Functional magnetic resonance imaging of cocaine craving

OBJECTIVE

Identification of brain activity associated with craving is important for understanding the neurobiology of addiction.

METHOD

Brain activity was measured in cocaine addicts and healthy subjects by functional magnetic resonance imaging (fMRI) while the subjects watched videotapes designed to elicit happy feelings, sad feelings, or the desire to use cocaine. The subjects indicated the onset of drug craving or emotional response, allowing comparison of groups before and after such feelings.

RESULTS

Robust activation of the anterior cingulate was evident in patients watching cocaine-cue tapes but not in patients watching happy or sad tapes or in healthy subjects under any condition. Anterior cingulate activation preceded the reported onset of craving and was evident in patients who did not report craving. In contrast, patients showed less activation than healthy subjects during the cocaine-cue tapes in areas of the frontal lobes. After the reported onset of craving, cocaine-dependent subjects showed greater activity than healthy subjects in regions that are more active in healthy subjects when they watch sad tapes than when they watch happy tapes, suggesting a physiologic link between cocaine-cue responses and normal dysphoric states. Dynamic aspects of regional brain activations, but not the location of activations, were abnormal in cocaine-dependent subjects watching sad tapes, suggesting more general affective dysregulation. Patients showed low activation of sensory areas during initial viewing of all videotapes, suggesting generalized alteration in neuroresponsiveness.

CONCLUSIONS

Cocaine cues lead to abnormally high cingulate and low frontal lobe activation in cocaine addicts. Addicts also show more general abnormalities in affect-related brain activation.

An fMRI study of the human cortical motor system response to increasing functional demands

Functional magnetic resonance imaging (fMRI) was used to study activation changes in the human primary motor-sensory areas (MAs), supplementary motor areas (SMAs), premotor areas (PMAs) and the superior and inferior parietal areas (SPAs, IPAs) during right hand finger movements as the rate, force and complexity of movement were varied. A preliminary reproducibility study of a single subject doing the same repetitive index finger movements in nine different sessions over a six week period demonstrated highly consistent and highly localized activation in the contralateral MA. ANOVAs demonstrated highly significant main effects of increasing the force and complexity of movement, thereby illustrating the distributed and integrated systemic character of the cortical motor system. Interactions between brain region and the rate and complexity of movements suggested functional specialization of some components of the system. Increasing the rate of movement led to increased activity only in the contralateral MA; increasing complexity led to greater increases in activity in the left and right SPAs and the left IPA than in other areas. Although activation was evident in varying degree throughout the multiple motor areas, only the MAs showed consistent lateralization of activation.

Neurocognitive enhancement therapy with work therapy: effects on neuropsychological test performance

BACKGROUND

Cognitive deficits are a major determinant of social and occupational dysfunction in schizophrenia. In this study, we determined whether neurocognitive enhancement therapy (NET) in combination with work therapy (WT) would improve performance on neuropsychological tests related to but different from the training tasks.

METHODS

Sixty-five patients with schizophrenia or schizoaffective disorder were randomly assigned to NET plus WT or WT alone. Neurocognitive enhancement therapy included computer-based training on attention, memory, and executive function tasks; an information processing group; and feedback on cognitive performance in the workplace. Work therapy included paid work activity in job placements at the medical center (eg, mail room, grounds, library) with accompanying supports. Neuropsychological testing was performed at intake and 5 months later.

RESULTS

Prior to enrollment, both groups did poorly on neuropsychological testing. Patients receiving NET + WT showed greater improvements on pretest-posttest variables of executive function, working memory, and affect recognition. As many as 60% in the NET + WT group improved on some measures and were 4 to 5 times more likely to show large effect-size improvements. The number of patients with normal working memory performance increased significantly with NET + WT, from 45% to 77%, compared with a decrease from 56% to 45% for those receiving WT.

CONCLUSIONS

Computer training for cognitive dysfunction in patients with schizophrenia can have benefits that generalize to independent outcome measures. Efficacy may result from a synergy between NET, which encourages mental activity, and WT, which allows a natural context for mental activity to be exercised, generalized, and reinforced.

Cortical dysfunction in schizophrenia during auditory word and tone working memory demonstrated by functional magnetic resonance imaging

BACKGROUND

Verbal learning and memory deficits are among the most severe cognitive deficits observed in schizophrenia. We have demonstrated that such deficits do not extend to working memory for tones in a substantial number of patients even when verbal working memory is impaired. In this study we used functional magnetic resonance imaging to study the neural basis of this dissociation of auditory verbal and nonverbal working memory in individuals with schizophrenia.

METHODS

While undergoing functional magnetic resonance imaging, 12 schizophrenic patients and 12 matched control subjects performed auditory Word Serial Position Task and Tone Serial Position Task.

RESULTS

Both tasks produced activation in frontal cortex and temporal and parietal lobes of the cerebrum in both groups. While robust activation was observed in the left inferior frontal gyrus (areas 6, 44, and 45) in the control group during the Word Serial Position Task, activation in the patient group was much reduced in these areas and failed to show the same task-specific activation as in controls. Reduced activation in patients was not confined to the inferior frontal gyrus, but also extended to a medial area during the Tone Serial Position Task and to premotor and anterior temporal lobe areas during both tasks.

CONCLUSIONS

These findings support the hypothesis that abnormalities in cortical hemodynamic response in the inferior frontal gyrus underlie the verbal working memory deficit in schizophrenia. The relationship of verbal working memory deficits to other cognitive functions suggests that abnormal functioning in the speech-related areas may reflect a critical substrate of a broad range of cognitive dysfunctions associated with schizophrenia.

Increasing the power of dichotic methods: the fused rhymed words test

A dichotic test made up of monosyllabic rhymed CVC words was modified to minimize stimulus dominance and errors and then administered to 194 dextrals and 175 sinistrals in four different laboratories. The proportion of subjects with left ear advantages in both the right and left-handed groups closely approximated that expected from neurologic data. This dichotic test appears to reflect hemispheric specialization for language function more accurately than previously available tests. Further direct validation studies are needed, however, comparing direction of ear asymmetry and other indices of hemispheric specialization for language on a subject by subject basis.

Preliminary evidence of improved verbal working memory performance and normalization of task-related frontal lobe activation in schizophrenia following cognitive exercises

OBJECTIVE

The authors' goal was to evaluate the possibility of treating brain and behavioral aspects of verbal memory dysfunction in patients with schizophrenia through cognitive exercises.

METHOD

Eight patients did daily verbal memory exercises that became progressively more difficult over a 10-week training period. Memory performance and regional brain activations during a verbal memory task were assessed before and after these exercises.

RESULTS

Verbal but not nonverbal memory performance improved after training; three patients made substantial gains, and five showed little change. Performance gains were correlated with increases in task-related activation of the left inferior frontal cortex. One patient given 5 extra weeks of training 6 weeks after the initial training period showed maintenance of initial performance gains 6 weeks after training, further improvement after the second period of training, and normalization of task-related activation of the left inferior frontal cortex.

CONCLUSIONS

Verbal memory deficits can be ameliorated by memory exercises in some patients with schizophrenia. Performance improvements are associated with increased task-related activation of the same brain region that is activated during verbal memory tasks in healthy individuals.

Cognitive remediation of working memory deficits: durability of training effects in severely impaired and less severely impaired schizophrenia

OBJECTIVE

To determine whether augmenting work therapy (WT) with neurocognitive enhancement therapy (NET) yields greater improvement in working memory performance than WT alone and whether there is an interaction with severity of impairment.

METHOD

A total of 102 participants with schizophrenia or schizoaffective disorder were categorized as severely or less severely cognitively impaired and randomly assigned to receive NET + WT or WT alone. NET consisted of cognitive training exercises in attention, memory, executive function, and social information processing, and WT was a 6-month work program.

RESULTS

Comparison on Digits Backwards from intake to follow-up revealed significantly greater improvement for participants receiving NET + WT, but there was no interaction with severity group. Follow-up 6 months after training showed that training effects endured.

CONCLUSION

NET + WT improved working memory for most participants regardless of impairment severity. Intensity and duration of training may have contributed to duration of effects. Findings support continued exploration of cognitive remediation.

Cerebral laterality and psychiatry: a review of the literature

The two sides of the human brain are functionally and anatomically different. Research methods based on this cerebral laterality have been used to investigate regional brain function in psychiatric illness. The author describes the functional and anatomic differences between the two sides of the brain, the research methods based on these differences, and the results of studies that have used these methods to investigate brain dysfunction in psychiatric illness.

Word and tone working memory deficits in schizophrenia

BACKGROUND

Verbal memory deficits have been reported in many studies of patients with schizophrenia. We evaluated the specificity of these deficits by comparing patients and control subjects on several verbal and nonverbal auditory memory tests.

METHODS

Performance of stable, medicated outpatients with DSM-III-R diagnoses of schizophrenia (N = 38) was compared with that of healthy subjects (N = 39) on a word list immediate recall task, tone delayed discrimination tasks, and word and tone serial position tasks. Before memory testing, patients were divided into 2 groups based on their ability to perform normally on a screening test requiring pitch discrimination and sustained attention.

RESULTS

The nonverbal tests were more difficult for control subjects than the verbal tests. Despite this, patients who performed normally on the screening test of perception and attention performed normally on both nonverbal tests but had highly significant deficits on both verbal tests (P<.001 and P = .02). Patients who performed poorly on the screening test had highly significant performance deficits on all the memory tests.

CONCLUSIONS

One subgroup of patients with schizophrenia has a selective deficit in verbal memory despite normal motivation, attention, and general perceptual function. Another group has deficits in multiple aspects of cognitive function suggestive of failure in early stages of information processing.

Functional significance of individual variations in callosal area

We considered the hypothesis that the richness of callosal interhemispheric connections has a role in determining the degree of behavioural laterality and time-sharing ability in dual-task performance. Behavioural laterality as measured by dichotic word listening, line bisection and turning bias tests correlated inversely with the midsagittal cross-sectional area of the corpus callosum, as seen on MRI. The amount of dual task interference was strongly inversely correlated with the callosal area in both within-hemisphere and between-hemispheres conditions. These relationships between normal variations in callosal area, and outcomes on tests both of laterally and time-sharing capacity in normal adults suggest that the corpus callosum assumes a cross-excitatory role when subjects perform these tasks.

Alterations in cerebral laterality during acute psychotic illness

A dichotic listening test was used to assess cerebral laterality in 26 right-handed patients with schizophrenic, schizoaffective, or primary major depressive illness and in 23 controls. Clinical state was assessed by twice-daily nurses' ratings and patient self-ratings. Ratings of psychotic thought and behavior were lower during the week of highest laterality than during the week of lowest laterality (P less than .01). Similarly, when most improved, patients had higher laterality than when most ill (P less than .01). Changes in laterality were not specific to diagnostic group, were not present in control subjects, could not be related to direct drug effects, and were independent of changes in accuracy of performance. There were large, stable, interindividual differences in degree of lateralization, but no differences between patients and controls. These results are consistent with the hypothesis that in acute psychotic illness there is a breakdown in the interhemisphere inhibition that normally mediates cerebral laterality.

Functional MR imaging of regional brain activation associated with the affective experience of pain

OBJECTIVE

Current models propose that the experience of pain includes both sensory and affective components. Our purpose was to use functional MR imaging to determine areas of the brain engaged by the affective dimension of pain.

SUBJECTS AND METHODS

Twelve healthy adults underwent functional MR imaging using a gradient-echo echoplanar technique while a cold pressor test, consisting of cold and pain tasks, was applied first to one foot and then to the other. The cold task involved the application of cold water (14-20 degrees C) that was not at a painful level. For the pain task, the water temperature was then lowered to a painful temperature (8-14 degrees C) and subsequently to the pain threshold (3-8 degrees C). Images acquired at room temperature before the cold and pain tasks served as a baseline task. Composite maps of brain activation were generated by comparing the baseline task with the cold task and the cold task with the pain task. The significance of signal changes was estimated by randomization of individual activation maps.

RESULTS

Cold-related activation (p < 0.01) was found in the postcentral gyrus bilaterally, laterally, and inferiorly to the primary motor-sensory area of the foot and at a site near the second somatosensory site. Activation also occurred in the frontal lobe (the bilateral middle frontal gyri and the right inferior frontal gyrus), the left anterior insula, the left thalamus, and the superior aspect of the anterior cingulate gyrus (seen at one slice location). Pain-related activation (p < 0.01) included the anterior cingulate gyrus (seen at four slice locations); the superior frontal gyrus, especially on the right; and the right cuneus.

CONCLUSION

Compared with the basic sensory processing of pain, the affective dimension of pain activates a cortical network that includes the right superior frontal gyrus, the right cuneus, and a large area of the anterior cingulate gyrus.

Computerized cognitive remediation training for schizophrenia: an open label, multi-site, multinational methodology study

A recent single-site study (Fisher et al., 2009. Am J Psychiatry. 166 (7) 805-11) showed that repeated training with the Brain Fitness Program (BFP) improved performance on a battery of neuropsychological tasks. If replicated these data suggest an important non-pharmacological method for ameliorating cognitive impairment in schizophrenia. Our study evaluated the BFP training effects in an open-label, multi-site, multinational clinical trial. Fifty-five stable adult patients with schizophrenia on regular antipsychotic medication completed ≥ 32 BFP training sessions over 8-10 weeks. Training effects on cognitive performance and functional capacity outcome measures were measured using CogState® schizophrenia battery, UCSD Performance based Skills Assessment (UPSA-2) and Cognitive Assessment Interview (CAI). BFP training showed a large and significant treatment effect on a training exercise task (auditory processing speed), however this effect did not generalize to improved performance on independent CogState® assessment. There were no significant effects on UPSA-2 or CAI scores. Our study demonstrated the feasibility of implementing BFP training in a multi-site study. However, BFP training did not show significant treatment effects on cognitive performance or functional capacity outcome measures despite showing large and significant effects on a training exercise.

Functional magnetic resonance imaging assessment of the human brain auditory cortex response to increasing word presentation rates

In an investigation of the auditory cortex response to speech, six subjects were studied using echo-planar functional magnetic resonance imaging (fMRI) at 2.1T. The subjects were asked to listen to English nouns presented at various rates ranging from 0 words per minute (wpm) to 130 wpm while fMRI images encompassing their primary and posterior superior secondary auditory cortices were acquired. An asymmetric spin echo imaging sequence was used with an induced T2 weighting of 50 ms to allow for transverse relaxation effects. Images were acquired in two or four axial-oblique slices with a repetition time of 3.75 or 7.5 s, in plane resolution of 6 x 3 mm, and a slice thickness of 5 mm. Localized activation centered over grey matter was consistently observed in all subjects in the transverse temporal gyrus (TTG), the transverse temporal sulcus (TTS), and the posterior superior aspect of the superior temporal gyrus (STG). The total activate volume and the integrated signal response in bilateral primary and posterior superior secondary auditory cortices increased with increasing rate of word presentation, peaking at 90 wpm (with some intersubject variability) with a subsequent fall at 130 wpm. There were no significant differences in the rate dependence of the signal response in bilateral primary and bilateral posterior superior secondary auditory cortices (P < 0.05).

Changes in perceptual asymmetry with the menstrual cycle

Changes in perceptual asymmetry between the premenstrual and postmenstrual phases of the menstrual cycle were assessed in 39 women. Perceptual asymmetry was measured with fused, single response dichotic listening tests. The usual right ear advantage (REA) for auditory language-related stimuli was significantly greater in the postmenstrual phase of the cycle. Subjects with repressive personality styles were less likely to show a change in REA with the cycle. These neuropsychological findings are related to previously described physiological and psychological features of the menstrual cycle and the repressive personality style.

Neuroleptic exposure following inpatient treatment of acute mania with lithium and neuroleptic

The authors examined continued neuroleptic exposure following inpatient treatment of mania with neuroleptics and lithium through structured chart review of 40 consecutive patients. At discharge, patients were receiving a mean of 793 mg/day (SD = 695) chlorpromazine equivalents; 6 months later they were receiving a mean of 634 mg/day (SD = 684). This decrease was statistically significant, but the patients' ongoing neuroleptic exposure remained substantial.

Decreased perceptual sensitivity to emotion-evoking stimuli in depression

We measured two aspects of emotional response in depressed patients, as a preliminary study of the potential usefulness of such measures for elucidating pathophysiological mechanisms. First we used electromyography to measure the automatic mimicry on an individual's own face of facial displays of emotion observed on the faces of others. Next we used the fused dichotic listening paradigm to measure selective perception of both positive and negative emotion-related words as opposed to neutral words. Patients failed to show the normal facial mimicry of both positive and negative facial displays, despite normal cognitive processing of the stimuli. They also heard significantly fewer positive and negative words on the dichotic tests than did healthy controls. This suggests that depressed patients are hyposensitive to emotion-related stimuli in general.

EEG and EMG responses to emotion-evoking stimuli processed without conscious awareness

Dichotic stimulus pairs were constructed with one word that was emotionally neutral and another that evoked either negative or positive feelings. Temporal and spectral overlap between the members of each pair was so great that the two words fused into a single auditory percept. Subjects were consciously aware of hearing only one word from most pairs; sometimes the emotion-evoking word was heard consciously, other times the neutral word was heard consciously. Subjects were instructed to let their thoughts wander in response to the word they heard, during which time EEG alpha activity over left and right frontal regions, and muscle activity (EMG) in the corrugator ("frowning") and zygomatic ("smiling") regions were recorded. Both EEG and EMG provided evidence of emotion-specific responses to stimuli that were processed without conscious awareness. Moreover both suggested relatively greater right hemisphere activity with unconscious rather than conscious processing.

The outpatient treatment of depression. Implications of outcome research for clinical practice

Multiple studies have demonstrated that individual psychotherapy, pharmacotherapy, and the two in combination are all effective treatments for depressed outpatients. However, the implications of these data for clinical practice have been incompletely considered, and the often drawn mistaken conclusion is that they support routine treatment with psychotherapy and pharmacotherapy together. Analyses of treatment success rates, treatment failure rates, and treatment dropout rates indicate that combined treatment offers no advantage over treatment with psychotherapy alone and only modest advantage over treatment with pharmacotherapy alone. Routine use of combined treatment, therefore, exposes patients to unnecessary costs and side effects. The data suggest that psychotherapy alone should usually be the initial treatment.

Effects of emotion on perceptual asymmetry: interactions with personality

Perceptual asymmetry on a series of four specially constructed dichotic word tests was found to change as a function of the emotional quality of the words in the tests (P = 0.05). This was most pronounced in the case of positively valued words which produced an increase in asymmetry consistent with facilitated left-hemisphere function (P less than 0.004). Changes in asymmetry with emotion differed as a function of personality characteristics of the subjects, with repressors and high anxious subjects showing an increase with emotion while true low anxious subjects showed a decrease (P less than 0.02). Personality groups also differed in asymmetry on an emotionally neutral test (P less than 0.04) and in changes in asymmetry over time independent of emotion (P less than 0.001). These data suggest that emotion mediated activation of the left hemisphere may facilitate information processing within that hemisphere. Moreover, they indicate that dichotic listening tests may provide a non-invasive and inexpensive method for assessing emotion mediated changes in brain state that are clinically relevant.

Abnormalities in rapid, automatic aspects of attention in schizophrenia: blunted inhibition of return

When a visual cue is presented at the same location but 100 ms prior to presentation of a visual stimulus, reaction time to the stimulus is decreased. However, in healthy subjects if the interval between the cue and the stimulus is between 500 and 1500 ms, reaction time is increased ('inhibition of return'). The present experiment compared inhibition of return in 11 medicated and clinically stable schizophrenic outpatients and 11 healthy control subjects screened by SADS-L. Healthy subjects responded faster to true cues than false cues when the interval between cue and stimulus was 100 ms, but responded equally fast in the two conditions with a 200 ms interval and responded faster to false than true cues at 700 and 1200 ms intervals. Schizophrenics, in contrast, responded faster to true than false cues at both 100 and 200 ms intervals and showed lower than normal advantages on false as compared to true cues at 700 and 1200 ms intervals (group x cue type x interval interaction p < 0.01). Thus while schizophrenics showed 'inhibition of return' it did not begin until greater than normal intervals between cue and stimulus and was blunted in magnitude. This suggests failure of inhibitory mechanisms that are important in very rapid and automatic aspects of normal attention.

Normal neurocognitive performance after extended practice in patients with schizophrenia

This study evaluated new methods for improving the performance of patients with schizophrenia on specific neurocognitive tasks. Patients (n = 22) practiced sustained perceptual, memory and motor tasks 5 times/week for 10 weeks. Tasks were initially easy enough for patients to do well, but were made gradually more difficult over the 10 weeks. Patients received base pay and performance-based monetary supplements. No coaching or ongoing instruction was provided, and performance gains were assumed to depend upon implicit learning. High functioning healthy controls (n = 5) were given the same tasks at difficulty levels comparable to those achieved by patients after 10 weeks of practice. After 10 weeks of practice, 16 of the 22 patients performed as well or better than the best control on the perceptual and memory tasks, and 11 patients performed within the range of control subjects on the motor task. Half of the patients retested 6 months after training maintained supranormal performance, while the others showed marked performance declines. Patients with schizophrenia appear to have greater potential for neurocognitive improvement, and potentially for employment, than generally appreciated.

Perceptual asymmetry differences between major depression with or without a comorbid anxiety disorder: a dichotic listening study

Predictions that anxious and nonanxious depression would differ in perceptual asymmetry (PA), as well as in sensitivity for perceiving emotional words, were evaluated using dichotic listening tasks. A total of 149 patients having a major depressive disorder (51 with and 98 without an anxiety disorder) and 57 healthy controls were tested on fused-word and complex tone tasks. The anxious and nonanxious depression groups showed a consistent difference in PA across tasks; that is, the anxious group had a larger left-ear advantage for tones and a smaller right-ear advantage for words when compared with the nonanxious group. There was no group difference in sensitivity for perceiving emotional words. Patients having an anxious depression appear to have a greater propensity to activate right than left-hemisphere regions during auditory tasks, whereas those having a nonanxious depression have the opposite hemispheric asymmetry.