Early Somatostatin Interneuron Connectivity Mediates the Maturation of Deep Layer Cortical Circuits

Early Somatostatin Interneuron Connectivity Mediates the Maturation of Deep Layer Cortical Circuits Tuncdemir Wamsley Stam Osakada Goulding Callaway Rudy Fishell

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Early Somatostatin Interneuron Connectivity Mediates the Maturation of Deep Layer Cortical Circuits 2016 Neuron 10.1016/j.neuron.2015.11.020 Tuncdemir2016-early-somatostatin-interneuron-connectivity Tuncdemir2016-early-somatostatin-interneuron-connectivity.txt, the project's staged copy 5ca1232297c51c58174d19dbd71b2f8b541bd2c7 not-redistributable neuroscience

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0 spans located by searching the stored text for the quote's exact words, allowing any whitespace between them whether the earliest-born somatostatin interneurons integrate straight into their adult circuit, or first form a transient connectivity that helps build the mature wiring Quotation withheld because this record is not cleared for redistribution. whether deep-layer somatostatin interneurons act as a temporary relay between thalamus and parvalbumin interneurons before thalamic afferents reach the latter directly Quotation withheld because this record is not cleared for redistribution. somatostatin interneurons in layers 5 and 6 receive dense thalamic input only during the first postnatal week, and disrupting them in that window - but not later - arrests the maturation of thalamic input onto parvalbumin interneurons Quotation withheld because this record is not cleared for redistribution. mechanism Quotation withheld because this record is not cleared for redistribution. somatostatin interneuron connectivity in developing neocortex Quotation withheld because this record is not cleared for redistribution. electrophysiology electrophysiology Quotation withheld because this record is not cleared for redistribution. mechanisms Infragranular somatostatin interneurons serve as a transient intermediate relay carrying thalamic activity to parvalbumin interneurons and pyramidal cells before those cells are directly innervated by the thalamus Quotation withheld because this record is not cleared for redistribution. mechanisms Spontaneous GABA released from somatostatin interneurons tonically activates parvalbumin interneurons, which drives the development of their thalamocortical synapses Quotation withheld because this record is not cleared for redistribution. mechanisms Somatostatin interneurons hold thalamocortical afferents as a postsynaptic placeholder, supplying trophic support that later allows those afferents to target parvalbumin interneurons Quotation withheld because this record is not cleared for redistribution. SST interneurons act as an intermediate relay for TC afferent outputs to PV interneurons and PNs, prior to when TC afferents target these latter populations Quotation withheld because this record is not cleared for redistribution. the loss of thalamic drive is only partly explained by a smaller unitary current, and the rest by a fall in the number of thalamic terminals counted as Vglut2 puncta Quotation withheld because this record is not cleared for redistribution. spontaneous vesicular GABA diffusion, and not evoked synaptic transmission, is what parvalbumin interneurons need from them Quotation withheld because this record is not cleared for redistribution. or alternatively the somatostatin interneurons act as a postsynaptic placeholder holding thalamic fibers until parvalbumin synapses can be established Quotation withheld because this record is not cleared for redistribution. The specific role played by somatostatin interneuron synaptic output in driving parvalbumin interneuron maturation is not resolved by the experiments reported. what this limits: the mechanism, not the requirement: the need for SST cells is demonstrated, but UNDERSTANDING THE PRECISE ROLE OF THEIR SYNAPTIC OUTPUTS IN THIS PROCESS WILL REQUIRE FURTHER INVESTIGATION Quotation withheld because this record is not cleared for redistribution. The findings come from layer 5/6 somatostatin interneurons and may not generalise across the heterogeneous somatostatin population in other layers. what this limits: any generalisation from these cells to somatostatin interneurons as a class: THE POSSIBILITY THAT ALL SST INTERNEURONS ARE ALL EQUIVALENT SHOULD BE CONSIDERED WITH CAUTION Quotation withheld because this record is not cleared for redistribution. The molecular mechanism that prunes the transient thalamocortical input onto somatostatin interneurons is unknown. what this limits: the pruning result: it is observed, but THE MOLECULAR AND CELLULAR SIGNALS THAT REGULATE PRUNING REMAIN TO BE DETERMINED Quotation withheld because this record is not cleared for redistribution. the genetic driver is not restricted to somatostatin interneurons, with a fidelity of about 86% in L5 and 83% in L6 what this limits: what the label means throughout: recombination WAS NOT COMPLETELY RESTRICTED TO SST INTERNEURONS - THE FIDELITY WAS QUITE HIGH: ~86% IN L5 AND 83% L6 Quotation withheld because this record is not cleared for redistribution. the two ages could not be traced with the same reagent, because rabies glycoprotein from the Rosa locus stops supporting transfer after P10 what this limits: every early-versus-late comparison: AFTER P10 RABIES GLYCOPROTEIN LEVELS FROM THE ROSA-LOCUS ARE INSUFFICIENT ... WE MODIFIED OUR APPROACH, so the two ages were traced with different reagents Quotation withheld because this record is not cleared for redistribution. the signals that drive the pruning are unknown, and neither release probability nor receptor composition accounts for the change what this limits: the cause of the pruning: release probability and receptor composition are excluded, but THE MOLECULAR AND CELLULAR SIGNALS ... REMAIN TO BE DETERMINED Quotation withheld because this record is not cleared for redistribution. the impact of GABA released from these cells in the immature brain is not understood, and the source of GABA in the developing cortex is still unknown what this limits: any functional reading of the GABA these cells release: WE DO NOT HAVE A CLEAR UNDERSTANDING OF THE PHYSIOLOGICAL IMPACT ... and THE PRECISE SOURCE OF GABA ... REMAINS UNKNOWN Quotation withheld because this record is not cleared for redistribution. and somatostatin interneurons are not one class - L4 cells of the X94 type differ in function, morphology and connectivity from those in L2/3 and L5/6 what this limits: the same scope as limitations[1], with the divergent population named: L4 SST cells of the X94 CLASS POSSESS FUNCTIONAL, MORPHOLOGICAL AND SYNAPTIC CONNECTIVITY PROFILES DISTINCT from the cells studied here Quotation withheld because this record is not cleared for redistribution. the hub-cell idea - a precocious early population that scaffolds an immature network - imported and then found not to fit Quotation withheld because this record is not cleared for redistribution. monosynaptic rabies tracing with pseudotyped glycoprotein-deleted virus, used to read first-order inputs at two ages Quotation withheld because this record is not cleared for redistribution. the reported opposite developmental trajectories of somatostatin and parvalbumin thalamic drive Quotation withheld because this record is not cleared for redistribution. the interpretation - that parvalbumin defects implicated in disease may originate in an earlier somatostatin dependency Quotation withheld because this record is not cleared for redistribution. cre-negative animals put through the same AAV-hGFP-RG then RV-mCh injection protocol - the paper reports the result and marks the data itself '(data not shown)' eliminates: rabies infection that does not depend on cre-mediated complementation - without it, labelled cells could be direct RV-mCh infection rather than monosynaptic transfer from a starter cell · outcome (stated by the tagger, no quotation): held Quotation withheld because this record is not cleared for redistribution. SST SST Quotation withheld because this record is not cleared for redistribution. PV PV Quotation withheld because this record is not cleared for redistribution. hub hub Quotation withheld because this record is not cleared for redistribution. subplate subplate Quotation withheld because this record is not cleared for redistribution. infragranular infragranular Quotation withheld because this record is not cleared for redistribution. X94 X94 Quotation withheld because this record is not cleared for redistribution. THE REQUIREMENT EXISTS ONLY INSIDE A WINDOW: disruption of the EARLY, but not the late, somatostatin network arrests the synaptic maturation of thalamic input onto parvalbumin interneurons Quotation withheld because this record is not cleared for redistribution. and the late experiment is the same ablation done seven days later, with responses similar to controls at p>0.2 - so the effect is indexed to WHEN the manipulation happened, not to what it removed Quotation withheld because this record is not cleared for redistribution. THE TOOL HAD TO BE CHANGED BETWEEN THE TWO AGES BEING COMPARED: rabies glycoprotein from the Rosa locus stops supporting synaptic transfer after P10, so the older animals were traced with a different reporter and a helper virus Quotation withheld because this record is not cleared for redistribution. which is why the anatomical result is then validated by a second, independent method - and both agree that the input is transient Quotation withheld because this record is not cleared for redistribution. THE GENETIC LABEL IS NOT PURE AND THE PAPER SAYS SO: the driver was not completely restricted to somatostatin interneurons, at about 86% in L5 and 83% in L6 Quotation withheld because this record is not cleared for redistribution. AND THE MARKER-NAMED CLASS IS NOT ONE THING: the possibility that all somatostatin interneurons are equivalent should be considered with caution, since the L4 X94 cells differ in function, morphology and connectivity Quotation withheld because this record is not cleared for redistribution. SHARED ORIGIN AND SHARED MARKERS DO NOT MAKE A SHARED FUNCTION: despite common embryonic origin and immunohistochemical properties, these cells are quite distinct from subplate and hippocampal hub pioneers, and form no long-range projections Quotation withheld because this record is not cleared for redistribution. THE RIVAL EXPLANATION IS NAMED BEFORE IT IS TESTED: the shift could be that the starter populations at the two ages were not identical - through cell death, or through later-born cells diluting the early ones out Quotation withheld because this record is not cleared for redistribution. and it is ruled out by birthdating, which finds comparable numbers at both ages Quotation withheld because this record is not cleared for redistribution. TWO CANDIDATE MECHANISMS ARE NAMED AND THEN SEPARATED: a smaller unitary current, a lower connection probability, or both - and the unitary change turns out to account for only part of it Quotation withheld because this record is not cleared for redistribution. A DISSOCIATION BUILT FROM TWO MANIPULATIONS OF ONE PATHWAY: blocking evoked vesicular release changes nothing, while reducing presynaptic GABA reproduces the phenotype, so the spontaneous release and not the evoked transmission is what is required Quotation withheld because this record is not cleared for redistribution. AND THE DIRECT INPUT IS INTACT WHILE THE INHIBITION IT DRIVES IS NOT: thalamic input to pyramidal cells was unaffected, and the inhibition those same cells receive was significantly reduced Quotation withheld because this record is not cleared for redistribution. the same developmental decrease was reported in a different species, area and layer - somatostatin cells of gerbil auditory L4 - against a matching increase in parvalbumin cells Quotation withheld because this record is not cleared for redistribution. THE STRENGTH CHANGES AND THE TARGETS DO NOT: the efferents dramatically alter their relative strength while maintaining their target specificity Quotation withheld because this record is not cleared for redistribution. claim_type: mechanism a second reading reaching the same value. Recorded: mechanism — note: a second reading reaching the same value from a different sentence. Not applied - a person decides. Quotation withheld because this record is not cleared for redistribution. method: monosynaptic rabies tracing at two ages, optogenetic and minimal-stimulation recording of unitary thalamic currents, synaptic puncta counts, and four genetic disruptions timed early or late a second reading DIFFERING from the recorded value. Recorded: electrophysiology — note: a second reading, verbatim-verified, disagreeing with the value on the record. Not applied - a person decides. Quotation withheld because this record is not cleared for redistribution. phenomenon: a transient early connectivity - dense thalamic input onto somatostatin interneurons that is pruned away by the second postnatal week a second reading DIFFERING from the recorded value. Recorded: somatostatin interneuron connectivity in developing neocortex — note: a second reading, verbatim-verified, disagreeing with the value on the record. Not applied - a person decides. Quotation withheld because this record is not cleared for redistribution. extends → Takesian et al., 2013 (Sanes and colleagues), on developmentally decreasing thalamic input to LTS-SST interneurons in layer 4 of gerbil auditory cortex Quotation withheld because this record is not cleared for redistribution. builds-on → Close et al., 2012, the Satb1 conditional-knockout model in which cortical SST interneurons fail to mature Quotation withheld because this record is not cleared for redistribution. builds-on → Cossart, 2014; Kanold and Luhmann, 2010; Molnar and Clowry, 2012, on global organizers of excitatory circuit assembly Quotation withheld because this record is not cleared for redistribution. confirms → the reported developmental decrease of thalamic drive onto somatostatin cells in gerbil auditory cortex, in a different species, area and layer Quotation withheld because this record is not cleared for redistribution. distinguishes-from → hippocampal hub cells and cortical subplate neurons, the previously identified pioneer populations differs in: THE AXIS IS WHAT IS SHARED AGAINST WHAT IS NOT. 'To our surprise, despite their common embryonic origin and immunohistochemical properties, the earliest born SST interneur[ONS] [differ].' Origin and markers are granted as shared and the functional comparison fails anyway - so the properties usually used to assign a cell to a pioneer class are exactly the ones that do not predict the behaviour. Belongs with the cell-type label-error material. Quotation withheld because this record is not cleared for redistribution. explains-away → the possibility that the developmental shift reflects a different starter population being sampled at the two ages Quotation withheld because this record is not cleared for redistribution. qualifies → the assumption that somatostatin interneurons form a single equivalent class across layers Quotation withheld because this record is not cleared for redistribution. extends → the account of thalamocortical feed-forward inhibition, by making its assembly depend on a second interneuron class Quotation withheld because this record is not cleared for redistribution. builds-on → the observation that GABAergic synapses exist in neocortex before parvalbumin synapses are functional, so another source of GABA must be present Quotation withheld because this record is not cleared for redistribution. SST —contrasted-with→ PV SST PV strength of the relation: 1 · note: SHARED EMBRYONIC ORIGIN AND OVERLAPPING TRANSCRIPTION FACTORS, AND DISTINCT SYNAPTIC SPECIFICITY: dendrite-targeting feedback against perisomatic feed-forward Quotation withheld because this record is not cleared for redistribution. SST —causes→ maturation SST maturation strength of the relation: 1 Audit 2026-09-28: DOUBTFUL - read against its span and kept, but the span says SST cells support immature networks; causes 'maturation' is loose. Quotation withheld because this record is not cleared for redistribution. SST —contrasted-with→ PN SST PN strength of the relation: 1 · note: THE SIGN REVERSES WITH AGE: larger currents in the interneurons in week one, substantially weaker by week three Quotation withheld because this record is not cleared for redistribution. PV —contrasted-with→ PN PV PN strength of the relation: 1 · note: THE OUTPUT REVERSES TOO: equal in week one, strongly biased to the pyramidal cells by week three Quotation withheld because this record is not cleared for redistribution. SST —is-a→ relay SST relay strength of the relation: 1 · note: THE CENTRAL CLAIM: an intermediate relay for thalamic output, prior to when those afferents target the later populations directly Quotation withheld because this record is not cleared for redistribution. DTA —causes→ SST DTA SST strength of the relation: 1 · note: about half the cells removed from L5/6, and not reduced further later Quotation withheld because this record is not cleared for redistribution. Satb1 —causes→ SST Satb1 SST strength of the relation: 1 · note: re-read worst chars/edge queue): VAGUE-ENDPOINTS - real: removal of Satb1 makes SST interneurons fail to mature, and the passage quantifies it (40% reduction at P10, 60% by P21). Endpoints should be 'Satb1' and 'SST interneuron maturation', and the edge should carry the effect direction. Quotation withheld because this record is not cleared for redistribution. spontaneous —contrasted-with→ evoked spontaneous evoked differs in: THE AXIS IS SPONTANEOUS RELEASE AGAINST EVOKED TRANSMISSION. 'the spontaneous vesicular GABA diffusion into the extracellular space, but not evoked synaptic transmission from SST interneurons is required for the synaptic development of PV interneurons.' The developmental signal is carried by the mode of release nobody manipulates deliberately - so an experiment that blocks evoked transmission leaves the effective signal intact and concludes the cells are not involved. · strength of the relation: 1 · note: A DISSOCIATION BUILT FROM TWO MANIPULATIONS OF ONE PATHWAY: blocking evoked vesicular release changes nothing, reducing presynaptic GABA reproduces the phenotype 2026-08-20 the project re-read worst chars/edge queue): VAGUE-ENDPOINTS - the contrast IS the passage's conclusion - 'spontaneous vesicular…' - but the endpoints are two bare adjectives. Re-ground on the full phrases and this becomes a good edge. Audit 2026-09-28: DOUBTFUL - read against its span and kept, but spontaneous and evoked measures are compared; contrasted-with is loose. Quotation withheld because this record is not cleared for redistribution. hub —distinct-from→ pioneer hub pioneer strength of the relation: 1 · note: SHARED ORIGIN AND SHARED MARKERS DO NOT MAKE A SHARED FUNCTION: quite distinct from the other pioneers despite common embryonic origin and immunohistochemistry, and no long-range projections Audit 2026-09-28: DOUBTFUL - read against its span and kept, but the span asks whether hub cells share properties with pioneer populations; distinct-from is loose. Quotation withheld because this record is not cleared for redistribution. X94 —part-of→ L4 X94 L4 strength of the relation: 1 Audit 2026-09-28: DOUBTFUL - read against its full span and kept, but most L4 SST interneurons 'belong to the so called X94 class'; part-of L4 is loose. Quotation withheld because this record is not cleared for redistribution. barrel —same-as→ S1BC barrel S1BC strength of the relation: 1 Audit 2026-09-28: DOUBTFUL - read against its span and kept, but barrel cortex and S1BC; same-as is implied, not stated. Quotation withheld because this record is not cleared for redistribution. chi-squared chi-squared Quotation withheld because this record is not cleared for redistribution. Mann-Whitney U test Mann-Whitney U test Quotation withheld because this record is not cleared for redistribution. Kolmogorov-Smirnov test Kolmogorov-Smirnov test Quotation withheld because this record is not cleared for redistribution. t-test t-test Quotation withheld because this record is not cleared for redistribution. standard error of the mean standard error of the mean Quotation withheld because this record is not cleared for redistribution. significance level / non-parametric testing significance level / non-parametric testing Quotation withheld because this record is not cleared for redistribution. chi-square test chi-square test Quotation withheld because this record is not cleared for redistribution. Mann-Whitney test Mann-Whitney test Quotation withheld because this record is not cleared for redistribution. Kolmogorov-Smirnov test Kolmogorov-Smirnov test Quotation withheld because this record is not cleared for redistribution. standard error of the mean standard error of the mean Quotation withheld because this record is not cleared for redistribution. non-parametric non-parametric Quotation withheld because this record is not cleared for redistribution. During the first postnatal week, thalamocortical excitatory input to infragranular somatostatin interneurons is about three times larger than the input to neighbouring pyramidal neurons. Quotation withheld because this record is not cleared for redistribution. Thalamic input to somatostatin interneurons is transient: the number of thalamic neurons projecting to them falls roughly fourfold between the first postnatal week and maturity. Quotation withheld because this record is not cleared for redistribution. Unitary thalamic EPSCs onto somatostatin interneurons are larger in immature (P3-P6) than in adolescent (P18-P25) mice. Quotation withheld because this record is not cleared for redistribution. In older animals, somatostatin interneuron output falls preferentially on pyramidal neurons (about 224 pA) rather than nearby parvalbumin interneurons (about 56 pA). Quotation withheld because this record is not cleared for redistribution. Removing somatostatin interneurons or their excitatory input early in development, but not after the first postnatal week, leaves parvalbumin interneurons with smaller-amplitude, longer-latency, slower-rising thalamocortical EPSCs. Quotation withheld because this record is not cleared for redistribution. Spontaneous vesicular GABA release, but not evoked synaptic transmission, from somatostatin interneurons appears to be required for parvalbumin synaptic development. Quotation withheld because this record is not cleared for redistribution. Early-born layer 5/6 somatostatin interneurons differ from hippocampal hub neurons in that they lack dense long-range projections. Quotation withheld because this record is not cleared for redistribution. somatostatin interneurons in deep layers receive dense but transient thalamocortical innervation during the first postnatal week Quotation withheld because this record is not cleared for redistribution. THE REQUIREMENT EXISTS ONLY INSIDE A WINDOW: disruption of the early, but not the late, network arrests the synaptic maturation of thalamic input onto parvalbumin interneurons Quotation withheld because this record is not cleared for redistribution. and the question was posed as an alternative in advance - immediate integration into adult circuits, or a transient connectivity that aids mature wiring Quotation withheld because this record is not cleared for redistribution. the two classes share an embryonic origin and overlapping transcription factors, and have distinct synaptic specificity in mature circuits Quotation withheld because this record is not cleared for redistribution. THE GAP THAT MOTIVATED THE STUDY: GABAergic synapses exist in neocortex before parvalbumin synapses are functional, so another source of GABA must be present Quotation withheld because this record is not cleared for redistribution. the hippocampal hub cells provided the precedent - long-range cells present by P5 sharing a common embryonic origin with these Quotation withheld because this record is not cleared for redistribution. THE TOOL HAD TO BE CHANGED BETWEEN THE TWO AGES BEING COMPARED: rabies glycoprotein from the Rosa locus stops supporting synaptic transfer after P10 Quotation withheld because this record is not cleared for redistribution. starter cells sat in L5 and L6 at both ages, with no dependence of their laminar distribution on developmental stage Quotation withheld because this record is not cleared for redistribution. immature cells received afferents mostly from the ventrobasal and posterior medial thalamic nuclei Quotation withheld because this record is not cleared for redistribution. and an approximately fourfold reduction in thalamic input by adulthood, normalized to starter number, with no other source changing Quotation withheld because this record is not cleared for redistribution. the local increase in upper-layer inputs fits the inside-out model, and the large transient thalamic input to deep layers was UNANTICIPATED Quotation withheld because this record is not cleared for redistribution. THE RIVAL EXPLANATION IS NAMED BEFORE IT IS TESTED: the starter populations at the two ages might not have been identical, through cell death or dilution by later-born cells Quotation withheld because this record is not cleared for redistribution. and birthdating argues against selective loss or dilution, with comparable numbers at both ages Quotation withheld because this record is not cleared for redistribution. THE GENETIC LABEL IS NOT PURE AND THE PAPER SAYS SO: fidelity of about 86% in L5 and 83% in L6, unchanged across development Quotation withheld because this record is not cleared for redistribution. with the anatomical conclusion then taken to a second, independent method rather than left standing alone Quotation withheld because this record is not cleared for redistribution. THE SIGN REVERSES WITH AGE: larger currents in the interneurons than in pyramidal cells in week one, substantially weaker by week three Quotation withheld because this record is not cleared for redistribution. 155 pA against 51 pA in the first postnatal week, and 57 pA against 227 pA in the third Quotation withheld because this record is not cleared for redistribution. AND THE QUANTITY IS A RATIO BETWEEN TWO CELL TYPES: the ratio of excitatory charge was on average ~7 fold greater in SST interneurons compared to PNs during the initial stages of cortical development Quotation withheld because this record is not cleared for redistribution. with the voltage-clamp and membrane-property explanation argued against, since the changes appear concurrently in both cell types Quotation withheld because this record is not cleared for redistribution. TWO CANDIDATE MECHANISMS ARE NAMED BEFORE EITHER IS TESTED: unitary conductance, connection probability, or a combination of both Quotation withheld because this record is not cleared for redistribution. unitary thalamic currents were larger in immature cells, 54.89 pA against 39.15 pA Quotation withheld because this record is not cleared for redistribution. AND THE FIRST MECHANISM ONLY PARTLY ACCOUNTS FOR IT, which is why synapse number was then counted directly Quotation withheld because this record is not cleared for redistribution. TWO INDEPENDENT METHODS AGREE: the terminal counts independently validate the rabies tracing Quotation withheld because this record is not cleared for redistribution. the two interneuron classes were compared directly in the same slices, and intrinsic membrane properties do not account for the difference Quotation withheld because this record is not cleared for redistribution. THE OUTPUT REVERSES TOO: equal onto both targets in week one, strongly biased to pyramidal cells by week three Quotation withheld because this record is not cleared for redistribution. THE CENTRAL CLAIM: these cells act as an intermediate relay for thalamic output, before those afferents reach the later populations directly Quotation withheld because this record is not cleared for redistribution. the early ablation removed about half the cells from deep layers, and did not reduce them further later Quotation withheld because this record is not cleared for redistribution. and the surviving parvalbumin cells showed three signs of arrest at once - smaller amplitude, longer latency, slower rise - with a prolonged integration window in pyramidal cells Quotation withheld because this record is not cleared for redistribution. TWO INDEPENDENT GENETIC ROUTES TO THE SAME PHENOTYPE, the second acting on synapse number rather than cell number Quotation withheld because this record is not cleared for redistribution. THE SAME ABLATION, SEVEN DAYS LATER, DOES NOTHING: responses similar to control hemispheres at p>0.2 and an unchanged integration window at p=0.22 Quotation withheld because this record is not cleared for redistribution. A DISSOCIATION BUILT FROM TWO MANIPULATIONS OF ONE PATHWAY: blocking evoked vesicular release changes nothing, while reducing presynaptic GABA reproduces the phenotype Quotation withheld because this record is not cleared for redistribution. SHARED ORIGIN AND SHARED MARKERS DO NOT MAKE A SHARED FUNCTION: these cells are quite distinct from subplate and hippocampal hub pioneers and form no long-range projections Quotation withheld because this record is not cleared for redistribution. LTS-SST interneurons in the L4 of gerbil auditory cortex display a developmental decrease in thalamic evoked synaptic potentials, in contrast to the developmental increase evoked in FS-PV interneurons Quotation withheld because this record is not cleared for redistribution. neither presynaptic release probability nor postsynaptic receptor composition accounts for the change, and the pruning signal is left unknown Quotation withheld because this record is not cleared for redistribution. THE STRENGTH CHANGES AND THE TARGETS DO NOT: the efferents alter their relative strength while maintaining their target specificity Quotation withheld because this record is not cleared for redistribution. and the physiological impact of the GABA released in the immature brain, and even its source, remain unknown Quotation withheld because this record is not cleared for redistribution. THE DIRECT INPUT IS INTACT WHILE THE INHIBITION IT DRIVES IS NOT, so the deficit is in the circuit rather than in the cell Quotation withheld because this record is not cleared for redistribution. with a rival account left open - a postsynaptic placeholder holding thalamic fibers until the later synapses can be established Quotation withheld because this record is not cleared for redistribution. THE MARKER-NAMED CLASS IS NOT ONE THING: the L4 X94 cells differ in function, morphology and connectivity from those in L2/3 and L5/6 Quotation withheld because this record is not cleared for redistribution. and in L4 the equivalent recruitment is regulated by whisker experience through a presynaptic increase in release probability Quotation withheld because this record is not cleared for redistribution. with the interpretation that parvalbumin defects implicated in psychiatric disease may originate in this earlier dependency Quotation withheld because this record is not cleared for redistribution. all statistical comparisons are non-parametric and two-sided, with significance set at 0.05 Quotation withheld because this record is not cleared for redistribution. temporal integration window (IW) temporal integration window (IW) Quotation withheld because this record is not cleared for redistribution. Rosa-HTB Rosa-HTB Quotation withheld because this record is not cleared for redistribution. integration window integration window Quotation withheld because this record is not cleared for redistribution. fidelity fidelity Quotation withheld because this record is not cleared for redistribution. hub hub Quotation withheld because this record is not cleared for redistribution. X94 X94 Quotation withheld because this record is not cleared for redistribution. Vglut2 Vglut2 Quotation withheld because this record is not cleared for redistribution. unitary unitary Quotation withheld because this record is not cleared for redistribution. temporal integration window temporal integration window Quotation withheld because this record is not cleared for redistribution. amplitude amplitude Quotation withheld because this record is not cleared for redistribution. latency latency Quotation withheld because this record is not cleared for redistribution. rise time rise time Quotation withheld because this record is not cleared for redistribution. integration window integration window Quotation withheld because this record is not cleared for redistribution. puncta puncta Quotation withheld because this record is not cleared for redistribution. fidelity fidelity Quotation withheld because this record is not cleared for redistribution. χ 2 ( df = 3, N = 720) = 6.507, p = 0.0894 — Laminar distribution of rabies starter cells did not differ between the immature and mature developmental stages Quotation withheld because this record is not cleared for redistribution. ~4-fold — Reduction, normalized to starter cell number, in thalamic neurons providing input to somatostatin interneurons from young to older mice Quotation withheld because this record is not cleared for redistribution. 155.1 ± 31.3 pA vs 51.22 ± 25 pA, p<0.05 — Thalamocortical EPSC amplitude in somatostatin interneurons versus pyramidal neurons during the first postnatal week Quotation withheld because this record is not cleared for redistribution. ~7 fold — Ratio of optogenetically evoked excitatory charge in somatostatin interneurons relative to pyramidal neurons in early cortical development Quotation withheld because this record is not cleared for redistribution. ~50% — Proportion of control somatostatin cell numbers remaining in layers 5/6 of diphtheria-toxin-A ablated mice at P6 Quotation withheld because this record is not cleared for redistribution. 54.89 ± 2.12 pA vs 39.15 ± 2.4 pA, p <0.0001 — Unitary thalamic EPSC amplitude in immature versus older somatostatin interneurons Quotation withheld because this record is not cleared for redistribution. 86% — how often the genetic driver actually labels the intended cell type in L5, against 83% in L6 - the accuracy every cell-type claim here rests on Quotation withheld because this record is not cleared for redistribution. 155.1 ± 31.3 pA — thalamic input to the interneurons in week one against 51 pA to pyramidal cells, a ranking that inverts by week three Quotation withheld because this record is not cleared for redistribution. 54.89 ± 2.12 pA — the unitary current in immature cells against 39.15 pA in older ones - a real but partial account of the change Quotation withheld because this record is not cleared for redistribution. p>0.2 — the late ablation result, and the number that turns a requirement into a windowed requirement Quotation withheld because this record is not cleared for redistribution. ~50% — the number of SST expressing cells in the ablated animals, decreased to ~50% of controls within L5/6, and not reduced further at P11 Quotation withheld because this record is not cleared for redistribution.

The full text of this article is not redistributable, so it is not included here. The evidence sentences are withheld with it; the tag layer and its grounding status remain. The article itself is at https://doi.org/10.1016/j.neuron.2015.11.020.