Child care quality matters

Love et al. (August 2003). Child care quality matters: how conclusions may vary with context. Child Development, 74, 4, 1021-1033.

A report from the NICHD concluded that more time spent in a variety of nonmaternal care arrangements leads to more externalizing behavior problems, regardless of child care quality. Authors were skeptical and tested the generalizability of these findings with 3 other studies. These new findings suggest that quality of child care is an important factor influencing children's development, and that quality may be an important moderator of the amount of time in care.

Cultural variation in infant's sleeping arrangements

Morelli, G.A., Rogoff, B., Oppenheim, D., & Goldsmith, D. (1992). Cultural variation in infant's sleeping arrangements: Questions of Independence. Developmental Psychology, Vol. 28, No. 4, 604-613.

Cultural practices differentiate infant sleep arrangements. In the middle-class US population, a common goal is to have infants sleep in their own rooms as soon as possible, consonant with the culture's importance on independence. In the Mayan population, it is not uncommon for children to sleep with their parents or other siblings well on into childhood, reflecting their culture's value on interpersonal relations. Changes are not prescribed by the authors; instead, broader cultural perspective is offered for American readers.

Seasonal changes of hippocampus volume in parasitic cowbirds

Clayton, N.S., Reboreda, J.C., & Kacelnik, A. (1997). Seasonal changes of hippocampus volume in parasitic cowbirds. Behavioral Processes, 41, 237-243.

This study compared a set of phylogenetically closely related species with striking differences in natural behavior, offering the opportunity for seeking neural differences in association with these behavioral changes. Notable differences exist in these South American cowbirds of the genus Molothrus related to parasitic nesting. In one species, the birds are especially active during the breeding season, searching and locating potential hosts' nests. In another two species, only females are active during the breeding season in locating potential hosts' nests (sexual dimorphism). A fourth species is non-parasitic and no sexual differences are known with respect to spatial memory use in either season. Results show that the first species shows significantly larger relative hippocampal volume in the breeding season. The sexual dimorphic species show significantly larger relative hippocampal volume in the breeding season, but only in females. The evidence suggests seasonal variation in neuroanatomy associated with specific changes in behavior, namely spatial memory demands, as opposed to purely seasonal fluctuations per se.

Continuous flash suppression reduces negative afterimages

Tsuchiya, N. & Koch, C. (August 2005). Continuous flash suppression reduces negative afterimages. Nature Neuroscience, Vol. 8, No. 8, 1096-1101.

Continuous flash suppression (CFS) is a tool that can be used to reliably suppress vivid images from conscious awareness for long periods of time. Here, different patterned images ("Mondrians") are flashed rapidly into one eye while input to the corresponding location in the other eye remains fixed, the latter typically remaining unseen often for durations greater than ten times what can be achieved with binocular rivalry or other masking methods, even though the image remains present on the retina for several minutes. Interestingly, researchers discovered that negative afterimages or "photogenes", effects lingering in view after termination of the visual stimulus, also seem to be diminished with exposure to CFS. Though it is widely believed that afterimages originate among retinal neurons, this evidence supports the conclusion that the weakened afterimage must be due to interference from sites at or beyond binocular convergence, such as the lateral geniculate nucleus (LGN) or cortex. Specifically, it must be an area which receives input from both eyes but does not correspond directly to the neuronal correlates of perceptual awareness. The results hint at differences between concepts of attention and awareness.

Sign Language in the Brain

Hickok, G., Bellugi, U. & Klima, E.S. (June 2001). Sign Language in the Brain. Scientific American.

Because sign language relies heavily upon visual-spatial contrast, one might expect sign language to be supported by systems in the right hemisphere rather than the traditional left hemisphere language systems. However, this does not appear to be the case. A deaf signer with damage to Wernicke's area is likely to have comprehension difficulties and one with damage to Broca's area may have difficulty producing signs, just like normal speakers. And signers with right hemisphere damage continued to be fluent and accurate in their production of signs, used normal grammar, and comprehended signs with ease. One exception of the left hemisphere's monopoly on language production is creation of a coherent discourse, where right hemisphere damage may lead to rambling as it tends to be involved in more global-level processes. Generally speaking, sign language abilities of lifelong signers appear to be independent of their nonlinguistic spatial skills. Thus, it is likely that signers maintain unique early stages of processing compared to regular speakers, but thereafter neural organization is quite similar, being translated into a format optimized for linguistic processing and being routed to central linguistic systems.

Marijuana use as a coping response

Preston, P. (2006). Marijuana use as a coping response to psychological strain: racial, ethnic, and gender differences among young adults. Deviant Behavior, 27, 397-420.

Besides tobacco and alcohol, marijuana is the most frequently used and abused substance. This study used data taken from the National Household Survey of Drug Abuse (from all 50 states), and examined 4601 subjects between the ages of 18-25 who used marijuana within the past year. Their dependent variable was marijuana use frequency, defined as either recreational or chronic, with chronic being greater than 12 times per month. Independent variables measured included strain, economic strain, norms favorable to drug use, number of friends who use drugs, and attitudes towards risky behavior. Results were also examined through the lenses of gender, ethnicity, marital status, employment status, and education.

Results indicate that social learning factors have the strongest effect on chronic marijuana use, operationalized as the number of friends who use drugs and a personal approval of drug use. Strain (operationalized as social nervousness) had the next strongest effect. Self control had a weak effect overall. High school dropouts and the unmarried were found to be particularly at risk for becoming chronic users. Strain appeared to have a stronger effect on minority groups, possibly suggesting fewer alternative coping strategies in this population. Minority women experience a "double-whammy", more likely than their nonminority counterparts to be chronic users and also more likely to be affected by social learning and self control variables.

Love in Infant Monkeys

Harlow, H.F. (June 1959). "Love in Infant Monkeys", Scientific American.

Harlow used baby rhesus monkeys to yield insights into the origin of the infant's love for its mother and concluded that bodily contact comfort is a decisive variable in this relationship. For example, newborn monkeys preferred a surrogate "cloth" mother to a "wire" mother, and sought out the cloth mother in times of emotional stress. Other variables were also explored. A mother's rocking motion appeared to enhance affection, but less so than simple contact. Heat of the mother did not appear to be an important variable. Other visual, auditory, and olfactory stimulation may also play a role. Additionally, a critical period to attachment formation seems to be evident.

Neuronal activity related to faces and matching

Ojemann, J.G., Ojemann, G.A., & Lettich, E. (1992). Neuronal activity related to faces and matching in human right nondominant temporal cortex. Brain, 115, 1-13.

Using microelectrode recording, this group set out to look at changes in neuronal activity in response to faces, previously described in monkey cortex but not well established in humans. Recording was restricted to areas of right anterior temporal cortex that would be later resected in an epileptic lobectomy, areas that showed the least epileptic activity on electrocorticography. Seven neuronal populations related to face perception were identified. In addition, three other populations, only in middle temporal gyrus, increased activity with the labelling of the emotional expression of a face. The ease with which a given task can elicit specific, temporally-coupled changes in neuronal activity suggest that human association cortex is compartmentalized into behaviorally specific systems.

Addressing Psychosocial Problems at Work

Probst, T.M. et al. (2008). A preliminary evaluation of SOLVE: Addressing Psychosocial Problems at Work. Journal of Occupational Health Psychology, Vol. 13, No. 1, 32-42.

SOLVE is a workplace intervention program implemented by many companies worldwide which aims to address the interrelated issues of job stress, workplace violence, tobacco use, drug and alcohol abuse, and HIV/AIDS. Psychosocial issues tend to coexist, e.g. stress leads to workplace hostility which spills over into home life and often results in poor coping strategies. SOLVE is based on cognitive behavioral therapy (CBT) models, which believe that behavior is influenced by cognitions, knowledge is necessary for behavioral change, and both are broadly influenced by dynamic interactions between numerous forces. Therefore, SOLVE attempts to make individuals aware of threats and their consequences, make them aware of benefits of the touted strategies, and provide specific information for tackling the health-related issues, while being both person- and organization-directed. Although SOLVE is used widely, its efficacy has not been evaluated. Current studies demonstrate improvements in knowledge among participants across locale which is encouraging. However, they do not assess attitudinal or behavioral changes, or bottom-line benefits to the organization.

The Visual Cliff

Gibson, E.J. & Walk, R.D. (April 1960). The "Visual Cliff". Scientific American.

To investigate depth perception in human and animal species, these authors created the "visual cliff" which allowed them to experimentally adjust the optical and tactical stimuli associated with a simulated cliff while protecting the subjects from injury. They discovered that all species can perceive and avoid a sharp drop by the time they take up independent locomotion, be it at Day 1 in chicks, 4 weeks in rats, or 6 months in humans. Most rely on visual cues for depth perception. The rat, however, relies predominantly on tactual cues (being nocturnal) but will fall back on sound vision when needed. Next, the experimenters wanted to find out which visual cues played the decisive role in depth perception. Using dark-reared animals, they concluded motion parallax is an innate cue for depth discrimination, whereas responses to differential pattern-density may be learned later.

(I, Doug Girard, am the author of this article, The Visual Cliff, and I release its content under the terms of the GNU Free Documentation License, Version 1.2 and later.)

Web-based Methods in Terrorism and Disaster Research

Schlenger, W.E. & Silver, R.C. (April 2006). Web-based Methods in Terrorism and Disaster Research. Journal of Traumatic Stress, Vol. 26, No. 2, 185-193.

Gaining access to a traumatized population in the aftermath of a disaster can be challenging. The need for rapid response and appropriate probability sampling along with the observational nature of the studies (i.e. no random assignment) and post-only design can be problematic for the generalizability of the results. Recently, web-based methods have helped to address some of these age-old issues. (1) The literature indicates that people respond more honestly to sensitive questions in self-report than in interview-based assessments. (2) The use of e-mail also assists greatly with retention rates in longitudinal studies. (3) Respondents can answer surveys within the privacy of their home at a time that is convenient to them. (4) Question delivery can be standardized. (5) Time-consuming and error-prone steps of data coding and entry are eliminated. (6) And most importantly, recent companies such as Knowledge Networks Inc. have recruited nationally representative probability samples for just such uses. Panels can even be created in advance of disasters, enabling premeasure to be linked to postevent responses. However, these new technologies are not without their issues, e.g. populations may suffer infrastructure disruptions due to disaster that render data collection impossible such as in Hurricane Katrina.

The Early Origins of Autism

Rodier, P.M. (February 2000). The Early Origins of Autism. Scientific American.

Miller and Stromland made a surprising observation that 5% of thalidomide victims had autism, a rate about 30 times higher than the rate among the general population. This suggested that autism originates in the early weeks of pregnancy when the nervous system is just beginning to develop. Examining these victims' specific malformations indicated that their development had been impacted about 20-24 days into gestation, before many pregnant women even know they are pregnant. This was way earlier than investigators would have guessed, since very few neurons are even formed by the 4th week. However, most are the motor nerves of the cranial nerves in the brain stem. And indeed, many subjects with autism exhibit abnormalities of eye movement and lack of facial expression, consistent with this observation.

However, it is more likely that these early brain injuries affect more than just the function of the cranial nerve, and may interfere with proper development or wiring of other brain regions in turn. People with autism consistently show a reduction in the number of neurons in the cerebellum of the brainstem, a structure typically thought to involved in fine motor control but also seen activated during certain tasks requiring high-level cognitive processing. Some people with autism also display marked decreases in the facial nucleus (controls muscles of facial expression) and superior olive (a relay station for auditory information). Interestingly, "knock-out" mice engineered to lack the expression of the gene known as Hoxa1 (active when brainstem neurons are forming), show all of these symptoms. While variant alleles of Hoxa1 have been identified, these are only one of many genes involved in the spectrum of autism disorder. Other genes must be found which also increase the risk (or decrease the risk) of developing the disorder.

Coping with stress in different phases of romantic development

Nieder, T. & Seiffge-Krenke, I. (2001). Coping with stress in different phases of romantic development. Journal of Adolescence, 24, 297-311.

This study followed adolescents longitudinally between ages 14 and 17, annually measuring their quality of relationships, their stress levels, and their coping styles. The results taken together provide support for a developmental sequence in romantic development. The percent of participants in a relationship increased over this time period, and the durations of these relationships increased with time. With this came increases in depth -- intimacy, affection, and extent of sexual activity. Romantic stress was highest in earlier years stemming from diverse sources, later decreasing and stabilizing with age. And active coping with romantic stress was lowest initially and significantly increased at 15, remaining high. As romantic relationships develop, stress is more and more related to conflicts between the romantic partners; yet such conflicts are increasingly resolved by dyadic communication as a coping strategy. Surprisingly, the development of a more active coping style over time was not associated with the decrease in amount of romantic stress. Instead, intimacy and affection is consistently associated with reduced stress, suggesting that as the relationship matures over time romantic stress decreases.

HPA Axis, neuroendocrine factors, and stress

Tsigos, C. & Chrousos, G.P. (2002). Hypothalamic-pituitary-adrenal axis, neuroendocrine factors, and stress. Journal of Psychosomatic Research, 53, 865-871.

Psychology is concerned with the transactions and interactions we have with the world. Stress research examines how we respond to transactions that are stressful. This paper does a great job to illustrate the complexity of our physiological responses to stressors.

CRH/AVP. The paper begins with our physiological response following detection of a stressor. CRH and AVP are secreted into a special portal system and activate neurons of the paraventricular nuclei (PVN) of the hypothalamus, which primarily kicks off activation of the greater hypothalamic-pituitary-adrenal (HPA) axis.

LC/NE system. The locus ceruleus and other noradrenergic cell groups of the medulla and pons, collectively known as the LC/NE system, serve as a global alarm system, using brain epinephrine to execute autonomic and neuroendocrine responses.

The autonomic axis. The ANS provides rapid response to stress, engaging the SNS and withdrawing the PSNS, and enacting cardiovascular, respiratory, gastrointestinal, renal, and endocrine changes.

The HPA Axis. CRH and AVP normally follow certain circadian rhythms, with increasing pulses seen in the early morning hours and decreasing throughout the day. During acute stress, pulsations in this portal system markedly increase, resulting in release of ACTH from the pituitary into the general bloodstream, which finally results in secretion of cortisol and other glucocorticoids from the adrenal cortex. These corticoids involve the whole body in the organism's response to stress and ultimately contribute to the termination of the response via inhibitory feedback.

Other changes. Concomitant with the aforementioned changes, the sympathetic-adrenomedullary system (SAM) influences the body organs, and vagal and sacral parasympathetic responses are also instantiated mediating our gut responses to stress.

The paper also goes into advanced topics including interactions that exist between the HPA axis and the immune system, interactions between the HPA and the gonadal and growth axes, and interactions between the HPA and metabolism. It also discusses pathologies related to the HPA axis. A spectrum of conditions may be associated with increased and prolonged activation of the HPA axis, including melancholic depression, anorexia nervosa, OCD, panic anxiety, excessive exercising, and childhood sexual abuse. Another group of conditions may be associated with hypoactivation of the stress system, including atypical depression, seasonal depression, and chronic fatigue syndrome. Antalarmin, a CRH-R1 antagonist, was also mentioned as being a potentially important drug to combat HPA axis disorders characterized by HPA and LC/NE hyperactivity in the future.

Language Interpretation and the Immediacy Assumption

Hagoort, P. & von Berkum, J. (April 3, 2007). Beyond the sentence given. Philosophical Transactions of the Royal Society, 362, 801-811.

The view that language interpretation takes place in a two-step process has predominated, with the meaning of the sentence being computed first and the sentence meaning then being integrated with other sources of information (e.g. context, world knowledge). However, event-related brain potentials (ERPs) appear to be inconsistent with this model, finding strong empirical evidence that linguistic and extra-linguistic information are integrated in the same time-frame during sentence interpretation. Similar latencies and amplitudes of the N400 effect witnessed for all types of semantic mismatches support the immediacy assumption, that disparate information is brought to bear on language interpretation as soon as it becomes available. Neuroimaging studies suggest that the left inferior frontal cortex, including Broca's area, is an important node in the semantic unification network, and that this area is not language specific but acts as a single integration space.

Depression and cortisol responses to psychological stress

Burke, H.M., Davis, M.C., Otte, C., & Mohr, D.C. (2005). Depression and cortisol responses to psychological stress: a meta-analysis. Psychoneuroendocrinology, 30, 846-856.

This meta-analysis pulled data from seven studies (196 participants with an average age of 40), each of which examined responses to psychological (non-pharmacological) stressors. Specifically, it examined the relationship between major depressive disorder (MDD) and levels of the stress hormone cortisol during three stages of experimentally-induced stress: (1) unstimulated 'baseline', (2) 'stress reactivity' in which cortisol increases from baseline, and (3) 'stress recovery' in which cortisol returns to baseline levels.

They concluded that at baseline MDD patients have lower cortisol levels than their non-depressed (ND) counterparts in morning studies and higher baseline cortisol levels than control groups in afternoon studies. This reveals somewhat opposite patterns of normal daily cortisol fluctuation (although some have described this as simply flattened diurnal activity). Therefore, it was critical to control for these baseline effects seen in the MDD group. After adjusting for these baseline effects, MDD individuals showed blunted stress reactivity and impaired stress recovery by comparison to controls.

Put simply, normal subjects show specific baseline patterns of cortisol release throughout the day and exhibit boosted cortisol levels and rapid recovery to baseline in response to stressors. These healthy cortisol activity curves are dynamic and responsive. MDD subjects, in contrast, show abnormal baseline patterns during the day and exhibit relatively flat and unresponsive patterns of cortisol secretion during and following stress. These effects were found to be most pronounced in older and more severely depressed patients. This altered hypothalamic-pituitary-adrenal (HPA) axis functioning appears somehow linked to depression.

Aversive learning enhances perceptual and cortical discrimination

Li, W, Howard, J.D., Parrish, T.B., & Gottfried, J.A. (March 28, 2008). Aversive learning enhances perceptual and cortical discrimination of indiscriminable odor cues. Science, Vol. 319, 1842-1844.

With this study, the authors explored the impact of aversive conditioning on olfactory discrimination. While most conditioning studies examine the acquisition of new behavioral responses (CR) to formerly benign stimuli presentations, this examined how associative learning can actually alter the perceptual processing of the conditioned stimulus (CS) itself. Following a conditioning regimen, behavioral accuracy for distinguishing by smell between a previously indistinguishable pair of molecules (CS+) rose by more than a factor of 2, exceeding both chance and preconditioning performance. Interestingly, following conditioning, no improvement in distinguishing between the unconditioned control pair (CS-) was witnessed, indicating that these effects are specific to the CS+. After conditioning, reorganization of neural coding was also observed in the posterior piriform cortex, where neural representations of odor identity are maintained. This may shed new light on anxiety disorders which are characterized by exaggerated sensory sensitivity and hypervigilance, potentially self-reinforcing patterns.

Prolongation of brainstem auditory-evoked responses in Autistic probands and their unaffected relatives

Maziade, M. et al. (2000). Prolongation of brainstem auditory-evoked responses in Autistic probands and their unaffected relatives. Arch Gen Psychiatry, 57, 1077-1083.

Genetic factors play a major role in autism, with heritability greater than 90%. As the search for biological markers of autism continues, electrophysiological markers have been considered more and more. Early EEG studies comparing autistic subjects to control subjects revealed differences in early brain auditory-evoked responses (BAER). Prolonged BAERs indicate a slowing in nerve conduction within the early auditory system. This study confirmed slow latencies between consecutive sequential waves in autistic individuals, and went further to show that first degree relatives also show significantly longer interpeak latencies (IPLs) than matched controls. Although no significant prolongation was found in second and third degree relatives, resemblance of the IPL trait was found within families. While autism is a complex disorder, perhaps a combination of many neurophysiological deficits, IPL prolongation could be a marker of one of these deficits.

Anterior prefrontal function

Koechlin, E. & Hyafil, A. (October 26, 2007). Anterior prefrontal function and the limits of human decision making. Science, Vol. 318, 594-598.

Based on recent empirical findings and predictions from a neurocomputational model, the authors of this review propose a role for the not-yet-well-understood frontopolar cortex (FPC), also known as the anterior prefrontal cortex or Brodmann's area 10. They argue that processing of 'cognitive branching' is the core function of the FPC. Cognitive branching enables a previously running task to be maintained in a pending state for subsequent retrieval and execution upon completion of the ongoing one. Many of our complex behaviors and mental activities require simultaneous engagement of multiple tasks, and the FPC may perform a domain-general function in these scheduling operations.

Empowering Techniques of Play Therapy

Griffith, M. (1997). Empowering Techniques of Play Therapy: A Method for Working with Sexually Abused Children. Journal of Mental Health Counseling. 19 (2), 130-42.

This article, like many others, begins with a brief survey of play therapy theory. It is remarked that play is the natural medium of expression for children and that sexual abuse seems to block many basic developmental needs. Treatment goals are outlined and plotted along a pattern which the process of therapy follows. A case study is provided to articulate these points and exemplify the "five stages" of play therapy. These stages are the establishment of the therapeutic relationship, the later exploratory stage (in which regressive and repetitive behaviors often appear), the limit-setting stage (in which the child tests the boundaries and safety of the therapeutic setting), the growth stage (see below), and the termination stage. Treatment goals in the growth stage involve confronting the "four characteristics of sexual trauma" which are sexual traumatization, stigmatization, betrayal, and powerlessness. Sexual traumatization can lead to confusion between sexuality and affection, confusion about sexual norms, age-inappropriate sexual knowledge, and sexual behavior. It is believed that through the use of empowering techniques of play therapy (expressive/imaginative play and non-direction), the emotional distress of sexual abuse can be relieved and normal psychological development can resume.