An fMRI meta-analysis of the role of the striatum in everyday-life vs laboratory-developed habits

Striatal functional connectivity associated with Sahaja Yoga meditation

Neuroscience research has associated meditation practice with effects on cognitive, motivational and emotional processes. These processes are mediated by several brain circuits, including the striatum and its associated cortical connections. The aim of this study was to focus on the striatum and test how its functional connectivity is affected in long-term practitioners of Sahaja Yoga Meditation. We studied differences between resting and meditation states in a group of 23 Sahaja Yoga Meditation experts. We also compared the resting state between meditation experts and a control group of 23 non-meditating participants. Functional connectivity contrasts between conditions and groups were performed using seeds in the dorsal and ventral striatum (caudate, putamen and nucleus accumbens). During meditation, compared to the resting state, meditators showed altered connectivity between the striatum and parietal, sensorimotor and cerebellar regions. Resting state in meditators relative to that of controls showed reduced functional connectivity between the left accumbens and the mid cingulate, which was correlated with reduced Simon Task interference reaction time effect in meditators. In conclusion, the striatum may play a pivotal role in the practice of Sahaja Yoga Meditation by altering attention and self-referencing, and by modulating bodily sensations. Furthermore, meditation practice could produce long-term changes in striatal connectivity.

Frontal Deactivation and the Efficacy of Statistical Learning: Neural Mechanisms Accompanying Exposure to Visual Statistical Sequences

Statistical learning is the cognitive ability to rapidly identify structure and meaning in unfamiliar streams of sensory experience, even in the absence of feedback. Despite extensive studies, the neurocognitive mechanisms underlying this phenomenon still require further clarification under varying cognitive conditions. Here, we examined neural mechanisms during the first exposure to visually presented sequences in 47 healthy participants. We used two types of visual objects: abstract symbols and pictures of cartoon-like animals. This allowed us to compare informational processing mechanisms with defined distinguishing features. Participants achieved better performance for sequences with easy-to-name than difficult-to-name abstract stimuli. fMRI results revealed greater activation in widespread brain regions in response to random versus statistical sequences for all stimuli types. Behavioral accuracy was associated with increased deactivation of the ventromedial PFC for easy-to-name statistical versus random sequences. For difficult-to-name statistical versus random sequences, performance correlated with dorsomedial prefrontal cortex deactivation. ROI analysis showed a generally positive involvement of the caudate head in sequence processing with significantly stronger activity during the first run of performing the task. Functional connectivity analysis of prefrontal deactivation regions revealed significant connectivity with nodes of the salience network for both object types and inverse connectivity with the caudate head only for easy-to-name objects. The results indicated that distinct subregions of PFC modulate task performance depending on the visual stimulus characteristic. They also showed that among striatal regions, only the head of the caudate was sensitive to initial exposure to visual statistical information.

Deconstructing the self and reshaping perceptions: An intensive whole-brain 7T MRI case study of the stages of insight during advanced investigative insight meditation

The stages of insight (SoI) are a series of psychological realizations experienced through advanced investigative insight meditation (AIIM). SoI provide a powerful structured framework of AIIM for understanding and evaluating insight-based meditative development through changes in perception, experiences of self, cognition, and emotional processing. Yet, the neurophenomenology of SoI remains unstudied due to methodological difficulties, rarity of suitable advanced meditation practitioners, and dominant research emphasis on attention-based meditative practices. We investigated the neurophenomenology of SoI in an intensively sampled adept meditator case study (4 hr 7T fMRI collected in 26 runs with concurrent phenomenology) who performed SoI and rated specific aspects of experience immediately thereafter. Linear mixed models and correlations were used to examine relations among the cortex, subcortex, brainstem, and cerebellum, and SoI phenomenology. We identified distinctive whole-brain activity patterns associated with specific SoI, and that were different from two non-meditative control states. SoI consistently deactivated regions implicated in self-related processing, including the medial prefrontal cortex and temporal poles, while activating regions associated with awareness and perception, including the parietal and visual cortices, caudate, several brainstem nuclei, and cerebellum. Patterns of brain activity related to affective processing and SoI phenomenology were also identified. Our study presents the first neurophenomenological evidence that SoI shifts and deconstructs self-related perception and conceptualization, and increases general awareness and perceptual sensitivity and acuity. Our study provides SoI as a foundation for investigative, and advanced meditation in particular.

Leveraging cognitive neuroscience for making and breaking real-world habits

Habits are the behavioral output of two brain systems. A stimulus-response (S-R) system that encourages us to efficiently repeat well-practiced actions in familiar settings, and a goal-directed system concerned with flexibility, prospection, and planning. Getting the balance between these systems right is crucial: an imbalance may leave people vulnerable to action slips, impulsive behaviors, and even compulsive behaviors. In this review we examine how recent advances in our understanding of these competing brain mechanisms can be harnessed to increase the control over both making and breaking habits. We discuss applications in everyday life, as well as validated and emergent interventions for clinical populations affected by the balance between these systems. As research in this area accelerates, we anticipate a rapid influx of new insights into intentional behavioral change and clinical interventions, including new opportunities for personalization of these interventions based on the neurobiology, environmental context, and personal preferences of an individual.

Control of goal-directed and inflexible actions by dorsal striatal melanocortin systems, in coordination with the central nucleus of the amygdala

The dorsomedial striatum (DMS) is associated with flexible goal seeking, as opposed to routinized habits. Whether local mechanisms brake this function, for instance when habits may be adaptive, is incompletely understood. We find that a sub-population of dopamine D1 receptor-containing striatal neurons express the melanocortin-4 receptor (MC4R) for α-melanocyte stimulating hormone. These neurons within the DMS are necessary and sufficient for controlling the capacity of mice to flexibly adjust actions based on the likelihood that they will be rewarded. In investigating MC4R function, we found that it suppresses immediate-early gene levels in the DMS and concurrently, flexible goal seeking. MC4R+ neurons receive input from the central nucleus of the amygdala, and behavioral experiments indicate that they are functionally integrated into an amygdalo-striatal circuit that suppresses action flexibility in favor of routine. Publicly available spatial transcriptomics datasets were analyzed for gene transcript correlates of Mc4r expression across the striatal subregions, revealing considerable co-variation in dorsal structures. This insight led to the discovery that the function of MC4R in the dorsolateral striatum complements that in the DMS, in this case suppressing habit-like behavior. Altogether, our findings suggest that striatal MC4R controls the capacity for goal-directed and inflexible actions alike.

Temperament impact on eating disorder symptoms and habit formation: a novel model to inform treatment

BACKGROUND

Temperament has long been described as the biological dimension of personality. Due to advancing brain-imaging technology, our understanding of temperament has deepened and transformed over the last 25 years. Temperament combines genetic, neurobiological and trait research. Temperament has been included peripherally in some eating disorder (ED) treatment approaches but has been ignored by most. Temperament fills a fundamental treatment gap by clarifying who is more vulnerable to develop ED and why some individuals are susceptible to specific ED symptoms while others are not. In addition, temperament targets possible treatment solutions.

MAIN TEXT

There is a need for a novel model that incorporates and explores the role of temperament in ED treatment intervention. This paper is a metaphoric temperament model to inform treatment intervention. It describes how temperament traits influences new decisions which impact new behavioural responses. In turn, it neurobiologically tracks how and why the brain efficiently transforms new decisions into new habits. This model integrates both temperament and habit research to explore (a) what temperament is; (b) how new decisions develop into habits neurobiologically; (c) that the brain wires destructive symptoms into habits in the same way that it wires healthy/productive behaviours into habits; (d) traits that trigger ED symptoms are the same traits that influence productive behaviours; and in regard to treatment implications (e) when treatment structure and intervention target client temperaments, the potential for new healthy "trait-syntonic" habits could develop.

CONCLUSIONS

This paper introduces a metaphoric model that synthesizes and integrates temperament neurobiological and trait findings with ED symptoms, habits, and client trait-based solutions. The model synthesizes and integrates different research domains to establish a brain-based foundation to inform treatment intervention. The model targets clients' temperament traits as central collections of innate self-expressions that could be utilized as tools to redirect client trait-syntonic ED responses into trait-syntonic productive outcomes. The brain bases of temperament and habit formation serve as a biological foundation for ED treatment intervention.

Measuring context-response associations that drive habits

People achieve important life outcomes of health, financial security, and productivity by repeating operant behavior. To identify whether such operants reflect goal pursuit or habit, the present research introduces a new paradigm that yields objective measures of learning and controls for the motivations of goal pursuit. In two experiments, participants practiced a sequential task of making sushi and then completed a test of the strength of cue-response (habit) associations in memory. Finally, they repeated the sushi task without instructions while under cognitive load (designed to impede deliberation about goals). As predicted, greater task practice yielded stronger cue-response associations, which in turn promoted task success. Practice did not improve performance by enhancing goal intentions or other task motivations. We conclude that repetition facilitates performance by creating mental associations that automatically activate practiced, habitual responses upon perception of recurring context cues.

Cortical glutamate and GABA are related to compulsive behaviour in individuals with obsessive compulsive disorder and healthy controls

There has been little analysis of neurochemical correlates of compulsive behaviour to illuminate its underlying neural mechanisms. We use 7-Tesla proton magnetic resonance spectroscopy (¹H-MRS) to assess the balance of excitatory and inhibitory neurotransmission by measuring glutamate and GABA levels in anterior cingulate cortex (ACC) and supplementary motor area (SMA) of healthy volunteers and participants with Obsessive-Compulsive Disorder (OCD). Within the SMA, trait and clinical measures of compulsive behaviour are related to glutamate levels, whereas a behavioural index of habitual control correlates with the glutamate:GABA ratio. Participants with OCD also show the latter relationship in the ACC while exhibiting elevated glutamate and lower GABA levels in that region. This study highlights SMA mechanisms of habitual control relevant to compulsive behaviour, common to the healthy sub-clinical and OCD populations. The results also demonstrate additional involvement of anterior cingulate in the balance between goal-directed and habitual responding in OCD.