Joseph J. Tecce

Contingent negative variation and the distraction--arousal hypothesis.

Thirty-two normal volunteers were tested in three conditions: (1) a constant-foreperiod reaction-time situation consisting of a flash--tone--key-press sequence (control condition); (2) the addition of a short-term memory task consisting of four letters presented within the flash--tone interval with the requirement that they be repeated after key-press to tone (letters--recall); (3) the presentation of letters without short-term memory (letters--no recall). The task involving short-term memory of letters produced a significant reduction in amplitude of CNV for central (Cz) and parietal (Pz) recording sites. The association of CNV decrease and lengthened reaction time to tone was interpreted as a CNV distraction effect. The accompaniment of this distraction effect by elevated heart rate levels and increased frequency of eyeblinks was considered a distraction--arousal association and an important source of disruption in CNV development. These results were interpreted as support for the distraction--arousal hypothesis and appear to provide a sensitive complex of four measures for the evaluation of psychological processes, including the assessment of psychotropic drug effects. Eyeblink frequency in particular appears to be a sensitive indicator of distraction--arousal processes and a potentially useful measure of disturbed psychological functioning. The finding in control conditions of lower CNV amplitude in frontal than in central and posterior recording sites was viewed as a distraction effect due to efforts at eye movement control. The possibility was raised that frontal areas of the brain mediate sustained (tonic) distraction effects whereas centro-parietal regions mediate phasic distraction effects, at least when produced by stimuli of a lexical nature.

Eye movement control of computer functions

The control of computer functions by eye movements was demonstrated in 14 normal volunteers. Electrical potentials recorded by horizontal and vertical electrooculography (EOG) were transformed into a cursor that represented a moving fixation point on a computer display. Subjects were able to spell words and sentences by using eye movements to place the cursor on target letters in the display of an alphabet matrix. The successful demonstration of computer-controlled syntactic construction by eye movements offers a potentially useful technique for computer-assisted communication in special groups, such as developmentally-disabled individuals who have motor paralysis and who cannot speak.

Cortical plasticity, contingent negative variation, and transcendent experiences during practice of the Transcendental Meditation technique.

This study investigated effects of transcendent experiences on contingent negative variation (CNV) amplitude, CNV rebound, and distraction effects. Three groups of age-matched subjects with few (<1 per year), more frequent (10-20 per year), or daily self-reported transcendent experiences received 31 simple RT trials (flash (S(1))/tone (S(2))/button press) followed by 31 divided-attention trials - randomly intermixed trials with or without a three-letter memory task in the S(1)-S(2) interval). Late CNV amplitudes in the simple trials were smallest in the group with fewest, and largest in the group with most frequent transcendent experiences. Conversely, CNV distraction effects were largest in the group with fewest and smallest in the group with most frequent transcendent experiences (the second groups values were in the middle in each case). These data suggest cumulative effects of transcendent experiences on cortical preparatory response (heightened late CNV amplitude in simple trials) and executive functioning (diminished distraction effects in letter trials).

Psychophysiologic responses of schizophrenics to drugs

Studies of psychophysiologic responses of schizophrenics to drugs have involved cardiovascular measures (heart rate, blood pressure, and finger pulse volume), electrical skin activity, digital temperature, pupillary response, muscle activity, and respiration. Drugs included phenothiazines and both sympathetic and parasympathetic agents. Effects of drugs were varied and complex and no simple conclusions are possible. Phenothiazines reduced generally elevated basal levels of psychophysiological activity of schizophrenics (except for heart rate) as well as their reactivity to stimuli. These changes were often accompanied by behavioral improvement, suggesting that schizophrenics can be characterized by excessive levels of arousal which are decreased by phenothiazines to more moderate levels. In contrast, Russian work indicated that the basal levels of schizophrenics are initially low and are generally elevated by drugs, including phenothiazines, with accompanying improvement in psychological functions. These diverse findings were interpreted as showing that the psychological functioning of schizophrenics is a nonmonotonic (inverted-U) function of psychophysiological arousal. A second hypothesis was proposed to account for nonphysiological (cognitive) deficits of schizophrenics, namely, that performance is a positive, monotonic function of attention. Consequently, a two-process theoretical model involving attention and arousal processes was proposed to account for schizophrenic behavior. Several methodological questions prevented clear interpretation of many drug findings. One particular problem involved possible effects from homeostatic restraint mechanisms (law of initial values or LIV effect). A technique for removal of LIV effects was described.

Effects of distracting stimuli on CNV amplitude and reaction time

The present study investigated the reliability of CNV distraction and rebound effects, and their relation with reaction time. Twenty-four subjects were presented three blocks of trials: (1) a control block--a fixed foreperiod reaction time task consisting of a flash-tone-key press sequence; (2) a divided-attention block--randomly intermixed trials with and without a short-term memory task (three visually-presented letters) in the S1-S2 interval (50% of each); and (3) a second control block. In trials with the short-term memory task, subjects recalled the letters after the key press to the tone. Compared to the control block, CNV amplitudes during trials with letters were significantly smaller and reaction times to S2 were significantly slower (distraction effect). In contrast, CNV amplitudes during trials with no-letters were significantly larger (CNV rebound), but the reaction times were again significantly slower. This dissociation of CNV rebound and reaction time could provide an objective neurophysiological tool to probe attention functions in both normal and clinical populations.

Chlorpromazine effects on brain activity (contingent negative variation) and reaction time in normal women

Electrical brain activity (contingent negative variation or CNV) and psychomotor behavior (reaction time or RT) were measured after 50 mg of chlorpromazine (CPZ) or placebo were given orally to 28 normal women. CPZ reduced CNV 2 and 3 hrs post-drug and slowed RT 3 hrs post-drug. CNV amplitude appears to be an accurate indicator of drug-produced changes in alertness.

CNV rebound and aging

Abstract Thirty-five young (ages 18–32 years), 38 older (ages 55–69 years), and 23 elderly (ages 70–85 years) individuals were tested in two CNV paradigms: (1) a constant-foreperiod reaction time task consisting of a light flash-tone-key press sequence (control trials); (2) a divided-attention (50%-letters) task in which two types of trials occurred randomly — no-letters trials (which were identical to control trials) and letters trials (which were similar to control trials except for the inclusion of visually presented letters within the flash-tone interval as part of a short-term memory task). In the divided attention task, all 3 groups showed significant decreases in frontal, central and parietal late CNV amplitudes during letters trials. In no-letters trials, young and older individuals showed significant elevations in late CNV amplitude (rebound effect); the oldest group did not. Early CNV amplitude was decreased in all groups when the short-term memory task was presented (letters trials). The oldest group also showed a paradoxical reduction in early CNV when the task was omitted (no-letters trials). This failure of elderly subjects to demonstrate frontal discrimination of early CNV between letters and no-letters trials suggests an age-related sluggishness in switching from a divided attention set (preparing for both letters and tone in letters trials) to an undivided attention set (preparing only for tone in the no-letters trials). The frontal brain areas appear to mediate, in part, this weakened capacity of the elderly to switch attention. Latency of P3 to S1 was longer and amplitude smaller in the two older groups compared to young subjects; these parameters did not differentiate older and oldest groups. Diminished amplitudes of central and parietal P3 found in both older groups appears to reflect impairment in attention functions. The robustness of frontal P3 amplitudes in both age groups suggests that orienting and/or dishabituation processes may hold up with aging.

CNV Rebound and Aging. I. Attention Functions

Publisher Summary This chapter discusses contingent negative variation (CNV) rebound and aging. The development of CNV appears optimal in a simple reaction-time task where a first stimulus (S1) serves as a ready signal for a second stimulus (S2) to which an operant motor response is made. An important feature of this paradigm is that of a unitary attention set in preparation for response to S2. When this attention set is compromised by requiring attention to a second task, other than that involving S2, the development of CNV is disrupted. For example, the presentation of a short-term memory task involving auditory letters appearing within the S1–S2 interval reduces the magnitude of CNV. This CNV decrease is accompanied by lengthened reaction times to S2 (CNV distraction effect). Most demonstrations of the CNV distraction effect have been limited to a gross assessment of one block of trials involving the short-term memory task for letters compared with another block of trials without the letters.

ERPs and Psychopathology. I. Behavioral process issues.

The clinical study of ERPs has an inherent defect--a self-selection of clinical populations that hampers equating of clinically defined groups on factors extraneous to the independent variables. Such ex post facto studies increase the likelihood of confounding variables in the interpretation of findings. Hence, the development of lawful relationships between clinical variables and ERPs is impeded and the fulfillment of description, explanation, prediction, and control in brain science is thwarted. Proper methodologies and theory development can increase the likelihood of establishing these lawful relationships. One methodology of potential value in the clinical application of ERPs, particularly in studies of aging, is that of divided attention. Two promising theoretical developments in the understanding of brain functioning and aging are the distraction-arousal hypothesis and the controlled-automatic attention model. The evaluation of ERPs in the study of brain-behavior relations in clinical populations might be facilitated by the differentiation of concurrent, predictive, content, and construct validities.

Characteristics of International Assaultive Psychiatric Patients: Review of Published Findings, 2000–2012

Abstract In international reviews of psychiatric inpatient violence, one study of all types of patient violence found hostility, involuntary admission, and longer hospital stays associated with violence. A second study of comparison-group papers of patient assaults found younger males with schizophrenia, past violence, and substance abuse assaultive. The present review of raw assault data studies assessed characteristics of assaultive patients worldwide. It was hypothesized that patients with schizophrenia would present greatest assault risk. There were three analyses: International/no American studies (reviewed earlier), European studies, and merged International/American studies. Results revealed that male and female patients with schizophrenia, affective disorders, personality disorders, and other diagnoses presented greatest worldwide risk. Results partially support earlier findings. Given that individual institutional studies in this review reported significant assailant characteristics, a second finding is the absence of most of these institutional characteristics in this international review. Possible explanations for findings and a detailed methodological review are presented.