Brain Circuits – Konstantinos Meletis group

We are investigating the circuit mechanisms that shape motivated behaviours and the circuit imbalance that underlies core phenotypes of mood disorders.

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Research

The Meletis Laboratory defines the brain circuit architectures that generate motivated behavior, decision-making, and adaptive learning, and examines how these architectures are disrupted in brain disorders.

Our research centers on subcortical systems—basal ganglia, midbrain dopamine, hypothalamus, and habenula, where discrete neuron subtypes and pathway motifs organize action selection, aversion, repetitive behaviors, and affective state control. We treat circuit organization as a primary determinant of function, and define how cellular identity, connectivity rules, and spatial embedding shape the functional repertoire of a circuit.

Our long-term vision is to leverage circuit-level knowledge to build mechanistic and predictive frameworks that explain behavioral control and cell-type- and circuit-specific vulnerability, with translational relevance to stress- and affective-related pathology and to prodromal Parkinson’s disease.

We build integrated maps of “wiring and identity” by combining advanced viral-genetic tracing and connectivity mapping with single-cell and spatial transcriptomics. These maps serve as experimental blueprints for functional studies by defining neuron subtypes through their molecular signatures and connectivity profiles, enabling targeted recording and perturbation during behavior.

We use in vivo electrophysiology and optical recordings, together with intersectional genetic access and optogenetic perturbations, to quantify circuit dynamics and establish causal contributions to action selection, reinforcement learning, and behavioral flexibility. Quantitative behavioral assays and statistical modeling link circuit mechanisms to clinically relevant phenotypes, including altered motivation, stress susceptibility, anhedonia-like states, and reduced movement vigor.

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Postal address

Department of Neuroscience
Attn: Konstantinos Meletis group
Karolinska Institutet, SE-171 77 Stockholm

Visiting address (visitors, couriers, etc.)

Karolinska Institutet, Biomedicum, Quarter B4
Solnavägen 9, SE-171 65 Solna

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Tomtebodavägen 16, SE-171 65 Solna

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Karolinska Institutet, Biomedicum, Solnavägen 9