“in vivo two-photon functional Ca2+ imaging” is a powerful tool to analyze neural circuits of the cerebral cortex in the physiological condition. To monitor activities of excitatory neurons, inhibitory (GABAergic) neurons and astrocytes, we applied this imaging method to visual cortex of transgenic mice, in which GABAergic neurons express fluorescent protein (EGFP or Venus). With this method, we can monitor the neural activities from hundreds of excitatory and GABAergic neurons (and also from astrocytes) in vivo. We found that the difference in response selectivity and ocular dominance plasticity between excitatory and GABAergic neuron in the mouse visual cortex.
Although cortical feedback signals are essential for modulating feedforward processing, no feedback error signal across hierarchical cortical areas has been reported. Here, we observed such a signal in the auditory cortex of awake common marmoset during an oddball paradigm to induce auditory duration mismatch negativity. Prediction errors to a deviant tone presentation were generated as offset calcium responses of layer 2/3 neurons in the rostral parabelt (RPB) of higher-order auditory cortex, while responses to non-deviant tones were strongly suppressed. Within several hundred milliseconds, the error signals propagated broadly into layer 1 of the primary auditory cortex (A1) and accumulated locally on top of incoming auditory signals. Blockade of RPB activity prevented deviance detection in A1. Optogenetic activation of RPB following tone presentation nonlinearly enhanced A1 tone response. Thus, the feedback error signal is critical for automatic detection of unpredicted stimuli in physiological auditory processing and may serve as backpropagation-like learning.
General IncorporatedAssociationunctear.Recently, we showed that the cellular rcdox {reduction-oxidation) peise deterrnines the phototactic sign/ ce]ls shew positive phototaxis after tTeutment with reactive oxygen species (ROS), whereas they show negative phototaxis after treatment with ROS quenchers.This finding raised two questions of 1) how cellular redox poise changes in vivo and 2) what is the motecutar basis for the redox-regulated switching ofthe phototactic sign.Regarding ]), we foeused on state transitions of photosynthesis, because the ROS generation has been suggested to greatly change depending on the state of photosynthesis.Low- temperuture fluoreseence spectroseopy revea]ed that cetls shewing positive phototaxis are in State 1, whereas those showing negative phDtotaxis are in State 2. We propose a rnode] that changes in the intrace]lular ROS amount.caused by state transitions.function as a slgna] for the phototactic sign switching.Regarding 2), we found that two previous]y isolated phototaxis-deficient mutants have defects in redox sensing.We also isolated a new mutant that responds to the treatment with redox reagents in an opposite manner to that of wilcl type.We will present the resu]ts ofphenotypic analyses.
Abstract Neural activity across the dorsal neocortex of rodents is dominated by orofacial and limb movements, irrespective of whether the movements are task-relevant or task-irrelevant. To examine the extent to which movements and a primitive cognitive signal, i.e., reward expectancy, modulate the activity of multiple cortical areas in primates, we conducted unprecedented wide-field one-photon calcium imaging of frontoparietal and auditory cortices in common marmosets while they performed a classical conditioning task with two auditory cues associated with different reward probabilities. Licking, eye movement, and hand movement strongly modulated the neuronal activity after cue presentation in the motor and somatosensory cortices in accordance with the somatotopy. By contrast, the posterior parietal cortex and primary auditory cortex did not show much influence from licking. Licking increased the activity in the caudal part of the dorsal premotor cortex, but decreased the activity in the central and lateral parts of the rostral part of the dorsal premotor cortex (PMdr). Reward expectancy that was separable from both spontaneous and goal-directed movements was mainly represented in the medial part of PMdr. Our results suggest that the influence of movement on primate cortical activity varies across areas and movement types, and that the premotor cortex processes motor and cognitive information in different ways within further subdivided areas.
