Dendritic spines in Purkinje cells.
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Biomedical subjects
Piergiorgio Strata
Publications and source records attributed to Piergiorgio Strata.
Spontaneous Gaze Shifts in Intact Head-free Rats and Following Inferior Olive and Cerebellar Lesions.
Recent experiments have shown that after lesions of the inferior olive or of the flocculus and paraflocculus of the cerebellum, in the pigmented rat, spontaneous saccades made when the head is completely restrained are followed by a large postsaccadic drift. The aims of the present paper were to study (i) the strategies and the characteristics of spontaneous eye - head coordinated gaze shifts in intact pigmented rats and to compare them with those described in other mammals, (ii) how they are affected by inferior olive and flocculus - paraflocculus lesions, and (iii) whether in these groups of animals the stability of the gaze is more deficient when the head is free to rotate in the horizontal plane (head-free condition) relative to the head-fixed condition. Three types of gaze shift strategy of intact rats are described and characterized. Following inferior olive or flocculus - paraflocculus lesion the dynamic parameters of such gaze shifts (the main sequences of head, gaze and eye and the timing of eye and head movement onset) are not significantly affected. The main deficits of lesioned animals affect the stability of gaze at the end of gaze shifts. After inferior olive lesion the amplitude of the postsaccadic drift of the gaze is 43.2% of the gaze saccade in the head-fixed condition, which is reduced to 22.9% in the head-free condition. Following flocculus - paraflocculus lesion the postsaccadic drift of gaze is even more reduced than after inferior olive lesion, changing from 39.2% in the head-fixed condition to only 9.7% in the head-free condition.
Journal Article↗
Embryonic Purkinje Cells Grafted on the Surface of the Cerebellar Cortex Integrate in the Adult Unlesioned Cerebellum.
The presence of an injury or the selective degeneration of specific neuronal populations is commonly assumed to be a necessary prerequisite for the survival and the integration of grafted neurons in the recipient brain. In the present study we have placed solid grafts of cerebellar anlage in the fourth ventricle of adult rats, in close contact with the host cerebellar cortex, to assess the capacity of embryonic Purkinje cells to interact with adult neurons and integrate in the unlesioned cerebellar cortex. Numerous grafted Purkinje cells are indeed able to leave the implant and migrate into the host molecular layer, where they develop adult structural features. In addition, such cells are able to elicit the growth of host climbing fibre sprouts which end in newly formed arborizations impinging upon their dendritic trees. Climbing fibre collateral branches also penetrate the implant to innervate Purkinje cells which have not migrated in the host cerebellum. These results show that embryonic Purkinje cells are able to survive and integrate in an adult unlesioned cerebellar cortex. In addition, adult olivary axons respond to the increased size of the target population by expanding their terminal domain to innervate grafted Purkinje cells.
Journal Article↗
Metabotropic glutamate receptor-mediated currents at the climbing fiber to Purkinje cell synapse.
Different forms of synaptic plasticity in the cerebellum expressed at the synapses onto Purkinje cells (PCs) are mediated by membrane metabotropic glutamate receptors (mGluRs). There are three main mGluR groups with a total of 8 subtypes. Although mGluRs are also found at the climbing fiber (CF) to PC synapses, the distribution and biological activity of their types is not well-known. Using whole cell patch-clamp recordings from PCs in rat cerebellar slices with inhibitors of ionotropic receptors and glutamate uptake blockers we demonstrate a complex pharmacology of currents obtained by CF stimulation. The mGluR1 specific antagonist CPCCOEt in a group of cells suppressed this response, but in a similar number of other cells it induced a potentiating effect. It was found that a switch between these two biopharmaceutical effects might occur with age.
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