Brain metabolic correlates of heroin addiction severity during abstinence and heroin versus social seeking: A PET study in rats.

September 8, 2026| Source: Proceedings of the National Academy of Sciences of the United States of America

Only a subset of heroin users develop addiction, characterized by binge-like heroin use and preference for heroin over other rewards, including social rewards. We recently established a rat model that captures these features. We trained rats to lever-press for social interaction and heroin (or saline, control) infusions and then tested heroin and social seeking and heroin-vs.-social choice. During 3 to 5 abstinence weeks, we used 2-deoxy-2-[ 18 F]fluoro-D-glucose (FDG) positron emission tomography (PET) imaging to assess regional brain metabolic activity at rest (homecage) and during heroin and social seeking. We assessed regional differences in FDG uptake using unbiased voxel-wise analysis and statistical parametric mapping, and correlated FDG uptake with principle-component-analysis-derived addiction severity score incorporating heroin intake, binge-like episodes, and heroin preference. Compared with saline-trained rats, heroin-trained rats showed overall higher FDG uptake across multiple brain regions at rest and during both reward-seeking tests. Comparison of heroin-vs.-social-seeking in heroin-trained rats showed higher uptake in claustrum/striatum and auditory cortex during social seeking. Analysis of individual differences showed that addiction severity was primarily associated with metabolic alterations under resting conditions rather than during heroin or social seeking. At rest, higher addiction severity was associated with lower uptake in piriform cortex and higher uptake in ventral hippocampus, whereas during heroin seeking, addiction severity was associated with lower uptake in postsubiculum and cerebellum. Addiction severity was not associated with differences in social measures or FDG uptake during social-seeking. These findings identify brain metabolic features of heroin addiction vulnerability in a rat model that may serve as brain biomarkers of human opioid addiction.

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Cerebellar microcircuits enable robust evidence-based decisions through cortico-cerebellar coupling.

The cerebellum is increasingly implicated in perceptual decision-making, yet it remains unclear how the cerebellar cortex can support sparse evidence accumulation over behavioral time scales without assuming cortical-style dense local excitatory recurrence. We present a biologically constrained modeling framework showing that cerebellar microcircuits can implement graded accumulation and competition in the absence of such recurrence. In our model, type-II Purkinje-neuron excitability generates f

Society & CultureSeptember 25, 2026

Loss of neuronal population organization links pathology to behavior in a model of Alzheimer's disease.

Alzheimer's disease and related dementias are typically described at two levels: the accumulation of molecular pathology and the emergence of cognitive impairment. Understanding the relationship between pathology, often studied in animal models, and human cognition will require measurements spanning intermediate scales, including single neurons, neuronal populations, and distributed networks. Here we combine longitudinal measurements of behavior and neuronal population activity with fluid and hi

Society & CultureSeptember 8, 2026

Retinotopic remapping of the visual system in deaf adults.

The absence of input from one sense can lead to a greater emphasis on the remaining senses, resulting in heightened performance. Numerous behavioral studies demonstrate that adults who have been deaf from an early age have superior visual sensitivity, particularly to far-peripheral stimuli. We asked whether the increased demand on peripheral vision throughout development that comes with early, profound deafness might be reflected in changes in early visual brain structures. Using functional MRI,

Society & CultureAugust 25, 2026

4000-year-old painted plaque from Southeast Indonesia reveals Austronesian Painting Tradition preceded Neolithic pottery.

The Austronesian dispersal is the largest such event in human history, with descendants of people from Taiwan colonizing islands from Rapa Nui to Madagascar. The extent to which this dispersal was facilitated by an economic package or a particular ideology is uncertain. The "Austronesian Painting Tradition" (APT) is a distinctive rock art style dominated by paintings of small human figures, boats, and geometric motifs found in eastern Wallacea and islands around New Guinea. The age of the APT is

Society & CultureAugust 25, 2026

A spinoreticular pathway mediates nocifensive responses to noxious mechanical stimuli.

Spinal projection neurons (SPNs) relay somatosensory information to the brain, yet how molecularly defined SPN subsets transmit noxious mechanical signals to drive nocifensive behaviors remains unclear. Here, we identify Sncg -expressing SPNs ( Sncg + SPNs) that convey noxious mechanical signals through a spinoreticular ascending pathway. Using intersectional genetics, anatomical tracing, and pathway-specific manipulations in mice, we show that Sncg + SPNs project predominantly to the parabrachi