The entorhinal area; Electrophysiological studies of its interrelations with rhinencephalic structures and the brainstem

Adey, W. R.; Sunderland, Sydney; Dunlop, Colin W.

doi:10.1016/0013-4694(57)90064-0

Cited by 57 publications

(11 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the stellate cells of EC layer II, which give rise to the main cortical projection to the hippocampus (Steward and Scoville 1976), I NaP has been shown to critically participate in the generation of subthreshold membrane-potential oscillations in the theta-rhythm range (Alonso and Llinás 1989; Klink and Alonso 1993). This particular intrinsic subthreshold activity is considered to be a critical determinant for the generation of the population theta oscillations generated by the EC network (Adey et al 1957, Adey et al 1960; Holmes and Adey 1960; Mitchell and Ranck 1980; Alonso and García-Austt 1987a,Alonso and García-Austt 1987b). The theta rhythm has been shown to contribute to synaptic-plasticity processes (Larson and Lynch 1986; Larson et al 1986; Greenstein et al 1988; Alonso et al 1990; Huerta and Lisman 1996; Hölscher et al 1997), and it is thus believed to play a major role in temporal lobe learning and memory functions (Doyère and Laroche 1992; Buzsáki 1996).…”

Section: Introductionmentioning

confidence: 99%

Biophysical Properties and Slow Voltage-Dependent Inactivation of a Sustained Sodium Current in Entorhinal Cortex Layer-II Principal Neurons

Magistretti

Alonso

1999

The Journal of General Physiology

148

126

View full text Add to dashboard Cite

The functional and biophysical properties of a sustained, or “persistent,” Na+ current (I NaP) responsible for the generation of subthreshold oscillatory activity in entorhinal cortex layer-II principal neurons (the “stellate cells”) were investigated with whole-cell, patch-clamp experiments. Both acutely dissociated cells and slices derived from adult rat entorhinal cortex were used. I NaP , activated by either slow voltage ramps or long-lasting depolarizing pulses, was prominent in both isolated and, especially, in situ neurons. The analysis of the gating properties of the transient Na+ current (I NaT) in the same neurons revealed that the resulting time-independent “window” current (I NaTW) had both amplitude and voltage dependence not compatible with those of the observed I NaP , thus implying the existence of an alternative mechanism of persistent Na+-current generation. The tetrodotoxin-sensitive Na+ currents evoked by slow voltage ramps decreased in amplitude with decreasing ramp slopes, thus suggesting that a time-dependent inactivation was taking place during ramp depolarizations. When ramps were preceded by increasingly positive, long-lasting voltage prepulses, I NaP was progressively, and eventually completely, inactivated. The V1/2 of I NaP steady state inactivation was approximately −49 mV. The time dependence of the development of the inactivation was also studied by varying the duration of the inactivating prepulse: time constants ranging from ∼6.8 to ∼2.6 s, depending on the voltage level, were revealed. Moreover, the activation and inactivation properties of I NaP were such as to generate, within a relatively broad membrane-voltage range, a really persistent window current (I NaPW). Significantly, I NaPW was maximal at about the same voltage level at which subthreshold oscillations are expressed by the stellate cells. Indeed, at −50 mV, the I NaPW was shown to contribute to >80% of the persistent Na+ current that sustains the subthreshold oscillations, whereas only the remaining part can be attributed to a classical Hodgkin-Huxley I NaTW. Finally, the single-channel bases of I NaP slow inactivation and I NaPW generation were investigated in cell-attached experiments. Both phenomena were found to be underlain by repetitive, relatively prolonged late channel openings that appeared to undergo inactivation in a nearly irreversible manner at high depolarization levels (−10 mV), but not at more negative potentials (−40 mV).

show abstract

Section: Introductionmentioning

confidence: 99%

Biophysical Properties and Slow Voltage-Dependent Inactivation of a Sustained Sodium Current in Entorhinal Cortex Layer-II Principal Neurons

Magistretti

Alonso

1999

The Journal of General Physiology

148

126

View full text Add to dashboard Cite

show abstract

“…In these structures, the neural mechanism of memory is believed to be organized by the theta rhythm (4-12 Hz), which has been shown to exist in the EC and the CA1 region of the hippocampus in vivo and in vitro (Adey, Sunderland, & Dunlop, 1957;Adey, Dunlop, & Hendrix, 1960).…”

Section: Of Two Such Cells (Stellate Cells Of the Entorhinal Cortex Amentioning

confidence: 97%

Low-Dimensional Maps Encoding Dynamics in Entorhinal Cortex and Hippocampus

et al. 2006

View full text Add to dashboard Cite

Cells that produce intrinsic theta oscillations often contain the hyperpolarization-activated current I(h). In this article, we use models and dynamic clamp experiments to investigate the synchronization properties of two such cells (stellate cells of the entorhinal cortex and O-LM cells of the hippocampus) in networks with fast-spiking (FS) interneurons. The model we use for stellate cells and O-LM cells is the same, but the stellate cells are excitatory and the O-LM cells are inhibitory, with inhibitory postsynaptic potential considerably longer than those from FS interneurons. We use spike time response curve methods (STRC), expanding that technique to three-cell networks and giving two different ways in which the analysis of the three-cell network reduces to that of a two-cell network. We show that adding FS cells to a network of stellate cells can desynchronize the stellate cells, while adding them to a network of O-LM cells can synchronize the O-LM cells. These synchronization and desynchronization properties critically depend on I(h). The analysis of the deterministic system allows us to understand some effects of noise on the phase relationships in the stellate networks. The dynamic clamp experiments use biophysical stellate cells and in silico FS cells, with connections that mimic excitation or inhibition, the latter with decay times associated with FS cells or O-LM cells. The results obtained in the dynamic clamp experiments are in a good agreement with the analytical framework.

show abstract

“…The results of investigations on marsupials in which area CA~ of the dorsal and ventral hippocampus was studied showed that heterogeneous connections can exist between different parts of the hippocampus and entorhinal cortex [13], The presence of large reciprocal conducting pathways has been postulated between the ventral part of the entorhinal cortex and the dorsal hippocampus and between the dorsal and ventral region of the hippocampus. The possibility of the existence of independent connections of the entorhinal cortex and ventral hippocampus with the dorsal region of the hippocampus has also been postulated.…”

Section: And Dtscussionmentioning

confidence: 99%

“…Deepening and lengthening of the positive wave and the appearance of a negative wave of relatively high amplitude in the evoked potential are observed. Several workers ( [4,12,13,15] etc.) have shown that stimulation of the hippocampus changes (increases) the excitability of brain structures.…”

Section: And Dtscussionmentioning

confidence: 99%

Effect of hippocampal stimulation on evoked electrical activity of various brain structures

Ungiadze

Davituliani

1976

Neurosci Behav Physiol

View full text Add to dashboard Cite

Functional relations between the entorhinal cortex and hippocampus were stud~ ~d in acute and chronic experiments on cats. The dorsal hippocampus depresses electrical activity and responses of the ventral hippocampus evoked by stimulation of the entorhinal cortex and responses of the entorhinal cortex and ventral hippocampus to cutaneous electrical stimulation. The ventral hippocampus, on the other hand, facilitates evoked electrical activity of the dorsal hippocampus in response to stimulation of the entorhinal cortex. and also responses of the entorhinal cortex and dorsal hippocampus evoked by cutaneous electrical stimulation. The results suggest regional differences in nervous connections of the different parts of the hippocampus with the entorhinal cortex.According to the theory of Papez [23] emotion has its structural basis, and the "limbic brain," with extensive afferent and efferent connections, plays a major role in its organization. It has been postulated that emotions arise as a result of activation of interacting structures: the hippocampus, entorhinal cortex, gyrus cinguli, hypothalamus, and anterior thalamic nuclei. The whole of this system is known in the literature as the "circle of Papez."Many investigations ([3, 18, 22] etc.) have pointed to the participation of the hippocampus in the manifestation of autonomic and somatic elements of emotional responses. Morphological and electrophysiological data indicate its extensive afferent and efferent connections both with the neocortex and with many subcortical brain formations. It has been found that however different the formations of the forebrain are in their structural organization, they share one common morphological feature: They all project on the hippocampus and the hippocampal pyramids are as it were the "final common path for the varied afferentation converging on them from these formations." It is at the hippocampal level that the functional relations which lie at the basis of emotional experience and which determine its character are formed [7].One of the principal afferent inputs into the hippocampus has been described, namely, the powerful temporo-ammonic tract {perforating tract) running from the temporal region through the lateral regions of the entorhinal cortex to Ammon's horn. On reaching the latter, it penetrates into it and terminates in the layer of the alveus [14].Tracts from the temporal region to the hippocampus have been shown to contain a nonperforating alvear bundle as well as the perforating bundle. The number of axons of temporal neurons which penetrate into the hippocampus in the composition of the perforating and alvear tracts and the number of contacts which they form with neurons in each part of the hippocampus differ [2]. There is also evidence of the presence of axon collaterals of hippocampal pyramidal cells forming contacts with collaterals of neurons of the entorhinal cortex [14,20].In experiments on marsupials (Trichosurus vulpecula), to study relations of the hippocampus with the entorhinal cortex, it was assume...

show abstract

The entorhinal area; Electrophysiological studies of its interrelations with rhinencephalic structures and the brainstem

Cited by 57 publications

References 23 publications

Biophysical Properties and Slow Voltage-Dependent Inactivation of a Sustained Sodium Current in Entorhinal Cortex Layer-II Principal Neurons

Biophysical Properties and Slow Voltage-Dependent Inactivation of a Sustained Sodium Current in Entorhinal Cortex Layer-II Principal Neurons

Low-Dimensional Maps Encoding Dynamics in Entorhinal Cortex and Hippocampus

Effect of hippocampal stimulation on evoked electrical activity of various brain structures

Contact Info

Product

Resources

About