The thalamic reticular nucleus (TRN) plays a crucial role in regulating sensory encoding, even at the earliest stages of visual processing, as evidenced by numerous studies. Orientation selectivity, a vital neural response, is essential for detecting objects through edge perception. Here, we demonstrate that somatostatin (SOM)-expressing and parvalbumin (PV)-expressing neurons in the TRN project to the dorsal lateral geniculate nucleus and modulate orientation selectivity and the capacity for visual information processing in the primary visual cortex (V1). These findings show that SOM-positive and PV-positive neurons in the TRN are powerful modulators of visual information encoding in V1, revealing a novel role for this thalamic nucleus in influencing visual processing.
Animals ; Somatostatin/metabolism* ; Parvalbumins/metabolism* ; Neurons/physiology* ; Thalamic Nuclei/physiology* ; Visual Pathways/physiology* ; Mice ; Mice, Inbred C57BL ; Visual Perception/physiology* ; Male ; Mice, Transgenic ; Visual Cortex/physiology* ; Primary Visual Cortex/cytology*

Low-intensity ultrasound stimulation of the retina has the ability to modulate neural activity in the primary visual cortex (V1), however, it is currently unclear how different intensities and durations of ultrasonic stimulation of the retina modulate neural activity in V1. In this paper, we recorded local field potential (LFP) signals in the V1 brain region of mice under different ultrasound intensities and different stimulation times. The amplitude of LFP corresponding to 1 s before ultrasound stimulation to 2 s after stimulation (-1-2 s) was analyzed, including the power and sample entropy of delta, theta, alpha beta, and low gamma frequency bands. The experimental results showed that, as the stimulation intensity increased, the peak value of the LFP in the visual cortex showed a linear upward trend; the power in the delta and theta frequency bands showed a linear upward trend, and the sample entropy showed a linear downward trend. With increases of stimulation duration, the peak value of the LFP in the visual cortex showed an upward trend, and the upward trend gradually weakened; the power in the delta frequency band showed an upward trend, the sample entropy showed a linear upward trend, and the sample entropy in the theta frequency band showed a downward trend. The results show that low-intensity ultrasonic stimulation of the retina has a significant modulatory effect on neural activity in the visual cortex. The study provides insights into the mechanisms by which ultrasonic stimulation regulates visual system function. Furthermore, it clarifies the patterns of parameter selection, facilitating the development of personalized multi-parameter modulation for the treatment of visual neural degeneration, retinal disorders and related research areas.
Animals ; Visual Cortex/radiation effects* ; Retina/radiation effects* ; Mice ; Ultrasonic Waves ; Primary Visual Cortex/physiology*

Fear memory contextualization is critical for selecting adaptive behavior to survive. Contextual fear conditioning (CFC) is a classical model for elucidating related underlying neuronal circuits. The primary visual cortex (V1) is the primary cortical region for contextual visual inputs, but its role in CFC is poorly understood. Here, our experiments demonstrated that bilateral inactivation of V1 in mice impaired CFC retrieval, and both CFC learning and extinction increased the turnover rate of axonal boutons in V1. The frequency of neuronal Ca²⁺ activity decreased after CFC learning, while CFC extinction reversed the decrease and raised it to the naïve level. Contrary to control mice, the frequency of neuronal Ca²⁺ activity increased after CFC learning in microglia-depleted mice and was maintained after CFC extinction, indicating that microglial depletion alters CFC learning and the frequency response pattern of extinction-induced Ca²⁺ activity. These findings reveal a critical role of microglia in neocortical information processing in V1, and suggest potential approaches for cellular-based manipulation of acquired fear memory.
Mice ; Animals ; Primary Visual Cortex ; Extinction, Psychological/physiology* ; Learning/physiology* ; Fear/physiology* ; Hippocampus/physiology*

Studies have shown that spatial attention remarkably affects the trial-to-trial response variability shared between neurons. Difficulty in the attentional task adjusts how much concentration we maintain on what is currently important and what is filtered as irrelevant sensory information. However, how task difficulty mediates the interactions between neurons with separated receptive fields (RFs) that are attended to or attended away is still not clear. We examined spike count correlations between single-unit activities recorded simultaneously in the primary visual cortex (V1) while monkeys performed a spatial attention task with two levels of difficulty. Moreover, the RFs of the two neurons recorded were non-overlapping to allow us to study fluctuations in the correlated responses between competing visual inputs when the focus of attention was allocated to the RF of one neuron. While increasing difficulty in the spatial attention task, spike count correlations were either decreased to become negative between neuronal pairs, implying competition among them, with one neuron (or none) exhibiting attentional enhancement of firing rate, or increased to become positive, suggesting inter-neuronal cooperation, with one of the pair showing attentional suppression of spiking responses. Besides, the modulation of spike count correlations by task difficulty was independent of the attended locations. These findings provide evidence that task difficulty affects the functional interactions between different neuronal pools in V1 when selective attention resolves the spatial competition.
Animals ; Attention/physiology* ; Macaca mulatta ; Neurons/physiology* ; Photic Stimulation ; Primary Visual Cortex ; Visual Cortex/physiology*