9:00-10:00

Chemogenetic stimulation of oxytocinergic neurons dynamically modulates fMRI connectivity

C. Montani¹, *A. Hayward¹, D. Gutierrez-Barragan¹, G. Morelli², F. G. Alvino¹, L. Coletta^1,3, A. Galbusera¹, M. Pasqualetti⁴, L. Cancedda², A. Gozzi¹

1) Functional Neuroimaging Lab., Inst. Italiano di Tecnologia, Rovereto, Italy; 2) Brain Develop. and Dis. Lab., Inst. Italiano di Tecnologia, Genoa, Italy; 3) CIMeC - Ctr. for Mind/Brain Sci., Univ. of Trento, Rovereto, Italy; 4) Unit of Cell and Developmental Biology, Dept. of Biol., Univ. of Pisa, Pisa, Italy

Presentation Number: 141.06
Presentation Time: Sun., Nov. 13, 2022 9:00 AM - 10:00 AM
Posterboard Number: Z11

Abstract:

Oxytocin (OXT) is a key modulator of complex socio-affective behaviors. However, the brain-wide networks endogenously modulated by OXT remain poorly understood.
Here, we combine chemogenetics and fMRI to map the topography and dynamics of brain networks engaged by endogenously-released OXT in the mammalian brain. To remotely stimulate endogenous OXT release, we crossed mice harboring a double-floxed DREADD activator hM3Dq with OXT-specific Cre-recombinase mice, leading to cell-type specific expression of hM3Dq in OXT-producing neurons. Stimulation of DREADD receptors with the selective JHU37160 actuator in OXT-hM3Dq mice produced physiologically-relevant release of OXT, an effect that was associated with increased grooming behavior as previously reported.
fMRI mapping of OXT-evoked activity in OXT-hM3Dq (n=20) vs. control (n=21) mice revealed sustained fMRI (cerebral blood volume) activation of parietal cortical areas, hypothalamus and dorsal hippocampal regions. These effects were associated with a dramatic reconfiguration of fMRI connectivity as assessed with resting state fMRI. Specifically, chemogenetic stimulation of OXT-producing neurons robustly increased functional connectivity between hypothalamic regions and prefrontal areas, and by inverse coupling between insular and amygdala regions of the rodent salience network, and between the hippocampus and fronto-cortical areas. Notably, these changes were paralleled by a distinct reorganization of the temporal structure of rsfMRI connectivity, with a robustly increased occurrence of dynamics states encompassing the rodent salience network, which were configured as network attractors.
Taken together, these results show that endogenous OXT can rapidly and robustly alter interareal communication between key components of the social brain via temporal re-organization of fMRI dynamics.

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10:00-11:00

Evolutionarily conserved fMRI coactivation dynamics in the human, macaque and mouse brain

*D. Gutierrez-Barragan¹, J. S. B. Ramirez², S. Panzeri³, T. Xu², A. Gozzi¹

1) Functional Neuroimaging Lab., Inst. Italiano di Tecnologia, CNCS, Rovereto, Italy; 2) Ctr. for the Developing Brain, Child Mind Inst., New York, NY; 3) Ctr. for Mol. Neurobiology, Dept. of Excellence for Neural Information Processing, Univ. Hamburg, Hamburg, Germany

Presentation Number: 141.19
Presentation Time: Sun., Nov. 13, 2022 10:00 AM - 11:00 AM
Posterboard Number: AA9

Abstract:

Evolutionarily relevant networks of spontaneous brain activity have been consistently mapped in humans, primates and rodents using resting-state fMRI (rsfMRI). It is however unclear whether the dynamic rules that govern rsfMRI network dynamics are species-invariant, or if they instead have evolved across the phylogenetic tree. Here, we used frame-wise clustering of rsfMRI timeseries acquired in awake mice, macaques, and humans, to map and compare the topography and dynamic properties of rsfMRI co-activation patterns (CAPs) across species.

We report that rsfMRI dynamics in the mammalian brain is characterized by recurrent transitions between fluctuating BOLD co-activation patterns (CAPs), whose topography and dynamics follow evolutionarily-conserved principles. Specifically, in all species rsfMRI activity could be reliably partitioned in a small number (k= 6, mouse, n=51; k=8, macaque, n=8 x 2 sessions, k = 8, human, n=10 x 5 sessions) of stable and reproducible CAPs across independent datasets/sessions, explaining a substantial fraction of rsfMRI variance (R2>0.6, all species). Moreover, mouse, macaque and human CAPs could be paired into spatially opposing topographies, indicative of peaks and throughs of fluctuating fMRI network activity. Spectral analyses revealed that CAPs fluctuate with centered power in the infraslow range (0.01-0.04Hz), and that CAPs exhibited preferential occurrence within Global fMRI Signal (GS) cycle that in all species, indicative of species-invariant relationship between CAP emergence and fMRI global signal cycles. Evolutionarily-conserved CAP topographies were also apparent, with evidence of a competing engagement of default-mode network (DMN) and somatosensory regions (CAPs 1-2), as well as the presence of pan-cortical patterns of fMRI coactivation (CAPs 3-4) in all species. In keeping with cortical expansion along the phylogenetic tree, one CAP pair was instead reliably identified only in human and macaque, exhibiting primate-specific features in high-order regions of dorsal-attention and executive-networks. Taken together, our results reveal a set of fundamental, evolutionarily-conserved principles underlying rsfMRI network dynamics in the awake mammalian brain.

 11:00-12:00

Cortical excitatory/inhibitory balance critically controls brain-wide fMRI

*D. Sastre Yagüe^1,3, F. Rocchi^1,3, A. Stuefer^1,3, S. Noei^2,3, L. Coletta¹, F. Alvino¹, A. Galbusera¹, S. Panzeri⁴, A. Gozzi¹;

1) Functional Neuroimaging Lab., 2) CNCS, Inst. Italiano di Tecnologia (IIT), Rovereto, Italy; 3) Cimec, Univ. of Trento, Rovereto, Italy; 4) Ctr. for Mol. Neurobio. Hamburg (ZMNH), Hamburg, Germany

Presentation Number: 141.12
Presentation Time: Sun., Nov. 13, 2022 11:00 AM - 12:00 PM
Posterboard Number: AA2

Abstract:

Resting-state fMRI (rsfMRI) is widely used to map intrinsic brain network organization in the healthy, as well as in psychiatric and neurological disorders, where evidence of disrupted or abnormal rsfMRI functional coupling has been largely documented. However, the neural underpinnings and dynamic rules governing brain-wide rsfMRI coupling remain unclear. Neocortical excitatory/inhibitory (E/I) balance critically affects local and long-range information processing and can conceivably bias brain-wide network coupling as measured with rsfMRI. This notion would be consistent with the emerging evidence of neocortical imbalance and altered interareal communication in multiple brain disorders such as Autism Spectrum Disorder or Schizophrenia. Here we combine chemogenetic manipulations, rsfMRI, electrophysiology and behavioral measurements to causally probe how neocortical excitatory-inhibitory balance affects brain-wide fMRI and neural coupling in the mouse brain. We used DREADD-based chemogenetics to remotely alter E/I balance in the mouse prefrontal cortex (PFC) by increasing pyramidal neuron excitability, or by reducing the activity of subclasses of inhibitory interneurons. For each of the employed manipulations, we recorded rsfMRI network activity, and the underlying neural rhythm via in-vivo multielectrode electrophysiology before and after CNO administration. We found that increasing PFC excitability via DREADD activation of CamkII-expressing pyramidal neurons dramatically desynchronized brain-wide rsfMRI functional connectivity in the mouse default network, an effect that was associated with increased gamma activity and reduced low frequency interareal coherence. Notably, analogous connectivity and neural desynchronization was observed upon chemogenetic inhibition of fast-spiking parvalbumin positive interneurons, but not somatostatin-positive cells. Importantly, all connectivity-affecting perturbations were associated with socio-communicative deficits as assessed in a three-chamber sociability test, hence underscoring the behavioral relevance of the employed manipulations. Our results show that excitatory/inhibitory balance critically biases brain-wide fMRI coupling and point at a possible unifying mechanistic link between E/I imbalance and connectivity disruption in brain disorders.

15:00-16:00

Chemogenetic excitation of pyramidal neurons during early development: a longitudinal behavioral and imaging study

*A. Stuefer^1,6, L. Balasco⁶, S. Bertozzi², L. Coletta^1,6, A. Hayward¹, F. Rocchi^1,6, C. Montani¹, F. Alvino¹, A. Galbusera¹, M. Aldrighetti¹, S. Gini¹, V. Curcic¹, F. Papaleo³, G. Iurilli⁴, L. Cancedda⁵, A. Armirotti², Y. Bozzi^6,7, A. Gozzi¹

1) Functional Neuroimaging Lab., Inst. Italiano di Tecnologia, Rovereto, Italy; 2) Analytical Chem. Facility, 3) Genet. of Cognition Lab., Inst. Italiano di Tecnologia, Genova, Italy; 4) Systems Neurobio. Lab., Inst. Italiano di Tecnologia, Rovereto, Italy; 5) Brain Develop. and Dis. Lab., Inst. Italiano di Tecnologia, Genova, Italy; 6) CIMeC - Ctr. for Mind/Brain Sci., Univ. degli Studi di Trento, Rovereto, Italy; 7) CNR Neurosci. Inst., Pisa, Italy

Presentation Number: 358.20
Presentation Time: Mon., Nov. 14, 2022 3:00 PM - 4:00 PM
Posterboard Number: C61

Abstract:

Autism and related developmental disorders encompass a wide range of etiologically heterogeneous conditions characterized by social and communicative impairment, as well as restricted and repetitive behaviors. Supported by evidence of altered inhibitory function in a substantial proportion of ASD subjects, one possible unifying mechanism underlying autism could be the onset of excitatory-inhibitory (E-I) imbalance as a consequence of genetic or developmental insult. To probe this hypothesis, we chemogenetically manipulated E-I balance in the cortex of infant mice and measured how this alteration affects brain connectivity as well as various domains of behavior throughout the life span of the mice. Cell-type specific increase of neuronal excitability was obtained via expression of DREADD receptors in Vglut1-cre mice and following chronic CNO treatment during the first two postnatal weeks. Subsequently, longitudinal behavioral tests and resting state fMRI were performed at multiple developmental stages, i.e. late infancy, adolescence and adulthood. Mice also underwent open field, habituation-dishabituation social interaction, y-maze, novel object recognition, rotarod and whisker nuisance tests. We found that chemogenetically manipulated mice exhibited impaired social behavior as assessed with direct social interaction habituation-dishabituation test at multiple timepoints, but not anxiety-like phenotypes, or impairments in working and long-term memory, motor coordination or tactile sensitivity. These effects were associated with atypical functional connectivity in socio-behaviorally relevant networks in adulthood as measured with rsfMRI. These initial results suggest that developmental hyperexcitability can lead to social dysfunction and functional dysconnectivity alteration reminiscent of hallmark findings in developmental disorders.

9:00-10:00

Optogenetic modulation of the mouse default mode network with a single tapered optical fiber

E. De Guzman¹, A. Galbusera¹, B. Spagnolo², F. Pisano², M. Pisanello², M. De Vittorio^2,4, T. Fellin³, F. Pisanello², A. Gozzi¹

1) Functional Neuroimaging Lab., Inst. Italiano di Tecnologia, Rovereto, Italy; 2) Ctr. for Biomolecular Nanotechnologies, Inst. Italiano di Tecnologia, Arnesano (Lecce), Italy; 3) Optical Approaches to Brain Function, Inst. Italiano di Tecnologia, Genova, Italy; 4) Dept. di Ingegneria dell’Innovazione, Univ. del Salento, Lecce, Italy

Presentation Number: 499.10
Presentation Time: Tue., Nov. 15, 2022 9:00 AM - 10:00 AM
Posterboard Number: ZZ25

Abstract:

The default mode network (DMN) is a functional network of the human brain widely studied with fMRI due to its association with higher cognitive processes and frequent dysregulation in human brain disorders. Evolutionarily relevant precursors of the DMN have been described in primates and rodents, offering opportunities to unveil the core constituents and neurobiological underpinnings of DMN (dys)function. However, the widely distributed topography of this network and its peculiar antero-posterior organization have so far prevented reliable manipulation of its constitutive elements via optogenetics. Tapered optical fibers (TFs) offer homogeneous illumination of large cortical volumes while minimizing risk of tissue heating and spurious hemodynamic responses as assessed with fMRI. Here, we describe reliable network-scale manipulation of the rodent DMN via single TF optogenetic stimulation of the mouse medial prefrontal cortex (PFC), an evolutionary conserved hub-region. We show that a single TF implanted at a 15o angle resulted in bilateral light delivery to the PFC in slice preparations, with negligible tissue damage. In keeping with this, in vivo optogenetic-fMRI studies revealed that stimulation of pyramidal cells with a single TF in the PFC resulted in exquisitely bilateral stimulation of key DMN afferents of the mouse PFC, with the largest response in the thalamus, a region recently recognized as an important component of the DMN. Notably, the bilateral response achieved with a single low-invasive TF was comparable to that obtained with a canonical dual flat fiber configuration, and distinct from the unilateral response obtained with a single flat fiber implant. Corroborating the specificity of the mapped effects, studies in opsin free mice did not reveal any heat or visually induced fMRI responses at irradiance up to 100mW/mm2. Similarly, blood pressure recordings showed that stimulation was uncoupled from peripheral cardiovascular changes. Proof-of-concept experiments performed using this technology showed that rhythmic stimulation of the PFC resulted in differential engagement of cortical and subcortical DMN substrates, demonstrating the possibility of using this platform to produce and test network-level perturbations of high translational relevance.

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11:00-12:00

Mapping the neuroconnectional landscape in autism via cross-species fMRI

*M. Pagani^1,2, V. Zerbi³, A. Galbusera¹, T. Xu², N. Wenderoth³, M. Milham², A. Di Martino², A. Gozzi¹

1) Inst. Italiano Di Tecnologia, Genova, Italy; 2) Child Mind Inst., New York City, NY; 3) Neural Control
of Movement Lab, ETH Zurich, Zurich, Switzerland

Presentation Number: 604.08
Presentation Time: Wed., Nov. 16, 2022 11:00 AM - 12:00 PM
Posterboard Number: B56

Abstract:

Background. Autism is characterized by high etiological heterogeneity. Brain imaging studies have revealed atypical functional connectivity in individuals with autism as measured by resting-state fMRI (rsfMRI). In keeping with the large etiological and biological variability of the disorder, diverse and diverging patterns of connectivity alterations have been reported in individuals with autism. However, the significance of heterogeneity in rsfMRI connectivity remains largely debated. By back-translating rsfMRI mapping in physiologically accessible species like the mouse, we recently showed the possibility to reliably map autism-related connectivity alterations with exquisite etiological specificity. Here we leveraged our mouse database to define a “ground-truth” etiologically-relevant neuroconnectional landscape of autism, and to inform analogous efforts in relevant clinical populations.
Methods. Mice: A total of 286 mice with 19 autism-related genetic alterations and 290 control littermates underwent rsfMRI mapping at 7T. Twelve etiologies were scanned at IIT Rovereto (Italy) and 7 etiologies were scanned at ETH Zürich (Switzerland). RsfMRI connectivity mapping was carried out by using global connectivity mapping. Humans: Global connectivity mapping was carried out on n=1123 individuals with ASD and n=1166 controls (6-30 yo) from ABIDE1 (Di Martino et al., 2014) and ABIDE2 (Di Martino et al., 2017). Replicability of findings was assessed by splitting our sample into discovery and replication datasets.
Results. Consistent with our recent work (Zerbi et al., 2020), we found that most etiologies had robust connectivity alterations, and many exhibited subtle and distinctive functional disconnections. Cross-etiological convergences were, however, notable.  To assess whether this variability can be parsed in functionally-meaningful subtypes, we used hierarchical cluster analysis. Results revealed at least two subtypes showing diverging patterns of connectopathy. We next turned to human rsfMRI imaging to obtain an analogous assessment of the connectional landscape. Here we found that rsfMRI connectivity mapping in subjects with idiopathic autism defined a pseudo-continuous landscape of connectivity alterations remarkably similar to the one mapped in the mouse database. Notably, we found an analogous landscape of autism-related atypicalities in the replication dataset.
Conclusion. Our cross-species approach suggests that atypical functional connectivity in autism can be conceptualized by a pseudo-continuous neuroconnectional landscape. Our findings support the notion that there is not unique signature of connectopathy for the disorder.

References
Di Martino A, O’connor D, Chen B, Alaerts K, Anderson JS, Assaf M, Balsters JH, Baxter L, Beggiato A, Bernaerts S (2017) Enhancing studies of the connectome in autism using the autism brain imaging data exchange II. Scientific data 4:1-15.
Di Martino A et al. (2014) The autism brain imaging data exchange: towards a large-scale evaluation of the intrinsic brain architecture in autism. Mol Psychiatry 19:659-667.
Zerbi V, Pagani M, Markicevic M, Matteoli M, Pozzi D, Fagiolini M, Bozzi Y, Galbusera A, Scattoni ML, Provenzano G (2020) Brain mapping across 16 autism mouse models reveals a spectrum of functional connectivity subtypes. bioRxiv.