Current topics in behavioral neurosciences
-
Curr Top Behav Neurosci · Jan 2013
ReviewTheoretical frameworks and mechanistic aspects of alcohol addiction: alcohol addiction as a reward deficit disorder.
Alcoholism can be defined by a compulsion to seek and take drug, loss of control in limiting intake, and the emergence of a negative emotional state when access to the drug is prevented. Alcoholism impacts multiple motivational mechanisms and can be conceptualized as a disorder that includes a progression from impulsivity (positive reinforcement) to compulsivity (negative reinforcement). The compulsive drug seeking associated with alcoholism can be derived from multiple neuroadaptations, but the thesis argued here is that a key component involves the construct of negative reinforcement. ⋯ A brain stress response system is hypothesized to be activated by acute excessive drug intake, to be sensitized during repeated withdrawal, to persist into protracted abstinence, and to contribute to the compulsivity of alcoholism. Other components of brain stress systems in the extended amygdala that interact with CRF and that may contribute to the negative motivational state of withdrawal include norepinephrine, dynorphin, and neuropeptide Y. The combination of loss of reward function and recruitment of brain stress systems provides a powerful neurochemical basis for a negative emotional state that is responsible for the negative reinforcement driving, at least partially, the compulsivity of alcoholism.
-
Curr Top Behav Neurosci · Jan 2012
ReviewThe role of diffusion tensor imaging in the study of cognitive aging.
This chapter gives an overview of the role that diffusion tensor MRI (DTI) can play in the study of cognitive decline that is associated with advancing age. A brief overview of biological injury processes that impinge on the aging brain is provided, and their overall effect on the integrity of neural architecture is described. ⋯ We then survey the existing findings on relationships between aging-associated neuropathological processes and DTI measurements on one hand; and relationships between DTI measurements and late-life cognitive function on the other. We conclude with a summary of current research directions in relation to DTI studies of cognitive aging.
-
Since the discovery of the endocannabinoid system, a growing body of psychiatric research has emerged focusing on the potential role of this system in schizophrenia. On the basis of earlier epidemiological studies and results from animal models, endocannabinoids and their relation to symptoms are considered in clinical studies as well as in post-mortem analyses of cannabinoid CB₁ receptor densities. A possible neurobiological mechanism for the deleterious influence of cannabis use in schizophrenia is discussed, involving the disruption of endogenous cannabinoid signalling and function.