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UP states protect ongoing cortical activity from thalamic inputs.

Watson BO, MacLean JN, Yuste R - PLoS ONE (2008)

Bottom Line: To examine how thalamic inputs interact with ongoing cortical UP state activity, we used calcium imaging and targeted whole-cell recordings of activated neurons in thalamocortical slices of mouse somatosensory cortex.Both thalamocortical and corticocortical PSPs were significantly reduced and neuronal input resistance was significantly decreased during cortical UP states -- mechanistically consistent with UP state insensitivity.Our results demonstrate that cortical dynamics during UP states are insensitive to thalamic inputs.

View Article: PubMed Central - PubMed

Affiliation: Howard Hughes Medical Institute, Department of Biological Sciences, Columbia University, New York, NY, USA. bow4@columbia.edu

ABSTRACT
Cortical neurons in vitro and in vivo fluctuate spontaneously between two stable membrane potentials: a depolarized UP state and a hyperpolarized DOWN state. UP states temporally correspond with multineuronal firing sequences which may be important for information processing. To examine how thalamic inputs interact with ongoing cortical UP state activity, we used calcium imaging and targeted whole-cell recordings of activated neurons in thalamocortical slices of mouse somatosensory cortex. Whereas thalamic stimulation during DOWN states generated multineuronal, synchronized UP states, identical stimulation during UP states had no effect on the subthreshold membrane dynamics of the vast majority of cells or on ongoing multineuronal temporal patterns. Both thalamocortical and corticocortical PSPs were significantly reduced and neuronal input resistance was significantly decreased during cortical UP states -- mechanistically consistent with UP state insensitivity. Our results demonstrate that cortical dynamics during UP states are insensitive to thalamic inputs.

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Spontaneous and thalamically-triggered coactivations in thalamocortical slices.(a) Schematic of somatosensory thalamocortical slice preparation. Calcium imaging and whole-cell recordings were made from somatosensory cortex. Bipolar electrical stimulation electrode was placed in the ventral basal nucleus of the thalamus. The region of cortex that responded earliest to thalamic stimulation when imaged at low magnification was chosen for single cell resolution imaging. Scale bars = 1 mm, 50 µm inset. (b). Representative whole-cell recording from a layer 4 neuron revealing spontaneous UP states. This neuron received direct synaptic inputs from the thalamus, as demonstrated by the thalamocortical EPSP observed with every thalamic stimulus (inset). A window discriminator monitored membrane potential in real time and, upon the start of an UP state, activated the thalamic stimulation paradigm from a pulse generator. The delay between the window discriminator output and the initiation of stimulation is under experimental control and was generally set to 350–1000 milliseconds. (c) Representative calcium imaging experiment. Slices were bulk loaded with the calcium indicator Fura 2-AM and network activity was monitored with single-cell resolution by measuring changes in fluorescence. Neurons were recognized automatically and action potential-related activity (spiking cells indicated by filled contours) was used for analysis of spatiotemporal activity patterns. Active neurons were targeted for patch clamp recordings. Scale bar 50 µm.
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pone-0003971-g001: Spontaneous and thalamically-triggered coactivations in thalamocortical slices.(a) Schematic of somatosensory thalamocortical slice preparation. Calcium imaging and whole-cell recordings were made from somatosensory cortex. Bipolar electrical stimulation electrode was placed in the ventral basal nucleus of the thalamus. The region of cortex that responded earliest to thalamic stimulation when imaged at low magnification was chosen for single cell resolution imaging. Scale bars = 1 mm, 50 µm inset. (b). Representative whole-cell recording from a layer 4 neuron revealing spontaneous UP states. This neuron received direct synaptic inputs from the thalamus, as demonstrated by the thalamocortical EPSP observed with every thalamic stimulus (inset). A window discriminator monitored membrane potential in real time and, upon the start of an UP state, activated the thalamic stimulation paradigm from a pulse generator. The delay between the window discriminator output and the initiation of stimulation is under experimental control and was generally set to 350–1000 milliseconds. (c) Representative calcium imaging experiment. Slices were bulk loaded with the calcium indicator Fura 2-AM and network activity was monitored with single-cell resolution by measuring changes in fluorescence. Neurons were recognized automatically and action potential-related activity (spiking cells indicated by filled contours) was used for analysis of spatiotemporal activity patterns. Active neurons were targeted for patch clamp recordings. Scale bar 50 µm.

Mentions: To investigate the role of cortical UP state activity in the processing of thalamic inputs, we used somatosensory thalamocortical slices from P13-18 mice. This preparation allowed us to stimulate small areas of the ventral basal nucleus of the thalamus, while monitoring the response of layer 4 at both the multi-neuronal level, using calcium imaging, and at the single cell level, with targeted whole-cell recordings (Figure 1). We imaged slices loaded with fura-2 AM to reconstruct, with single-cell resolution, the spiking activity of populations of hundred neurons simultaneously [13], taking advantage of the strict correspondence between calcium transients from fura-2 AM loaded cells and action potentials [14], [15]. We imaged between 142 and 524 neurons per experiment, detecting activated cells with online analysis of movies and then patch clamped 195 of them, allowing for whole-cell recordings and post-hoc anatomical analysis. Multiple neurons were often simultaneously recorded.


UP states protect ongoing cortical activity from thalamic inputs.

Watson BO, MacLean JN, Yuste R - PLoS ONE (2008)

Spontaneous and thalamically-triggered coactivations in thalamocortical slices.(a) Schematic of somatosensory thalamocortical slice preparation. Calcium imaging and whole-cell recordings were made from somatosensory cortex. Bipolar electrical stimulation electrode was placed in the ventral basal nucleus of the thalamus. The region of cortex that responded earliest to thalamic stimulation when imaged at low magnification was chosen for single cell resolution imaging. Scale bars = 1 mm, 50 µm inset. (b). Representative whole-cell recording from a layer 4 neuron revealing spontaneous UP states. This neuron received direct synaptic inputs from the thalamus, as demonstrated by the thalamocortical EPSP observed with every thalamic stimulus (inset). A window discriminator monitored membrane potential in real time and, upon the start of an UP state, activated the thalamic stimulation paradigm from a pulse generator. The delay between the window discriminator output and the initiation of stimulation is under experimental control and was generally set to 350–1000 milliseconds. (c) Representative calcium imaging experiment. Slices were bulk loaded with the calcium indicator Fura 2-AM and network activity was monitored with single-cell resolution by measuring changes in fluorescence. Neurons were recognized automatically and action potential-related activity (spiking cells indicated by filled contours) was used for analysis of spatiotemporal activity patterns. Active neurons were targeted for patch clamp recordings. Scale bar 50 µm.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2597736&req=5

pone-0003971-g001: Spontaneous and thalamically-triggered coactivations in thalamocortical slices.(a) Schematic of somatosensory thalamocortical slice preparation. Calcium imaging and whole-cell recordings were made from somatosensory cortex. Bipolar electrical stimulation electrode was placed in the ventral basal nucleus of the thalamus. The region of cortex that responded earliest to thalamic stimulation when imaged at low magnification was chosen for single cell resolution imaging. Scale bars = 1 mm, 50 µm inset. (b). Representative whole-cell recording from a layer 4 neuron revealing spontaneous UP states. This neuron received direct synaptic inputs from the thalamus, as demonstrated by the thalamocortical EPSP observed with every thalamic stimulus (inset). A window discriminator monitored membrane potential in real time and, upon the start of an UP state, activated the thalamic stimulation paradigm from a pulse generator. The delay between the window discriminator output and the initiation of stimulation is under experimental control and was generally set to 350–1000 milliseconds. (c) Representative calcium imaging experiment. Slices were bulk loaded with the calcium indicator Fura 2-AM and network activity was monitored with single-cell resolution by measuring changes in fluorescence. Neurons were recognized automatically and action potential-related activity (spiking cells indicated by filled contours) was used for analysis of spatiotemporal activity patterns. Active neurons were targeted for patch clamp recordings. Scale bar 50 µm.
Mentions: To investigate the role of cortical UP state activity in the processing of thalamic inputs, we used somatosensory thalamocortical slices from P13-18 mice. This preparation allowed us to stimulate small areas of the ventral basal nucleus of the thalamus, while monitoring the response of layer 4 at both the multi-neuronal level, using calcium imaging, and at the single cell level, with targeted whole-cell recordings (Figure 1). We imaged slices loaded with fura-2 AM to reconstruct, with single-cell resolution, the spiking activity of populations of hundred neurons simultaneously [13], taking advantage of the strict correspondence between calcium transients from fura-2 AM loaded cells and action potentials [14], [15]. We imaged between 142 and 524 neurons per experiment, detecting activated cells with online analysis of movies and then patch clamped 195 of them, allowing for whole-cell recordings and post-hoc anatomical analysis. Multiple neurons were often simultaneously recorded.

Bottom Line: To examine how thalamic inputs interact with ongoing cortical UP state activity, we used calcium imaging and targeted whole-cell recordings of activated neurons in thalamocortical slices of mouse somatosensory cortex.Both thalamocortical and corticocortical PSPs were significantly reduced and neuronal input resistance was significantly decreased during cortical UP states -- mechanistically consistent with UP state insensitivity.Our results demonstrate that cortical dynamics during UP states are insensitive to thalamic inputs.

View Article: PubMed Central - PubMed

Affiliation: Howard Hughes Medical Institute, Department of Biological Sciences, Columbia University, New York, NY, USA. bow4@columbia.edu

ABSTRACT
Cortical neurons in vitro and in vivo fluctuate spontaneously between two stable membrane potentials: a depolarized UP state and a hyperpolarized DOWN state. UP states temporally correspond with multineuronal firing sequences which may be important for information processing. To examine how thalamic inputs interact with ongoing cortical UP state activity, we used calcium imaging and targeted whole-cell recordings of activated neurons in thalamocortical slices of mouse somatosensory cortex. Whereas thalamic stimulation during DOWN states generated multineuronal, synchronized UP states, identical stimulation during UP states had no effect on the subthreshold membrane dynamics of the vast majority of cells or on ongoing multineuronal temporal patterns. Both thalamocortical and corticocortical PSPs were significantly reduced and neuronal input resistance was significantly decreased during cortical UP states -- mechanistically consistent with UP state insensitivity. Our results demonstrate that cortical dynamics during UP states are insensitive to thalamic inputs.

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