal-dependent noise determines motor planning.
Nature,
394:780-784,
1998.
Keywords: neuroscience,
motor control,
minimum variance,
feedback.
| Abstract: When we make saccadic eye movements or goal-directed arm movements, there is an infinite number of possible trajectories that the eye or arm could take to reach the target. However, humans show highly stereotyped trajectories in which velocity profiles of both the eye and hand are smooth and symmetric for brief movements. Here we present a unifying theory of eye and arm movements based on the single physiological assumption that the neural control signals are corrupted by noise whose variance increases with the size of the control signal. We propose that in the presence of such signal-dependent noise, the shape of a trajectory is selected to minimize the variance of the final eye or arm position. This minimum-variance theory accurately predicts the trajectories of both saccades and arm movements and the speed accuracy trade-off described by Fitt s law. These profiles are robust to changes in the dynamics of the eye or arm, as found empirically. Moreover, the relation between path curvature and hand velocity during drawing movements reproduces the empirical two-thirds power law. This theory provides a simple and powerful unifying perspective for both eye and arm movement control. |
| Comments: très bon (un modèle au niveau du style). reste le léger malaise de tout faire reposer sur le bruit: très certainement pertinent, mais mériterait un développement important car les conséquences sont vastes et profondes. |
@Article{harr_wolp_98,
author = {Harris, Christopher M. and Wolpert, Daniel M.},
title = {Signal-dependent noise determines motor planning},
journal = {Nature},
year = {1998},
volume = {394},
pages = {780-784},
comments = {très bon (un modèle au niveau du style). reste le léger malaise de tout faire reposer sur le bruit: très certainement pertinent, mais mériterait un développement important car les conséquences sont vastes et profondes.},
keywords = {neuroscience, motor control, minimum variance, feedback},
rating = {B},
url = {http://www.hera.ucl.ac.uk/sml/publications/papers/HarWol98.pdf},
abstract = {When we make saccadic eye movements or goal-directed arm movements, there is an infinite number of possible trajectories that the eye or arm could take to reach the target. However, humans show highly stereotyped trajectories in which velocity profiles of both the eye and hand are smooth and symmetric for brief movements. Here we present a unifying theory of eye and arm movements based on the single physiological assumption that the neural control signals are corrupted by noise whose variance increases with the size of the control signal. We propose that in the presence of such signal-dependent noise, the shape of a trajectory is selected to minimize the variance of the final eye or arm position. This minimum-variance theory accurately predicts the trajectories of both saccades and arm movements and the speed accuracy trade-off described by Fitt s law. These profiles are robust to changes in the dynamics of the eye or arm, as found empirically. Moreover, the relation between path curvature and hand velocity during drawing movements reproduces the empirical two-thirds power law. This theory provides a simple and powerful unifying perspective for both eye and arm movement control. }
}
-
Aapo Hyvärinen.
Independent Component Analysis in the Presence of Gaussian Noise by Maximizing Joint Likelihood.
Neurocomputing,
22:49-67,
1998.
Keywords: ICA.
@Article{hyva_98,
author = {Hyvärinen, Aapo},
title = {Independent Component Analysis in the Presence of Gaussian Noise by Maximizing Joint Likelihood},
journal = {Neurocomputing},
year = {1998},
volume = {22},
pages = {49-67},
rating = {C},
keywords = {ICA}
}
-
Junko Kitamoto,
Katsuhiko Sakamoto,
Koichi Ozaki,
Yuji Mishina,
and Kentaro Arikawa.
Two visual pigments in a single photoreceptor cell: identification and histological localization of three mRNAs encoding visual pigment opsins in the retina of the butterfly Papilio xuthus.
Journal of Experimental Biology,
201(9):1255-1261,
1998.
Keywords: neuroscience,
genetics,
color,
photopigments.
| Abstract: This paper describes the localization of newly identified visual pigment opsins in the tiered retina of the Japanese yellow swallowtail Papilio xuthus. We first cloned three cDNAs encoding visual pigment opsins, PxRh1, PxRh2 and PxRh3, and then carried out histological in situ hybridization to localize their mRNAs in the retina. By combining the present data with our previous electrophysiological results, we concluded that both PxRh1 and PxRh2 correspond to visual pigments expressed in photoreceptor cells sensitive in the green wavelength region (green receptors), whereas PxRh3 corresponds to a pigment in red receptors. The in situ hybridization studies showed that some photoreceptor cells express two opsin mRNAs. In the ventral half of the eye, all green receptors in the distal tier were labelled by both PxRh1 and PxRh2 probes. The labelling by the PxRh2 and PxRh3 probes was detected throughout the eye in the proximal tier; in 18 \% of ommatidia, the probes labelled the same photoreceptor cell. These results suggest that the possible co-localization of two different visual pigments will broaden the sensitivity spectrum of the photoreceptor cells. |
| Comments: intéressant vis-à-vis des modèles de la perception par identité des cones |
@Article{kita_98,
author = {Kitamoto, Junko and Sakamoto, Katsuhiko and Ozaki, Koichi and Mishina, Yuji and Arikawa, Kentaro},
title = {Two visual pigments in a single photoreceptor cell: identification and histological localization of three mRNAs encoding visual pigment opsins in the retina of the butterfly Papilio xuthus},
journal = {Journal of Experimental Biology},
year = {1998},
volume = {201},
number = {9},
pages = {1255-1261},
url = {http://jeb.biologists.org/cgi/reprint/201/9/1255.pdf},
comments = {intéressant vis-à-vis des modèles de la perception par identité des cones},
rating = {C},
keywords = {neuroscience, genetics, color, photopigments},
abstract = {This paper describes the localization of newly identified visual pigment opsins in the tiered retina of the Japanese yellow swallowtail Papilio xuthus. We first cloned three cDNAs encoding visual pigment opsins, PxRh1, PxRh2 and PxRh3, and then carried out histological in situ hybridization to localize their mRNAs in the retina. By combining the present data with our previous electrophysiological results, we concluded that both PxRh1 and PxRh2 correspond to visual pigments expressed in photoreceptor cells sensitive in the green wavelength region (green receptors), whereas PxRh3 corresponds to a pigment in red receptors. The in situ hybridization studies showed that some photoreceptor cells express two opsin mRNAs. In the ventral half of the eye, all green receptors in the distal tier were labelled by both PxRh1 and PxRh2 probes. The labelling by the PxRh2 and PxRh3 probes was detected throughout the eye in the proximal tier; in 18 \% of ommatidia, the probes labelled the same photoreceptor cell. These results suggest that the possible co-localization of two different visual pigments will broaden the sensitivity spectrum of the photoreceptor cells. }
}
-
J.E. Marsden and J. Ostrowski.
Symmetries in Motion: Geometric Foundations of Motion Control.
Nonlinear Sci. Today,
1998.
Keywords: mathematics,
geometry,
motor control.
| Comments: Ce que j'aurais voulu écrire... contrôle dynamique à partir de la modification de forme, i.e. de modification du tenseur des moments, le tout dans un cadre de fibré, de connection, d'holonomie et de groupe de Jauge. |
@Article{mard_ostr_98,
author = {Marsden, J.E. and Ostrowski, J.},
title = {Symmetries in Motion: Geometric Foundations of Motion Control},
journal = {Nonlinear Sci. Today},
year = {1998},
comments = {Ce que j'aurais voulu écrire... contrôle dynamique à partir de la modification de forme, i.e. de modification du tenseur des moments, le tout dans un cadre de fibré, de connection, d'holonomie et de groupe de Jauge.},
url = {http://citeseer.nj.nec.com/marsden98symmetries.html},
keywords = {mathematics, geometry, motor control},
rating = {B}
}
-
F. Rieke and D.A. Baylor.
Single-photon detection by rod cells of the retina.
Reviews of Modern Physics,
70(3):1027-1035,
1998.
Keywords: vision,
photon,
rod.
| Abstract: At low light levels, the visual system detects and counts photon absorptions with a reliability close to limits set by statistical fluctuations in the number of absorbed photons. Thus the rod photoreceptors that provide the input signals to the dark-adapted visual system act as nearly perfect photon counters. This elegant performance is possible because light detection in the rods satisfies four functional requirements: high quantum efficiency, sufficient amplification to produce a measurable response, low dark noise, and low trial-to-trial variability in the elementary response. The rod meets these requirements using biochemical reactions rather than the solid-state reactions of silicon detectors, yet its performance equals or exceeds that of man-made detectors in several ways. |
| Comments: Review des méchanismes physiques et chimiques a la base du fonctionnement des batonnets: sensibilité à un unique photon, dark current |
@Article{riek_bayl_98,
author = {Rieke, F. and Baylor, D.A.},
title = {Single-photon detection by rod cells of the retina},
journal = {Reviews of Modern Physics},
year = {1998},
volume = {70},
number = {3},
pages = {1027-1035},
abstract = {At low light levels, the visual system detects and counts photon absorptions with a reliability close to limits set by statistical fluctuations in the number of absorbed photons. Thus the rod photoreceptors that provide the input signals to the dark-adapted visual system act as nearly perfect photon counters. This elegant performance is possible because light detection in the rods satisfies four functional requirements: high quantum efficiency, sufficient amplification to produce a measurable response, low dark noise, and low trial-to-trial variability in the elementary response. The rod meets these requirements using biochemical reactions rather than the solid-state reactions of silicon detectors, yet its performance equals or exceeds that of man-made detectors in several ways.},
comments = {Review des méchanismes physiques et chimiques a la base du fonctionnement des batonnets: sensibilité à un unique photon, dark current},
keywords = {vision, photon, rod},
rating = {C},
url = {http://rieke-server.physiol.washington.edu/~lab/People/Fred/Classes/545/rieke-baylor.pdf}
}
-
Davida Y. Teller.
Spatial and temporal aspects of infant color vision.
Vision Research,
38:3275-3282,
1998.
Keywords: ontogenesis,
color,
perception.
| Abstract: The present paper constitutes a review of the literature on young infants' chromatic discrimination capabilities. A series of early studies showed that infants as young as two months postnatal can make at least some chromatic discriminations between stationary, homogeneous fields of different wavelength compositions. Current studies of spatial and temporal contrast sensitivity functions (CSFs) for red/green isoluminant stimuli suggest that spatial chromatic CSFs show developmental changes in sensitivity and spatial scale, but not curve shape; while temporal chromatic CSFs (tCSFs) show developmental changes in sensitivity and curve shape, but not temporal scale. Infants can also code the direction of motion of moving isoluminant red/green gratings, for both continuous and quadrature motion. The possible mechanisms that underlie infants' chromatic discriminations are discussed. |
| Comments: l'auteur se prend les pieds dans le tapis dans sa conclusion, où apparait clairement le problème: que veut dire "perception" des couleurs. |
@Article{tell_98,
author = {Teller, Davida Y.},
title = {Spatial and temporal aspects of infant color vision},
journal = {Vision Research},
year = {1998},
volume = {38},
pages = {3275-3282},
comments = {l'auteur se prend les pieds dans le tapis dans sa conclusion, où apparait clairement le problème: que veut dire "perception" des couleurs.},
rating = {D},
url = {http://linkinghub.elsevier.com/retrieve/pii/S0042698997004689},
keywords = {ontogenesis, color, perception},
abstract = {The present paper constitutes a review of the literature on young infants' chromatic discrimination capabilities. A series of early studies showed that infants as young as two months postnatal can make at least some chromatic discriminations between stationary, homogeneous fields of different wavelength compositions. Current studies of spatial and temporal contrast sensitivity functions (CSFs) for red/green isoluminant stimuli suggest that spatial chromatic CSFs show developmental changes in sensitivity and spatial scale, but not curve shape; while temporal chromatic CSFs (tCSFs) show developmental changes in sensitivity and curve shape, but not temporal scale. Infants can also code the direction of motion of moving isoluminant red/green gratings, for both continuous and quadrature motion. The possible mechanisms that underlie infants' chromatic discriminations are discussed.}
}
-
J. B. Tenenbaum.
Mapping a Manifold of Perceptual Observations.
NIPS-10,
1998.
Keywords: geometry,
dimension reduction.
| Abstract: Nonlinear dimensionality reduction is formulated here as the problem of trying to find a Euclidean feature-space embedding of a set of observations that preserves as closely as possible their intrinsic metric structure the distances between points on the observation manifold as measured along geodesic paths. Our isometric feature mapping procedure, or isomap, is able to reliably recover low-dimensional nonlinear structure in realistic perceptual data sets, such as a manifold of face images, where conventional global mapping methods find only local minima. The recovered map provides a canonical set of globally meaningful features, which allows perceptual transformations such as interpolation, extrapolation, and analogy highly nonlinear transformations in the original observation space to be computed with simple linear operations in feature space. |
| Comments: Description of the Isomap algorithm, that uses MDS to embed high-dimensional data into a lower dimensional space conserving the order of distances between a set of sampled points. |
@Article{tene_98,
author = {Tenenbaum, J. B.},
title = {Mapping a Manifold of Perceptual Observations},
editor = {MIT Press},
volume = {NIPS-10},
year = {1998},
Comments = {Description of the Isomap algorithm, that uses MDS to embed high-dimensional data into a lower dimensional space conserving the order of distances between a set of sampled points.},
keywords = {geometry, dimension reduction},
rating = {B},
url = {http://web.mit.edu/cocosci/Papers/man_nips.pdf},
abstract = {Nonlinear dimensionality reduction is formulated here as the problem of trying to find a Euclidean feature-space embedding of a set of observations that preserves as closely as possible their intrinsic metric structure the distances between points on the observation manifold as measured along geodesic paths. Our isometric feature mapping procedure, or isomap, is able to reliably recover low-dimensional nonlinear structure in realistic perceptual data sets, such as a manifold of face images, where conventional global mapping methods find only local minima. The recovered map provides a canonical set of globally meaningful features, which allows perceptual transformations such as interpolation, extrapolation, and analogy highly nonlinear transformations in the original observation space to be computed with simple linear operations in feature space.}
}
-
Frank Tong,
K. Nakayama,
J. T. Vaughan,
and N. Kanwisher.
Binocular rivalry and visual awareness in human extrastriate cortex.
Neuron,
21:753-759,
1998.
Keywords: binocular rivalry,
awareness,
NCC.
| Abstract: We used functional magnetic resonance imaging (fMRI) to monitor stimulus-selective responses of the human fusiform face area (FFA) and parahippocampal place area (PPA) during binocular rivalry in which a face and a house stimulus were presented to different eyes. Though retinal stimulation remained constant, subjects perceived changes from house to face that were accompanied by increasing FFA and decreasing PPA activity; perceived changes from face to house led to the opposite pattern of responses. These responses during rivalry were equal in magnitude to those evoked by nonrivalrous stimulus alternation, suggesting that activity in the FFA and PPA reflects the perceived rather than the retinal stimulus, and that neural competition during binocular rivalry has been resolved by these stages of visual processing. |
@Article{tong_98,
author = {Tong, Frank and Nakayama, K. and Vaughan, J. T. and Kanwisher, N.},
title = {Binocular rivalry and visual awareness in human extrastriate cortex},
journal = {Neuron},
year = {1998},
volume = {21},
pages = {753-759},
url = {http://www.princeton.edu/~ftong/Tong.neuron.1998.pdf},
rating = {B},
keywords = {binocular rivalry, awareness, NCC},
abstract = {We used functional magnetic resonance imaging (fMRI) to monitor stimulus-selective responses of the human fusiform face area (FFA) and parahippocampal place area (PPA) during binocular rivalry in which a face and a house stimulus were presented to different eyes. Though retinal stimulation remained constant, subjects perceived changes from house to face that were accompanied by increasing FFA and decreasing PPA activity; perceived changes from face to house led to the opposite pattern of responses. These responses during rivalry were equal in magnitude to those evoked by nonrivalrous stimulus alternation, suggesting that activity in the FFA and PPA reflects the perceived rather than the retinal stimulus, and that neural competition during binocular rivalry has been resolved by these stages of visual processing.}
}
-
Duncan J. Watts and Steven H. Strogatz.
Collective dynamics of small-world networks.
Nature,
393:440-442,
1998.
Keywords: information theory,
networks,
graphs.
| Abstract: Networks of coupled dynamical systems have been used to model biological oscillators, Josephson junction arrays, excitable media, neural networks, spatial games, genetic control networks and many other self-organizing systems. Ordinarily, the connection topology is assumed to be either completely regular or completely random. But many biological, technological and social networks lie somewhere between these two extremes. Here we explore simple models of networks that can be tuned through this middle ground: regular networks 'rewired' to introduce increasing amounts of disorder. We find that these systems can be highly clustered, like regular lattices, yet have small characteristic path lengths, like random graphs. We call them 'small-world' networks, by analogy with the small-world phenomenon (popularly known as six degrees of separation. The neural network of the worm Caenorhabditis elegans, the power grid of the western United States, and the collaboration graph of film actors are shown to be small-world networks. Models of dynamical systems with small-world coupling display enhanced signal-propagation speed, computational power, and synchronizability. In particular, infectious diseases spread more easily in small-world networks than in regular lattices. |
| Comments: une belle idée pour étudier les graphes à connectivité partielle: partir d'un graph complet, qu'on modifie de manière probabiliste. |
@Article{watt_stro_98,
author = {Watts, Duncan J. and Strogatz, Steven H.},
title = {Collective dynamics of "small-world" networks},
journal = {Nature},
year = {1998},
volume = {393},
pages = {440-442},
comments = {une belle idée pour étudier les graphes à connectivité partielle: partir d'un graph complet, qu'on modifie de manière probabiliste.},
rating = {C},
url = {http://tam.cornell.edu/SS_nature_smallworld.pdf},
keywords = {information theory, networks, graphs},
abstract = {Networks of coupled dynamical systems have been used to model biological oscillators, Josephson junction arrays, excitable media, neural networks, spatial games, genetic control networks and many other self-organizing systems. Ordinarily, the connection topology is assumed to be either completely regular or completely random. But many biological, technological and social networks lie somewhere between these two extremes. Here we explore simple models of networks that can be tuned through this middle ground: regular networks 'rewired' to introduce increasing amounts of disorder. We find that these systems can be highly clustered, like regular lattices, yet have small characteristic path lengths, like random graphs. We call them 'small-world' networks, by analogy with the small-world phenomenon (popularly known as six degrees of separation. The neural network of the worm Caenorhabditis elegans, the power grid of the western United States, and the collaboration graph of film actors are shown to be small-world networks. Models of dynamical systems with small-world coupling display enhanced signal-propagation speed, computational power, and synchronizability. In particular, infectious diseases spread more easily in small-world networks than in regular lattices.}
}