Peyman Golshani

Flexible behavior in complex environments requires animals to infer which sensory inputs are relevant for guiding action and which need to be ignored. Yet, how cognitive control circuits apply contextual knowledge during decision-making is poorly understood. To address this question, we trained head-fixed mice on a cross-modal, context-dependent two-alternative forced-choice (2-AFC) decision-making task. In this task, animals simultaneously received visual and auditory inputs, and the behaviorally relevant modality switched covertly between blocks of trials, requiring animals to infer rule changes from reward feedback alone. Mice successfully adapted their behavior after rule switches and recovered to expert performance. Using simultaneous Neuropixels recordings in the primary visual cortex (V1) and the anterior cingulate cortex (ACC) during task performance, we found that neuronal responses in both regions showed mixed selectivity, multiplexing sensory, choice, and outcome signals. However, V1 neural responses more strongly encoded visual stimulus orientation, while ACC neural responses preferentially encoded outcome. Population decoding further revealed that V1 and ACC neurons maintained a persistent representation of task context throughout the trial, occupying a subspace approximately orthogonal to visual stimulus coding. This contextual representation strengthened progressively as mice adapted their behavior following each switch. Critically, context representations emerged in parallel in V1 and ACC, and decoding accuracies in these two regions were strongly correlated with each other and with behavioral performance across trial blocks. Orthogonal to this shared emergent and sustained context signal, visual stimulus decoding was enhanced when vision was task-relevant. This attentional enhancement in V1 occurred not only during the stimulus presentation period but also after stimulus offset. Similarly, in ACC, a persistent increase of visual stimulus identity encoding in visually relevant session blocks was present after stimulus offset. Taken together, these findings reveal a distributed, inter-areal representation of task context spanning sensory and frontal cortices, suggesting that V1 and ACC contribute to maintaining task-relevant sensory information beyond the immediate sensory response period to provide a circuit-level mechanism for cross-modal attentional control.

Behavioral timescale synaptic plasticity (BTSP) is a form of synaptic potentiation where a single plateau potential in hippocampal neurons forms a place field during spatial learning. However, it remains unknown whether BTSP also forms non-spatial responses and what roles the medial and lateral entorhinal cortex (MEC and LEC) play in driving non-spatial BTSP. Using two-photon calcium imaging of CA1 pyramidal neurons in mice learning an odor-cued working memory task, we observed spontaneously-occurring large plateau-like calcium events during odor cues, forming stable odor representations. Using holographic optogenetics, we induced similar plateau-like calcium events in single neurons that were followed by novel odor representations. Chemogenetic inhibition of MEC reduced the frequency of plateau-like events, whereas LEC inhibition reduced their efficiency in forming odor representations. Together, our findings demonstrate that rare large somatic calcium events, consistent with BTSP, precede and drive novel odor representations in a manner differentially regulated by medial and lateral entorhinal cortex.

Mesial temporal lobe epilepsy (TLE) is the most common form of acquired epilepsy involving the hippocampus and is a frequent sequelae of head trauma. TLE is associated with refractory seizures and significant cognitive deficits. Yet, the gene expression patterns and cell types driving epileptogenesis and the associated cognitive deficits are poorly understood. To address this, we performed single nucleus RNA sequencing on hippocampal tissue from mice at 3 and 6 weeks following pilocarpine-induced status epilepticus, a robust model of TLE. At these early timepoints, epilepsy samples showed reductions in specific Cck and Lamp5-Lhx6 interneuron subclusters, alongside increases in Cajal-Retzius cells, dentate granule (DG) cell precursors, and a mature DG cell subcluster. Among glia, an astrocyte subcluster and a markedly expanded microglia sublcuster were increased. We term this microglia population epilepsy-associated microglia (EAM). The transcriptomic profile of EAM partially overlaps with microglia described in models of Alzheimer’s disease and traumatic brain injury, with enrichment of genes including Myo1e and Igf1 . EAM display amoeboid morphology, can be found in dense clumps around pyramidal and granule cell body layers, and exhibit enlarged vesicles and mitochondria on electron microscopy. Cell-cell interaction analysis predict that DG cells are the main interaction partners of EAM. This dataset recapitulates known cellular alterations in TLE while defining their underlying transcriptomic programs, enabling mechanistic dissection of the key processes driving epileptogenesis.

SignificanceObserving the activity of large populations of neurons in vivo is critical for understanding brain function and dysfunction. The use of fluorescent genetically encoded calcium indicators (GECIs) in conjunction with miniaturized microscopes is an exciting emerging toolset for recording neural activity in unrestrained animals. Despite their potential, current miniaturized microscope designs are limited using image sensors with low frame rates, sensitivity, and resolution. Beyond GECIs, there are many neuroscience applications that would benefit from the use of other emerging neural indicators, such as fluorescent genetically encoded voltage indicators (GEVIs) that have faster temporal resolution to match neuron spiking, yet require imaging at high speeds.AimWe integrated an advanced CMOS image sensor into a popular open-source one-photon miniaturized microscope platform.ApproachMiniFAST is a fast and sensitive miniaturized microscope capable of 1080p video (1920×1080 pixels), 1.5 μm resolution, frame rates up to 500 Hz (achieved with windowing: 1920×55 pixels height), and high gain ability (up to 70 dB) to image in extremely low-light conditions.ResultsWe report results of ∼300-Hz in vivo imaging of freely behaving transgenic Thy1-GCaMP6f mice, high-speed 500-Hz in vitro imaging of a GEVI, and in vivo GEVI imaging in head-fixed mice.ConclusionsOur results extend miniaturized microscope capabilities in high-speed imaging, high sensitivity, and increased resolution.

Volumetric functional imaging of transient cellular signaling and motion dynamics is often limited by hardware bandwidth and the scarcity of photons under short exposures. To overcome these challenges, we introduce squeezed light field microscopy (SLIM), a computational imaging approach that rapidly captures high-resolution three-dimensional light signals using only a single, low-format camera sensor. SLIM records over 1,000 volumes per second across a 550-µm diameter field of view and 300-µm depth, achieving 3.6-µm lateral and 6-µm axial resolution. Here we demonstrate its utility in blood cell velocimetry within the embryonic zebrafish brain and in freely moving tails undergoing high-frequency swings. Millisecond-scale temporal resolution further enables precise voltage imaging of neural membrane potentials in the leech ganglion and hippocampus of behaving mice. Together, these results establish SLIM as a versatile and robust tool for high-speed volumetric microscopy across diverse biological systems.

The medial prefrontal cortex (MPF) regulates autonomic and neuroendocrine responses to stress^1,2 and coordinates goal-directed behaviours such as attention, decision-making and social interactions^3,4,5,6,7,8. However, the underlying mechanisms remain unclear due to incomplete circuit-level MPF characterization⁷. Here, using integrated neuroanatomical, physiological and behavioural approaches, we construct a comprehensive wiring diagram of the MPF, focused on the dorsal peduncular area (DP)—a poorly understood prefrontal area. We identify its deep (DPd) and superficial (DPs) layers, along with the infralimbic area, as major components of the visceromotor cortex that directly project to hypothalamic and brainstem structures to govern neuroendocrine, sympathetic and parasympathetic output. Notably, the DP functions as a network hub integrating diverse cortical inputs and modulating goal-directed behaviour through a largely unidirectional cortical information flow. On the basis of the mesoscale MPF connectome, we propose a unified network model in which distinct MPF areas orchestrate physiological and behavioural responses to internal and external stimuli.

Here we describe the UCLA 2P Miniscope, an open-source miniature 2-photon microscope capable of recording calcium dynamics from neurons in deep structures and from dendrites over a 445 µm × 380 µm field of view. The system utilizes two on-board silicon-based photon detectors for approximately 4-fold greater light collection compared to an optical fiber bundle-based approach. The microscope can electronically focus within a 150 µm range at a native working distance of 720 µm. To test the 2P Miniscope, we recorded calcium dynamics from place cells in hippocampus, resolved calcium transients from dendrites in retrosplenial cortex and we recorded dentate granule cell activity at a depth of over 620 µm, through an intact hippocampus during open field behavior. The miniature microscope itself and all supporting equipment are open-source and all files needed for building the scope can be accessed through the Golshani Lab GitHub repository.