Search Results - (Author, Cooperation:E. Buhl)

2015-11-19

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; CLOCK Proteins/metabolism ; Circadian Clocks/*physiology ; Circadian Rhythm/*physiology ; Drosophila Proteins/genetics/*metabolism ; Drosophila melanogaster/cytology/*physiology ; Extremities/innervation ; Female ; Male ; Mechanoreceptors/cytology/metabolism ; Receptors, Ionotropic Glutamate/genetics/*metabolism ; Sensory Receptor Cells/metabolism ; *Temperature

1460-9568

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Hippocampal pyramidal cells receive GABA-mediated synaptic input from several distinct interneurons. In order to define the effect of perisomatic synapses, intracellular recordings were made with biocytin-containing microelectrodes from synaptically connected inhibitory and pyramidal cell pairs in subfields CA1 and CA3 of the rat hippocampus. Subsequent physiological analysis was restricted to the category of cells, here referred to as basket cells (n= 14), which had an efferent synaptic target profile (n= 282 synaptic contacts) of predominantly somatic (48.2%) and proximal dendritic synapses (45.0%). Electron microscopic analysis revealed that in two instances identified postsynaptic pyramidal cells received a total of 10 and 12 labelled basket cell synapses respectively. At an average membrane potential of -57.8 ± 4.6 mV, unitary inhibitory postsynaptic potentials (IPSPs; n= 24) had a mean amplitude of 450 ± 238 μV, a 10–90% rise time of 4.6 ± 3.2 ms and, measured at half-amplitude, a mean duration of 31.6 ± 18.2 ms. In most instances (n= 19) the IPSP decay could be fitted with a single exponential with a mean time constant of 32.4 ± 18.0 ms. Unitary basket cell-evoked IPSPs fluctuated widely in amplitude, ranging from the level of detectability to 〈2 mV. The response reversal of IPSPs (n= 5) was extrapolated to be at -74.9 ± 6.0 mV. Averages of unitary IPSPs had a mean calculated conductance of 0.95 ± 0.29 nS, ranging from 0.52 to 1.16 nS. Unitary basket cell IPSPs (n= 3) increased in amplitude by 26.3 ± 19.9% following bath application of the GABAB receptor antagonist CGP 35845A (1–4 μM), whereas subsequent addition of the GABAA receptor antagonist bicuculline (10–13 μM) reduced the IPSP amplitude to 13.5 ± 3.1% of the control response. Rapid presynaptic trains of basket cell action potentials resulted in the summation of up to four postsynaptic responses (n= 5). However, any increase in the rate of tonic firing (2- to 10-fold) led to a 〈50% reduction of the postsynaptic response amplitude. At depolarized membrane potentials, averaged IPSPs could be followed by a distinct depolarizing overshoot or postinhibitory facilitation (n= 4). At firing threshold, pyramidal cells fired postinhibitory rebound-like action potentials, the latter in close temporal overlap with the depolarizing overshoot. In conclusion, hippocampal basket cells have been identified as one source of fast, GABAA receptor-evoked perisomatic inhibition. Unitary events are mediated by multiple synaptic release sites, thus providing an effective mechanism to avoid total transmission failures.

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] Cortical oscillatory activity at the electroencephalogram (EEG) level11 has been correlated to distinct patterns of behaviour. One form of rhythmic activity, 9 oscillations (4-7 Hz), are prominent in the hippocampal EEG during exploratory behaviour12 and have been proposed to serve as a reference ...

Electronic Resource

1432-0568

Terminalis system ; Olfactory system ; Autonomic system ; Toothed whales ; Odontoceti

Springer Online Journal Archives 1860-2000

Medicine

Summary For the first time in cetaceans, the development of the terminalis system and its continuity between the olfactory placode and the telencephalon has been demonstrated by light microscopy. In the early development of toothed whales (Odontoceti) this system is partially incorporated within the fila olfactoria which grow out from the olfactory placode. As the peripheral olfactory system is reduced in later stages, a strongly developed ganglionlike structure (terminalis ganglion) remains within the primitive meninx. Peripherally it is connected via the cribriform plate with ganglionic cell clusters near the septal mucosa. Centrally it is attached to the telencephalon (olfactory tubercle, septal region) by several nerve fibre bundles. In contrast to all other mammalian groups, toothed whales and dolphins are anosmatic while being totally adapted to aquatic life. Therefore the remaining ganglion and plexus must have non-olfactory properties. They may be responsible for the autonomic innervation of intracranial arteries and of the large mucous epithelia in the accessory nasal air sacs. The morphology, evolution and functional implications of the terminalis system in odontocetes and other mammals are discussed.

Electronic Resource

1432-0533

Cortical slices ; Iontophoresis ; Lucifer Yellow ; Dendritic morphology ; Photo-oxidation

Springer Online Journal Archives 1860-2000

Medicine

Summary To examine the complete morphology and ultrastructure of lipofuscin-containing human pyramidal cells, epitumourous biopsy tissue was lightly fixed in paraformaldehyde. Cortical slice preparations were immersed in an injection chamber which was transferred to a fixed stage microscope. Electrodes were filled with an aqueous solution of the fluorescent dye Lucifer Yellow and attached to a micromanipulator. Epifluorescence illumination was used to visualize and guide the tip of the Lucifer pipette towards lipofuscin-containing, autofluorescent pyramidal cell somata. After impaling, the neuron was intracellularly stained by iontophoretic injection of Lucifer Yellow. Subsequent graphical reconstructions of injected pyramidal cells revealed complete filling of their dendritic arborizations. Comparison with published Golgi-material prepared for light microscopy revealed no patho-morphological changes in the tissue. Eventually, dye-filled cells were photo-oxidized in the presence of diaminobenzidine, which resulted in the formation of a homogeneously brown reaction product. Bleached cells were then osmicated and embedded in plastic. Electron microscopy revealed fine electron-opaque label distributed through-out the karyo- and cytoplasm and there were no apparent gross ultrastructural changes. Cytological details, such as organelles and membranes were not obscured by the reaction product. Due to its autofluorescence, the pigment part of the lipofuscin also underwent photoconversion, resulting in a highly enhanced electron-dense matrix. Due to its high selectivity and relative methodological simplicity, the approach presented is considered to be a promising alternative to the gold-toning modification of the Golgi-electron microscope technique.

Electronic Resource

1432-1106

Corpus callosum ; Area 17/18 ; Morphology ; Fast blue ; Lucifer yellow

Springer Online Journal Archives 1860-2000

Medicine

Summary The neuronal composition of callosally projecting cells in cat visual cortex was determined with a combination of retrograde labelling and intracellular injection. Fluorescent tracers were stereotaxically injected into the proximity of the area 17/18 border, corresponding to the representation of the visual vertical meridian. In fixed slice preparations of homotopic regions of the contralateral hemisphere retrogradely labelled cells were filled with Lucifer Yellow. Of more than a hundred injected cells a morphological variety of pyramidal cells, located in cortical layers II–IV and VI, constituted the prevalent cell class in the contralateral projection. A minor proportion of spiny stellate cells was encountered in layer IV. Despite the presence of a contralaterally projecting smooth stellate cell, presumed to be a basket cell, it is concluded that the efferents to contralateral visual cortex predominantly arise from pyramidal and spiny stellate cells. Thus, in agreement with findings from anterograde degeneration studies, the interhemispheric pathway most likely conveys a direct excitatory input to postsynaptic target cells.

Electronic Resource