1. Intradendritic recordings from Purkinje cells in vitro indicate that white matter stimulation produces large synaptic responses by the activation of climbing fibre afferent, but antidromic potentials do not actively invade dendritic tree. 2. Climbing may be reversed a manner similar to observed at somatic level. However, reversal does show biphasicity often seen 3. Input resistance these dendrites was found range 15 30 M omega. The non‐linear properties level for depolarizing currents are...

1. The electrical activity of Purkinje cells was studied in guinea‐pig cerebellar slices vitro. Intracellular recordings from cell somata were obtained under direct vision, and antidromic, synaptic electroresponsiveness demonstrated. Synaptic potentials produced by the activation climbing fibre afferent could be reversed membrane depolarization. 2. Input resistance impaled neurones ranged 10 to 19 M omega demonstrated non‐linearities both hyperpolarizing depolarizing directions. 3. Direct a...

Increases in intracellular calcium concentration are required for the release of neurotransmitter from presynaptic terminals all neurons. However, mechanism by which exerts its effect is not known. A low-sensitivity calcium-dependent photoprotein ( n -aequorin-J) was injected into terminal giant squid synapse to selectively detect high microdomains. During transmitter release, light emission occurred at specific points or quantum domains that remained same place during protracted...

Synapsin I and calcium/calmodulin-dependent protein kinase II were pressure-injected into the preterminal digit of squid giant synapse to test directly possible regulation neurotransmitter release by these substances. Neurotransmitter was determined measuring amplitude, rate rise, latency postsynaptic potential generated in response presynaptic depolarizing steps under voltage clamp conditions. Injection dephosphosynapsin decreased amplitude rise potential, whereas injection either...

A Ca2+-channel blocker derived from funnel-web spider toxin (FTX) has made it possible to define and study the ionic channels responsible for Ca2+ conductance in mammalian Purkinje cell neurons preterminal squid giant synapse. In cerebellar slices, FTX blocked Ca2+-dependent spikes cells, reduced spike afterpotential hyperpolarization, increased Na+-dependent plateau potential. synapse, synaptic transmission without affecting presynaptic action Presynaptic voltage-clamp results show blockage...

Genome-encoded microRNAs (miRNAs) are potent regulators of gene expression. The significance miRNAs in various biological processes has been suggested by studies showing an important role these small RNAs regulation cell differentiation. However, the differentiated physiology is not well established. Mature neurons express a large number distinct miRNAs, but postmitotic examined. Here, we provide evidence for essential survival neurons. We show that conditional Purkinje cell–specific...

We have studied the effect of purified toxin from funnel-web spider venom (FTX) and its synthetic analog (sFTX) on transmitter release presynaptic currents at mouse neuromuscular junction. FTX specifically blocks omega-conotoxin- dihydropyridine-insensitive P-type voltage-dependent Ca2+ channel (VDCC) in cerebellar Purkinje cells. Mammalian transmission, which is insensitive to N- or L-type blockers, was effectively abolished by sFTX. These substances blocked muscle contraction...

Microfluorometric imaging was used to study the correlation of intracellular calcium concentration with voltage-dependent electrical activity in guinea pig cerebellar Purkinje cells. The spatiotemporal dynamics are demonstrated during spontaneous and evoked activity. results agreement hypotheses dendritic segregation conductances suggested by electrophysiological experiments. These vitro slice fluorescence methods applicable a wide range problems central nervous system biochemical functions.

Huntington's disease (HD) is caused by polyglutamine expansion (exp) in huntingtin. Here, we used a yeast artificial chromosome (YAC) transgenic mouse model of HD to investigate the connection between disturbed calcium (Ca 2+ ) signaling and apoptosis medium spiny neurons (MSN). Repetitive application glutamate elevates cytosolic Ca levels MSN from YAC128 but not wild-type or control YAC18 mouse. Application results MSN. Analysis glutamate-induced revealed that ( i actions are mediated...

1. Presynaptic or simultaneous pre‐ and postsynaptic voltage‐clamp protocols were implemented in the squid giant synapse order to determine magnitude time course of presynaptic calcium current (ICa) its relation transmitter release before after injection proteins. These included several forms synapsin I, calcium‐calmodulin‐dependent protein kinase II (CaM II) avidin. 2. The quantities location these proteins monitored by fluorescence video‐enhanced microscopy during electrophysiological...

The distribution of the P-type calcium channel in mammalian central nervous system has been demonstrated immunohistochemically by using a polyclonal specific antibody. This antibody was generated after P-channel isolation via fraction from funnel-web spider toxin (FTX) that blocks voltage-gated P channels cerebellar Purkinje cells. In cortex, immunolabeling to appeared throughout molecular layer, while all other regions were negative. Intensely labeled patches reactivity seen on cell...

Of fundamental importance in understanding neuronal function is the unambiguous determination of smallest unit integration. It was recently suggested that a whole dendritic branchlet, including tens spines, acts as terms calcium dynamics Purkinje cells. By contrast, we demonstrate such single spine. The results show, by two-photon excited fluorescence laser scanning microscopy, individual spines are capable independent activation. Moreover, two distinct spine populations were distinguished...

Synaptic transmission produced by artificially generated presynaptic depolarizations, having the same waveform as normal action potentials, was studied in squid giant synapse. These stimulated spikes synaptic virtually indistinguishable from that obtained with original spike activation. The technique allows a direct determination of onset and amplitude Ca current, ICa, triggered potential relationship between ICa postsynaptic response. results closely resemble theoretical predictions...

Synaptotagmins (syts) are a family of membrane proteins present on variety intracellular organelles. In vertebrates, 16 isoforms syt have been identified. The most abundant isoform, I, appears to function as Ca 2+ sensor that triggers the rapid exocytosis synaptic vesicles from neurons. functions remaining less well understood. cytoplasmic domain I binds membranes in response , and this interaction has proposed play key role secretion. Here, we tested -triggered membrane-binding activity...

The GTPase dynamin I is required for synaptic vesicle (SV) endocytosis. Our observation that binds to the SV protein synaptophysin in a Ca(2+)-dependent fashion suggested possibility dynamin/synaptophysin complex functions recycling. In this paper we show disruption of interaction by peptide injection into squid giant synapse preterminal results decrease transmitter release during high-frequency stimulation, indicating an inhibition Electron microscopy these synapses reveals depletion SVs,...