Biomedical subjects

C C Turbes

Publications and source records attributed to C C Turbes.

At least 19 recordsLinked to original sources

PubMed2003

Dorsal root implant on lesioned spinal cord morphologic findings of regeneration of synapses in the mammalian spinal cord--repair and recovery.

Earlier work concerning regeneration of synaptic connection had been studied primarily in amphibia. Sperry and Miner and Stevens showed that functional regeneration of synapses followed sectioning and anastomosis of the central process of the dorsal root of one side to the proximal stump of the dorsal root of the opposite. A number of studies have shown that the dorsal roots and dorsal columns of mammals have adequate regenerative capacities. There is no functional or morphologic evidence for reestablishment of synaptic connections reported in the mammalian studies. A number of authors have reported that regenerating dorsal root fibers are confronted with a barrier at the neutilemmal-glial junctions. Previous studies have shown that peripheral nerve fibers inserted into the spinal cord grow profusely. Theorizing that regenerating dorsal root fibers would grow and reestablish synaptic connection more readily, it was decided to insert the neurilemmal portion- including Schwann cells- of the dorsal roots into the spinal cord to the depths of the gray columns.

Animals↗

PubMed2002

Implantation of multiple intercostal nerve neuromas in lesioned spinal cord-repair, regeneration and rehabilitation strategies.

Multiple intercostals nerve neuromas are surgically implanted in the lesioned spinal cord by bridging transaction lesions at T6 or T8 by removing one centimeter of spinal cord. In these experiments one to four intercostals nerves with origin proximal to the transection and the distal stumps, the neuroma was implanted distal to the transection. These procedures plus rehabilitation resulted in enhancing of regeneration of axons in the spinal cord lesion and dogs developed standing, stepping and reflex walking locomotion. Surgical resection of the implanted nerve resulted in paraplegia. Multiple nerve implants bridging the transaction of 34 mature female dogs. A pattern of neurological deficits developed when a sequence of resection of the implanted nerves were performed. If four nerves were implanted and one nerve resected usually no deficits were observed. When the second nerve was resected certain deficits were observed. When three nerves were resected some dogs became paraplegic, and some dogs showed increased sign of paraplegia but were not completely paralyzed and showed hind limb movements but no weight bearing. When four nerves were resected full paraplegia was observed.

Animals↗

PubMed2001

Intercostal nerve neurouma (PNS) implantation in spinal cord bridging spinal cord transection a functional internuncal pathway system result in recovery from paraplegia.

In these studies 76 mature female dogs were used. The spinal cord was transacted at T6 or T8. The intercostal nerve or nerves originating cephalic to the transaction were inserted into the distal isolated cord close to the transaction and plasma clot sutured to anchor the peripheral end of the nerve into the spinal cord. The transacted isolated spinal cord at the mid thoracic level results in paraplegia. 3, 4, 21 The isolated distal transacted spinal cord is capable of producing complex, detailed locomotor functions. The anatomical substrate is produced by systems of interconnected interneurons in the lumbar spinal cord that forms the central pattern generators (CPG). 3, 4, 21 The interneurons comprising (CPG) coordinates patterned movements of the rear limbs as flexion, extension, weight bearing, postural adjustments and alternating patterned limb movements. 3, 4, 21 In the case of implantation of a peripheral nerve distal stump into the transacted spinal cord the procedure enhances the function mediated by the central patterned generators (CPG) by training, conditioning and chemical and molecular treatments. 3, 4, 7, 8, 15, 1, 18, 19, 21.

Animals↗

PubMed1999

Surgical implantation of a peripheral nerve neuroma in lesioned spinal cord and brain--axonal sprouting regeneration and synaptogenesis.

Thirty-six mature female dogs weighing fifteen to twenty-five pounds, then spinal cord transected at T6 or T8. An intercostal nerve neuroma with cellular origin proximal to the transection site was dissected free to near the intervertebral foramen and the distal nerve stump was implanted in the spinal cord distal but near to the transection site and anchored with a plasma clot suture. These dogs were studied, treated and rehabilitated over a period of six months to two years or until they could stand, step and show reflex walking locomotion. Peripheral nerve distal stump neuroma, for example, intercostal nerve and cranial nerve XI are transected and surgically implanted in the lesions of the spinal cord or brain. 1, 2, 3, 4, 5, 8. The implantation of the unfrozen XI cranial nerve neuromas in each case showed extensive invasion and neuroma axon in growth in to the temporal lobe of the brain. In some cases there was axon in growth in to the hippocampus and amygdala was noted.

Accessory Nerve↗

PubMed1999

Intercostal nerve nerve neurouma (PNS) implantation in spinal cord transection--enhancement of locomotor recovery.

In these studies 76 mature female dogs were used. The sinal cord was transected at T6 or T8. The intercostal nerve or nerves originating cephalic to the transection were inserted into the distal isolated cord close to the transection and plasma clot sutured to anchor the peripheral end of the nerve into the spinal cord. The transected isolated spinal cord at the mid thoracic level results in rear limb paralysis. The isolated distal transected spinal cord is capable producing complex, detailed locomotor functions. The anatomical substrate is produced by systems of interconnected interneurons in the lumbar spinal cord that forms the central pattern generators (CPG). The interneurons comprising (CPG) coordinates patterned movements of the rear limbs as flexion, extension, weight bearing, postural adjustments and alternating patterned limb movements. In the case of implantation of a peripheral nerve distal stump into the transected spinal cord the procedure enhances the function mediated by the central patterned generators (CPG) by training, conditioning and chemical and molecular treatments.

Animals↗

PubMed1997

Intercostal nerve nerve neuroma (PNS) implantation in spinal cord anastomosis bridging spinal cord transection--enhancement of central neurons (CNS) axonal regeneration.

The enhancement of axonal regeneration in the spinal cord transection is shown by implanting intercostal nerve neuroma with origin cephalic to spinal cord transection site. The nerve is implanted in the distal spinal cord near the transection site. The intercostal nerve peripheral portion is anchored in the distal spinal cord using a plasma clot suture. 2,3,4 Regeneration of (CNS) axons and (PNS) axons in the spinal cord transaction lesion demands care, rehabilitation, no infections, and maintenance of normal body functions. After a period of repair and rehabilitation "reflex" standing and walking developed in 26 mature female dogs. Surgical section of the implanted nerve resulted in loss of standing and reflex walking and return to a paraplegic condition. 2,3,4,5 Stimulation of the motor cortex and implanted intercostal nerve resulted in movements of the hind limbs of the standing and reflex walking dogs all having cord transection and intercostal nerve neuroma implantation. 2,3,4,5 The neuroma generates spontaneous electrical activity as unit discharges similar to seizure and epleptic activity. This activity has a role in spinal cord lesions in the induction of regeneration of axonal sprouting. 1,2,3,4,12,13,15

Animals↗

PubMed1997

Repair, reconstruction, regeneration and rehabilitation strategies to spinal cord injury.

The structural changes seen in the transected spinal cord followed by transplantation of the distal ends (neuroma) of intercostal nerve inserted into the spinal cord proximal and distal to the transection lesion site. This activates CNS axonal regeneration. 2,3,4 These changes refer to the plasticity in the nervous system following damage to the spinal cord. There is regeneration and growth and synapotogenesis and remodeling of synaptic connections, development of reflex activity in the denervated cord. Nerve growth factors and neurotrophic factors sustain and maintain a degree of functional integrity of structural neural circuitry. 2,3,4,13 The end result is standing, stepping, and reflex walking in 28 female mature dogs. 2,3,4,5 Electrical stimulation of the anastomosed intercostal nerves resulted in hind limb movements and recording of the electromyograms of the contracting muscles. Twenty-six control dogs and animals with behavioral depression are unable to follow rehabilitative procedures developed muscle atrophy, ankylosis of joints, decrease in bone density, decrease in reflex activity of the spinal cord distal to the transection. 2,3,4,5

Animals↗

PubMed1997

Peripheral nerve (PNS) spinal cord anastomoses bridging spinal cord transection--enhancement of central neurons (CNS) axonal regeneration.

These studies involve 76 mature female dogs at 5.5 to 16 kg. The enhancement of axonal regeneration in the spinal cord transection is shown by implanting intercostal nerve with origin cephalic to spinal cord transection. The nerve is implanted in the distal isolated spinal cord near the transection site. The intercostal nerve peripheral portion is anchored in the distal spinal cord using a plasma clot suture. Regeneration of CNS axons and PNS axons in the spinal cord transection demands care, rehabilitation, and maintenance of normal body functions. After a period of two years repair and rehabilitation "reflex" standing and walking developed in 26 mature female dogs. Surgical section of the implanted nerve resulted in loss of standing and reflex walking and return to a paraplegic condition in 12 dogs. Stimulation of the motor cortex and implanted intercostal nerve resulted in movements of the hind limbs of the standing and reflex walking dogs all having cord transection and intercostal nerve anastomoses.

Anastomosis, Surgical↗

PubMed1996

Neurons' and glia role in electrocephalogram--evoked potential (EEG-EP) dynamics.

These studies are concerned with the interactive mechanisms of the EEG-EP in the processing of sensory and cognitive information. The (EP) following auditory and visual stimulation are studied in unanesthesized free moving cats. Special attention is given to frequency and time domain studies of the (EEG) preceding stimulation and the changes in the EEG following auditory and visual stimuli. Special consideration is given to glial and neuronal interactive and their role in the electrogenesis of evoked potentials. Synchronous electrical activity of groups of neurons are likely to depolarize glial cells in distributed brain areas as in (EEG-EP) and sequences of (EP) in periodic flicker light stimulation. These may play a role in coupling processes in neuronal groups. Glial membranes share with neuronal membranes in the extracellular space which neuronal activities can enrich with potassium.

Animals↗

PubMed1996

Frequency and time domain studies of the micro-EEG from the brain extracellular space.

In these studies, recordings from the brain extracellular space of cats are considered. Macro and microelectrodes are utilized. Special studies using visual, auditory stimuli and certain drugs are done. Coherence, power phase and partial coherence spectra of wave field potentials and unit potentials are investigated. The electrographic profile of the micro electroencephalogram (EEG) and micro evoked response (ER) of the extracellular space is different than the macropotentials of the macro (EEG) and the macro (ER). The electrographic patterns of the micro (EEG) and the micro (ER) will vary with the microelectrode size, location and the variable microanatomy. There are many single neuron field potentials differentiated in space and time. In these unit fields there are varying electronic interactions varying in space and time. There are patterned inputs varying in space and time. There are fluctuating microfields distributed in overlapping layers, columns, slabs and patches and periaxonal extracellular spaces of the cerebral and cerebellar white matter. In these anatomical situations there are variable, degrees of local and general selective patterns of synchronization with variable direction, and selective spread. The extracellular space micro (EEG) shows complex and dynamic shifts of the micro (EEG) to the macro (EEG) frequencies and tuned macrofields.

Animals↗

PubMed1995

Cerebral cortical and hippocampal interactions and sequencing of perceptual information.

In these studies, recordings from cerebral cortical and limbic systems of cats are made of the dynamics of the electroencephalogram and evoked potentials. The hippocampus receives inputs from classification couples in global mappings and sends outputs back to the cortical regions that are originally responsible for input to the hippocampus. Because of the hippocampal loop structure operating parallel it appears to maintain an ordering of perceptual information in time of input from cortical networks. Repetitive stimuli are used to test the interaction patterns of evoked potentials in cortical and limbic regions.

Animals↗

PubMed1995

Hippocampal and cerebral cortical sequencing of cardiac activity--theta rhythm (4-10Hz).

Interaction of repetitive evoked potentials using visual and auditory stimuli has been show for the hippocampus and cerebral cortex. Selected components of the electrocardiogram (EKG) are used to stimulate certain nuclei of the amygdala. Extracellular unit potentials of the hippocampus shown repetitive activity. The micro-EEG of the cerebral cortex and dorsal hippocampus show rhythmic activity. In the hippocampus computer analysis of these analog signals show an increase of the theta rhythm related to the EKG (QRST) stimulation. Repetitive activity related to the heart rate (EKG) is evident in the cerebral cortex during stimulation.

Animals↗

PubMed1993

Brain self-organization dynamics.

During early phases of brain development gene expression and postranslational modifications of gene expression are controlled by biochemical signals which are produced in a cellular microenvironment. Later in brain development there is a difference from the development of other organs because electrical signals are added to biochemical messengers as a further signaling in the self-organizing between genes and their respective environments. It must be considered that these electrical signals are capable in influencing gene expression and postranslational modifications. Electrical signals are transported by neuronal processes over distances and with highly topological selectively. This enlarges the range and complexity of the "environment" available to self-organization process. The "environment" relevant to brain self-organization includes all domains with which the evolving brain is capable to interact and from which it receives messages. The same electrical signals which convey messages are used by the brain as information carriers for computational process. The key concept in theories and modeling is that of refference. Cyclical process of emergent goal seeking, refference and sensory feedback constitute the basis for a subject consciousness. This cycle suggest further "inference" that the physiological basis of cause and effect lies in the mechanism of reafference. This tract results in the replacement of sensory stimuli by self-organization activity patterns that are contingent on past experience, present motivational state and expectancy of the future.

Amygdala↗

PubMed1993

Hippocampal extracellular space micro-EEG--high frequency oscillations.

The hippocampal extracellular space electro-magnetic field interactions and related integrative mechanisms are important factors in the make-up of the micro-EEG. Combinations of ion currents give rise to complex patterns of neuronal electrical activity in the brain cell microenvironment, the extracellular space. The flow of ions through populations of ion channels in the neuronal plasma membrane and give rise to trans membrane ion currents. It is the sum of various currents flowing at any point in time that determines the neurons membrane potential. The multiple ion channels with their diverse and interacting regulatory mechanisms allow the neuron to modulate its electrical properties in complex ways of high frequency oscillations and electrical fields. Some of the hippocampal neurons have ionic conductances organized to endow them with auto rhythmicity. In many neurons the kinetics of these ionic voltage dependent conductances are such that the cells may respond preferentially to inputs at a certain frequency or frequencies acting as a resonators.

Amygdala↗

PubMed1992

EEG dynamics. Brain processing of sensory and cognitive information.

The EEG oscillations and resonances before sensory stimulation are variable; unstable frequencies and amplitudes. The EEG time-coherency is variable and tends to be incoherent preceding sensory stimulation. The phase angle of the EEG between brain structures tends to be random and coherence between various brain structures is low before the stimulus. Following sensory stimulation, the frequency is stabilized and the amplitude is greatly enhanced. These responses are considered to be related to coupling of neural oscillators and nuclear resonance. The shift to a time-coherent state is considered to be related to a probabilistic harmonic oscillators. The phase angle after the stimulus is zero-phase in the brain rhythm channels in all brain structures as noted in the phase spectra. In the post stimulation period there is a change to high coherency between brain structures in the inherent frequencies of their brain rhythms. Internal evoked potentials shown in all the brain nuclei studied. All the frequencies in the evoked potential responses are dependent on spontaneous EEG activities prior to the stimulus.

Animals↗

PubMed1992

Brain states--brain rhythms--brain responses.

Oscillation and resonance of electrical activity of certain sets of neurons in the brain and spinal cord is an important factor in the organization of those properties of connectivity that must be tuned by function. Once connectivity has reached some degree of specificity important biological and chemical events must occur to stabilize synaptic inputs and localize excitable sites to particular areas of the cell surface. It has been proposed that intrinsic electroresponsiveness generates internal computational states that serves as a reference frame or context for incoming information. The intrinsic activity is proposed to be a part of the vectorial coordinate space that sensory and motor transformations occur in context of a particular functional state such as attention and expectation that can modify the relevance of a given sensory input. The most significant mechanism in generation of oscillation properties of the brain are the intrinsic properties of individual neurons. This concept presents a shift of emphasis from properties of circuits to properties of single neurons. Feedback circuits and synchronization of single oscillators into sets of coupled oscillators which in turn generates field potentials such as (EEG) and evoked response (ER).

Animals↗

PubMed1991

Studies of stereodynamic interaction of the EEG and auditory potentials of the limbic system and non-auditory frontal cortex.

These studies use 24 cats under non-anesthetic states. Electrodes are implanted, under appropriate anesthetic and stereotoxic procedures in non-auditory neocortical areas, nucleus accumbens, and certain nuclei of the amygdala complex. Auditory stimulation was done using the free field method with periodic tones at 2.0 KHz to 3.0 KHz at 80db. The auditory stimulation and recording was performed with hard wire and telemetry methods. The analog data is collected on FM tape and processed with minicomputer. Digital filtering, cross, coherence, phase, spectral and cycle time analyses are used on the analog data. In these studies, we have looked at the electroencephalogram (EEG) and the auditory evoked potentials (AEP) of cortical and subcortical regions using frequency and time domain methods. The analyses of the interaction of spatially distributed neuronal networks during EEG and AEP activity may give insights to topographical relations in the brain.

Animals↗

PubMed1991

Partial (coherence & correlation) estimates of brain autorhythmicity.

These experiments try to exhibit the interactions of the electrical activity of the microenvironment of a neuronal population spatially distant from the microenvironment of a different neuronal population. These experiments involve 18 cats with chronic electrodes surgically implanted into cerebral cortex, septal nuclei and amygdala. The Fast Fourier Transform (FFT) algorithm is done to process frequency domain data. In order to compare the phase relations between two channels, x(t) and y(T), use is often made of the coherence function. Computing partial coherence implies first eliminating from each two signals, that part which can be considered as being determined by, or predictable, on the basis of a third signal. It is assumed that there are three stochastic signals Y1, Y2, Y3. These variables can be considered as spectral components for a particular frequency. We assume that the correlations can be interpreted as square root of the coherence. For simplicity we use, in the partial correlations analyses.

Animals↗