Cues

Navigation requires us to take account of multiple spatial cues with varying levels of informativeness and learn their spatial relationships. Here we investigate this process in the Drosophila head direction system, which functions as a ring attractor and a topographic map of head direction. Using population calcium imaging and multimodal virtual reality environments, we show that increasing cue informativeness improves encoding accuracy and produces a narrower and higher bump of activity. When cues conflict, the more informative cue exerts more weight. A familiar cue is weighted more heavily and used to guide the remapping of a less familiar cue. When a cue is less informative, it is remapped more readily in response to cue conflict. All these results can be explained by an attractor model with plastic sensory synapses. Our findings provide a mechanistic explanation for how the brain assembles spatial representations through inference and learning.

Neural activity in sensory cortex is modulated by behavioral and cognitive factors, and this modulation is thought to contribute to the selection of specific sensory information needed to achieve behavioral goals. In contrast, more abstract behavioral variables that are independent of stimulus selection, such as stimulus-response mapping, are thought to be encoded by neurons outside of sensory cortex. We show that information about such mapping is robustly encoded in the responses of neurons in primate visual cortex. Monkeys were trained to alternate between two tasks that differed in the rule governing the mapping of a remembered visual cue onto an eye movement response. During the memory-delay period, neurons in area V4 reliably signaled the remembered cue location in both tasks. However, the encoding of cue location depended critically on the stimulus-response mapping rule. Thus, V4 delay activity encoded the mapping rule and signaled the preparation of the appropriate motor response rather than spatial working memory per se, contrary to previous assumptions. In addition, we probed the origins of motor-related delay activity and found that it was reduced during local inactivation of the frontal eye field (FEF). The results demonstrate that behavioral modulation of visual cortical activity is not solely related to the selection of sensory stimuli but instead reflects a distinct mechanism for sensory-guided motor output.

ImportanceThe neurobiology of avoidant/restrictive food intake disorder (ARFID) is poorly understood.ObjectiveTo evaluate whether individuals with ARFID exhibit disruptions in fear, appetite, and disgust brain regions compared with healthy control (HC) participants when shown images of food and objects.Design, setting, and participantsIn this case-control study conducted from July 2016 to January 2021, children, adolescents, and young adults completed structured interviews and a validated functional magnetic resonance imaging (fMRI) food cue paradigm. The study was conducted at a single academic medical center. Data analysis was conducted from April 2023 to August 2024.ExposuresPresence vs absence of ARFID and its phenotypes (ARFID-fear, ARFID-lack of interest in eating, ARFID-sensory sensitivity); pictures of food vs objects during fMRI food cue paradigm.Main outcomes and measuresBlood oxygenation level-dependent activation in regions of interest (ROIs; amygdala, hypothalamus, insula, anterior cingulate cortex [ACC]) and the whole brain.ResultsParticipants were 110 children, adolescents, and young adults with full or subthreshold ARFID (75 participants; mean [SD] age, 16.2 [3.8] years; 41 [55%] female) and age-matched HC participants (35 participants; mean [SD] age, 17.3 [4.0] years; 27 [69%] female) recruited for studies of the neurobiology of ARFID and restrictive eating disorders. Participants with ARFID demonstrated greater activation than HC participants of the ACC (mean difference, 0.48 [95% CI, 0.19 to 0.77]; P = .009), sensory association cortex (mean difference on left side, 0.54 [95% CI, 0.29 to 0.79]; P = .005; right side, 0.52 [95% CI, 0.28 to 0.76]; P = .02), and supplementary motor cortex (mean difference, 0.81 [95% CI, 0.47 to 1.15]; P = .04). The ARFID-fear group showed greater amygdala activation vs HC (mean difference, 0.49 [95% CI, 0.16 to 0.82]; P = .04), and greater lack of interest was associated with lower hypothalamus activation in the ARFID-lack of interest group (r = -0.38 [95% CI, -0.69 to -0.11]; P = .03). The ARFID-sensory sensitivity group did not show greater insula activation vs HC but showed greater activation of the ACC (mean difference, 0.48 [95% CI, 0.22 to 0.74]; P = .005) and somatosensory cortex (mean difference on left side, 0.60 [95% CI, 0.33-0.87]; P = .001; right side, 0.54 [95% CI, 0.29 to 0.80]; P = .03).Conclusions and relevanceResults indicate generalized hyperactivation of ACC, sensory association cortex, and supplementary motor cortex in response to visual food stimuli in children, adolescents, and young adults with ARFID, suggesting a novel neurobiological circuit associated with this disorder. Activation appears consistent with ARFID phenotypic rationales for food avoidance, with hyperactivation of fear regions in ARFID-fear and hypoactivation of appetite regions with increasing ARFID-lack of interest severity.

Wolves (Canis lupus) recolonizing human-dominated landscapes encounter anthropogenic risks and opportunities, but how this shapes their fear of humans is unknown. We tested 185 individually identified wild wolves across 44 locations covering a wide urbanization gradient, exposing them to novel objects and human playbacks. Wolves from more urbanized areas showed reduced fear at first exposure to an object but heightened caution when the object changed, indicating increased attention to environmental changes, rather than uniform fear reduction. By contrast, playbacks of human voices elicited strong fear responses (>80%), regardless of urbanization. However, individuals habituated to both stimuli quickly and at a similar pace, highlighting their rapid learning abilities. Sociality buffered fear, with wolves in groups reacting less fearfully than wolves alone. Results show that wolves are capable of flexibly modulating their behavioral responses to both the risks and opportunities of human-dominated landscapes, which likely underpins their urban success and requires us to rise to the challenge of peaceful coexistence.