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ref: -0 tags: synaptic plasticity 2-photon imaging inhibition excitation spines dendrites synapses 2p date: 05-31-2019 23:02 gmt revision:2 [1] [0] [head]

PMID-22542188 Clustered dynamics of inhibitory synapses and dendritic spines in the adult neocortex.

  • Cre-recombinase-dependent labeling of postsynapitc scaffolding via Gephryn-Teal fluorophore fusion.
  • Also added Cre-eYFP to lavel the neurons
  • Electroporated in utero e16 mice.
    • Low concentration of Cre, high concentrations of Gephryn-Teal and Cre-eYFP constructs to attain sparse labeling.
  • Located the same dendrite imaged in-vivo in fixed tissue - !! - using serial-section electron microscopy.
  • 2230 dendritic spines and 1211 inhibitory synapses from 83 dendritic segments in 14 cells of 6 animals.
  • Some spines had inhibitory synapses on them -- 0.7 / 10um, vs 4.4 / 10um dendrite for excitatory spines. ~ 1.7 inhibitory
  • Suggest that the data support the idea that inhibitory inputs maybe gating excitation.
  • Furthermore, co-inervated spines are stable, both during mormal experience and during monocular deprivation.
  • Monocular deprivation induces a pronounced loss of inhibitory synapses in binocular cortex.

{1451}
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ref: -2018 tags: sparse representation auditory cortex excitatation inhibition balance date: 03-11-2019 20:47 gmt revision:1 [0] [head]

PMID-30307493 Sparse Representation in Awake Auditory Cortex: Cell-type Dependence, Synaptic Mechanisms, Developmental Emergence, and Modulation.

  • Sparse representation arises during development in an experience-dependent manner, accompanied by differential changes of excitatory input strength and a transition from unimodal to bimodal distribution of E/I ratios.

{1078}
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ref: Mirabella-2011.08 tags: DBS STN inhibition nogo Italy date: 02-22-2012 18:26 gmt revision:6 [5] [4] [3] [2] [1] [0] [head]

PMID-21810782[0] Deep Brain Stimulation of Subthalamic Nuclei Affects Arm Response Inhibition In Parkinson’s Patients

  • Inhibitory control is improved only when both DBS are active, that is, the reaction time to the stop signal is significantly shorter in the DBS-ON condition than in all the others (left, right, or neither).
    • Inhibition is probably not lateralized.
  • CF [1]
  • The STN plays a critical role in the control of movements by integrating cortical inputs from several motor areas (Mink 1996, Romanelli et al 2005) (but how -- in what role?)
    • Alteration of STN functioning leads to loss of the ability to control movements as in the case of Parkinson's disease (Obeso et al 2008).
    • This control can be partially restored by DBS (Perlmutter and Mink 2006).
    • I don't agree with this. Things are far more nuanced, and the STN likely has a different role.
  • Theri metric is the SSRT:the stop signal reaction time.
    • One study found that SSRT was longer when DBS was on.
    • Two others bilateral DBS decreased length of the SSRT.
  • This task creates conflict on all trials, as they are instructed to both move as fast as possible, but also avoid hitting the target on stop trials.
    • In healthy subjects this leads to a delay strategy.
  • SSRT is not measured, but rather estimated from a 'race condition' between Go and Stop cues.
  • They propose that DBS affects the procrastination strategy, and that this strategy was less often adopted by PD patients than normal controls.
    • Or that STN / BG affects the ability to stop currently proceeding active movements.

____References____

[0] Mirabella G, Iaconelli S, Romanelli P, Modugno N, Lena F, Manfredi M, Cantore G, Deep Brain Stimulation of Subthalamic Nuclei Affects Arm Response Inhibition In Parkinson's Patients.Cereb Cortex no Volume no Issue no Pages (2011 Aug 1)
[1] Frank MJ, Samanta J, Moustafa AA, Sherman SJ, Hold your horses: impulsivity, deep brain stimulation, and medication in parkinsonism.Science 318:5854, 1309-12 (2007 Nov 23)