Vagus nerve stimulation: a new form of therapeutic brain stimulation

Although the vagus nerve has traditionally been considered to perform efferent functions, in reality it performs significant afferent functions as well, carrying information from the body, head, and neck to the brain. Preliminary studies examining this afferent activity led to the theory that vagus nerve stimulation (VNS) could successfully control seizure activity in persons who are refractory to antiepileptic medications. Unlike other forms of brain stimulation, VNS is unable to directly stimulate multiple discrete areas of the brain; however, through several pathways, it is able to relay sensory information to higher brain regions. An implantable VNS device known as the VNSTM NeuroCybernetic Prosthesis (NCP) System has been used in approximately 9,000 epilepsy patients in Europe and the United States since 1994. The implant has reduced seizure frequency by an average of 25% to 30%, with minimal side effects. Studies underway are also showing some degree of success in the management of treatment-refractory depression. The future efficacy of the implantable system in other disorders may depend on whether the implant can be more precisely focused to affect different brain regions. Research in this area is underway.     

Humean dispositionalism

Humean metaphysics is characterized by a rejection of necessary connections between distinct existences. Dispositionalists claim that there are basic causal powers. The existence of such properties is widely held to be incompatible with the Humean rejection of necessary connections. In this paper I present a novel theory of causal powers that vindicates the dispositionalist claim that causal powers are basic, without embracing brute necessary connections. The key assumptions of the theory are that there are natural types of causal processes, and that manifestations of powers are identified with certain kinds of causal processes. From these assumptions, the modal features of powers are explained in terms of internal relations between powers themselves and the process-types in which powers are manifested.     

Relevant Restricted Quantification

The paper reviews a number of approaches for handling restricted quantification in relevant logic, and proposes a novel one. This proceeds by introducing a novel kind of enthymematic conditional.     

Detection of random responding on the MMPI-A

We examined random responding on the MMPI-A in 106 adolescents from the general population. Participants were asked to report on the frequency, location, and reasons for any random responses occurring during a standard administration of the MMPI-A. Relationships between self-reported random responding and validity indices (F1, F2, F, and Variable Response Inconsistency [VRIN] scale) were examined. In addition, each participant was randomly assigned to 1 of 5 groups, with each group completing an assigned portion (0, 25%, 50%, 75%, or 100%) of an MMPI-A answer sheet without access to the test booklet, and the utility of the validity scales in discriminating standard protocols from all or partially random protocols was investigated. Most adolescents acknowledged one or more random responses correlated significantly with F but not VRIN. Validity scales were sensitive to all or partially random protocols, and produced high classification rates when discriminating among groups.     

Biochemical correlates of personality traits in normals: An exploratory study

This study attempted to identify biochemical systems associated with the personality dimensions of Extraversion (E), Neuroticism (N), Psychoticism (P), Sensation Seeking (SS) and Impulsivity (Imp). The subjects were 43 normal volunteers who volunteered to take a battery of psychological tests and allow investigators to obtain samples of blood, urine and cerebrospinal fluid (CSF) for biochemical assessment.Substantial positive correlations were found between CSF norepinephrine (NE), MHPG (the principal metabolite of NE), DBH (an enzyme involved in the production of NE) and plasma MHPG and DBH; all of these are regarded, in some part, as putative indicators of central noradrenergic activity. After partialling out the influences of age, height and weight, a number of significant relationships were found between psychological traits and biochemical variables. Extraversion correlated positively and introversion and neuroticism correlated negatively with CSF Ca. Neuroticism also correlated negatively with plasma MHPG. Ego Strength (inversely related to Neurotic Introversion), P and Disinhibitory SS correlated negatively with CSF cort. General SS correlated negatively with CSF NE and plasma DBH, and these correlations were significant in both males and females, as well as in the total group. The results are consistent with some biological models of personality, but suggest the need for modification in others.