Distinct neurochemical influences on fMRI response polarity in the striatum.

The striatum, known as the input nucleus of the basal ganglia, is extensively studied for its diverse behavioral roles. However, the relationship between its neuronal and vascular activity, vital for interpreting functional magnetic resonance imaging (fMRI) signals, has not received comprehensive examination within the striatum. Here, we demonstrate that optogenetic stimulation of dorsal striatal neurons or their afferents from various cortical and subcortical regions induces negative striatal fMRI responses in rats, manifesting as vasoconstriction.

Intrinsic Functional Connectivity between the Anterior Insular and Retrosplenial Cortex as a Moderator and Consequence of Cocaine Self-Administration in Rats.

While functional brain imaging studies in humans suggest that chronic cocaine use alters functional connectivity (FC) within and between key large-scale brain networks, including the default mode network (DMN), the salience network (SN), and the central executive network (CEN), cross-sectional studies in humans are challenging to obtain brain FC prior to cocaine use. Such information is critical to reveal the relationship between individual's brain FC and the subsequent development of cocaine dependence and brain changes during abstinence. Here, we performed a longitudinal study examining functional magnetic resonance imaging (fMRI) data in male rats ( = 7), acquired before cocaine self-administration (baseline), on 1 d of abstinence following 10 d of cocaine self-administration, and again after 30 d of experimenter-imposed abstinence.

Putative neurochemical and cell type contributions to hemodynamic activity in the rodent caudate putamen.

Functional magnetic resonance imaging (fMRI) is widely used by researchers to noninvasively monitor brain-wide activity. The traditional assumption of a uniform relationship between neuronal and hemodynamic activity throughout the brain has been increasingly challenged. This relationship is now believed to be impacted by heterogeneously distributed cell types and neurochemical signaling.

Computing hemodynamic response functions from concurrent spectral fiber-photometry and fMRI data.

Although emerging evidence suggests that the hemodynamic response function (HRF) can vary by brain region and species, a single, canonical, human-based HRF is widely used in animal studies. Therefore, the development of flexible, accessible, brain-region specific HRF calculation approaches is paramount as hemodynamic animal studies become increasingly popular. To establish an fMRI-compatible, spectral, fiber-photometry platform for HRF calculation and validation in any rat brain region.

Automatic Skull Stripping of Rat and Mouse Brain MRI Data Using U-Net.

Accurate removal of magnetic resonance imaging (MRI) signal outside the brain, a.k.a.

Animal Functional Magnetic Resonance Imaging: Trends and Path Toward Standardization.

Animal whole-brain functional magnetic resonance imaging (fMRI) provides a non-invasive window into brain activity. A collection of associated methods aims to replicate observations made in humans and to identify the mechanisms underlying the distributed neuronal activity in the healthy and disordered brain. Animal fMRI studies have developed rapidly over the past years, fueled by the development of resting-state fMRI connectivity and genetically encoded neuromodulatory tools.

An Adeno-Associated Virus-Based Toolkit for Preferential Targeting and Manipulating Quiescent Neural Stem Cells in the Adult Hippocampus.

Quiescent neural stem cells (qNSCs) with radial morphology are the only proven source of new neurons in the adult mammalian brain. Our understanding of the roles of newly generated neurons depends on the ability to target and manipulate adult qNSCs. Although various strategies have been developed to target and manipulate adult hippocampal qNSCs, they often suffer from prolonged breeding, low recombination efficiency, and non-specific labeling.

Nucleus accumbens core neurons encode value-independent associations necessary for sensory preconditioning.

Reinforcement-based learning models predict that the strength of association between cues and outcomes is driven by aspects of outcome value. However, animals routinely make associations between contingent stimuli in the world, even if those associations hold no value to the organism. At the neural level, the nucleus accumbens (NAc) is known to encode associative information, but it is not known whether this encoding is specific for value-based information (consistent with reinforcement-based models) or if the NAc additionally plays a more general role in forming predictive associations, independent of outcome value.

Risk-responsive orbitofrontal neurons track acquired salience.

Decision making is impacted by uncertainty and risk (i.e., variance).

Normal aging alters learning and attention-related teaching signals in basolateral amygdala.

Normal aging has been associated with an increased propensity to wait for rewards. When this is tested experimentally, rewards are typically offered at increasing delays. In this setting, persistent responding for delayed rewards in aged rats could reflect either changes in the evaluation of delayed rewards or diminished learning, perhaps due to the loss of subcortical teaching signals induced by changes in reward; the loss or diminution of such teaching signals would result in slower learning with progressive delay of reward, which would appear as persistent responding.

Willingness to wait and altered encoding of time-discounted reward in the orbitofrontal cortex with normal aging.

Normal aging has been associated with cognitive changes, including shifts in responding for time-discounted rewards. The orbitofrontal cortex, an area previously associated with aging-related cognitive changes, is critical for normal discounting. Previously we have shown in a choice task that rats prefer immediate over delayed reward and that neural representations of delayed reward in orbitofrontal cortex were attenuated, whereas immediate reward elicited strong responses.

Normal Aging does Not Impair Orbitofrontal-Dependent Reinforcer Devaluation Effects.

Normal aging is associated with deficits in cognitive flexibility thought to depend on prefrontal regions such as the orbitofrontal cortex (OFC). Here, we used Pavlovian reinforcer devaluation to test whether normal aging might also affect the ability to use outcome expectancies to guide appropriate behavioral responding, which is also known to depend on the OFC. Both young and aged rats were trained to associate a 10-s conditioned stimulus (CS+) with delivery of a sucrose pellet.

Nucleus Accumbens Core and Shell are Necessary for Reinforcer Devaluation Effects on Pavlovian Conditioned Responding.

The nucleus accumbens (NA) has been hypothesized to be part of a circuit in which cue-evoked information about expected outcomes is mobilized to guide behavior. Here we tested this hypothesis using a Pavlovian reinforcer devaluation task, previously applied to assess outcome-guided behavior after damage to regions such as the orbitofrontal cortex and amygdala that send projections to NA. Rats with sham lesions or neurotoxic lesions of either the core or shell subdivision of NA were trained to associate a 10-s CS+ with delivery of three food pellets.