All-optical Electrophysiology in Behaving Animals with Optimized Two-photon Excitation

**All-optical electrophysiology in behaving animals with optimized two-photon excitation**:

- Réf **ABG-129199**
- Sujet de Thèse
- 06/03/2025
- Contrat doctoral
- NeuroSchool, Aix-Marseille Université
- Lieu de travail- Marseille - Provence-Alpes-Côte d'Azur - France
- Intitulé du sujet- All-optical electrophysiology in behaving animals with optimized two-photon excitation
- Champs scientifiques- Psychologie, neurosciences
- Biologie
- Santé, médecine humaine, vétérinaire
- Mots clés- neuroscience, neurobiology, cognition, neural networks, brain, behavior, neurodegenerative diseases, ageing,

**Description du sujet**:
**_The NeuroSchool PhD Program of Aix-Marseille University (France) has launched its annual calls for PhD contracts for students with a master's degree in a non-French university and for international co-supervised PhDs._**

**_This project is one of the proposed projects. Not all proposed projects will be funded, check our website for details._**

**State of the art**:Today, two-photon excitation (TPE) is routinely used to study function and connectivity in neural circuits by combining genetically encoded fluorescent calcium or voltage (GEVI) indicators with photosensitive actuators (e.g., channelrhodopsins), the goal being to photostimulate a large number of cells while being temporally accurate. Two main approaches are available today: one scans a user-selected 3D pattern of focal _points_ in spirals the size of a cell body; the other generates a chosen 3D pattern of _holograms_ of similar size as the spirals. The latter is temporally accurate but curbs TPE efficiency, the heating threshold thus drastically limiting the number of excitable cells. Conversely, spiral-scanning is TPE-efficient but lacks temporal accuracy: cells respond when a threshold number of opsins is activated and their spatial distribution varies among cells.

**Complementarity**:Today, this specific microscope exists within the CIRCUITPHOTONICS facility (joint INMED-INT-Inst. Fresnel Equipex+ 2020) at **INMED** and will be **replicated at INT** within ~1 year (ERC F. Cazettes). J-C Platel (collaborator) from R. Cossart’s team that already practices PS, will contribute also their experience in PS, fostering the collaboration between the two institutes.

**Expected results**: The patch-clamp characterization will yield, for various opsins, the key information on the maximal power usable for imaging without unwantedly inducing PS. This will allow using the fluorescence from cells co-expressing a GECI and a fast opsin as readout of their response to 3D-ULoVE stimulation, expected to (~3x) outperform spiral scan both in timing accuracy and addressable number of neurons at given laser power. Last, the protocol developed at INMED for benchmarking the new 3D-ULoVE against existing methods shall become available to the community as a standard reading/writing procedure.

**Feasibility (#APAFIS)**: INT: 51819-2024101716408210_v6, 48723-202403251009126_v3, 16235-2017122017031124_v7. INMED: 30716-2021032215171216_v8, microscope is available for project and training assured

**Prise de fonction**:

- 01/10/2025

**Nature du financement**:

- Contrat doctoral

**Précisions sur le financement**:

- 3 years

**Présentation établissement et labo d'accueil**:

- NeuroSchool, Aix-Marseille Université

Within **Aix Marseille Université, NeuroMarseille**brings together 8 research laboratories and NeuroSchool, a graduate school in neuroscience, to increase the attractiveness of the university, international collaborations, interdisciplinarity, links with the clinical and industrial worlds and the integration of students into professional life.

Launched in July 2018, **NeuroSchool**unifies and harmonizes the training of the third year of the Bachelor of Life Sciences (Neuroscience track), the Master's and the PhD in Neuroscience.

**Site web**:
**Intitulé du doctorat**:

- Doctorat de neurosciences

**Pays d'obtention du doctorat**:

- France

**Etablissement délivrant le doctorat**:

- Aix Marseille Université

**Ecole doctorale**:

- Sciences de la vie et de la santé
- Master's degree from a non-French university in neuroscience or related field
- Fluent in English- 14/04/2025