摘要:

PREVIOUSLY we have shown that the dorsal lateral geniculate body (LGB), which is strictly visual in sighted mammals, receives a strong auditory input in the naturally blind mole rat (Spalax ehrenbergi). Here we show with the 2-deoxyglucose technique and with single-unit recordings that in this species the initially non-degenerated visual cortex, as defined by its connection with LGB, is also activated by the auditory modality. These findings suggest that cross-modal compensation may occur as a natural consequence of the degeneration of a sense organ.

ISSN:0959-4965    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

THE direct application of colchicine to the hamster olfactory bulb has engendered the appearance of a broader distribution of substance P-like immunoreactivity (SP-LI) than has been previously reported. In the glomerular layer, both external tufted and periglomerular cells were strongly immunopositive. These two classes could be identified by somal size and the presence and branching pattern of intraglomerular dendrites. SP-LI neurons were also identified in the external plexiform layer and many were similar to middle tufted cells. These findings demonstrate that substance P expression is not uniquely associated with classes of projection neurons, but is also found in periglomerular cells, a class of inhibitory local circuit neurons.

ISSN:0959-4965    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

WE have begun a study of the intrinsic circuitry of the cat's upper cervical cord, in part to elucidate the role of spinal interneurons in vestibulocollic reflexes. Using retrograde labelling with Fluoro-Gold and intra-spinal microstimulation, we have identified commissural neurons projecting to the contralateral ventral horn. Neurons tended to be in the medial half of lamina VIII. Approximately half of the neurons were propriospinal neurons that could be activated antidromically from the rostral border of the cervical enlargement. Most of the tested, spontaneously active neurons were driven by stimulation of the ipsi- and/or contralateral vestibular nerve, in some cases disynaptically.

ISSN:0959-4965    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

LARGE changes in somatotopic organization can be induced in adult primate somatosensory cortex by cutting peripheral afferents. The role, if any, of the thalamus in these changes has not been investigated previously. In the present experiments, electrophysiological recording in the ventroposterior lateral nucleus (VPL) has revealed that not only can reorganization occur in the thalamus, but it may be as extensive as that revealed in the cortex of the same monkeys. Thus, for at least some types of deafferentation, the reorganization revealed in the cortex may depend largely on subcortical changes.

ISSN:0959-4965    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

ALTHOUGH cells in ventral part of the medial superior temporal area (MST) do not respond to movements of a wide textured field, many of them start to respond when a stationary object is placed in front of the moving field. The effective direction in this stimulus configuration is opposite to the preferred direction of individual cells for movement of an object. Here, we examined what stimulus cues were detected by the cells in response to movements of a background pattern behind an object. The responses disappeared when the border of the object was blurred. Because blurring the border degraded an occlusion-related cue, i.e., appearance and disappearance of components of the background at the border, we conclude that the occlusion-related cue is essential for the responses.

ISSN:0959-4965    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

CORRELATION of electrophysiological and morphological, including ultrastructural, characteristics of neurones is important for understanding the functional organization of neuronal systems. Further correlation with neuro-transmitter content is essential for determining the ncurochemical(s) used by a given neurone for propagating its signal. The two main neuronal markers presently available (lucifer yellow and horseradish peroxidase) are not satisfactory for correlating all three aspects. We have devised a new simple procedure whereby retinal interneurones can be labelled with biocytin by positive ionophoresis of an unbuffered solution. Biocytin readily crosses gap junctions thus revealing extensive networks of coupled cells. In the case of H1 horizontal cells, which are known to be GABAergic, the neurotransmitter can also be demonstrated by superimposed immunocytochemistry.

ISSN:0959-4965    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

A combination of intracellular recording and fluoromet-ric measurements of cytosolic calcium ([Ca2+]i) was used to locate changes in [Ca2+], induced by the specific meta-botropic glutamate receptor (mGluR) agonist trans-D,L-l-amino-1,3-cyclopentanedicarboxylic acid (t-ACPD), in Purkinje cells of rat cerebellar slices. Under voltage-clamp conditions, application of t-ACPD (100 μM) induced an inward current accompanied by a large increase in [Ca2+] located primarily in the soma but also, to a lesser degree, in restricted parts of the dendrites. In contrast, elevations of [Ca2+]; associated with calcium spikes were confined to the dendrites and inward currents of a similar amplitude induced by (RS)-α-amino-3-hydroxy-5-me-thyl-4-isoxazolepropionic acid (AMPA), an agonist of ionotropic glutamate receptors, did not raise [Ca2+]i.

ISSN:0959-4965    

出版商:OVID    

年代:1991

数据来源: OVID

ISSN:0959-4965    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

DEVELOPMENTAL changes of mRNAs for α-subunits of GTP binding protein (G-protein) such as Gsa and Gi2α during neuronal development were examined in both primary cultured cerebral cortical neurons and cerebral cortices obtained from age-matched mice. The expression of mRNAs for both G-protein a-subunits in primary cultured neurons showed a development pattern similar to that in the cerebral cortexin vivo. Both mRNAs were expressed at an early stage of neuronal development, and the expression patterns of mRNA for both G-protein α-subunits were found to be only slightly changed during development. These results suggest that the G-protein appears at an early stage of neuronal development and may play an important role therein.

ISSN:0959-4965    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

WHEN inferior temporal area TE is removed bilaterally in infant monkeys, the normally transient projection from area TEO to the lateral basal nucleus of the amygdala is maintained, and the normally limited projection from area TEO to the dorsal part of the lateral nucleus of the amygdala expands to invade the terminal space in the lateral nucleus that is normally occupied by terminals from area TE. The maintenance and sprouting of these projections from area TEO could play a role in the permanent preservation of visual memory ability in monkeys that have received bilateral removal of area TE in infancy.

ISSN:0959-4965    

出版商:OVID    

年代:1991

数据来源: OVID