Overlapping neural systems mediating extinction, reversal and regulation of fear

Learned fear is a process allowing quick detection of associations between cues in the environment and prediction of imminent threat. Adaptive function in a changing environment, however, requires organisms to quickly update this learning and have the ability to hinder fear responses when predictions are no longer correct. Here we focus on three strategies that can modify conditioned fear, namely extinction, reversal and regulation of fear, and review their underlying neural mechanisms. By directly comparing neuroimaging data from three separate studies that employ each strategy, we highlight overlapping brain structures that comprise a general circuitry in the human brain. This circuitry potentially enables the flexible control of fear, regardless of the particular task demands.

Identification of abnormal motor cortex activation patterns in children with cerebral palsy by functional near-infrared spectroscopy

We demonstrate the utility of functional near-infrared spectroscopy (fNIRS) as a tool for physicians to study cortical plasticity in children with cerebral palsy (CP). Motor cortex activation patterns were studied in five healthy children and five children with CP (8.4+/-2.3 years old in both groups) performing a finger-tapping protocol. Spatial (distance from center and area difference) and temporal (duration and time-to-peak) image metrics are proposed as potential biomarkers for differentiating abnormal cortical activation in children with CP from healthy pediatric controls. In addition, a similarity image-analysis concept is presented that unveils areas that have similar activation patterns as that of the maximum activation area, but are not discernible by visual inspection of standard activation images. Metrics derived from the images presenting areas of similarity are shown to be sensitive identifiers of abnormal activation patterns in children with CP. Importantly, the proposed similarity concept and related metrics may be applicable to other studies for the identification of cortical activation patterns by fNIRS.

Reliability of the Tardieu Scale for assessing spasticity in children with cerebral palsy

OBJECTIVE

To measure the Tardieu Scale's reliability in children with cerebral palsy (CP) when used by raters with and without experience in using the scale, before and after training.

DESIGN

Single-center, intrarater and interrater reliability study.

SETTING

Institutional ambulatory care.

PARTICIPANTS

Referred children with CP in the pretraining phase (n=5), during training (n=3), and in the posttraining phase (n=15).

INTERVENTIONS

The Tardieu Scale involves performing passive muscle stretch at 2 velocities, slow and fast. The rater derives 2 parameters; the Spasticity Angle X is the difference between the angles of arrest at slow speed and of catch-and-release or clonus at fast speed; the Spasticity Grade Y is an ordinal variable that grades the intensity (gain) of the muscle reaction to fast stretch. In phase 1, experienced raters without formalized training in the scale graded elbow, knee, and ankle plantar flexors bilaterally, without and with a goniometer. In phase 2, after training, the experienced and nonexperienced raters graded the same muscles unilaterally.

MAIN OUTCOME MEASURES

Intrarater and interrater reliability of the Tardieu Scale.

RESULTS

After training, nonexperienced raters had mean +/- SD intrarater and interrater agreement rates across all joints and parameters of 80%+/-14% and 74%+/-16%, respectively. For experienced raters, intrarater and interrater agreement rates before training were 77%+/-13% and 66%+/-15%, respectively, versus 90%+/-8% and 81%+/-13%, respectively, after training (P<.001 for both). Specific angle measurements at the knee were less reliable for the angles of catch measured at fast speed. Across all joints, agreement rates were similar using visual or goniometric measurements.

CONCLUSIONS

Both parameters of the Tardieu Scale have excellent intrarater and interrater reliability when assessed at the elbow and ankle joints of children with CP, with no difference noted between visual and goniometric measurements. Angle measurements were less reliable at the knee joints. Training was associated with a highly significant improvement in reliability.

Management of children with holoprosencephaly

Holoprosencephaly (HPE) is the most common malformation of the embryonic forebrain in humans. Although HPE occurs along a continuous spectrum, it has been categorized into four types from most severe to least severe: alobar, semilobar, lobar, and middle interhemispheric (MIH) variant. Facial malformations are often associated with HPE and usually correlate with the severity of brain malformation. With the most severely affected newborns, there is a high mortality rate in the first month of life, however, with milder forms of HPE, the majority survive beyond infancy. The Carter Centers for Brain Research in Holoprosencephaly and Related Malformations have enrolled 182 living children in a prospective research study. Based on previously published reports using this database, reports from other investigators, as well as our experience and personal observations, the range of developmental, neurological, and medical problems found in children with HPE is described in this article. Virtually all children with HPE have some developmental disability and the severity correlates with the severity of the brain malformation on neuroimaging. Common medical problems include hydrocephalus, seizures, motor impairment, oromotor dysfunction with risk of poor nutrition and aspiration, chronic lung disease, gastroesophageal reflux, constipation, hypothalamic dysfunction with disturbed sleep-wake cycles and temperature dysregulation, as well as endocrine dysfunction. Diabetes insipidus in particular is found in about 70% of children with classic HPE. Recommendations for management of these problems are given based on experiences of the authors and familiarity with the literature.

Practice parameter: pharmacologic treatment of spasticity in children and adolescents with cerebral palsy (an evidence-based review): report of the Quality Standards Subcommittee of the American Academy of Neurology and the Practice Committee of the Child Neurology Society

OBJECTIVE

To evaluate published evidence of efficacy and safety of pharmacologic treatments for childhood spasticity due to cerebral palsy.

METHODS

A multidisciplinary panel systematically reviewed relevant literature from 1966 to July 2008.

RESULTS

For localized/segmental spasticity, botulinum toxin type A is established as an effective treatment to reduce spasticity in the upper and lower extremities. There is conflicting evidence regarding functional improvement. Botulinum toxin type A was found to be generally safe in children with cerebral palsy; however, the Food and Drug Administration is presently investigating isolated cases of generalized weakness resulting in poor outcomes. No studies that met criteria are available on the use of phenol, alcohol, or botulinum toxin type B injections. For generalized spasticity, diazepam is probably effective in reducing spasticity, but there are insufficient data on its effect on motor function and its side-effect profile. Tizanidine is possibly effective, but there are insufficient data on its effect on function and its side-effect profile. There were insufficient data on the use of dantrolene, oral baclofen, and intrathecal baclofen, and toxicity was frequently reported.

RECOMMENDATIONS

For localized/segmental spasticity that warrants treatment, botulinum toxin type A should be offered as an effective and generally safe treatment (Level A). There are insufficient data to support or refute the use of phenol, alcohol, or botulinum toxin type B (Level U). For generalized spasticity that warrants treatment, diazepam should be considered for short-term treatment, with caution regarding toxicity (Level B), and tizanidine may be considered (Level C). There are insufficient data to support or refute use of dantrolene, oral baclofen, or continuous intrathecal baclofen (Level U).

Mutations in ZIC2 in human holoprosencephaly: description of a novel ZIC2 specific phenotype and comprehensive analysis of 157 individuals

BACKGROUND

Holoprosencephaly (HPE), the most common malformation of the human forebrain, may be due to mutations in genes associated with non-syndromic HPE. Mutations in ZIC2, located on chromosome 13q32, are a common cause of non-syndromic, non-chromosomal HPE.

OBJECTIVE

To characterise genetic and clinical findings in patients with ZIC2 mutations.

METHODS

Through the National Institutes of Health and collaborating centres, DNA from approximately 1200 individuals with HPE spectrum disorders was analysed for sequence variations in ZIC2. Clinical details were examined and all other known cases of mutations in ZIC2 were included through a literature search.

RESULTS

By direct sequencing of DNA samples of an unselected group of unrelated patients with HPE in our NIH laboratory, ZIC2 mutations were found in 8.4% (49/582) of probands. A total of 157 individuals from 119 unrelated kindreds are described, including 141 patients with intragenic sequence determined mutations in ZIC2. Only 39/157 patients have previously been clinically described. Unlike HPE due to mutations in other genes, most mutations occur de novo and the distribution of HPE types differs significantly from that of non-ZIC2 related HPE. Evidence is presented for the presence of a novel facial phenotype which includes bitemporal narrowing, upslanting palpebral fissures, a short nose with anteverted nares, a broad and well demarcated philtrum, and large ears.

CONCLUSIONS

HPE due to ZIC2 mutations is distinct from that due to mutations in other genes. This may shed light on the mechanisms involved in formation of the forebrain and face and will help direct genetic counselling and diagnostic strategies.

Avoiding negative outcomes: tracking the mechanisms of avoidance learning in humans during fear conditioning

Previous research across species has shown that the amygdala is critical for learning about aversive outcomes, while the striatum is involved in reward-related processing. Less is known, however, about the role of the amygdala and the striatum in learning how to exert control over emotions and avoid negative outcomes. One potential mechanism for active avoidance of stressful situations is postulated to involve amygdala–striatal interactions. The goal of this study was to investigate the physiological and neural correlates underlying avoidance learning in humans. Specifically, we used a classical conditioning paradigm where three different conditioned stimuli (CS) were presented. One stimulus predicted the delivery of a shock upon stimulus offset (CS+), while another predicted no negative consequences (CS−). A third conditioned cue also predicted delivery of a shock, but participants were instructed that upon seeing this stimulus, they could avoid the shock if they chose the correct action (AV+). After successful learning, participants could then easily terminate the shock during subsequent stimulus presentations (AV−). Physiological responses (as measured by skin conductance responses) confirmed a main effect of conditioning, particularly showing higher arousal responses during pre (AV+) compared to post (AV−) learning of an avoidance response. Consistent with animal models, amygdala–striatal interactions were observed to underlie the acquisition of an avoidance response. These results support a mechanism of active coping with conditioned fear that allows for the control over emotional responses such as fears that can become maladaptive and influence our decision-making.

Clinical spectrum of SIX3-associated mutations in holoprosencephaly: correlation between genotype, phenotype and function

BACKGROUND

Holoprosencephaly (HPE) is the most common structural malformation of the human forebrain. There are several important HPE mutational target genes, including the transcription factor SIX3, which encodes an early regulator of Shh, Wnt, Bmp and Nodal signalling expressed in the developing forebrain and eyes of all vertebrates.

OBJECTIVE

To characterise genetic and clinical findings in patients with SIX3 mutations.

METHODS

Patients with HPE and their family members were tested for mutations in HPE-associated genes and the genetic and clinical findings, including those for additional cases found in the literature, were analysed. The results were correlated with a mutation-specific functional assay in zebrafish.

RESULTS

In a cohort of patients (n = 800) with HPE, SIX3 mutations were found in 4.7% of probands and additional cases were found through testing of relatives. In total, 138 cases of HPE were identified, 59 of whom had not previously been clinically presented. Mutations in SIX3 result in more severe HPE than in other cases of non-chromosomal, non-syndromic HPE. An over-representation of severe HPE was found in patients whose mutations confer greater loss of function, as measured by the functional zebrafish assay. The gender ratio in this combined set of patients was 1.5:1 (F:M) and maternal inheritance was almost twice as common as paternal. About 14% of SIX3 mutations in probands occur de novo. There is a wide intrafamilial clinical range of features and classical penetrance is estimated to be at least 62%.

CONCLUSIONS

Our data suggest that SIX3 mutations result in relatively severe HPE and that there is a genotype-phenotype correlation, as shown by functional studies using animal models.

Acute stress modulates risk taking in financial decision making

People's decisions are often susceptible to various demands exerted by the environment, leading to stressful conditions. Although a goal for researchers is to elucidate stress-coping mechanisms to facilitate decision-making processes, it is important to first understand the interaction between the state created by a stressful environment and how decisions are performed in such environments. The objective of this experiment was to probe the impact of exposure to acute stress on financial decision making and examine the particular influence of stress on decisions with a positive or negative valence. Participants' choices exhibited a stronger reflection effect when participants were under stress than when they were in the no-stress control phase. This suggests that stress modulates risk taking, potentially exacerbating behavioral bias in subsequent decision making. Consistent with dual-process approaches, decision makers fall back on automatized reactions to risk under the influence of disruptive stress.

The role of the striatum in aversive learning and aversive prediction errors

Neuroeconomic studies of decision making have emphasized reward learning as critical in the representation of value-driven choice behaviour. However, it is readily apparent that punishment and aversive learning are also significant factors in motivating decisions and actions. In this paper, we review the role of the striatum and amygdala in affective learning and the coding of aversive prediction errors (PEs). We present neuroimaging results showing aversive PE-related signals in the striatum in fear conditioning paradigms with both primary (shock) and secondary (monetary loss) reinforcers. These results and others point to the general role for the striatum in coding PEs across a broad range of learning paradigms and reinforcer types.

Computational and FTIR spectroscopic studies on carbon monoxide and dinitrogen adsorption on a high-silica H-FER zeolite

Adsorption (at a low temperature) of carbon monoxide and dinitrogen on a high-silica ferrierite-type zeolite (H-FER, Si : Al = 27.5 : 1) was investigated by means of variable temperature infrared spectroscopy and theoretical calculations at the periodic DFT level. This combined experimental and computational approach led to detailed characterization of several types of hydrogen-bonded OHCO and OHN(2) complexes, formed by interaction between the adsorbed molecules and the Brønsted acid OH groups of the zeolite. CO or N(2), forming linear complexes with OH groups pointing towards a sufficiently ample void space, show the largest adsorption enthalpy which was found to be in the (approximate) range of -25 to -29 kJ mol(-1) for CO and -15 to -19 kJ mol(-1) for N(2). Less stable OHCO or OHN(2) complexes can be formed when either the Brønsted acid OH group is involved in intra-zeolite hydrogen bonding or when the free space available is too small to allow formation of linear complexes without previous re-location of the proton of the OH group involved. The details of experimental IR spectra in the O-H, C-O, and N-N stretching regions could be interpreted on the basis of good agreement between experimental and calculated results.

Neural circuitry underlying the regulation of conditioned fear and its relation to extinction

Recent efforts to translate basic research to the treatment of clinical disorders have led to a growing interest in exploring mechanisms for diminishing fear. This research has emphasized two approaches: extinction of conditioned fear, examined across species; and cognitive emotion regulation, unique to humans. Here, we sought to examine the similarities and differences in the neural mechanisms underlying these two paradigms for diminishing fear. Using an emotion regulation strategy, we examine the neural mechanisms of regulating conditioned fear using fMRI and compare the resulting activation pattern with that observed during classic extinction. Our results suggest that the lateral PFC regions engaged by cognitive emotion regulation strategies may influence the amygdala, diminishing fear through similar vmPFC connections that are thought to inhibit the amygdala during extinction. These findings further suggest that humans may have developed complex cognition that can aid in regulating emotional responses while utilizing phylogenetically shared mechanisms of extinction.

Understanding overbidding: using the neural circuitry of reward to design economic auctions

We take advantage of our knowledge of the neural circuitry of reward to investigate a puzzling economic phenomenon: Why do people overbid in auctions? Using functional magnetic resonance imaging (fMRI), we observed that the social competition inherent in an auction results in a more pronounced blood oxygen level-dependent (BOLD) response to loss in the striatum, with greater overbidding correlated with the magnitude of this response. Leveraging these neuroimaging results, we design a behavioral experiment that demonstrates that framing an experimental auction to emphasize loss increases overbidding. These results highlight a role for the contemplation of loss in understanding the tendency to bid "too high." Current economic theories suggest overbidding may result from either "joy of winning" or risk aversion. By combining neuroeconomic and behavioral economic techniques, we find that another factor, namely loss contemplation in a social context, may mediate overbidding in auctions.

Response of motor complications in Cockayne syndrome to carbidopa-levodopa

BACKGROUND

Gait difficulties, tremors, and coordination difficulties are common features of Cockayne syndrome that are consequences of leukodystrophy, cerebellar atrophy, and demyelinating neuropathy, but no pharmacotherapy for these disabling symptoms is available.

OBJECTIVE

To determine whether carbidopa-levodopa relieves tremors and other motor complications of Cockayne syndrome.

DESIGN

Mutation analysis and case report study.

SETTING

Hospital clinic and genetics research laboratory. Patients We studied 3 patients with Cockayne syndrome, a rare autosomal recessive neurodegenerative disorder for which no known treatments are available. Intervention Carbidopa-levodopa therapy.

MAIN OUTCOME MEASURES

Status of tremors, ability to perform daily tasks, serial physical examinations, and results of handwriting samples.

RESULTS

All 3 patients had a clear reduction in tremors and improvements in handwriting and manipulation of utensils and cups.

CONCLUSIONS

Patients with Cockayne syndrome should be evaluated carefully for movement disorders. A clinical trial should be considered to evaluate this therapy further.

Effect of smoking opportunity on responses to monetary gain and loss in the caudate nucleus

The authors examined the effects of smoking opportunity on neural responses to monetary outcomes in nicotine-deprived cigarette smokers. Participants who were told that they would be able to smoke during the study exhibited smaller responses to monetary gains and losses in the caudate nucleus than did those who anticipated having to wait several hours before having the opportunity to smoke. These findings highlight the importance of investigating the effects of perceived drug use opportunity on motivational processing in addicted populations.

Fool me once, shame on you; fool me twice, shame on oxytocin

In this issue of Neuron, a study by Baumgartner et al. investigates the influence of oxytocin on trust behavior and its neural mechanisms. The authors report that, following breaches of trust, oxytocin facilitates prosocial behavior while modulating neural signals in the amygdala and caudate nucleus. The findings have implications for an array of mental disorders where social behavior is compromised.

The role of the dorsal striatum in reward and decision-making

Although the involvement in the striatum in the refinement and control of motor movement has long been recognized, recent description of discrete frontal corticobasal ganglia networks in a range of species has focused attention on the role particularly of the dorsal striatum in executive functions. Current evidence suggests that the dorsal striatum contributes directly to decision-making, especially to action selection and initiation, through the integration of sensorimotor, cognitive, and motivational/emotional information within specific corticostriatal circuits involving discrete regions of striatum. We review key evidence from recent studies in rodent, nonhuman primate, and human subjects.

Reward-Related Responses in the Human Striatum

Much of our knowledge of how reward information is processed in the brain comes from a rich animal literature. Recently, the advancement of neuroimaging techniques has allowed researchers to extend such investigations to the human brain. A common finding across species and methodologies is the involvement of the striatum, the input structure of the basal ganglia, in a circuit responsible for mediating goal-directed behavior. Central to this idea is the role of the striatum in the processing of affective stimuli, such as rewards and punishments. The goal of this article is to probe the human reward circuit, specifically the striatum and its subdivisions, with an emphasis on how the affective properties of outcomes or feedback influence the underlying neural activity and subsequent decision making. Discussion will first focus on anatomical and functional considerations regarding the striatum that have emerged from animal models. The rest of the article will center on how human neuroimaging studies map to findings from the animal literature, and how more recently, this research can be extended into the social and economic domains.

Genotype/phenotype correlation in 325 individuals referred for a diagnosis of tuberous sclerosis complex in the United States

Tuberous sclerosis complex is an autosomal dominant neurocutaneous disorder marked by hamartoma growth in multiple organ systems. We performed mutational analyses on 325 individuals with definite tuberous sclerosis complex diagnostic status. We identified mutations in 72% (199/257) of de novo and 77% (53/68) of familial cases, with 17% of mutations in the TSC1 gene and 50% in the TSC2 gene. There were 4% unclassified variants and 29% with no mutation identified. Genotype/phenotype analyses of all observed tuberous sclerosis complex findings in probands were performed, including several clinical features not analyzed in two previous large studies. We showed that patients with TSC2 mutations have significantly more hypomelanotic macules and learning disability in contrast to those with TSC1 mutations, findings not noted in previous studies. We also observed results consistent with two similar studies suggesting that individuals with mutations in TSC2 have more severe symptoms. On performing meta-analyses of our data and the other two largest studies in the literature, we found significant correlations for several features that individual studies did not have sufficient power to conclude. Male patients showed more frequent neurologic and eye symptoms, renal cysts, and ungual fibromas. Correlating genotypes with phenotypes should facilitate the disease management of tuberous sclerosis complex.

How personal experience modulates the neural circuitry of memories of September 11

Brown and Kulik [Brown R, Kulik J (1977) Cognition 5:73-99] introduced the term "flashbulb memory" to describe the recall of shocking, consequential events such as hearing news of a presidential assassination. They proposed that the vivid detail of such memories results from the action of a unique neural mechanism. In the present study of personal recollections of the terrorist attacks of September 11, 2001 (9/11) in New York City, we combine behavioral and brain imaging techniques, with two goals: (i) to explore the neural basis of such memories and (ii) to clarify the characteristics of the emotional events that may give rise to them. Three years after the terrorist attacks, participants were asked to retrieve memories of 9/11, as well as memories of personally selected control events from 2001. At the time of the attacks, some participants were in Downtown Manhattan, close to the World Trade Center; others were in Midtown, a few miles away. The Downtown participants exhibited selective activation of the amygdala as they recalled events from 9/11, but not while they recalled control events. This was not the case for the Midtown participants. Moreover, only the Downtown participants reported emotionally enhanced recollective experiences while recalling events from 9/11, as compared with control events. These results suggest that close personal experience may be critical in engaging the neural mechanisms that underlie the emotional modulation of memory and thus in producing the vivid recollections to which the term flashbulb memory is often applied.

Definition and classification of negative motor signs in childhood

In this report we describe the outcome of a consensus meeting that occurred at the National Institutes of Health in Bethesda, Maryland, March 12 through 14, 2005. The meeting brought together 39 specialists from multiple clinical and research disciplines including developmental pediatrics, neurology, neurosurgery, orthopedic surgery, physical therapy, occupational therapy, physical medicine and rehabilitation, neurophysiology, muscle physiology, motor control, and biomechanics. The purpose of the meeting was to establish terminology and definitions for 4 aspects of motor disorders that occur in children: weakness, reduced selective motor control, ataxia, and deficits of praxis. The purpose of the definitions is to assist communication between clinicians, select homogeneous groups of children for clinical research trials, facilitate the development of rating scales to assess improvement or deterioration with time, and eventually to better match individual children with specific therapies. "Weakness" is defined as the inability to generate normal voluntary force in a muscle or normal voluntary torque about a joint. "Reduced selective motor control" is defined as the impaired ability to isolate the activation of muscles in a selected pattern in response to demands of a voluntary posture or movement. "Ataxia" is defined as an inability to generate a normal or expected voluntary movement trajectory that cannot be attributed to weakness or involuntary muscle activity about the affected joints. "Apraxia" is defined as an impairment in the ability to accomplish previously learned and performed complex motor actions that is not explained by ataxia, reduced selective motor control, weakness, or involuntary motor activity. "Developmental dyspraxia" is defined as a failure to have ever acquired the ability to perform age-appropriate complex motor actions that is not explained by the presence of inadequate demonstration or practice, ataxia, reduced selective motor control, weakness, or involuntary motor activity.

Performance feedback drives caudate activation in a phonological learning task

Adults have difficulty discriminating nonnative phonetic contrasts, but under certain circumstances training can lead to improvement in this ability. Despite the ubiquitous use of performance feedback in training paradigms in this and many other domains, the mechanisms by which feedback affects learning are not well understood. In this event-related functional magnetic resonance imaging study, we examined how performance feedback is processed during perceptual learning. Thirteen Japanese speakers for whom the English phonemes [r] and [l] were nondistinct performed an identification task of the words "road" and "load" that has been shown to be effective in inducing learning only when performance feedback is present. Each subject performed alternating runs of training with and without feedback, followed by performance of a card-guessing task with monetary reward and punishment outcomes. We found that the caudate nucleus was more robustly activated bilaterally when performing the perceptual identification task with feedback than without feedback, and the right caudate nucleus also showed a differential response to positive and negative feedback. Moreover, using a within-subjects design, we found that the caudate nucleus also showed a similar activation pattern to monetary reward and punishment outcomes in the card-guessing task. These results demonstrate that the caudate responds to positive and negative feedback during learning in a manner analogous to its processing of extrinsic affective reinforcers and indicate that this region may be a critical moderator of the influence of feedback on learning. These findings impact our broader understanding of the mechanisms underlying nondeclarative learning and language acquisition.

Factor analysis of neuroanatomical and clinical characteristics of holoprosencephaly

The objective of this study is to better understand the relationship between neuroradiologic and clinical characteristics in holoprosencephaly (HPE) using the multivariate analysis called factor analysis. HPE is a brain malformation characterized by incomplete cleavage of the cerebral hemispheres and deep gray structures. We performed evaluations on 89 children with HPE that included their history, developmental assessment, and physical examination. Ten clinical variables included in factor analysis were the grade of spasticity, dystonia, choreoathetosis, hypotonia, mobility, upper extremity/hand function, expressive language, feeding/swallowing difficulty, endocrinopathies, and temperature dysregulation. Five neuroimaging variables graded by pediatric neuroradiologists were the grade of HPE (from least to most severe: lobar, semilobar, and alobar) and the degree of non-separation of caudate, lentiform, thalamic, and hypothalamic nuclei. Factor analysis using principle component extraction and varimax rotation was utilized. Four significant factors were identified: (1) neuroimaging/developmental factor, (2) motor factor, (3) hypothalamic/oromotor factor, and (4) hypotonia factor. These four factors accounted for 65.2% of the variance. In this factor analysis of HPE patients, we were able to reduce the large number of clinical and radiological variables into four factors. These factors and the constructs underlying them provide structure to the data and provide key parameters for future studies involving neurodevelopmental outcomes in HPE.

Extending animal models of fear conditioning to humans

A goal of fear and anxiety research is to understand how to treat the potentially devastating effects of anxiety disorders in humans. Much of this research utilizes classical fear conditioning, a simple paradigm that has been extensively investigated in animals, helping outline a brain circuitry thought to be responsible for the acquisition, expression and extinction of fear. The findings from non-human animal research have more recently been substantiated and extended in humans, using neuropsychological and neuroimaging methodologies. Research across species concur that the neural correlates of fear conditioning include involvement of the amygdala during all stages of fear learning, and prefrontal areas during the extinction phase. This manuscript reviews how animal models of fear are translated to human behavior, and how some fears are more easily acquired in humans (i.e., social-cultural). Finally, using the knowledge provided by a rich animal literature, we attempt to extend these findings to human models targeted to helping facilitate extinction or abolishment of fears, a trademark of anxiety disorders, by discussing efficacy in modulating the brain circuitry involved in fear conditioning via pharmacological treatments or emotion regulation cognitive strategies.