ISSN:0022-3034    

DOI:10.1002/neu.480060105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1975

数据来源: WILEY

摘要:

AbstractThe role of some meso‐ and diencephalic structures in eye movements was investigated by ablation and stimulation experiments. Optokinetic nystagmus was abolished by small lesions in the lateral pretectum, but not by complete removal of the superior colliculi. Stimulation of the superior colliculus and other visual centers was effective in eliciting nystagmus (slow phase ipsilateral), but the most efficient trigger zones are found in the lateral pretectum and the midbrain tegmentum. Only from these areas could nystagmus still be elicited after degeneration of the primary optic fibers. The lateral pretectal trigger zone is probably identical with the nucleus of the optic tract. It is postulated that this nucleus is an essential station for horizontal optokinetic reactions. Saccades were obtained by stimulation of the mesencephalic central grey, but not for any visual centers such as the superior colliculu

ISSN:0022-3034    

DOI:10.1002/neu.480060106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1975

数据来源: WILEY

摘要:

AbstractCutaneous receptive fields of dorsal roots T11through S3in rats were mapped by recording dorsal root multiple unit activity. The receptive fields, having the shape of transverse bands on the skin, are arranged in order according to their dorsal roots, and there are extensive overlaps between adjacent fields. Routes followed by peripheral sensory innervation of skin were also studied by observing effects of various methods of skin denervation on dorsal root responses to cutaneous stimulation. The results are discussed with respect to the somatosensory control of female rat mating reflexes.

ISSN:0022-3034    

DOI:10.1002/neu.480060107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1975

数据来源: WILEY

摘要:

AbstractMonkeys had nonpolarizable electrodes implanted bilaterally in prefrontal (principal sulcus), precentral, and occipital cortex. They were trained on a spatial delayed‐response (DR) task (8‐sec intratrial delay), while cortical potentials were recorded. Three groups of monkeys were trained to 90% criterion: (A) 4 monkeys with only the right hand (the left wrist was attached to the testing chair); (B) 2 monkeys with only the left hand; and (C) 2 monkeys with the left and right hands on alternate sessions. Intermanual transfer tests were then given.Averaged steady potential (SP) shifts of several seconds duration were found in prefrontal cortex during cue presentation and the early portion of the intratrial delay and from the precentral area during the choice response. Evaluations of these SP shift magnitudes indicated: (1) Training with only one hand resulted in substantially larger SP shifts in the prefrontal and precentral areas contralateral to the responding hand; (2) alternate hand training resulted in somewhat larger prefrontal SP shifts in the right hemisphere; (3) intermanual transfer had marked effects on the precentral SP shifts, with larger magnitudes in the hemisphere contralateral to the responding hand, but had little effect on the magnitudes of both prefrontal SP shifts. (4) Subsequent training of Group C monkeys with only one hand resulted in greater SP shifts in the prefrontal area contralateral to the responding hand and in decreased SP shifts in the ipsilateral prefrontal area; and (5) additional intermanual transfer tests had no effects on SP shift magnitudes from both prefrontal areas. These findings indicate a dissociation in interhemispheric functions between the precentral and prefrontal cortical areas, with the former implicated in motor organization for the contralateral limb, and the latter in mediation of mnemonic processes, primarily in one hemisphere. This hemispheric specialization is affected by the hand‐training procedure, but other endogenous or experiential factors may be inv

ISSN:0022-3034    

DOI:10.1002/neu.480060108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1975

数据来源: WILEY

摘要:

AbstractThe use of 2, 2, 2‐trichloroethanol as a solvent for myelin from both the central and peripheral nervous systems is described. Concentrated, optically clear solutions of lyophilized myelin in this solvent are stable for weeks. The preparation of highly concentrated myelin proteins by gel filtration in trichloroethanol is describe

ISSN:0022-3034    

DOI:10.1002/neu.480060109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1975

数据来源: WILEY

摘要:

AbstractThe cerebral cortex of normal oxygenated and of asphyxiated mice has been studied by freeze‐fracturing technique with a twofold purpose. First, to investigate changes, if any, in the molecular organization of the plasma membrane of any specific cell type(s) that could be correlated with permeability changes thought to take place as a consequence of asphyxiation. Secondly, to attempt characterization of plasma membranes on the basis of the organization of their fractured faces. The decrease in the extracellular material in asphyxiated cerebral cortex seen in electron micrographs of thin sections could not be correlated with change(s), if any, in the molecular organization of the plasma membrane of any particular cell type. Plasma membranes of various types could be characterized on the basis of the arrangement of particles on the fractured faces. Some of these types correspond to identifiable cell processes, while others have not yet been identified with certainty. Fusion of synaptic vesicles with the presynaptic membrane is mediated through clustering of 100–150 Å membrane‐associated par

ISSN:0022-3034    

DOI:10.1002/neu.480060110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1975

数据来源: WILEY

摘要:

AbstractChemical distribution measurements of radioactive sodium‐thiosulfate (35S) and of the brain water indicate that infusion of 2.4‐dinitrophenol into a carotid artery of rats caused a water uptake and fluid shifts from the extra‐ into the intracellular compartments in the central nervous system.The extracellular marker compound was administered to the brain via ventriculo‐cisternal perfusion and intravenous injection yielding almost equal concentrations in plasma‐ water and perfusate. In order to prevent an active efflux of the label from the tissue, high concentrations were utilized in the perfusate to saturate potential outward transport mechanisms. The indicator space (based on total brain water) was 16% in controls and 12% in experimental animals when marker equilibrium had been attained, which is equivalent in reduction of the extracellular space of about 1/4. Intracellular water and Na+rose after DNP, while K+remained all but unchanged.The fluid shift into the intracellular compartment was found to relate closely with a cellular uptake of Na+. The Na+concentration both in plasma and in the perfusion fluid leaving the ventricular system was consistently reduced in experimental animals. The K+concentration was significantly elevated in the plasma of experimental animals but virtually unchanged in the cisternal

ISSN:0022-3034    

DOI:10.1002/neu.480060111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1975

数据来源: WILEY

摘要:

Abstract1) Fast axoplasmic transport in mammalian nervein vitrowas studied using an isotope labeling technique. The rate of outflow in cat sciatic nerve fibers of 410 mm/dayin vitrowas reduced at temperatures below 38°C with aQ10of 2.0 in the range 38–18°C and aQ10of 2.3 at 38–13°C.2) At a temperature of 11°C a partial failure of transport occurred. At temperatures below 11°C a complete block of fast axoplasmic transport occurred, a phenomenon termed “cold‐block.” No transport at all was seen over the temperature range of 10–0°C for times lasting up to 48 hr.3) Transport was resumed after a period of cold‐block lasting up to 22 hr when the nerves were brought back to a temperature of 38°C. Some deleterious effects due to cold‐block were seen in the recovery phase as indicated by a reduction in crest amplitude, change in its form, and slowed rate.4) The ∼P level (combined ATP and creatine phosphate) remained near control level in nerves kept at low or cold‐block temperatures for times as long as 64 hr. The reduction in fast axoplasmic transport rate seen at low temperatures for times up to 22 hr was therefore considered due to a decrease in the utilization of ATP, a concept in accord with the “transport filament” model proposed to account for fast axoplasmic transport.5) The sloping of the front of the crest over the temperature range of 18–13°C suggests an additonal factor at the lower temperatures. A disassembly of microtubules is discussed as a possible explana

ISSN:0022-3034    

DOI:10.1002/neu.480060112

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1975

数据来源: WILEY

摘要:

AbstractAsphyxiation of the spinal cord for periods of 2–4 min leads to block of the monosynaptic pathway. At about the same time this blockage takes place, the afferent action potentials fail to invade the presynaptic terminals. Asphyxiation also interferes with the antidromic invasion of motoneurons, and the failure of the antidromic action potentials to invade the motoneuron dendrites coincides with the time of the disappearance of the orthodromic monosynaptic responses. During reoxygenation, both the presynaptic terminals and the dendrites recover their function, or rather their polarization, in a few seconds and yet synaptic transmission reappears only after several minutes. It is postulated that failure of synaptic transmission during asphyxia is due to depolarization of both the presynaptic terminals and the dendrites of the postsynaptic elements. However, repolarization of these elements during reoxygenation, is not sufficient to reestablish synaptic transmission, but recovery of some unidentified biochemical process is apparently necessar

ISSN:0022-3034    

DOI:10.1002/neu.480060113

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1975

数据来源: WILEY

摘要:

AbstractMemory responses of the optomotor system to rotations of various stripe patterns were studied. The separate elements of the visual background are individually remembered in terms of the parts of the eye on which their images fell. A visual illusion resulting from this property is described.All parts of the retina have an equal capacity to contribute to memory. The memory response results from the summation of contributions from individual elements rather than the maintenance of a fixation upon any particular feature of the situation. Both the separation between background elements for angles from 6° up to 60° and the number of elements present affect the size of the memory evoked respons

ISSN:0022-3034    

DOI:10.1002/neu.480060114

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1975

数据来源: WILEY