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Effect of posterior hypothalamic injection of procaine on the hippocampal theta rhythm in freely moving cats

100%
Bocian R., Konopacki J.
Acta Neurobiologiae Experimentalis
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2001
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vol. 61
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issue 2
125-134
EN
Earlier in vivo studies conducted on freely moving and anesthetized rats demonstrated that the posterior hypothalamus (PH) comprises pathways critical for producing the synchronous hippocampal formation (HPC) theta rhythm. In addition, these findings suggested that the frequency of the HPC theta was encoded in the PH and then was fed via the medial forebrain bundle to the medial septum and HPC. In the present study we attempted to verify this hypothesis with use of a different in vivo model - freely moving cats. The microinjection of the local anaesthetic, procaine, into the PH region reversibly suppressed the spontaneous as well as sensory and electrically induced HPC theta. However, in contrast to rats, in freely moving cats microinjection of procaine into the PH reduced the amplitude of the HPC theta but had no effect on theta frequency. We conclude that in freely moving cats the PH region comprises a critical part of the ascending brainstem pathway, for production of the HPC theta rhythm. In contrast to rats, in freely moving cats ascending inputs from the brainstem to the PH contribute mainly to the amplitude of the HPC theta rhythm.
2

A novel parameter of quantitative evaluation of the hippocampal field activity-density of theta

81%
Golebiewski H., Eckersdorf B., Bocian R., Konopacki J.
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EN
Our experiments conducted in the last decade on freely moving cats, showed that commonly used theta parameters: frequency, amplitude and power are not sufficient for a precise characterization of theta field activity. It is specially seen in condition when the experimental protocol involves sensory or chemical stimalation in order to induce hippocampal theta. We described a novel theta parameter ? ?theta density?, that allows more adequate quantitative evaluation of this EEG pattern in freely moving cats.
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In vitro recorded theta-like activity in the limbic cortex: comparison with spontaneous theta and epileptiform discharges

71%
Konopacki J., Golebiewski H., Eckersdorf B., Kowalczyk T., Bocian R.
Acta Neurobiologiae Experimentalis
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2000
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vol. 60
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issue 1
67-85
EN
The generation of EEG theta rhythm in the mammalian limbic cortex is a prime example of rhythmic activity that involves central mechanisms of oscillations and synchrony. This EEG pattern has been extensively studied since 1938, when Jung and Kornmller (1938) demonstrated the first theta recordings in the hippocampal formation of rabbits. In 1986 in collaboration with Drs. B.H. Bland, S.H. Roth and B.M. MacIver we demonstrated for the first time that bath perfusion of hippocampal slices with the cholinergic agonist, carbachol, resulted in theta-like oscillations. Since this initial demonstration of in vitro theta-like activity, we have carried out a number of experiments in an attempt to answer the basic question: what are the similarities between cholinergic-induced in vitro theta-like activity and theta rhythm which naturally occurs in the in vivo preparation. Thus far, our studies have provided strong evidence that theta-like activity recorded in vitro shares many of the physiological and pharmacological properties of theta rhythm observed in vivo. The question whether in vitro theta-like oscillations reflect features of epileptiform activity is also adressed in this review.
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