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Biomedical subjects

M M Patterson

Publications and source records attributed to M M Patterson.

At least 55 records · Page 3Linked to original sources
PubMed1984

Fimbrial lesions and sensory preconditioning.

The effects of fimbrial and cortical lesions on sensory preconditioning in the rabbit were examined. Damage to the cortex or the fimbria had no apparent effect on the acquisition of classically conditioned responses. However, fimbrial lesions virtually abolished the effects of preconditioning, whereas cortical lesions had no significant effect. Because fimbrial damage disrupts hippocampal output, these findings are interpreted to indicate that the hippocampus is vital to learning functions other than spatial cognition or working memory.

Animals↗
PubMed1984

Influence of mercurial sulfhydryl agents on aqueous outflow pathways in enucleated eyes.

Enucleated calf and primate eyes were perfused with either p-chloromercuribenzene sulfonate (PCMBS) or p-chloromercuribenzene (PCMB). Both caused a decrease in aqueous outflow that did not result from inhibition of glycolysis in trabecular cells. Morphologic studies of PCMBS-treated primate eyes suggested that the reduction in aqueous outflow occurred as the result of cellular swelling in the trabecular meshwork and, particularly, in the juxtacanalicular connective tissue. These findings suggest that changes in cell volume may influence trabecular outflow resistance and that mercurial-sensitive membrane sulfhydryl groups could participate in the regulation of aqueous outflow.

4-Chloromercuribenzenesulfonate↗
PubMed1983

Obstruction of aqueous outflow by sodium hyaluronate in enucleated human eyes.

Instillation of sodium hyaluronate into the anterior chambers of enucleated human eyes caused a 65% decrease in outflow facility (from 0.33 +/- 0.16 microliters/min/mm Hg to 0.08 +/- 0.02 microliters/min/mm Hg). Vigorous anterior chamber irrigation, performed either immediately or three hours after introduction of the sodium hyaluronate, failed to relieve this obstruction. However, irrigation with hyaluronidase restored the facility values to baseline. Tying limbal or corneal 9-0 nylon sutures (for example, in cataract surgery), followed by instillation of sodium hyaluronate into the anterior chamber and subsequent irrigation, produced an overall decrease of 76% in outflow facility (final outflow values were 0.08 +/- 0.03 microliters/min/mm Hg in eyes with corneal wounds and 0.08 +/- 0.04 microliter/min/mm Hg in eyes with limbal wounds). Postoperative intraocular pressure should be monitored closely when sodium hyaluronate is used in cataract surgery. Irrigating the anterior chamber with balanced salt solution after using sodium hyaluronate does not eliminate the possibility of severe postoperative glaucoma.

Anterior Chamber↗
PubMed1983

Extinction and retention of a classically conditioned flexor nerve response in acute spinal cat.

These experiments were conducted to examine extinction and retention of a classically conditioned response in acute spinal cats. Conditioning was obtained by pairing a mild electrical stimulus to the superficial peroneal sensory nerve (CS) with a stronger electrical stimulus to the ankle skin (US) of the same leg. Subsequent extinction was produced by presenting CS-alone trials. In the first experiment, animals given massed extinction trials showed response decrements to base levels. Response decrements were not found in animals that received distributed extinction trials. In the second experiment, .5-, 1-, 2-, 3-, or 4-hr intervals between acquisition and extinction produced no significant differences in the extinction data. In the third experiment, animals received extinction trials immediately or 30 min after acquisition trials, followed by 20 additional extinction trials 30 min later. Analyses of these data indicated significant acquisition and extinction in the 10- and 20- acquisition trial groups. As in Experiment 2, varying the interval between acquisition and extinction did not produce any group differences in the extinction data. The results of these experiments demonstrate that response increases produced by paired trials in the spinal preparation do not decay spontaneously over time and are not caused by sensitization effects.

Animals↗
PubMed1983

Effects of local anesthesia on persistence of peripherally induced postural asymmetries in rats.

Hindlimb flexion induced by direct stimulation of the hindlimb has been observed subsequent to spinal section if an appropriate time interval was allowed to elapse between onset of flexion and spinal cord section. The present series of experiments was conducted to test the possibility that asymmetry persistence is a product of ongoing cutaneous input that continues after stimulation offset and spinal cord section. A local anesthetic (lidocaine) was injected in the general area of stimulation, and its effects on asymmetry were assessed in three experiments. The results generally indicated that ongoing cutaneous input was not a sufficient explanation for persistence of flexion in animals stimulated with intact or severed spinal cords. The data revealed, however, that ongoing cutaneous input may partially explain results of a previous study that employed a "stimulation-wait" preparation to obtain peripherally induced spinal fixation.

Afferent Pathways↗
PubMed1982

Effects of manipulating stimulation intensity and duration on fixation of a peripherally-induced spinal reflex alteration in rats.

Two studies were conducted to examine the effects of manipulating stimulation intensity and duration on post-spinal-section retention of a peripherally induced postural asymmetry. In the first experiment, two groups of rats received 1-3 mA of hindlimb stimulation for 60 or 90 min followed by a spinal cord section. Even though all animals demonstrated postsection persistence of asymmetry, significant differences between the two groups of animals were not discerned. Experiment 2 was conducted to more systematically evaluate intensity and duration manipulations. Twelve groups of rats that received 1, 3, or 5 mA of stimulation for either 30, 45, 60, or 90 min were used. Significant differences were found between intensity groups when presection asymmetry, postsection asymmetry, and percentage retention measures were analyzed. Significant differences between duration groups were found only when the 90 min groups were compared with animals that were given shorter periods of stimulation and when 60 min groups were compared to 30 min groups. From these data we have concluded that the intensity of the fixating stimulus is a major determinant of the magnitude of asymmetry persistence observed after spinal section.

Animals↗
PubMed1982

Central and peripheral influences on retention of postural asymmetry in rats.

Four studies were conducted to delineate potential neural processes involved in retention of a peripherally induced postural asymmetry. In the first experiment, dorsal and ventral spinal root section following varying intervals of stimulation successfully abolished peripherally induced hindlimb asymmetry. Experiment 2 revealed that 50 min of ventral root stimulation, in the absence of central connection, was not effective in producing asymmetry persistence. In an attempt to more closely delineate the time parameters involved in peripherally induced asymmetry retention, Experiment 3 was conducted. Asymmetry was found to consistently outlast a spinal transection if 40 min of stimulation was given. Finally, possible modulatory higher brain center influences on the retention processes were demonstrated in Experiment 4. Asymmetry persistence was consistently observed in animals that received 10, 20, 30, 40, or 50 min of hindlimb stimulation if 50 min were allowed to elapse between the onset of stimulation and spinal section. These results, when coupled with the findings of earlier studies, suggest an active involvement of spinal reflex centers in the fixation process. In addition, these studies indicate that the manner in which reflex activity is altered is not crucial as long as underlying time parameters are adhered to. Finally, the present studies demonstrate that higher center influences can modulate retention of a postural asymmetry in a complex manner.

Animals↗
PubMed1982

Temporal parameters involved in retention of reflex alterations in spinal rats.

Temporal parameters concerning retention of a stimulation-induced hindlimb flexion were investigated. After spinal transection, 60 rats received 10, 20, 30, 40, 45, or 50 min of hindlimb stimulation. Consistent persistence of flexion following stimulus cessation was observed in rats that were stimulated for at least 30 min. When the results ae compared with previous data, the spinalized rat shows a 10-min reduction in the critical time interval needed to consistently obtain poststimulation persistence of flexion.

Animals↗
PubMed1982

N-ethylmaleimide increases the facility of aqueous outflow of excised monkey and calf eyes.

Freshly enucleated eyes were quantitatively perfused via the anterior chamber at 15 mm Hg pressure with various concentrations of the sulfhydryl (-SH) agent. N-ethylmaleimide (NEM). In the monkey eye a dosage of 9.4 mM NEM produced a 108% increase in facility of outflow. In calf eyes a dosage of NEM of 4.7 mM or greater also produced a significant increase in outflow facility. At the threshold dosage of 4.7 mM NEM there was only slight (12%) inhibition of glycolysis in the calf meshwork, which was excised after perfusion. The results suggest that the effect of NEM on outflow facility is not caused by a metabolic inhibitory action. We propose that alteration of cell membrane -SH groups in the outflow pathways can influence aqueous outflow resistance.

Animals↗
PubMed1981

Fixation of spinal reflexes in rats by central and peripheral sensory input.

Two methods were used to demonstrate retention of postural asymmetries after spinal cord section in adult rats. In the first preparation, postural asymmetries of the hindlimbs were induced by placing electrolytic lesions in the anterior cerebellum. Asymmetry was found to consistently outlast a spinal cord section if 45 min were allowed between brain lesion and cord section. A certain percentage of rats allowed 35 or 40 min also demonstrated the retention. In the second preparation, postural asymmetries induced by 45 min of direct hindlimb stimulation were also retained after spinal section. Rhizotomy prior to stimulation resulted in a lack of appreciable asymmetry upon termination of the stimulation. Finally, retention of a hindlimb-stimulation-induced asymmetry was observed in animals that underwent a spinal section prior to the stimulation. The present series of studies demonstrates that the "spinal fixation" phenomenon can be obtained by induction of postural alterations from central (cerebellar lesion) and peripheral (hindlimb stimulation) sources. In addition, results obtained from spinal animals indicate that retention of peripherally induced asymmetry is not crucially dependent on higher brain center activity but rather seems to be more dependent on long-term alterations that occur directly in the spinal reflex system.

Animals↗
PubMed1979

Neuronal unit activity in the abducens nucleus during classical conditioning of the nictitating membrane response in the rabbit (Oryctolagus cuniculus).

Neuronal unit activity was recorded from the abducens (6th nerve) nucleus, the "final common path," during classical conditioning of the nictitating membrane (NM) response in the rabbit, with the use of a tone conditioned stimulus, an air puff unconditioned stimulus (UCS), 250-msec interstimulus interval, and 60-sec intertrial interval. Animals were given 2 days of conditioning training (104 trials in eight blocks per day) and 1 day of extinction. Control animals were given comparable periods of stimulus presentations, explicitly unpaired. Activity of small clusters of units--"multiple unit" recording--was compared with the amplitude-time course of the NM response. Between-blocks comparisons of neural and behavioral responses indicated an essentially perfect correlation during acquisition of the conditioned response (Day 1, r = .99; Day 2, r = .98) and a slightly lower correlation during extinction (r = .93) for the conditioning animals. Within-blocks comparisons indicated a close correspondence between the histograms of unit activity and the amplitude-time course of the NM response for the conditioning animals in all phase of training and for the control animals in the UCS trial blocks.

Abducens Nerve↗
PubMed1977

Classical nictitating membrane conditioning in the awake, normal, restrained cat.

Present knowledge of its central nervous system makes the cat a desirable subject for studies of brain-behavior relationships. Response frequencies and latency characteristics in conditioning and control groups indicate that the response of the nictitating membrane can be classically conditioned in a new restraint system in which detailed brain and behavior measures can be easily obtained.

Animals↗