Timothy Y. Mariano

Impulsive choice in hippocampal but not orbitofrontal cortex-lesioned rats on a nonspatial decision-making maze task

Orbitofrontal cortical (OFC) and hippocampal (HPC) lesions in primates and rodents have been associated with impulsive behaviour. We showed previously that OFC‐ or HPC‐lesioned rats chose the immediate low‐reward (LR) option in preference to the delayed high‐reward (HR) option, where LR and HR were associated with different spatial responses in a uniform grey T‐maze. We now report that on a novel nonspatial T‐maze task in which the HR and LR options are associated with patterned goal arms (black‐and‐white stripes vs. gray), OFC‐lesioned rats did not show impulsive behaviour, choosing the delayed HR option, and were indistinguishable from controls. In contrast, HPC‐lesioned rats exhibited impulsive choice in the nonspatial decision‐making task, although they chose the HR option on the majority of trials when there was a 10‐s delay associated with both goal arms. The previously reported impairment in OFC‐lesioned rats on the spatial version of the intertemporal choice task is unlikely to reflect a general problem with spatial learning, because OFC lesions were without effect on acquisition of the standard reference memory water‐maze task and spatial working memory performance (nonmatching‐to‐place) on the T‐maze. The differential effect of OFC lesions on the two versions of the intertemporal choice task may be explained instead in terms of the putative role of OFC in using associative information to represent expected outcomes and generate predictions. The impulsivity in HPC‐lesioned rats may reflect impaired temporal information processing, and emphasizes a role for the hippocampus beyond the spatial domain.

Can Transcranial Direct Current Stimulation Augment Extinction of Conditioned Fear

BACKGROUND Exposure-based therapy parallels extinction learning of conditioned fear. Prior research points to the ventromedial prefrontal cortex as a potential site for the consolidation of extinction learning and subsequent retention of extinction memory. OBJECTIVE/HYPOTHESIS The present study aimed to evaluate whether the application of non-invasive transcranial direct current stimulation (tDCS) during extinction learning enhances late extinction and early recall in human participants. METHODS Forty-four healthy volunteers completed a 2-day Pavlovian fear conditioning, extinction, and recall paradigm while skin conductance activity was continuously measured. Twenty-six participants received 2 mA anodal tDCS over EEG coordinate AF3 during extinction of a first conditioned stimulus. The remaining 18 participants received similar tDCS during extinction of a second conditioned stimulus. Sham stimulation was applied for the balance of extinction trials in both groups. Normalized skin conductance changes were analyzed using linear mixed models to evaluate effects of tDCS over late extinction and early recall trials. RESULTS We observed a significant interaction between timing of tDCS during extinction blocks and changes in skin conductance reactivity over late extinction trials. These data indicate that tDCS was associated with accelerated late extinction learning of a second conditioned stimulus after tDCS was combined with extinction learning of a previous conditioned stimulus. No significant effects of tDCS timing were observed on early extinction recall. CONCLUSIONS Results could be explained by an anxiolytic aftereffect of tDCS and extend previous studies on tDCS-induced modulation of fear and threat related learning processes. These findings support further exploration of the clinical use of tDCS.

Toward a more holistic understanding of filicide: a multidisciplinary analysis of 32 years of U.S. arrest data.

Filicide is the killing of one or more children by a parent, stepparent, or other parental figure. This study presents the first comprehensive analysis of U.S. filicide, drawn from 94,146 filicide arrests tabulated over a 32-year period in the U.S. Federal Bureau of Investigations Supplementary Homicide Reports (SHR). Filicides comprised 15% of all murders during this period. Modal victim age was less than one year old. One-third of the victims were under a year old; over two-thirds of the victims were age six or less. Fathers were as likely as mothers to kill infants. The mean age of offenders was 32 years with a mode of 22 years, and nearly three-quarters were aged 18-45. Female offenders were notably younger than their male counterparts. Black (or African American) offenders were significantly overrepresented in filicide compared to Whites. Most common killing methods included using hands and feet, strangulation, beating, asphyxiation, drowning, and defenestration. Stepparents were not at higher risk of filicide than genetic parents, but were twice as likely to kill using firearms. Synthesizing these results with studies from other fields, we propose three transdisciplinary, empirically informed filicide categories primarily defined by effects of (1) psychopathology associated with neurotransmitter disturbances, (2) gender and sex hormones, and (3) evolutionary motives. Approaching filicide using this proposed hypothetical framework for future research may help identify at-risk populations and improve prevention and treatment.

The Feline Dorsal Nerve of the Penis Arises from the Deep Perineal Nerve and Not the Sensory Afferent Branch

The cat has been used extensively as an animal model for urogenital studies involving the pudendal nerve. However, discrepancies persist in the literature regarding the origin of the dorsal nerve of the penis (DNP). This study used gross dissections and serial histological cross sections to demonstrate that the DNP arises from the deep perineal nerve and not the sensory afferent branch as previously reported. This finding indicates a better than previously appreciated neuroanatomical homology between the cat and human.

Sexual homicide in the USA committed by juveniles and adults, 1976–2007: Age of arrest and incidence trends over 32 years

BACKGROUND Reliable epidemiological data on sexual homicide are sparse, especially on trends in its incidence over time and age at arrest. AIMS Our main aims were to study age at arrest and incidence trends for sexual homicide in the USA over about three decades (1976-2007). METHODS We conducted longitudinal analyses of data from the largest USA homicide database available for the years 1976-2007. RESULTS The mean age at arrest for a sexual homicide was 26.3 years (range 7-76; modal 21 years). Three quarters of these offenders were young adults aged 18-35. Age at probable first arrest for a sexual homicide rose significantly from a mean of 25 to a mean of 29 years over the study period. The last decade of the three studied accounted for just one quarter of the homicides as charged in the whole period, but the proportion of sexual homicides specifically fell with each decade, so that the first period accounted for 56% of those in the whole period, the second for 33% and the final decade for just 11%. This was reflected in a reduction in the proportion of all homicides that were sexual, from 1.4% in the first decade to 0.8% in the second and 0.4% in the third, declining by a factor of five for adults and seven for juveniles. CONCLUSIONS Use of official national criminal statistics has limitations in studying the epidemiology of any particular behaviour. Nonetheless, our findings of falling sexual homicide rates and of changes in at least one important demographic of these killers indicate a need for a considered reappraisal of such crimes. Establishment of accurate epidemiology and a study of associated factors may assist in the improvement of investigative and preventive strategies.

Suppression of reflex urethral responses by sacral dermatome stimulation in an acute spinalized feline model

Reflex contractions of the external urethral sphincter (EUS) are a major component of voiding dysfunction after neurological injury or disease. Aberrant urethral reflexes can prevent voiding and cause serious medical complications. Characterizing these urethral reflexes during genitourinary studies is necessary for evaluating novel pharmacological or neuroprosthetic approaches. The objectives of the present study were to generate urethral reflexes in the acute spinal feline, to quantify these reflexes, and to suppress them with electrical stimulation of the sacral dermatomes.

Sexual Homicide by Older Male Offenders

Recent research has expanded our understanding of sexual homicide offenders (SHOs). However, little exists beyond case reports for older SHOs. We characterized male SHOs ≥ 55 years, comparing them to typical adult male SHOs who are in their 20s. Analysis of 37 years (1976–2012) of US Supplementary Homicide Reports data provided a large SHO sample (N = 3453). Three case reports provide clinical context for the diverse nature and patterns of older SHOs. Only 32 older male SHOs and no older female SHOs were identified. Murders by older SHOs accounted for only 0.5% of US sexual homicides. Unlike typical SHOs that generally target young adult females, over two‐thirds of older SHO victims were ≥40 years, and one‐third were ≥55 years. Sexual homicides by older SHOs, like sexual homicide in general, decreased over the study period. These crimes, while exceedingly rare, do occur, warranting special consideration.

Transcranial Direct Current Stimulation for Affective Symptoms and Functioning in Chronic Low Back Pain: A Pilot Double-Blinded, Randomized, Placebo-Controlled Trial

Background and Objective Chronic low back pain (CLBP) is highly prevalent, with a substantial psychosocial burden. Pain has both sensory and affective components. The latter component is a significant driver of disability and psychiatric comorbidity but is often inadequately treated. Previously we reported that noninvasive transcranial direct current stimulation (tDCS) may modulate pain-associated affective distress. Here we tested whether 10 daily tDCS sessions aimed to inhibit the left dorsal anterior cingulate cortex (dACC), a region strongly implicated in the affective component of pain, would produce selective reduction in pain-related symptoms. Methods In this multisite, double-blinded, randomized placebo-controlled trial (RCT), 21 CLBP patients received 10 weekday sessions of 2-mA active tDCS or sham (20 minutes/session). A cathodal electrode was placed over FC1 (10-20 electroencephalography coordinates), and an identical anodal return electrode was placed over the contralateral mastoid. Participants rated pain intensity, acceptance, interference, disability, and anxiety, plus general anxiety and depression. Results Regression analysis noted significantly less pain interference (P =0.002), pain disability (P =0.001), and depression symptoms (P =0.003) at six-week follow-up for active tDCS vs sham. Omnibus tests suggested that these improvements were not merely due to baseline (day 1) group differences. Conclusions To our knowledge, this is the first double-blinded RCT of multiple tDCS sessions targeting the left dACC to modulate CLBPs affective symptoms. Results are encouraging, including several possible tDCS-associated improvements. Better-powered RCTs are needed to confirm these effects. Future studies should also consider different stimulation schedules, additional cortical targets, high-density multi-electrode tDCS arrays, and multimodal approaches.

Corrigendum to "Toward a more holistic understanding of filicide: A multidisciplinary analysis of 32 years of U.S. arrest data" [Forensic Sci. Int. 236 (2014) 46-53].

The study analyzed 15,961 filicide arrests comprising 2.5% of all murders during the study period. Materials and methods 15,961 (2.5%) of cases were classified as filicides.