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  • 1
    Publication Date: 2012-11-13
    Description: Active dendrites provide neurons with powerful processing capabilities. However, little is known about the role of neuronal dendrites in behaviourally related circuit computations. Here we report that a novel global dendritic nonlinearity is involved in the integration of sensory and motor information within layer 5 pyramidal neurons during an active sensing behaviour. Layer 5 pyramidal neurons possess elaborate dendritic arborizations that receive functionally distinct inputs, each targeted to spatially separate regions. At the cellular level, coincident input from these segregated pathways initiates regenerative dendritic electrical events that produce bursts of action potential output and circuits featuring this powerful dendritic nonlinearity can implement computations based on input correlation. To examine this in vivo we recorded dendritic activity in layer 5 pyramidal neurons in the barrel cortex using two-photon calcium imaging in mice performing an object-localization task. Large-amplitude, global calcium signals were observed throughout the apical tuft dendrites when active touch occurred at particular object locations or whisker angles. Such global calcium signals are produced by dendritic plateau potentials that require both vibrissal sensory input and primary motor cortex activity. These data provide direct evidence of nonlinear dendritic processing of correlated sensory and motor information in the mammalian neocortex during active sensation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Xu, Ning-long -- Harnett, Mark T -- Williams, Stephen R -- Huber, Daniel -- O'Connor, Daniel H -- Svoboda, Karel -- Magee, Jeffrey C -- Howard Hughes Medical Institute/ -- England -- Nature. 2012 Dec 13;492(7428):247-51. doi: 10.1038/nature11601. Epub 2012 Nov 11.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Janelia Farm Research Campus, Ashburn, Virginia 20147, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23143335" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Behavior, Animal/*physiology ; Calcium/metabolism ; Dendrites/*physiology ; Male ; Mice ; Mice, Inbred C57BL ; Motor Activity/*physiology ; Patch-Clamp Techniques ; Pyramidal Cells/physiology ; Sensation/*physiology ; Signal Transduction
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2012-10-30
    Description: Dendritic spines are the nearly ubiquitous site of excitatory synaptic input onto neurons and as such are critically positioned to influence diverse aspects of neuronal signalling. Decades of theoretical studies have proposed that spines may function as highly effective and modifiable chemical and electrical compartments that regulate synaptic efficacy, integration and plasticity. Experimental studies have confirmed activity-dependent structural dynamics and biochemical compartmentalization by spines. However, there is a longstanding debate over the influence of spines on the electrical aspects of synaptic transmission and dendritic operation. Here we measure the amplitude ratio of spine head to parent dendrite voltage across a range of dendritic compartments and calculate the associated spine neck resistance (R(neck)) for spines at apical trunk dendrites in rat hippocampal CA1 pyramidal neurons. We find that R(neck) is large enough (~500 MOmega) to amplify substantially the spine head depolarization associated with a unitary synaptic input by ~1.5- to ~45-fold, depending on parent dendritic impedance. A morphologically realistic compartmental model capable of reproducing the observed spatial profile of the amplitude ratio indicates that spines provide a consistently high-impedance input structure throughout the dendritic arborization. Finally, we demonstrate that the amplification produced by spines encourages electrical interaction among coactive inputs through an R(neck)-dependent increase in spine head voltage-gated conductance activation. We conclude that the electrical properties of spines promote nonlinear dendritic processing and associated forms of plasticity and storage, thus fundamentally enhancing the computational capabilities of neurons.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3504647/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3504647/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Harnett, Mark T -- Makara, Judit K -- Spruston, Nelson -- Kath, William L -- Magee, Jeffrey C -- 090915/Wellcome Trust/United Kingdom -- NS-046064/NS/NINDS NIH HHS/ -- NS-077601/NS/NINDS NIH HHS/ -- R01 NS046064/NS/NINDS NIH HHS/ -- R01 NS077601/NS/NINDS NIH HHS/ -- Howard Hughes Medical Institute/ -- England -- Nature. 2012 Nov 22;491(7425):599-602. doi: 10.1038/nature11554. Epub 2012 Oct 28.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉HHMI Janelia Farm Research Campus, Ashburn, Virginia 20147, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23103868" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Dendritic Spines/*physiology ; Electric Impedance ; Excitatory Postsynaptic Potentials/physiology ; Male ; Models, Neurological ; Pyramidal Cells/*physiology ; Rats ; Rats, Sprague-Dawley ; Rats, Wistar ; Synapses/*metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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