One way that discrete acoustic events may be signaled to the central nervous system is through sp... more One way that discrete acoustic events may be signaled to the central nervous system is through spike synchrony over a subpopulation of cochlear axons. Each of the four corners of a trapezoidally modulated tone burst is such an event. Ordinarily, each comer comprises both an abrupt change in envelope slope and a singularity in the modulated waveform. In this study, in addition to stimuli of this sort, we employed a stimulus waveform in which a comer occurred without a waveform singularity. We obtained masker tuning curves for the CAPS corresponding to both kinds of comers and single-unit responses to both kinds of comers. The results suggest that the subpopulation of cochkzu axons excited by the singularity component of a comer is distinct from that excited by the abrupt change in envelope slope.
When electrical resonances were observed in acoustic sensory cells of lower vertebrates, the hear... more When electrical resonances were observed in acoustic sensory cells of lower vertebrates, the hearing research community was presented with the exciting possibility that tuning in the ears of those animals might be explained directly in terms of familiar molecular devices. It is reported here that in the frog sacculus, where electrical resonances have been observed in isolated hair cells, the effects of those resonances are completely obscured in the tuning properties of the sacculus in the intact ear. This observation has important implications not only for students of the ear, but for reductionist biologists in general. All of the dynamic properties of a system of connected, bidirectional processes are consequences of all of those processes at once; in such a system, the properties of an experimentally isolated subsystem may be totally obscured in the operation of the system as a whole. 'Strictly speaking, phase is not well defined for transfer functions of nonlinear processes.
O n a dinner cruise through Matsushima, in early summer 1999, I filled my plate at the buffet and... more O n a dinner cruise through Matsushima, in early summer 1999, I filled my plate at the buffet and sat down at an empty table. I soon was joined by six colleagues. Looking around the table, I realized that I was surrounded by six of the most important leaders in the field of hearing research. Then I realized that the majority of them were electrical engineers by training and commented on that fact. It turned out that five were trained as electrical engineers. The sixth, trained as a physiologist, spent his career to date collaborating with an electrical engineer at MIT's Research Laboratory of Electronics. And he is an excellent engineer in his own right. By their biomedical colleagues, all six are considered to be biologists of the first rank. But each of them, at core, remains an engineer. What each of them does is reverse engineeringVreverse engineering of systems, devices, communication strategies, and signal processing strategies designed by nature rather than by other engineers.
We begin with premises about natural science, its fundamental protocols and its limitations. With... more We begin with premises about natural science, its fundamental protocols and its limitations. With those in mind, we construct alternative descriptive models of consciousness, each comprising a synthesis of recent literature in cognitive science. Presuming that consciousness arose through natural selection, we eliminate the subset of alternatives that lack selectable physical phenotypes, leaving the subset with limited free will (mostly in the form of free won't). We argue that membership in this subset implies a two-way exchange of energy between the conscious mental realm and the physical realm of the brain. We propose an analogy between the mental and physical phases of energy and the phases (e.g., gas/liquid) of matter, and a possible realization in the form of a generic resonator. As candidate undergirdings of such a system, we propose astroglial-pyramidal cell and electromagnetic-field models. Finally, we consider the problem of identification of the presence of consciousness in other beings or in machines.
Single fiber recordings were made from auditory nerve fibers of the American bullfrog (Rana cates... more Single fiber recordings were made from auditory nerve fibers of the American bullfrog (Rana catesbelana). As temperature was raised: (1) Best frequencies of fibers from the amphibian papilla (N = 15) increased. Below 600 Hz best frequency changes up to 0.06 oct/"C were found; above 600 Hz changes were less than 0.03 oct/"C. In the basilar papilla (N = 4) no significant increase of best frequency was found. (2) Spike rates in response to fixed-RMS-amplitude stimuli increased considerably: Q,, of spike rate ranged from 5 to 10. (3) Spontaneous activity, found in basilar papilla fibers. increased with average Q ,a = 1.6 (kO.3). (4) A conspicious change of tuning quality factor Q,ede was only observed in two fibers, that were taken to low temperatures (< 16°C). (5) the nearly linear frequency vs. phase relation in amphibian papilla shifts to higher frequency (along with shift of best frequency), while its average slope remains nearly unchanged.
Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears... more Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.
Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears... more Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.
Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears... more Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.
Zeitschrift f�r Zellforschung und Mikroskopische Anatomie, 1972
Scanning electron microscopy revealed two types of hair cells in the sacculus of an amphibian, th... more Scanning electron microscopy revealed two types of hair cells in the sacculus of an amphibian, the mudpuppy (Necturus maculosus). Both types were surrounded by microvilli-covered sustentacular cells. The peripheral hair cells have shorter, thinner stereocilia and longer kinocilia than the hair cells in the central macula. The hair cells generally were found to be oriented with their stereocilia gradient directed toward the periphery of the macula. A nearly semicircular stria separated those directed forward and outward from those directed rearward and outward. Two basic types of otoconia were found in the otolith, and X-ray analysis revealed the entire otolith to be composed of aragonite.
The morphology of typical anuran amphibian papillae is thoroughly distinct from that of urodeles.... more The morphology of typical anuran amphibian papillae is thoroughly distinct from that of urodeles. However, the morphological discontinuity lies not between the frogs and the salamanders, but between the most primitive living frog, Ascaphus truei, and the more derived anurans. Three features distinguishing the papillae of more derived anurans from that of Ascaphus apparently provide peripheral tonotopy in the former. The adaptive significance of a fourth feature, kinocitiary bulbs, is not clear. Auditory sensitivity in the frogs and toads (the Anurans) has been attributed in part to a specialized inner-ear organ, the amphibian papilla1, 6-s. Beginning with the discoglossids, generally accepted to be among the most primitive of anurans, and progressing to the ranids and their relatives, generally accepted to be among the most derived4,24, a2, one finds that the anuran amphibian papilla consistently exhibits 4 morphological features not found in the amphibian papilla of the salamanders. (1) The typical anuran amphibian papilla consists of two patches of sensory epithelium, each innervated by a separate branchlet of the VIIIth nerve and each having two populations of sensory (hair) cells, oppositely polarized ls-16; the urodele (salamander) amphibian papilla consists of a single patch2~, 22, with a single pair of oppositely-polarized hair-cell populations (Fig. 1). (2) The amphibian periotic canal contacts the posterior end of the typical anuran amphibian papillar chamber (through the contact membrane); in the urodeles it contacts the medial side of the chamber1,9,21,~L (3) Hanging from the typical anuran amphibian papilla, the tectorium (an acellular, mucopolysaccharide structure) is thick where it is adjacent to the rostral patch of sensory epithelium and thin where it is adjacent to the caudal patchS,la,a°,35; in urodeles it is intermediate in thickness over the entire papilla. (4) In the typical anuran amphibian papilla, the single cilium (kinocilium) of the hair cell has a bulb at its distal end (Fig. 2); the kinocilium of the urodele amphibian-papillar hair cell has no bulb. Recently we extended the morphological observations to the tailed frog (Ascaphus truei), one of four living anuran species generally accepted to be even more
In 1952, Hodgkin and Huxley and others generated a revolution in our concept of the axon membrane... more In 1952, Hodgkin and Huxley and others generated a revolution in our concept of the axon membrane and how it propagates the action potential. In 1959, Bullock described another revolution, a "quiet revolution" in our concept of the functions performed by the remainder of the nerve cell. In this paper we have attempted to show a possible connection between these two revolutions. We have proposed that a single unifying concept, that of the Modem Ionic Hypothesis, can account for almost all of the diverse behavior described by Bullock. In addition, we have attempted to demonstrate the value of electronic analogs in the study of systems as complex as that of the neural membrane.
During the breeding season, each tympanic membrane of males of the Old World treefrog Petropedete... more During the breeding season, each tympanic membrane of males of the Old World treefrog Petropedetes parkeri is decorated with a single, prominent, fleshy tympanic papilla. The tympanic papilla, located dorsally on the tympanic membrane, is covered by an epidermal surface and is composed of non-ossified, spongiform tissue containing a number of globular, fluid-filled vesicles found at highest density near the papillar tip. These vesicles appear to have exit pores and are probably simple alveolar exocrine glands. Injecting sound into the pressurized vocal cavity of the male and measuring the vibration velocity response of the tympanic membrane revealed that from 0.3 to 2.0 kHz the tympanic papilla velocity amplitude is on average 20 dB lower than that of a point diametrically opposite on the ventral half of the tympanic membrane. The close agreement between the dominant frequency of the call and the frequency of the maximum spectral peak of the Fast Fourier Transform of the impulse res...
whose absolute values summed to approximately 20 dB/decade, implying typical dynamic order of one... more whose absolute values summed to approximately 20 dB/decade, implying typical dynamic order of one. We conclude that steep band-edge slopes and high dynamic order are indeed special features of acoustic sensors, not shared by vestibular sensors.
We present a simplified model of the micromechanics of the human cochlea, realized with electrica... more We present a simplified model of the micromechanics of the human cochlea, realized with electrical elements. Simulation of the model shows that it retains four signal processing features whose importance we argue on the basis of engineering logic and evolutionary evidence. Furthermore, just as the cochlea does, the model achieves massively parallel signal processing in a structurally economic way, by means of shared elements. By extracting what we believe are the five essential features of the cochlea, we hope to design a useful front-end filter to process acoustic images and to obtain a better understanding of the auditory system.
The Hodgkin-Huxley description of ek&kaUy excitable a m d-is combined with the Eccles description... more The Hodgkin-Huxley description of ek&kaUy excitable a m d-is combined with the Eccles description of synaptic condnctnnces to provide the basis of an electronic model of w n e-c d membrane. The m o d & are med to explore nearoeleetrie interactiom between spatially distrhted regious of a single nearon a d neoroelectric activities in very snnllgroagsofwaronsAmoogotserthings,oscillrtio~arefo~tocoodud with progressively increasing phrse lead along an axon modd. Miniature r e s e c t e a s p i k e s f r o m a t r i g g e r r e g i o o a r e a b l e t o r~s l o w p o t~~m a n mtegrative r egi on. Spike syoehrony b f d to be cornmoll in a mutually mhibitiug pair of nearal models. Spike bars@ OCQU m a mutually exciting pair. Eleehicpl coawetion between trigger regiom is f d to be excitatory or inhibitory, depeadiag on ph.se relatioas. A simpler electmk model is described and sbown to be reasooably adeqmte for S i m e l p h of mall neurpl nets.
As one progresses from the most primitive to the most derived frogs, one observes remarkable chan... more As one progresses from the most primitive to the most derived frogs, one observes remarkable changes in that peculiarly amphibian auditory organ, the amphibian papilla. In all but the most primitive frog, the papilla comprises two patches with separate innervation and apparently corresponding to a spatial separation of frequency sensitivity (i.e. tonotopic organization). The caudal patch is quite variable and in the more derived frogs exhibits an elongation that apparently corresponds to extension of auditory sensitivity to higher frequencies.
One way that discrete acoustic events may be signaled to the central nervous system is through sp... more One way that discrete acoustic events may be signaled to the central nervous system is through spike synchrony over a subpopulation of cochlear axons. Each of the four corners of a trapezoidally modulated tone burst is such an event. Ordinarily, each comer comprises both an abrupt change in envelope slope and a singularity in the modulated waveform. In this study, in addition to stimuli of this sort, we employed a stimulus waveform in which a comer occurred without a waveform singularity. We obtained masker tuning curves for the CAPS corresponding to both kinds of comers and single-unit responses to both kinds of comers. The results suggest that the subpopulation of cochkzu axons excited by the singularity component of a comer is distinct from that excited by the abrupt change in envelope slope.
When electrical resonances were observed in acoustic sensory cells of lower vertebrates, the hear... more When electrical resonances were observed in acoustic sensory cells of lower vertebrates, the hearing research community was presented with the exciting possibility that tuning in the ears of those animals might be explained directly in terms of familiar molecular devices. It is reported here that in the frog sacculus, where electrical resonances have been observed in isolated hair cells, the effects of those resonances are completely obscured in the tuning properties of the sacculus in the intact ear. This observation has important implications not only for students of the ear, but for reductionist biologists in general. All of the dynamic properties of a system of connected, bidirectional processes are consequences of all of those processes at once; in such a system, the properties of an experimentally isolated subsystem may be totally obscured in the operation of the system as a whole. 'Strictly speaking, phase is not well defined for transfer functions of nonlinear processes.
O n a dinner cruise through Matsushima, in early summer 1999, I filled my plate at the buffet and... more O n a dinner cruise through Matsushima, in early summer 1999, I filled my plate at the buffet and sat down at an empty table. I soon was joined by six colleagues. Looking around the table, I realized that I was surrounded by six of the most important leaders in the field of hearing research. Then I realized that the majority of them were electrical engineers by training and commented on that fact. It turned out that five were trained as electrical engineers. The sixth, trained as a physiologist, spent his career to date collaborating with an electrical engineer at MIT's Research Laboratory of Electronics. And he is an excellent engineer in his own right. By their biomedical colleagues, all six are considered to be biologists of the first rank. But each of them, at core, remains an engineer. What each of them does is reverse engineeringVreverse engineering of systems, devices, communication strategies, and signal processing strategies designed by nature rather than by other engineers.
We begin with premises about natural science, its fundamental protocols and its limitations. With... more We begin with premises about natural science, its fundamental protocols and its limitations. With those in mind, we construct alternative descriptive models of consciousness, each comprising a synthesis of recent literature in cognitive science. Presuming that consciousness arose through natural selection, we eliminate the subset of alternatives that lack selectable physical phenotypes, leaving the subset with limited free will (mostly in the form of free won't). We argue that membership in this subset implies a two-way exchange of energy between the conscious mental realm and the physical realm of the brain. We propose an analogy between the mental and physical phases of energy and the phases (e.g., gas/liquid) of matter, and a possible realization in the form of a generic resonator. As candidate undergirdings of such a system, we propose astroglial-pyramidal cell and electromagnetic-field models. Finally, we consider the problem of identification of the presence of consciousness in other beings or in machines.
Single fiber recordings were made from auditory nerve fibers of the American bullfrog (Rana cates... more Single fiber recordings were made from auditory nerve fibers of the American bullfrog (Rana catesbelana). As temperature was raised: (1) Best frequencies of fibers from the amphibian papilla (N = 15) increased. Below 600 Hz best frequency changes up to 0.06 oct/"C were found; above 600 Hz changes were less than 0.03 oct/"C. In the basilar papilla (N = 4) no significant increase of best frequency was found. (2) Spike rates in response to fixed-RMS-amplitude stimuli increased considerably: Q,, of spike rate ranged from 5 to 10. (3) Spontaneous activity, found in basilar papilla fibers. increased with average Q ,a = 1.6 (kO.3). (4) A conspicious change of tuning quality factor Q,ede was only observed in two fibers, that were taken to low temperatures (< 16°C). (5) the nearly linear frequency vs. phase relation in amphibian papilla shifts to higher frequency (along with shift of best frequency), while its average slope remains nearly unchanged.
Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears... more Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.
Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears... more Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.
Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears... more Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.
Zeitschrift f�r Zellforschung und Mikroskopische Anatomie, 1972
Scanning electron microscopy revealed two types of hair cells in the sacculus of an amphibian, th... more Scanning electron microscopy revealed two types of hair cells in the sacculus of an amphibian, the mudpuppy (Necturus maculosus). Both types were surrounded by microvilli-covered sustentacular cells. The peripheral hair cells have shorter, thinner stereocilia and longer kinocilia than the hair cells in the central macula. The hair cells generally were found to be oriented with their stereocilia gradient directed toward the periphery of the macula. A nearly semicircular stria separated those directed forward and outward from those directed rearward and outward. Two basic types of otoconia were found in the otolith, and X-ray analysis revealed the entire otolith to be composed of aragonite.
The morphology of typical anuran amphibian papillae is thoroughly distinct from that of urodeles.... more The morphology of typical anuran amphibian papillae is thoroughly distinct from that of urodeles. However, the morphological discontinuity lies not between the frogs and the salamanders, but between the most primitive living frog, Ascaphus truei, and the more derived anurans. Three features distinguishing the papillae of more derived anurans from that of Ascaphus apparently provide peripheral tonotopy in the former. The adaptive significance of a fourth feature, kinocitiary bulbs, is not clear. Auditory sensitivity in the frogs and toads (the Anurans) has been attributed in part to a specialized inner-ear organ, the amphibian papilla1, 6-s. Beginning with the discoglossids, generally accepted to be among the most primitive of anurans, and progressing to the ranids and their relatives, generally accepted to be among the most derived4,24, a2, one finds that the anuran amphibian papilla consistently exhibits 4 morphological features not found in the amphibian papilla of the salamanders. (1) The typical anuran amphibian papilla consists of two patches of sensory epithelium, each innervated by a separate branchlet of the VIIIth nerve and each having two populations of sensory (hair) cells, oppositely polarized ls-16; the urodele (salamander) amphibian papilla consists of a single patch2~, 22, with a single pair of oppositely-polarized hair-cell populations (Fig. 1). (2) The amphibian periotic canal contacts the posterior end of the typical anuran amphibian papillar chamber (through the contact membrane); in the urodeles it contacts the medial side of the chamber1,9,21,~L (3) Hanging from the typical anuran amphibian papilla, the tectorium (an acellular, mucopolysaccharide structure) is thick where it is adjacent to the rostral patch of sensory epithelium and thin where it is adjacent to the caudal patchS,la,a°,35; in urodeles it is intermediate in thickness over the entire papilla. (4) In the typical anuran amphibian papilla, the single cilium (kinocilium) of the hair cell has a bulb at its distal end (Fig. 2); the kinocilium of the urodele amphibian-papillar hair cell has no bulb. Recently we extended the morphological observations to the tailed frog (Ascaphus truei), one of four living anuran species generally accepted to be even more
In 1952, Hodgkin and Huxley and others generated a revolution in our concept of the axon membrane... more In 1952, Hodgkin and Huxley and others generated a revolution in our concept of the axon membrane and how it propagates the action potential. In 1959, Bullock described another revolution, a "quiet revolution" in our concept of the functions performed by the remainder of the nerve cell. In this paper we have attempted to show a possible connection between these two revolutions. We have proposed that a single unifying concept, that of the Modem Ionic Hypothesis, can account for almost all of the diverse behavior described by Bullock. In addition, we have attempted to demonstrate the value of electronic analogs in the study of systems as complex as that of the neural membrane.
During the breeding season, each tympanic membrane of males of the Old World treefrog Petropedete... more During the breeding season, each tympanic membrane of males of the Old World treefrog Petropedetes parkeri is decorated with a single, prominent, fleshy tympanic papilla. The tympanic papilla, located dorsally on the tympanic membrane, is covered by an epidermal surface and is composed of non-ossified, spongiform tissue containing a number of globular, fluid-filled vesicles found at highest density near the papillar tip. These vesicles appear to have exit pores and are probably simple alveolar exocrine glands. Injecting sound into the pressurized vocal cavity of the male and measuring the vibration velocity response of the tympanic membrane revealed that from 0.3 to 2.0 kHz the tympanic papilla velocity amplitude is on average 20 dB lower than that of a point diametrically opposite on the ventral half of the tympanic membrane. The close agreement between the dominant frequency of the call and the frequency of the maximum spectral peak of the Fast Fourier Transform of the impulse res...
whose absolute values summed to approximately 20 dB/decade, implying typical dynamic order of one... more whose absolute values summed to approximately 20 dB/decade, implying typical dynamic order of one. We conclude that steep band-edge slopes and high dynamic order are indeed special features of acoustic sensors, not shared by vestibular sensors.
We present a simplified model of the micromechanics of the human cochlea, realized with electrica... more We present a simplified model of the micromechanics of the human cochlea, realized with electrical elements. Simulation of the model shows that it retains four signal processing features whose importance we argue on the basis of engineering logic and evolutionary evidence. Furthermore, just as the cochlea does, the model achieves massively parallel signal processing in a structurally economic way, by means of shared elements. By extracting what we believe are the five essential features of the cochlea, we hope to design a useful front-end filter to process acoustic images and to obtain a better understanding of the auditory system.
The Hodgkin-Huxley description of ek&kaUy excitable a m d-is combined with the Eccles description... more The Hodgkin-Huxley description of ek&kaUy excitable a m d-is combined with the Eccles description of synaptic condnctnnces to provide the basis of an electronic model of w n e-c d membrane. The m o d & are med to explore nearoeleetrie interactiom between spatially distrhted regious of a single nearon a d neoroelectric activities in very snnllgroagsofwaronsAmoogotserthings,oscillrtio~arefo~tocoodud with progressively increasing phrse lead along an axon modd. Miniature r e s e c t e a s p i k e s f r o m a t r i g g e r r e g i o o a r e a b l e t o r~s l o w p o t~~m a n mtegrative r egi on. Spike syoehrony b f d to be cornmoll in a mutually mhibitiug pair of nearal models. Spike bars@ OCQU m a mutually exciting pair. Eleehicpl coawetion between trigger regiom is f d to be excitatory or inhibitory, depeadiag on ph.se relatioas. A simpler electmk model is described and sbown to be reasooably adeqmte for S i m e l p h of mall neurpl nets.
As one progresses from the most primitive to the most derived frogs, one observes remarkable chan... more As one progresses from the most primitive to the most derived frogs, one observes remarkable changes in that peculiarly amphibian auditory organ, the amphibian papilla. In all but the most primitive frog, the papilla comprises two patches with separate innervation and apparently corresponding to a spatial separation of frequency sensitivity (i.e. tonotopic organization). The caudal patch is quite variable and in the more derived frogs exhibits an elongation that apparently corresponds to extension of auditory sensitivity to higher frequencies.
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Papers by Edwin Lewis