Karl Deisseroth, Postdoctoral Faculty Sponsor
Genetically targeted chemical assembly of functional materials in living cells, tissues, and animals.
Science (New York, N.Y.)
2020; 367 (6484): 1372–76
The structural and functional complexity of multicellular biological systems, such as the brain, are beyond the reach of human design or assembly capabilities. Cells in living organisms may be recruited to construct synthetic materials or structures if treated as anatomically defined compartments for specific chemistry, harnessing biology for the assembly of complex functional structures. By integrating engineered-enzyme targeting and polymer chemistry, we genetically instructed specific living neurons to guide chemical synthesis of electrically functional (conductive or insulating) polymers at the plasma membrane. Electrophysiological and behavioral analyses confirmed that rationally designed, genetically targeted assembly of functional polymers not only preserved neuronal viability but also achieved remodeling of membrane properties and modulated cell type-specific behaviors in freely moving animals. This approach may enable the creation of diverse, complex, and functional structures and materials within living systems.
View details for DOI 10.1126/science.aay4866
View details for PubMedID 32193327
Cortical layer-specific critical dynamics triggering perception.
Science (New York, N.Y.)
Perceptual experiences may arise from neuronal activity patterns in mammalian neocortex. We probed mouse neocortex during visual discrimination using a red-shifted channelrhodopsin (ChRmine, discovered through structure-guided genome mining) alongside multiplexed multiphoton-holography (MultiSLM), achieving control of individually-specified neurons spanning large cortical volumes with millisecond precision. Stimulating a critical number of stimulus-orientation-selective neurons drove widespread recruitment of functionally-related neurons, a process enhanced by (but not requiring) orientation-discrimination task learning. Optogenetic targeting of orientation-selective ensembles elicited correct behavioral discrimination. Cortical layer specific-dynamics were apparent, as emergent neuronal activity asymmetrically propagated from layer-2/3 to layer-5, and smaller layer-5 ensembles were as effective as larger layer-2/3 ensembles in eliciting orientation discrimination behavior. Population dynamics emerging after optogenetic stimulation both correctly predicted behavior and resembled natural neural representations of visual stimuli.
View details for DOI 10.1126/science.aaw5202
View details for PubMedID 31320556
- Structural mechanisms of selectivity and gating in anion channelrhodopsins NATURE 2018; 561 (7723): 349-+
- Crystal structure of the natural anion-conducting channelrhodopsin GtACR1 NATURE 2018; 561 (7723): 343-+
Excitation of diverse classes of cholecystokinin interneurons in the basolateral amygdala facilitates fear extinction.
There is growing evidence that interneurons orchestrate neural activity and plasticity in corticoamygdala circuits to regulate fear behaviors. However, defining the precise role of cholecystokinin-expressing interneurons (CCK INs) remains elusive due to the technical challenge of parsing this population from CCK-expressing principal neurons (CCK PNs). Here we used an intersectional genetic strategy in CCK-Cre;Dlx5/6-Flpe double-transgenic mice to study the anatomical, molecular and electrophysiological properties of CCK INs in the basal amygdala (BA) and optogenetically manipulate these cells in fear extinction. Electrophysiological recordings confirmed that this strategy targeted GABAergic cells and that a significant proportion expressed functional cannabinoid CB1 receptors; a defining characteristic of CCK-expressing basket cells. However, immunostaining showed that subsets of the genetically-targeted cells expressed either neuropeptide Y (NPY) (29%) or parvalbumin (PV) (17%), but not somatostatin (SOM) or CaMKII-alpha. Further morphological and electrophysiological analyses showed that four interneuron types could be identified among the EYFP-expressing cells: CCK/CB1R-expressing basket cells, neurogliaform cells, PV+ basket and PV+ axo-axonic cells. At the behavioral level, in vivo optogenetic photostimulation of the targeted population during extinction acquisition led to reduced freezing on a light-free extinction retrieval test, indicating extinction memory facilitation; whereas photosilencing was without effect. Conversely, non-selective (i.e., inclusive of INs and PNs) photostimulation or photosilencing of CCK-targeted cells, using CCK-Cre single-transgenic mice, impaired extinction. These data reveal an unexpectedly high degree of phenotypic complexity in a unique population of extinction-modulating BA INs.Significance statement Distinct types of interneurons in the basolateral amygdala (BA) are known to control principal cell activity, allowing complex behaviors. Despite their importance, the role of cholecystokinin (CCK)-expressing inhibitory cells remains unknown. In this work, we could specifically alter the function of CCK-expressing interneurons in the BA by using an INTRSECT viral strategy. Using a combination of anatomical and electrophysiological methods, we found that CCK+ interneurons in the BA are comprised of CB1R-expressing basket cells, neurogliaform cells, parvalbumin-expressing basket as well as axo-axonic cells. Importantly, we provided the first direct evidence that CCK-expressing interneurons in the BA can modulate fear extinction learning. Our data thus show that CCK is expressed in functionally diverse interneuron populations, positioned to impact amygdala operation.
View details for DOI 10.1523/ENEURO.0220-19.2019
View details for PubMedID 31636080
Mapping Brain-Wide Afferent Inputs of Parvalbumin-Expressing GABAergic Neurons in Barrel Cortex Reveals Local and Long-Range Circuit Motifs.
2019; 28 (13): 3450
Parvalbumin (PV)-expressing GABAergic neurons are the largest class of inhibitory neocortical cells. We visualize brain-wide, monosynaptic inputs to PV neurons in mouse barrel cortex. We develop intersectional rabies virus tracing to specifically target GABAergic PV cells and exclude a small fraction of excitatory PV cells from our starter population. Local inputs are mainly from layer (L) IV and excitatory cells. A small number of inhibitory inputs originate from LI neurons, which connect to LII/III PV neurons. Long-range inputs originate mainly from other sensory cortices and the thalamus. In visual cortex, most transsynaptically labeled neurons are located in LIV, which contains a molecularly mixed population of projection neurons with putative functional similarity to LIII neurons. This study expands our knowledge of the brain-wide circuits in which PV neurons are embedded and introduces intersectional rabies virus tracing as an applicable tool to dissect the circuitry of more clearly defined cell types.
View details for DOI 10.1016/j.celrep.2019.08.064
View details for PubMedID 31553913