Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
2000-05-30
2002-06-04
Jastrzab, Jeffrey R. (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
C623S004100, C623S010000, C607S055000
Reexamination Certificate
active
06400989
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention concerns an information processing system including an adaptive, sensory-motor encoder for a visual prosthesis or acoustic prosthesis for bi-directional coupling using implanted micro-contacts both for stimulation of neural or glial tissue as well as for the purpose of functional monitoring of brain function.
2. Description of Related Art
A number of attempts have been made to develop vision prostheses for various groups of blind persons by implantation of micro-contacts at the output layer of the retina (RET) or within the visual cortex (VCO) and by coupling these implants with an external signal transmitter (the encoder) in order to elicit functional visual perceptions. For example, encoders for implantable vision prostheses are described in U.S. Pat. No. 5,498,521, U.S. Pat. No. 5,351,314 or WO95/06288; implantable micro-contacts for the retina, visual cortex or auditory system are described in U.S. Pat. No. 5,597,381; U.S. Pat. No. 5,569,307; U.S. Pat. No. 5,549,658; U.S. Pat. No. 5,545,219; U.S. Pat. No. 5,496,369; U.S. Pat. No. 5,411,540; U.S. Pat. No. 2,215,088; U.S. Pat. No. 5,109,844 and U.S. Pat. No. 4,628,933. U.S. Pat. No. 5,277,886, EP 0435559 and U.S. Pat. No. 3,766,311 are concerned with neural networks and the visual system and U.S. Pat. No. 5,571,148, U.S. Pat. No. 5,512,906, U.S. Pat. No. 5,501,703, U.S. Pat. No. 5,441,532, U.S. Pat. No. 5,411,540 are concerned with addressing micro-contacts.
The target groups of the RET projects suffer retinal degenerative disease (for example, retinitis pigmentosa, macular degeneration) whereby the photoreceptor layer has degenerated but at least a portion of the retinal ganglion cells and part of the optic nerve originating there, as well as the central visual system are still functional. As is demonstrated by the publications mentioned above, work is being done on development of a variety of types of implantable micro-contact structures (stimulators), that are applied inside the globus oculi (eyeball) onto the ganglion cell layer of the retina and on the development of wireless signal and energy transfer systems for connection between the external encoder and the implanted stimulator, or generally to the interface.
The inventor has confronted the task of further developing an adaptive encoder for a visual prostheses that is coupled at the retina or to the visual cortex for conversion of image patterns or for acoustic prostheses coupled to the appropriate areas of the neural auditory system for conversion of sound patterns into stimulation signals through adaptive, spatio-temporal filters using receptive field characteristics of the respective sensory neurons (RF filters) addressed and their optimal adjustment by neural networks acting as adaptive function approximators.
The target groups of VCO projects typically no longer have recoverable optic nerve function and therefore require implantation of, for example, comblike micro-contact structures into regions of the visual cortex; that is the occipital cortex, that are directly adjacent to the cranium.
There are also several familiar types of acoustic prostheses (for example, the cochlear implant) using implanted micro-contacts that make possible partial recovery of auditory perception in deaf persons.
The current designs of implant systems do not provide for any information processing of the dynamic image pattern data within the visual system (for example, the retina), from the optical input up to the neural layer contacted by the implanted micro-contacts (for example, the ganglion layer of the retina or the neural layer in the visual cortex). Instead, simple image patterns (for example, lines) are forwarded directly as stimulation signals at the locally distributed micro-contacts without individually adapted information processing as a substitute for that part of the visual system that is to be technologically bridged (for example, the retina). The visual system that has been so rudimentarily and unadaptively stimulated is confronted with the difficult problem of generating visual perceptions, that are sufficiently similar to the image pattern, from the locally and temporally incorrectly processed or coded signal paths. Furthermore, the physiological adjustment of the visual sensitivity (brightness adaptation) over approximately 10 decades and the functional alteration of the receptive field characteristics or features connected with it in technical photosensor systems is not taken into account.
The currently developed implant systems using available technology do not use visual prostheses for the purpose of warning the implant carrier of hazards and reporting technically identified patterns. The same applies to currently developed implant systems for the auditory system.
Because of its ontogenetically established structure and its stabilized structure and function through years of visual perceptual experience prior to the occurrence of blindness, the visual system expects, for example, a particular kind of information processing of the image pattern data by each retinal ganglion cell via the optic nerve. This expectation is neurophysiologically transcribed by the corresponding receptive field features (RF) of the neuron and is very variable, is not fulfilled, inasmuch as, for example, the function of the retina, electrically stimulated by static pre-processing, cannot be individually adjusted for each single, stimulation contact produced by implantation. The same applies to the auditory system.
The collaboration necessary for the normal vision process of the central vision system receiving its inputs from the retina with the respective eye movement system is called the sensory-motor “Active Vision” system.
Such systems for pattern recognition, object tracking, object position recognition, etc. are taken into consideration in conventional applications. The visual system nevertheless requires eye movements for all vision performances and produces not only recognition performances (what?), but very importantly recognition performances (where?) as well as orientation in space, all of which have a very high priority for the visually challenged person who is in the process of partially recovering his ability to see. Triggering of visually induced eye movements, however, in the case of actual stimulation by the use of the implant system, cannot be expected from only a small fraction of the retinal ganglion cells or the cells in the visual cortex. Therefore, the visual system, using the implants that are currently in the development stage and which are based on normal cooperation with eye movements, can perform only unsatisfactory visual perception, if any at all.
In various visually challenged persons there occur, in addition, undesired, non-visually induced eye movements with slow and fast phases, that can significantly impair optimal utilization—and thus the acceptance—of this type of visual prosthesis. If, for example, the encoder with photosensor array is fixed onto the globus oculi, the then desired locus of fixation is constantly shifted by the undesired eye movements. If, on the other hand, the encoder is built into an eyeglass frame, then the visual system will interpret the image pattern with the eye movements that have not been harmonized with the image pattern, as ambiguous visual perceptions, for example, as apparent movement, as is, for example, the case in vertiginous perceptions.
Without the possibility of visually induced, real eye movements and the additional conflict with undesired spontaneous eye movements, visual orientation in space, position identification of various objects relative to the location of one's own body—for example for the intentional grasping of a door knob—using visual prostheses currently in development, which are dependent on head and upper-body movements for the change in direction of vision, are barely possible. The structures to be implanted have a very limited number of micro-contacts. The number of effective usable micro-contacts is even sma
Intelligent Implants GmbH
Jastrzab Jeffrey R.
Venable Baetjer Howard & Civiletti LLP
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