Decreased levels of N-acetylaspartate in dorsolateral prefrontal cortex in a case of intractable severe sympathetically mediated chronic pain (complex regional pain syndrome,type I)

In our previous in vivo proton magnetic resonance spectroscopy ((1)H MRS) study we found reduced levels of N-acetylaspartate in dorsolateral prefrontal cortex of chronic back pain patients. This study tests whether these chemical abnormalities can be detected in other pain states. Using (1)H MRS, we measured levels for N-acetylaspartate and other identifiable chemicals relative to creatine in four bilateral brain regions, including dorsolateral prefrontal cortex, orbitofrontal cortex, cingulate, and thalamus, in a case of intractable severe sympathetically mediated chronic pain [complex regional pain syndrome (CRPS) type I]. The subject's chemical variations in the brain were compared to the same regional chemicals in 10 normal subjects (age- and sex-matched). Univariate statistics showed reduced levels of N-acetylaspartate in bilateral dorsolateral prefrontal cortex and increased levels of myo-inositol in left orbitofrontal cortex of the patient with intractable severe CRPS type I. These data support our original hypothesis that depletion of N-acetylaspartate in dorsolateral prefrontal cortex is a chemical marker of chronic pain, indicating for neuronal degeneration. Unpredicted changes of orbitofrontal myo-inositol may be related to the specific mood/affective state in an extreme pain perception. This is the first report, which identifies chemical markers in the prefrontal cortex for objective measurement and monitoring of CRPS type I. This information might lead to valuable insights into diagnosis and future effective interventions of CRPS type I (e.g., prefrontal brain stimulation).     

Experiments on the role of painted cues in Hughes's reverspectives

The English artist Patrick Hughes has created an extraordinary class of painted artpieces, most commonly referred to as 'reverspectives'. They consist of truncated pyramids and prisms with their smaller faces closer to the viewer, in such a way as to allow a realistic scene to be painted on them. The works of art contain rich perspective and other painted cues that conspire to elicit an illusory depth percept that is the reverse of the physical depth arrangement. This reverse depth is obtained under a wide range of viewing conditions, and competes with the veridical depth percept in a classical bistable paradigm that was found to exhibit a high degree of hysteresis. Under the illusory depth percept, reverspectives appear to move vividly as the viewer moves in front of them. This paper reports two experiments that were designed to assess the effectiveness of the painted cues in eliciting the illusory depth percept by using three different measures for the strength of the illusion. As expected, the illusion was favored by monocular viewing and large viewing distances. The results from these two experiments are in close agreement with each other, and they indicate that the painted cues are powerful in influencing the ultimate percept.     

Processing of temporal duration information in working memory after frontodorsal tumour excisions

This study aimed to test the hypothesis that impairments of temporal duration processing after frontal lobe lesions reflect deficits in executive monitoring functions rather than a domain-specific deficit in the maintenance of duration information in working memory. Patients with frontodorsal lesions, clinical controls with post-central lesions, and healthy controls performed recognition and classification tasks, which should allow for testing maintenance and monitoring functions, respectively. Results showed mild non-selective impairments of the frontal patients on both temporal and spatial recognition tasks, but a marked selective degradation on temporal classification while performance on spatial classification was unimpaired. This suggests that maintenance of duration information in working memory after frontal lesions is basically preserved but that, depending on executive task characteristics, there is a specific deficit in the strategic organization of this type of information.     

Ethical and practical considerations in managing incidental findings in functional magnetic resonance imaging

Functional magnetic resonance imaging has emerged as a powerful tool for mapping the neurologic underpinnings of sensory, motor and cognitive function. Much of this evolution carries assumptions about the subject population under study and, in particular, the neurologic status of subjects entered into studies either as healthy controls or as belonging to a specific disease group. Recent reports of incidental MRI abnormalities in normal volunteers for fMRI studies have brought to attention a variety of practical challenges and ethical dilemmas for researchers, many of whom are not physicians and most of whom have no formal radiological training. We propose a minimum standard for consenting subjects in fMRI protocols, and consider strategies over the longer term that call for expert physician participation, archiving of incidental findings including false positives, and the adoption of guidelines for handling variation in neural activations or performance that appear outside expected norms.     

The trajectory of suicidal behavior over time

Some empirical work on genetic and prenatal factors in suicidality is presented. These factors may represent enduring predispositions that comprise risk for initial as well as later suicidal behavior. The existence of enduring predispositions does not preclude the possibility, however, that initial suicidal behavior sets processes into motion that spur later suicidal behavior. Based on past conceptual and empirical work, I suggest two psychological processes--cognitive sensitization and opponent processes--that may partly explain the link between past and future suicidal behavior.     

Assault victimization and suicidal ideation or behavior within a national sample of U.S. adults

Data from a nationally representative sample of 5,238 U.S. adults were used to examine the extent to which physical assault victimization was associated with suicidal ideation or behavior (SIB). The results from multivariable logistic regression analyses indicate that physical assault victimization was positively associated with SIB after adjusting for sociodemographic characteristics and alcohol use (OR = 3.6; 95% CI = 2.4-5.5). Those who were injured during the most recent physical assault (OR = 2.7; 95% CI = 1.2-6.0) and those who were assaulted by a relative (OR = 3.4; 95% CI= 1.0-11.0) or intimate partner (OR = 7.7; 95% CI = 2.7-22.5) were significantly more like to report SIB than victims who were not injured or were assaulted by a stranger. Also, those who were victimized but not injured (OR = 5.6; 95% CI = 3.8-8.2) and those who were victimized by a stranger (OR = 2.9; 95% CI = 1.4-6.0) were more likely to report SIB than non-victims. These results highlight the need for legal, medical, mental health, and social service providers to address the co-occurrence of violent victimization and suicidal ideation, particularly, but not exclusively, victimization by family members and intimates.     

Psychiatric and substance use disorders as risk factors for attempted suicide among adolescents: a case control study

The objective of this research was to test substance-related and non-substance-related psychiatric disorders as predictors of attempted suicide among adolescents. Ninety-six psychiatrically disordered suicide attempters were matched one-to-one to 96 psychiatrically disordered non-attempters on age, race, gender, and the presence/absence of major depression. Conditional logistic regression was used to test psychiatric risk factors for their power to predict attempted suicide among adolescents. Bipolar disorder, cocaine use disorders, and conduct disorder were found to be predictive of attempted suicide in univariate testing. Bipolar disorder, inhalant use disorders, cocaine use disorders, and hallucinogen use disorders were found to be predictive of attempted suicide, after adjusting for all other covariates. Loglinear analyses revealed high odds ratios associated with the comorbidities of alcohol use disorder with conduct disorder and drug use disorders with conduct disorder in both groups. Higher rates of cocaine use disorder/conduct disorder, hallucinogen use disorder/conduct disorder, and alcohol use disorder/ conduct disorder were found among suicide attempters. Evaluation of these particular comorbid conditions should be part of the adolescent suicide risk assessment.     

Gender role and personality disorders

Many researchers have hypothesized relationships between personality disorders and gender role (i.e., masculinity and femininity). However, research has not addressed if people who are masculine or feminine more often meet the criteria for personality disorders. The present study examined whether college students (N = 665, 60% women) higher in masculinity or femininity more often exhibited features of the 10 DSM-IV personality disorders. Feminine men exhibited more features of all the personality disorders except antisocial. Dependent traits were associated with higher femininity and lower masculinity. Antisocial traits were associated with masculinity. Both men and women who typically behaved consistent with their gender had more narcissistic and histrionic features, whereas participants who typically behaved unlike their gender had more features of the Cluster A personality disorders.     

When timing the mind one should also mind the timing: biases in the measurement of voluntary actions

Trevena and Miller (2002, this issue) provide further evidence that readiness potentials occur in the brain prior to the time that participants claim to have initiated a voluntary movement, a contention originally forwarded by Libet, Gleason, Wright, and Pearl (1983). In their examination of this issue, though, aspects of their data lead them to question whether their measurement of the initiation of a voluntary movement was accurate. The current article addresses this concern by providing a direct analysis of biases in this task. This was done by asking participants to make subjective timing decisions regarding a stimulus that could be measured objectively. Our findings suggest that their timing task was indeed biased such that participants' tend to report events as happening approximately 70 ms later than they actually happened. Implications for the original Libet et al. claims are discussed.     

Coincident induction of long-term facilitation at sensory-motor synapses in Aplysia: presynaptic and postsynaptic factors

Induction of long-term synaptic changes at one synapse can facilitate the induction of long-term plasticity at another synapse. Here we show that if Aplysia sensory neuron (SN) somata and their remote motor neuron (MN) synapses are simultaneously exposed to serotonin (5HT) pulses, which at either site alone are insufficient to induce long-term facilitation (LTF), processes activated at these sites interact to induce LTF. Coincident induction of LTF requires: (1) that the synaptic pulse occurs within a brief temporal window of the somatic pulse and (2) that local protein synthesis occurs immediately at the synapse, followed by delayed protein synthesis at the soma. LTF at the SN-MN synapses can also be induced with cell-wide application of repeated pulses of 5HT. However, these two forms of LTF differ mechanistically: (1) coincident LTF requires protein synthesis in the postsynaptic motor neuron, whereas repeated 5HT LTF does not, and (2) repeated 5HT LTF is accompanied by intermediate-term (3 h) facilitation, whereas coincident LTF is not. Thus LTF expressed in the same temporal domain can result from different underlying mechanisms.