Top-Down Control of Serotonin Systems by the Prefrontal Cortex: A Path toward Restored Socioemotional Function in Depression

Sustained anterior cingulate cortex activation during reward processing predicts response to psychotherapy in major depressive disorder

BACKGROUND

The purpose of the present investigation was to evaluate whether pre-treatment neural activation in response to rewards is a predictor of clinical response to Behavioral Activation Therapy for Depression (BATD), an empirically validated psychotherapy that decreases depressive symptoms by increasing engagement with rewarding stimuli and reducing avoidance behaviors.

METHODS

Participants were 33 outpatients with major depressive disorder (MDD) and 20 matched controls. We examined group differences in activation, and the capacity to sustain activation, across task runs using functional magnetic resonance imaging (fMRI) and the monetary incentive delay (MID) task. Hierarchical linear modeling was used to investigate whether pre-treatment neural responses predicted change in depressive symptoms over the course of BATD treatment.

RESULT

MDD and Control groups differed in sustained activation during reward outcomes in the right nucleus accumbens, such that the MDD group experienced a significant decrease in activation in this region from the first to second task run relative to controls. Pretreatment anhedonia severity and pretreatment task-related reaction times were predictive of response to treatment. Furthermore, sustained activation in the anterior cingulate cortex during reward outcomes predicted response to psychotherapy; patients with greater sustained activation in this region were more responsive to BATD treatment.

LIMITATION

The current study only included a single treatment condition, thus it unknown whether these predictors of treatment response are specific to BATD or psychotherapy in general.

CONCLUSION

Findings add to the growing body of literature suggesting that the capacity to sustain neural responses to rewards may be a critical endophenotype of MDD.

Cortical-Subcortical Interactions in Depression: From Animal Models to Human Psychopathology

Depression is a debilitating disorder causing significant societal and personal suffering. Improvements in identification of major depressive disorder (MDD) and its treatment are essential to reduce its toll. Recent developments in rodent models of MDD and neuroimaging of humans suffering from the disorder provide avenues through which gains can be made towards reducing its burden. In this review, new findings, integrating across rodent models and human imaging are highlighted that have yielded new insights towards a basic understanding of the disorder. In particular, this review focuses on cortical-subcortical interactions underlying the pathophysiology of MDD. In particular, evidence is accruing that dysfunction in prefrontal-subcortical circuits including the amygdala, ventral striatum (VS), hippocampus and dorsal raphe nucleus (DRN) are associated with MDD status.

Depression: Evolutionary New Neural Circuitries Are Still Adjusting for Cognition

Depression can be both normal and abnormal, and the balance of its expression determines the behavioral outcome/diagnosis. It is a complex pathophysiology based on a heterogeneous syndrome whose etiology is diverse as well. Within the context of a central nervous system, the nervous system blueprint can be found in single cells (sensory, motor, and integrative processes). These consolidated functions provide for novel coping strategies for survival. The maintenance and evolvement of this system into a central nervous system is based on conserving these functions, including chemical messengers and functionality in having specific cells medi-ate these primordial functions. Additionally, this neural coping strategy provides advantages for DNA. Thus, with different neural cells at work, pathways/networks would evolve, producing more complex behaviors and become a very critical phenomenon for future advances. This evolvement has taken over 1 billion years to de-velop. In so doing, as with any new programming (e.g., cognition), errors will occur. Given the widespread qual-ities of depression, it is surmised that this abnormality, and other psychiatric disorders, may emerge due to in-herent neural weaknesses related to cognition being a recent evolutionary development.

The Programming of the Social Brain by Stress During Childhood and Adolescence: From Rodents to Humans

The quality and quantity of social experience is fundamental to an individual's health and well-being. Early life stress is known to be an important factor in the programming of the social brain that exerts detrimental effects on social behaviors. The peri-adolescent period, comprising late childhood and adolescence, represents a critical developmental window with regard to the programming effects of stress on the social brain. Here, we discuss social behavior and the physiological and neurobiological consequences of stress during peri-adolescence in the context of rodent paradigms that model human adversity, including social neglect and isolation, social abuse, and exposure to fearful experiences. Furthermore, we discuss peri-adolescent stress as a potent component that influences the social behaviors of individuals in close contact with stressed individuals and that can also influence future generations. We also discuss the temporal dynamics programmed by stress on the social brain and debate whether social behavior alterations are adaptive or maladaptive. By revising the existing literature and defining open questions, we aim to expand the framework in which interactions among peri-adolescent stress, the social brain, and behavior can be better conceptualized.