Abstract:
:Transient changes in extracellular potassium concentration ([K+]o) and field potentials were evoked by 4-aminopyridine (4-AP; 50-100 microM) and recorded with ion-selective microelectrodes in CA1b, CA3b and dentate sectors of adult rat hippocampal slices. Long-lasting field potentials recurred at a frequency of approximately 1/60 s (0.016 +/- 0.003 Hz) in association with increases in [K+]o which were largest and most sustained in the dendritic regions where afferent fibers terminate (dentate > CA1 > CA3) and in the hilus. In stratum radiatum of CA1 or stratum moleculare of the dentate these fields had a peak amplitude of 1.4 +/- 0.29 mV, duration 8.3 +/- 1.6 s, and were accompanied by increases in [K+]o of 1.8 +/- 0.22 mM that lasted 32 +/- 5.5 s (n = 17 slices). Interictal epilentiform potentials, which were brief (< 0.2 s) and more frequent at approximately 1/3 s (0.30 +/- 0.02Hz) were also present in CA1, CA3 and the hilus and associated with small increases in [K+]o (< or = 0.5 mM, duration < or = 2 s). Interictal activity was blocked by 6-cyano-7-nitroquinoxalone-2,3-dione (CNQX; 5-20 microM); the slow, less frequent potentials were resistant to both CNQX and DL-2-amino-5-phosphonovaleric acid (APV; 50 microM) and reversibly blocked (or attenuated by approximately 80%) by bicuculline methiodide (BMI) (25-100 microM). The BMI-sensitive potentials were also abolished by baclofen (100 microM), an effect which was reversed by 2-OH-saclofen (100 microM). Focal application of KCI or GABA in the absence of 4-AP evoked long-lasting field and [K+]o potentials which were similar to those evoked by 4-AP but more sustained. The proportional relationship between the amplitudes of field and K+ potentials with GABA closely resembled that observed for 4-AP; in contrast the slope of KC1-evoked responses was lower. Our results demonstrate that in the adult rat hippocampus 4-AP induces in many different regions accumulations of [K+]o in synchrony with the long-lasting field potentials, which are known to correspond to an intracellular long-lasting depolarization of the pyramidal cells. These changes are smaller than those which occur in the immature rat hippocampus--which may be related to differences in Na-K-ATPase and susceptibility to seizures. These events involve the activation of GABAA receptors, are under the modulatory control of GABAB receptors, and likely arise from the activity of GABAergic interneuron and/or afferent terminals. The long-lasting field potentials appear to reflect mainly the direct depolarizing actions of GABA and to much more limited extent the associated accumulation of [K+]o.
journal_name
Exp Brain Resjournal_title
Experimental brain researchauthors
Morris ME,Obrocea GV,Avoli Mdoi
10.1007/BF00228628subject
Has Abstractpub_date
1996-04-01 00:00:00pages
71-82issue
1eissn
0014-4819issn
1432-1106journal_volume
109pub_type
杂志文章abstract::Although postural control requires the integration of different sensory cues, little is known about the role of attentional artifacts on the individual's ability to properly respond to postural challenges. This study investigated the effects of concomitant tasks (cognitive and postural) on the relationship between vis...
journal_title:Experimental brain research
pub_type: 杂志文章
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journal_title:Experimental brain research
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abstract::Haptic perception is based on the integration of afferent proprioceptive and tactile signals. A further potential source of information during active touch is predicted sensory feedback (PSF) derived from a copy of efferent motor commands that give rise to the exploratory actions. There is substantial evidence that PS...
journal_title:Experimental brain research
pub_type: 杂志文章
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journal_title:Experimental brain research
pub_type: 杂志文章
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abstract::Prior studies have shown that procedural learning is severely impaired in patients with diffuse cerebellar damage (cortical degeneration) as measured by the serial reaction time task (SRTT). We hypothesize that focal cerebellar lesions can also have lateralized effects on procedural learning. Our objective was to asse...
journal_title:Experimental brain research
pub_type: 杂志文章
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更新日期:1998-05-01 00:00:00
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journal_title:Experimental brain research
pub_type: 杂志文章
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更新日期:1980-01-01 00:00:00
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journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00231777
更新日期:1991-01-01 00:00:00
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journal_title:Experimental brain research
pub_type: 杂志文章
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更新日期:1998-03-01 00:00:00
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journal_title:Experimental brain research
pub_type: 临床试验,杂志文章
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更新日期:2005-12-01 00:00:00
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journal_title:Experimental brain research
pub_type: 杂志文章
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更新日期:2013-10-01 00:00:00
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journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00236735
更新日期:1980-01-01 00:00:00
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journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00235707
更新日期:1977-06-27 00:00:00
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journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00248549
更新日期:1987-01-01 00:00:00
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journal_title:Experimental brain research
pub_type: 杂志文章
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更新日期:2001-05-01 00:00:00
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journal_title:Experimental brain research
pub_type: 杂志文章
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更新日期:2015-10-01 00:00:00
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journal_title:Experimental brain research
pub_type: 杂志文章
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更新日期:2001-01-01 00:00:00
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journal_title:Experimental brain research
pub_type: 杂志文章
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更新日期:2011-12-01 00:00:00
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journal_title:Experimental brain research
pub_type: 杂志文章
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更新日期:1983-01-01 00:00:00
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pub_type: 临床试验,杂志文章
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journal_title:Experimental brain research
pub_type: 杂志文章
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更新日期:2008-10-01 00:00:00
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更新日期:2014-02-01 00:00:00
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journal_title:Experimental brain research
pub_type: 杂志文章
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更新日期:2015-01-01 00:00:00
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journal_title:Experimental brain research
pub_type: 杂志文章
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更新日期:1988-01-01 00:00:00
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journal_title:Experimental brain research
pub_type: 杂志文章
doi:10.1007/BF00228754
更新日期:1994-01-01 00:00:00
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journal_title:Experimental brain research
pub_type: 临床试验,杂志文章,随机对照试验
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更新日期:2001-08-01 00:00:00
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journal_title:Experimental brain research
pub_type: 杂志文章
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更新日期:2018-10-01 00:00:00
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journal_title:Experimental brain research
pub_type: 杂志文章
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更新日期:1995-01-01 00:00:00
abstract::A series of step-tracking experiments was conducted before, during, and after a 3-week space mission to assess the effects of prolonged microgravity on a non-postural motor-control task. In- and post-flight accuracy was affected only marginally. However, kinematic analyses revealed a considerable change in the underly...
journal_title:Experimental brain research
pub_type: 杂志文章
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更新日期:1999-12-01 00:00:00