Updated September 27, 2022
Research Spotlight
The very act of remembering some experiences can cause forgetting of other related and competing material, in both humans and rats. This phenomenon is called retrieval-induced forgetting and is thought to be driven by the inhibition of the competing memories when target memories are repeatedly retrieved. Here, Gallo and colleagues started disentangling the neurochemical signals in the prefrontal cortex that are essential to retrieval-induced forgetting. They found, in rats, the release of dopamine in the medial prefrontal cortex, acting through D1 receptors, was essential to causing active forgetting of competing memories. Inhibition of these dopamine receptors impaired forgetting, while their activation increased forgetting. These findings are important, because the mechanisms of active forgetting and their linkage to the control of behavior are only beginning to be understood.
In the natural visual stream, orientations are not equally distributed within a certain time window, thus their probabilities fluctuate across time. Feng and colleagues found that slightly higher probability induced significant response enhancement, while extremely higher probability led to response inhibition which was well-known as orientation adaptation. This rapid bi-directional plasticity can be induced within minutes and exists in multi-stages of visual system. As a result, the neural response to a repetitively presented new stimulus will initially “pop-up” (novel) and then subsequently “pop-down” (redundant), and this study sheds light on the neural basis of saliency-detection of dynamic visual inputs.
Prolactin action is necessary for parental behavior in male mice
How do males become dads? For male mice, which are typically aggressive towards pups, becoming paternal relies on the act of mating, which suppresses pup-directed aggression and triggers the onset of paternal behavior. In this paper, Smiley and colleagues investigated whether prolactin, a hormone most well-known for its role in lactation and maternal behavior in females, is required for this behavioral transition in male mice. The authors found that multiple populations of prolactin-responsive neurons are activated throughout the brain when father mice interact with their pups. Using a combination of genetic approaches, they show that prolactin action on these neurons is required to show pup retrieval behavior (bringing pups into the nest), an important paternal behavior displayed by mouse sires. The next question was: when is this action of prolactin required? They showed that there is a surge of the prolactin that occurs during mating in males, but surprisingly, this did not seem to be the signal to make the behavioral transition from aggressive to paternal. Instead, it was found that prolactin is required only at the time of pup care to show paternal behaviors. These data provide a long-sought explanation for a role of prolactin in males and show prolactin acts similarly in both sexes to promote offspring care.
Most-Discussed Research Published in July
Below are five Early Release articles that generated the most online discussion in August 2022, as measured by Altmetric. Altmetric data is available for all articles published in JNeurosci on the Info & Metrics tab. Learn more about how the Altmetric score is calculated.
This study provides insights into the neural processes that transfer effects of brain-computer interface neurofeedback to subsequent motor behavior. Specifically, volitional control of cortical oscillations and proprioceptive feedback enhances both cortical activity and behaviorally relevant connectivity to the periphery in a topographically circumscribed and frequency-specific way. This enhanced cortico-muscular control can be induced in the healthy and post-stroke brain. Thereby, activating the motor cortex with mental rehearsal of the impaired movement and closing the loop by robot-assisted feedback synchronizes ipsilesional premotor cortex and spinal neural pools in the beta-frequency band. This facilitates, in accordance with the communication-through-coherence hypothesis, cortico-spinal communication and may, thereby, be therapeutically relevant for functional restoration after stroke, when voluntary movements are no longer possible.
Mitochondrial dysfunction and antioxidant defense play essential role in brain damage after intracerebral hemorrhage (ICH). Astrocytes release functional mitochondria (Mt) that enter adjacent cells to help brain homeostatic function. Here, we show that systemic transplantation of astrocytic Mt restores ICH-impaired neuronal anti-oxidative defense, enhances neurite outgrowth, and improves stroke recovery after ICH. Our study suggests that systemic transplantation of astrocytic Mt could be considered as a novel and potentially promising strategy for ICH treatment.
Glycerol-3-phosphate shuttle is a backup system securing metabolic flexibility in neurons
Ca2+ ions are known to provide a link between the energy-demanding electrical activity and an adequate ATP supply in neurons. To do so, Ca2+ acts both, from outside and inside of the mitochondrial inner membrane. Neuronal function critically depend on this regulation and its defects are often found in various neurological disorders. Although interest in neuronal metabolism increases, many aspects thereof have remained unresolved. In particular, a Ca2+-sensitive NADH shuttling system, the glycerol-3-phosphate shuttle, has been largely ignored with respect to its function in neurons. Our results demonstrate that this shuttle is functional in hippocampal neurons and safeguards ATP supply and appropriate action potential firing when malate aspartate shuttle and mitochondrial Ca2+ uniporter are unavailable, thereby ensuring neuronal metabolic flexibility.
In these studies we identify early developmental alterations in principal neurons in the FXS BLA. We show that as early as P14, excitability and feed-forward excitation, and synaptic plasticity is enhanced in Fmr1KO lateral amygdala. This correlates with precocious emergence of fear-learning in the Fmr1KO mouse. Early life THIP intervention restores CP plasticity in WT mice and ameliorates fear-learning in the Fmr1KO mouse.
Causal inference of body ownership in the posterior parietal cortex
How does the brain create a coherent perceptual experience of one’s own body based on information from the different senses? We examined how the likelihood of eliciting a classical bodily illusion that depends on vision and touch – the rubber hand illusion – is related to neural activity measured by functional magnetic resonance imaging. We found that trial-by-trial variations in the neural signal in the posterior parietal cortex, a well-known center for sensory integration, fitted a statistical function that describes how likely it is that the brain infers that a rubber hand is one’s own given the available visual and tactile evidence. Thus, probabilistic analysis of sensory information in the parietal lobe underlies our unitary sense of bodily self.
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