Russell Meares

Amygdala-Prefrontal Dissociation of Subliminal and Supraliminal Fear

Facial expressions of fear are universally recognized signals of potential threat. Humans may have evolved specialized neural systems for responding to fear in the absence of conscious stimulus detection. We used functional neuroimaging to establish whether the amygdala and the medial prefrontal regions to which it projects are engaged by subliminal fearful faces and whether responses to subliminal fear are distinguished from those to supraliminal fear. We also examined the time course of amygdala‐medial prefrontal responses to supraliminal and subliminal fear. Stimuli were fearful and neutral baseline faces, presented under subliminal (16.7 ms and masked) or supraliminal (500 ms) conditions. Skin conductance responses (SCRs) were recorded simultaneously as an objective index of fear perception. SPM2 was used to undertake search region‐of‐interest (ROI) analyses for the amygdala and medial prefrontal (including anterior cingulate) cortex, and complementary whole‐brain analyses. Time series data were extracted from ROIs to examine activity across early versus late phases of the experiment. SCRs and amygdala activity were enhanced in response to both subliminal and supraliminal fear perception. Time series analysis showed a trend toward greater right amygdala responses to subliminal fear, but left‐sided responses to supraliminal fear. Cortically, subliminal fear was distinguished by right ventral anterior cingulate activity and supraliminal fear by dorsal anterior cingulate and medial prefrontal activity. Although subcortical amygdala activity was relatively persistent for subliminal fear, supraliminal fear showed more sustained cortical activity. The findings suggest that preverbal processing of fear may occur via a direct rostral–ventral amygdala pathway without the need for conscious surveillance, whereas elaboration of consciously attended signals of fear may rely on higher‐order processing within a dorsal cortico–amygdala pathway. Hum Brain Mapp, 2005.

Quantified EEG Activity in Adolescent Attention Deficit Hyperactivity Disorder

The aim of this study was to explore elements of the maturational and cortical hypoarousal models in adolescent ADHD, by examining EEG activity in a rest eyes open condition, in 26 adolescent unmedicated ADHD males and 26 age and sex matched normal controls. ADHD adolescents were found to have increased anterior EEG absolute theta activity and reduced posterior relative beta activity compared with controls. These results lend some support to the continuation of a maturational lag and reduced cortical arousal in adolescent ADHD. These measures need to be further explored using concomitant EEG with electrodermal measures of arousal.

Simultaneous EEG and EDA measures in adolescent attention deficit hyperactivity disorder

Adolescent unmedicated ADHD males and age- and sex-matched normal control subjects were examined simultaneously using EEG and EDA measures in a resting eyes-open condition. ADHD adolescents showed increased absolute and relative Theta and Alpha1 activity, reduced relative Beta activity, reduced skin conductance level (SCL) and a reduced number of non-specific skin conductance responses (NS.SCRs) compared with the control subjects. Our findings indicate the continuation of increased slow wave activity in ADHD adolescents and the presence of a state of autonomic hypoarousal in this clinical group.

The differential diagnosis of dementia using P300 latency

The P300 component was elicited by an auditory oddball paradigm in 55 normal adults from a wide age range: 19 patients with dementia, 17 patients with depression, and 15 patients with schizophrenia. Normal P300 latency at a given age was predicted by using an age regression equation that had been calculated on the basis of the entire normal sample. Using this procedure, an abnormal delay in latency (greater than 2 SD) was found in approximately 80% of the dementia patients. However, when normal latency was predicted with a slightly greater degree of reliability according to separate equations for adults younger and older than 63 years, an abnormal delay in P300 was found to be less sensitive and specific to dementia. Suggestions for enhancing the diagnostic utility of the P300 component are proposed.

Synchronous cortical gamma-band activity in task-relevant cognition.

Widespread synchronous oscillatory activity, particularly in the gamma (‘40 Hz’) band, has been postulated to exist in the brain as a mechanism underlying binding. A new method of examining phase synchronicity across multiple electrode sites in specific EEG frequency bands as a function of time was employed, in a conventional cognitive ERP paradigm in 40 normal subjects. A significant late post-stimulus gamma synchronicity response occurred for task-relevant stimuli, whereas for task-irrelevant stimuli no such response was evident. However, an early response was seen for both task-relevant and irrelevant stimuli. This is the first empirical demonstration that widespread synchronous high frequency oscillations occur in humans in relation to cognition.

Psychotherapy with borderline patients: I. A comparison between treated and untreated cohorts

Objective: The aim of this study is to compare the clinical outcome of patients with borderline personality disorder (BPD) who had received outpatient psychotherapy for 1 year with BPD patients who received no formal psychotherapy for the same period. Method: Thirty patients with BPD were treated by trainee psychotherapists working according to clearly described therapeutic principles. They received intensive audiotaped supervision. Patients were seen twice weekly for 1 year. They were compared with 30 patients subsequently referred to the clinic, for whom no therapist was available and who remained on a waiting list for 1 year, receiving their usual treatment. The outcome measure was a score derived from DSM criteria. It was taken at the beginning and end of the years treatment, in the former case, and after at least 1 year on the waiting list in the latter. (The average waiting period was 17.1 months.) Results and Conclusions: Patients who received psychotherapy were significantly improved in terms of the DSM score. Thirty percent of treated patients no longer fulfilled DSM-III criteria for BPD. The untreated patients were unchanged.

The Modulation of Late Component Event Related Potentials by Pre-Stimulus EEG Theta Activity in ADHD

Electroencephalography (EEG) and Event Related Potentials (ERPs) studies in ADHD have generally been studied separately. This study examined these measures simultaneously in 54 adolescent unmedicated ADHD males and age and gender matched normal controls during an auditory oddball paradigm. Compared with controls, ADHD patients showed increased pre-stimulus EEG Theta activity and post-stimulus reduced N200 amplitude, increased P200 amplitude and delayed N200 and P300 latencies evoked to target stimuli. Moreover, Theta activity was negatively correlated with N200 amplitude and positively correlated with P200, N200 and P300 latency in ADHD. There were no correlations in the control group. Pre-stimulus preparatory state increases in Theta activity in ADHD may underlie some of the reported disturbances in information processing reflected in ADHD.

The P300 ERP component: an index of cognitive dysfunction xin depression?

A number of measures of brain function have suggested that depression is associated with cerebral hypoactivity. This study examines the late components of the event-related potential (ERP), in particular the P300 component, in depression. The P300 component is thought to index the updating of neurocognitive models which are concerned with the prediction of future events. Cognitive theories of depression include the proposition that depression may be characterized by abnormalities in the prediction of future events. The P300 component may therefore provide one neurophysiological index of cognitive dysfunction in depression. Twenty-seven subjects (14 medicated, 13 drug-free) fulfilling DSM-III criteria for Major Depression were compared to 27 age- and sex-matched normal controls. The amplitudes and latencies of N100, P200, N200 and P300 ERP components, reaction time and task accuracy were recorded during a standard auditory discrimination task. No significant differences were found in any ERP component measure or in reaction-time between the groups. Depressed subjects performed the experimental task significantly less accurately than normal controls, but this was not reflected in the ERPs.

NATURAL HISTORY OF SPASMODIC TORTICOLLIS, AND EFFECT OF SURGERY

Abstract 41 cases of spasmodic torticollis were followed up in an attempt to discover the natural history of the condition, and the effect of surgery upon it. Unoperated cases generally deteriorated during the first five years of the illness, which then became static or tended to improve. 10 significant remissions occurred, 9 of these in the first five years. It was during this period that operation was usually performed. Those patients who received bilateral cervical rhizotomies fared considerably worse than the unoperated cases, and in some the operation was followed by severe disability. Such disability was not seen in any unoperated case.

Psychotherapy with Borderline Patients: II. A Preliminary Cost Benefit Study

Objective: The aim of this study was to conduct a preliminary cost benefit study of the effect of outpatient psychotherapy, twice a week for 1 year, in 30 borderline patients. Method: Costs to the health system in terms of inpatient care for the year before treatment were compared with the costs for the year following treatment. Results: The cost of hospital admissions for the 30 patients for the year before treatment was