Barrel cortex function

“Two-photon calcium imaging in L2/3 of barrel cortex in vivo (Helmchen and Denk, 2005; Wallace et al., 2008; Grewe and Helmchen, 2009) has provided additional insights into the spatiotemporal aspects of population reponses.”

“This subcellular target structure specificity of the inhibitory neurons’ axon is the hallmark of many classifications and has been suggested to be independent of the laminar location of the cell body within a cortical column (Markram et al., 2004), but this view is far from unequivocal.”

“Particular potential is offered further by in vivo calcium imaging using genetically-encoded calcium indicators (GECIs) such as GCaMP-3 (Tian et al., 2009) or Yellow Cameleon 3.60 (Nagai et al., 2004; Lütcke et al., 2010).”

“From data obtained in cat visual cortex, Douglas and Martin defined a ‘canonical’ microcircuit of neocortex implying that most cortical areas have a rather similar basic neuronal network structure (Gilbert and Wiesel, 1983; Gilbert, 1983; Douglas and Martin, 1991, 2004).”

“…different molecules and their combinations, including oligopeptide co-transmitters, calcium binding proteins, and receptor subunits, suggesting a huge functional variability amongst cortical GABAergic neurons (Markram et al., 2004; Sugino et al., 2006; Ascoli et al., 2008; Taniguchi et al., 2011).”

“Knowledge about its development may contribute important aspects needed to understand its mechanisms of operation in the adult, both under physiological as well as pathophysiological conditions, such as neurodevelopmental disorders (for review Amaral et al., 2008; Courchesne et al., 2007).”

“The literature on neocortical GABAergic neurons is vast and many efforts have been made to describe their features and to characterize their synaptic connections (e.g. Ascoli et al., 2008).”

“…Loos 1970) and is thought to represent the major input layer for thalamocortical (TC) afferents from the somatosensory periphery, and thus, the first station of cortical information processing (Armstrong-James et al. 1992; but see Constantinople and Bruno 2013; reviewed by Feldmeyer et al. 2013).”

“Such functional columns are often termed “barrels” or “intracortical modules” by neurophysiologists, and the pattern of dendritic bundles and of thalamocortical projections may determine their integrity (Feldmeyer et al., 2013; Li et al., 2013; Rockland and Ichinohe, 2004).”

“Therefore, we investigated functional alterations in the barrel cortex, a well-suited model to study intracortical processing of sensory information (for review, Feldmeyer et al. 2013).”

“In rodents, the thalamus is recognized as one of the most important brain areas for driving cortical processing (Devor et al., 2005; Poulet et al., 2012; Feldmeyer et al., 2013).”

“The activity of these two parallel pathways is then integrated (1) in infra-granular layers, a major target of layer II/III axons; (2) in supra-granular layer II/III, where the axonal projections from both layer IV and layer V converge [9]; (3) through layer IV control of layer V interneurons [10]; and (4) through lay…”

“We found that although of high amplitude, spindle band frequency oscillations in the most immature mouse pups were highly and uniformly confined to localized regions of cortex (200–500 mm) roughly corresponding to cortical columns (Yang et al., 2013; Feldmeyer et al., 2013).”

“However, arguably, the most important function of cortex (including primary sensory cortices) is the association with other cortical areas for cognitive and/or mnemonic functions (Feldmeyer et al., 2013).”

“The rodent whisker system has been widely used to study sensorimotor integration in the brain (Bosman et al. 2011; Kleinfeld & Deschenes, 2011; Diamond & Arabzadeh, 2013; Feldmeyer et al. 2013; Petersen, 2014).”

“This mechanism probably ensures increased specificity to stimuli in the columns of the visual cortex by limiting spreading of the excitation, in contrast to the barrels in the somatosensory cortex where spreading of neuronal activity through trans-columnar processing is more extensive (Feldmeyer et al., 2013).”

“The functional role of primary sensory cortex in detection has, however, been controversial across visual, auditory, gustatory, and somatosensory behaviors (Feldmeyer et al 2013, Stüttgen & Schwarz 2018).”

“The strong central representation along with the welldefined connectivity and discreet response to whisker inputs (Brecht and Sakmann, 2002; Feldmeyer et al., 2013; Petersen, 2007) render the whisker somatosensory system an ideal experimental model, enabling access to fundamental neurobiological processes using neuroi…”

“The neuronal circuitry orchestrating whisker-guided sensorimotor behavior consists of well-defined pathways connecting sensory and motor areas (Petersen, 2007; Feldmeyer et al., 2013).”

“First, we took advantage of the mouse whisker system, which is naturally discretized (Feldmeyer et al., 2013; Petersen, 2007), to probe the logic of cortical integration across stimulus space in awake, actively sensing animals.”

“Yet the cerebral cortex is a three-dimensional structure composed of up to six layers, as in the somatosensory cortex, where the generation of spontaneous and somatosensory-induced network activities involves dynamic interactions between thalamocortical inputs and intracortical circuits within and between cortical lay…”

“, the barrel cortex response to a whisker touch [31]) but also other dynamic neuronal processes occurring on larger spatiotemporal scales such as neuromodulation and sleep [37].”

“as an anatomical reflection of cortical columns [34–36] that have in turn been proposed as a fundamental unit of the mammalian”

“The dendrites in our study may have behaved differently from deeper dendrites because the latter receive direct L4 and thalamocortical inputs (Oberlaender et al., 2012a; Feldmeyer et al., 2012).”

“Compared with humans, rodents, for example, rely less on cortical (rather than subcortical) areas for, for example, somatosensation [60,61] and vision [62].”

“…key models for active sensing (reviewed in Petersen 2007; Ahissar and Knutsen 2008; Diamond et al. 2008; Diamond 2010; Kleinfeld and Deschênes 2011; Feldmeyer et al. 2013) and has been especially prominent in studies of closed loops through sensory and motor areas back to peripheral sensors…”

“The rodent whisker system provides a suitable model system in systems neuroscience due to its functional efficiency and structural organisation (Brecht, 2007; Petersen, 2007; Feldmeyer, 2012; Feldmeyer et al., 2013; Adibi, 2019); known as nocturnal animals, rodents rely on their vibrissal sensorimotor system to garner…”

“Moreover, neurons located at laminar depths consistent with stronger direct lemniscal thalamocortical input integrate little, while some neurons in the upper layers (Lefort et al. 2009; Feldmeyer et al. 2013) convey appreciable information about earlier intervals over timescales of several hundred milliseconds—i.”

“S10 B demonstrate the characteristic pattern when applying a relatively high correlation threshold across hemispheres, 0.85 in this case, which correspond to the secondary (S2) somatosensory cortex and somatosensory parietal–ventral area (PV) in both hemispheres, respectively (75).”

“Connectivity was particularly strong in layers V–VI, consistent with known physiology studies (Feldmeyer et al., 2013; Petreanu et al., 2007).”

“The synaptic organization of the olfactory bulb includes structural and functional columns,(74,75) similar to the barrels or radial units of the neocortex.(76,77) Lateral synaptic connectivity within the olfactory bulb is much sparser.”

“Each neuronal column associated with a barrel processes primarily the information coming from its corresponding whisker (Feldmeyer et al., 2013; Petersen, 2003, 2007).”

“The current study has three further advantages: (1) the S2p and M1p neurons are imaged simultaneously, and thus during identical mouse behavior; (2) the neurons were imaged across days revealing relatively stable representations; and (3) we introduced a second rewarded sensory stimulus, allowing to compare the respons…”

“L2/3 receives major ascending input from intra-columnar L4 and L5A and trans-columnar L4 input from nearby barrel columns (Schubert et al., 2007; Feldmeyer et al., 2013).”

“This is at odds with a number of previous studies reliant exclusively on electrical stimulation (Hanganu et al., 2002; Friauf et al., 1990), which obtained levels of connectivity approaching our initial electrical stimulation paradigm.”

“In this regard, over-responsivity to auditory and tactile stimulus on PND 30–50, and disturbed auditory sensory gating on PND 90–120, were observed in valproic-treated animals (Feldmeyer et al., 2013; Reynolds et al., 2012).”

“primary sensory cortices (Matyas et al. 2010; Feldmeyer et al. 2012; Bastos et al. 2012).”

“It is probable that the intrinsic recurrent synaptic connections between sensory and motor cortices and within the motor cortex are the cortical circuits that allow coupling between the spatial location of the pellet and the spatial location to which the limb is commanded to move (Capaday et al., 2013; Feldmeyer et al…”

“…using extracellular electrophysiology recordings and functional magnetic resonance imaging (fMRI) it has been shown that electrical stimulation of the forelimb after thoracic SCI elicits responses in deafferented hindlimb S1 (Endo et al., 2007) and an expansion of forelimb S1 (Ghosh et al., 2009).”

“Here we will discuss the specialization of sensory inputs, as well as the interaction between these inputs and circuit formation in the mouse neocortex (for a review of thalamocortical connectivity in the adult somatosensory cortex, see (Feldmeyer, 2012) and (Feldmeyer et al., 2013)).”

“This type of well-defined structure is most clear in the rat barrel cortex (Lubke et al., 2000; Bureau et al., 2004; Feldmeyer et al., 2013) but Mountcastle and others have pointed out that although there are occasional discontinuities in physiological and anatomical properties, there is a diverse…”

“information to other structures in the sensory-motor vibrissae-barrel loop, and especially the vS1 barrel cortex (Aronoff et al., 2010; Veinante and Deschênes, 2003; Mao et al., 2011; Feldmeyer et al., 2013).”

“If, for instance, one of a rat’s whiskers is moved by the experimenter, a change in firing of specific neurons can be measured in the barrel cortex, one of the most well studied parts of the primary sensory cortex [1].”

“…involves not only the activation of the primary cortical region, called the barrel cortex (wS1), but also of the secondary region (wS2), two areas which have been found to be activated upon a tactile event received by the whiskers (Condylis et al. 2020; Feldmeyer et al. 2013; Hubatz et al. 2020).”

“The vibrissal system is thus a common model system to investigate principles of sensory information processing (Feldmeyer et al., 2013), mechanisms that underlie motor control (Deschenes et al., 2016), and for studying interactions between sensory and motor pathways (Schwarz, 2016).”

“Rodent primary somatosensory cortex (S1) is an established model to study the sensory representation of tactile stimuli, structural and functional plasticity, perceptual decisionmaking, and development (Campagner, Evans, Loft, & Petersen, 2018; Feldmeyer et al., 2013).”

“To summarize, optogenetic inhibition of PV+ interneurons (1) increased firing rate regardless of stimulus strength, indicative of an additive rather than multiplicative effect of PV+ neurons, (2) affected neuronal discriminability for a moderate-intensity stimulus, (3) was most pronounced during the first 100 ms of a…”

“Perhaps the best-studied neuronal microcircuits are the primary somatosensory (S1) and primary visual (V1) cortices (Reyes and Sakmann, 1999; Lefort et al., 2009; Feldmeyer et al., 2013; Jiang et al., 2015; Markram et al., 2015; Seeman et al., 2018; Campagnola et al., 2022).”

“…previously restricted to quantifying the representation of stimulus features – tools such as spike counts, fi ring rates and temporal patterns 19 – 21 , 23 – Inourhands,photoexcitation-evokedchangesinthevS1response to vibrissal vibration were seen in the peak of the initial response and, to a…”

“The structural and functional connectivity of the rodent somatomotor whisker system has been extensively elucidated 30,46 – 49 .”

“…functions, including the exploration of novel environments, object recognition, spatial navigation, prey capture, and social interactions (Anjum et. al, 2006; Brecht, 2007; Mitchinson et al., 2011; Feldmeyer et al., 2013; Bobrov et al., 2014; Sofroniew et al., 2014; Sofroniew and Svoboda, 2015).”

“…example, in the rodent barrel cortex, whisker driven thalamic inputs that mainly project to L4 neurons, are sequentially processed via the canonical L4 – L2/3 – L5 glutamatergic pathway [for review, (Douglas and Martin, 2004; Brecht, 2007; Petersen, 2007; Feldmeyer, 2012; Feldmeyer et al., 2013)].”

“Layer 2/3 is considered as a hub in cortical processing 16,43 , where the majority of neurons fi re sparsely due to a balanced feedforward excitation and feedback inhibition 44 .”

“In rodents, the whisker-associated area of the somatosensory cortex, known as the vibrissal cortex, provides an example of efficient functionality and a well-described circuitry (Ahissar and Kleinfeld 2003; Brecht 2007; Diamond and Arabzadeh 2013; Feldmeyer et al. 2013).”

“OUR CONCEPT OF THE NEOCORTICAL organization has emphasized the vertical column as the major canonical functional unit, in which neurons share similar sensory-evoked response properties and present a relatively high correlation in their firing (recently reviewed by Reid 2012; Feldmeyer et al. 2013).”

“L5a is the main output layer, and the two layers are monosynaptically connected [2, 6, 49].”