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Biomedical subjects

C A Sandman

Publications and source records attributed to C A Sandman.

At least 19 recordsLinked to original sources
PubMed1992

Cardiovascular phase relationships to the cortical event-related potential of schizophrenic, depressed, and normal subjects.

Cardiovascular phase, especially diastole, influences attention and the event-related potential (ERP) of the right hemisphere of the brain. Depression and schizophrenia are characterized by attentional deficits, unique lateralization of brain function, and deviant phase relationships of biological oscillators. In the present study, the ERP was recorded during stimulation triggered by diastole and systole in control (n = 16), depressed (n = 16), and schizophrenic (n = 9) subjects. Fifty tones were presented and subjects were instructed to count them silently. Previous findings were supported of delayed latencies and increased amplitude in depressed patients and decreased amplitudes and delayed latencies in schizophrenics. An exaggerated effect of diastole on the ERP in the right hemisphere was observed in depressed patients, however, no cardiovascular effect on the ERP was apparent in schizophrenic patients. Results suggested that heart/brain networks are tightly coupled in normal controls, perhaps "overdriven" in depressed patients, and uncoupled in schizophrenics.

Arousal↗
PubMed1992

Evidence for terminal decline in the event-related potential of the brain.

Precipitous decline (terminal decline) characterizes changes in the elderly just prior to death. The neurological and temporal parameters of terminal decline are not defined. The present study compared sensitive changes in the brain event-related potential (ERP) in 7 subjects who died within 1 year of evaluation with matched controls. Cross-correlation of annual ERPs revealed disorganization within and between subjects in response to memory dependent conditions but not in response to a novel stimulus (oddball). Motor reaction time to targets was not sensitive to decline. The changes associated with impending death were restricted to decline in reliability of the ERP within 1 year of death.

Acoustic Stimulation↗
PubMed1991

Effect of naltrexone upon self-injurious behavior, learning and activity: a case study.

Naltrexone significantly attenuated self-injurious behavior in a 20-year-old mildly retarded autistic male patient. The patient was videotaped daily and behavior was evaluated with a time-sampling procedure. Behavioral ratings of SIB frequency, SIB severity, and activity were collected automatically with a computerized system. Learning and memory were tested on a weekly basis with a modification of a paired associate learning test (PALT). Treatment with naltrexone resulted in (a) attenuation of SIB in the unstructured setting and (b) improvements in learning and memory without influencing activity levels.

Adult↗
PubMed1990

Abnormal EEG responses to photic stimulation in schizophrenic patients.

Numerous studies have differentiated schizophrenic patients and normal controls in electroencephalography (EEG) spectral patterns recorded at rest. We replicated the resting EEG spectral differences between these groups and observed significant differences in periodic photic stimuli on the EEG spectra. Drug-free schizophrenic male patients (n = 8, mean age = 23.9) and normal male controls (n = 11, mean age = 24.3) were studied. Eighty seconds of EEG were collected from each subject for each of four experimental conditions: one resting and three photic-driving conditions (2.38, 4.54, and 8.33 Hz). Eye movement and other movement artifacts were minimized by use of an automatic amplitude threshold filter. Although large eye movements could be excluded as confounding factors, the filter could not for certain exclude small eye movements. Subjects were instructed to keep their eyes closed throughout. A significant difference was found between the groups both at rest and following photic stimulation in EEG activity. This result was characterized by increased delta activity and decreased alpha activity in schizophrenic patients at rest. The EEG activity following the photic driving also differentiated the groups. Schizophrenic patients had decreased sensitivity to the photic stimulation in the alpha range for spectra derived from both fundamental and harmonic analysis.

Adult↗
PubMed1990

Age-related change in P3 amplitude as a function of predictable and unpredictable rare events.

The auditory event-related potentials (ERP's) of young, middle-aged and elderly subjects were measured over Fz, Pz, C3 and C4 in two different rare tone conditions. In the fixed condition, the rare tone occurred predictably, every fourth stimulus. In the random condition, the rare tone was presented unpredictably, with 1:4 probability. Large amplitude late positive waves (P3's) of middle aged subjects (N = 22) were present in the random condition at all placements, but absent in the fixed condition. Elderly subjects (N = 23) responded identically to both rare tone conditions at all placements. Young subjects (N = 7) had large amplitude P3 responses to both random and fixed conditions at all placements except Pz. Over Pz, young subjects had patterns similar to middle-aged subjects, with large P3's to the random rare tone but not the fixed rare tone. Elderly subjects may not differentiate the two conditions, either because they have less efficient memory, or because they primarily attend to the global probability of rare tone occurrence. The results with young subjects suggest that recent memory processes involved in discriminating rare tone conditions initially develop over the posterior (Pz) areas.

Adult↗
PubMed1990

Plasma B-endorphin levels in patients with self-injurious behavior and stereotypy.

B-endorphin and cortisol concentrations were examined in the plasma of mentally retarded patients who displayed symptoms of self-injurious behavior (SIB) (n = 9), stereotypy (n = 17), or SIB plus stereotypy (n = 14). Morning and evening samples were compared with a matched patient control group (n = 13) and a group of nonretarded controls (n = 17). Compared with nonretarded controls, the retarded control group had significantly lower b-endorphin concentrations for the morning sample and nonsignificantly lower concentrations for the evening sample. The combined patient groups had lower b-endorphin levels than did nonretarded controls for both samples. Patients with SIB and stereotypy had significantly higher morning levels of b-endorphin than the retarded controls. The evening levels of the SIB plus stereotypy group also were higher than retarded controls but were not significant. Levels in the SIB and stereotypy group were slightly elevated compared with retarded controls. Cortisol levels were identical for all groups. B-endorphin and cortisol significantly covaried for the nonretarded controls but not the patients. Results indicated that compared to a matched control group, patients with SIB plus stereotypy have elevated b-endorphin plasma.

Adult↗
PubMed1990

An orally administered opiate blocker, naltrexone, attenuates self-injurious behavior.

Several recent reports have indicated that opioid blockers are effective in attenuating self-injurious behavior (SIB). In the present study, four patients with SIB were challenged with four fixed doses (0, 25, 50, 100 mg) of naltrexone. In a double-blind procedure, all patients received each dose on a different week as determined by latin square design. Naltrexone was given on Monday and Wednesday of each week, and patients were videotaped daily for 10 minutes in the morning and afternoon. The tapes were scored for incidents of SIB, stereotypy, and activity, with interrater reliability of 0.93. The Conners Teacher Rating Scale was administered by staff in the morning and afternoon each day. The Vineland was completed each week (Thursday). All patients had decreased SIB when treated with naltrexone. Three patients decreased their SIB as dose of naltrexone increased. There were no consistent effects of naltrexone on stereotypy, activity, or performance on the Conners or the Vineland. These results suggest that endogenous opioids are implicated in SIB and that naltrexone is a powerful tool for examination of this treatment-resistant behavior.

Adult↗
PubMed1989

A characterization of a single-trial adaptive filter and its implementation in the frequency domain.

A single-trial adaptive filter (SAF) was implemented in the frequency domain (FDAF) by using the Fast Fourier Transform. The FDAF is significantly more efficient than the SAF. In the data presented the FDAF ran approximately 2 times faster than the SAF. For time series containing larger numbers of data points (n) the efficiency of the calculation will increase on the order of N/Ln(N). The FDAF was tested under a variety of conditions to determine the limits of its usefulness. Pre-filtering the data was found to be necessary to prevent the FDAF from lining up on high frequency activity not related to the signal. The importance of minimizing the amount of low frequency noise was emphasized since it adversely affected the performance of the FDAF and was difficult to filter. The single-trial latencies predicted by the FDAF were much more sensitive to increasing noise than the final wave form. In the absence of excessive low frequency noise a negative exponential relationship was found between the mean error in latency prediction and the SNR estimate. Since the SAF technique is also used to determine signal latency in single sweep data the SNR estimate can be a useful test to determine if the FDAF is locating the signal correctly or merely amplifying chance regularities in noisy data.

Electroencephalography↗
PubMed1989

EEG alpha photic driving abnormalities in chronic schizophrenia.

Periodic photic stimuli across the entire electroencephalographic (EEG) frequency range were used in an attempt to assess EEG functional differences between chronic schizophrenic patients and control subjects. The EEG responses to these photic stimuli were significantly attenuated in the schizophrenic patients, specifically at the frequencies within the EEG alpha range. The schizophrenic patients also showed an alpha range attenuation in the "no stimulus" EEG alpha measure, such that there was a significant correlation across subjects between the "stimulus" and "no stimulus" EEG alpha range abnormalities. These abnormalities are discussed with reference to possible dysfunctional thalamic mechanisms involved in the pacing of EEG alpha activity and the gating of information through the cerebral cortex.

Adult↗
PubMed1988

Beta-endorphin disregulation in autistic and self-injurious behavior: a neurodevelopmental hypothesis.

Peptides derived from pro-opiomelanocortin (POMC) influence neurodevelopmental processes. Earlier studies indicated that MSH/ACTH compounds improved behavioral efficiency in retarded individuals. Recent studies have shown that opiate blockers reduce treatment-resistant self-injurious behavior (SIB), an autistic-like, developmental disorder. Although the exact mechanisms are unknown, prenatal POMC disregulation, addiction to endogenous opiates and elevated pain threshold have been proposed to account for this behavior. In study one, four SIB patients were given 0, 25, 50 or 100 mg of naltrexone on separate weeks in a double blind, Latin square design. A specific dose dependent reduction in SIB was observed in three patients. In study two, plasma b-endorphin was measured in 40 patients with SIB, a related behavior, stereotypy (ST) or controls. SIB and ST patients had higher levels of endorphin than controls. These data added new support for the role of b-endorphin in a treatment-resistant patient group.

Adult↗
PubMed1988

Brain responses to semantic anomaly in natural, continuous speech.

In the present study, brain responses were recorded during the presentation of naturally spoken sentences. In two separate experiments, the same set of stimulus sentences was presented with subjects either being asked to pay close attention in order to answer content questions following the run ('memory instruction' - MI) or to press one of two buttons to indicate a normal or unusual ending to a sentence ('response instruction' - RI). Brain event-related potentials were not averaged across the exact same acoustic information but across 49 different words spoken in natural, uninterrupted sentences. There was no attempt to standardize the acoustic features of stimulus words by electronic means. Rather than splicing stimulus words (and trigger pulse needed for computer averaging) onto sentence stems, consonant-vowel-consonant (CVC) monosyllablic words were selected with voiceless stop consonants in the word initial position. This not only avoids acoustic overlap with the preceding word of the sentence but also allows the point of stimulus word onset to be precisely located. In the MI group, brain responses to the semantically anomalous endings were distinguished by the presence of a late negative wave (N300) followed by a sustained positive wave (P650). Responses to anomally in the RI group data was not consistently differentiated from normal in the 650-1000 ms range. Within conditions, the MI and RI waveforms were differentiated by the presence of an augmented positive-going slow wave in the RI condition which may reflect an augmented CNV release. The feasibility of averaging brain electrical responses across non-isolated words which differed acoustically but were of similar phonemic structure was demonstrated. This paradigm provides a means of studying speech-activated neurolinguistic processes in the stream of speech and may make complex spoken language contexts available for event-related potential investigations of brain and language functions.

Adolescent↗
PubMed1987

Neonatal exposure to a high level of ACTH4-10 impairs adult learning performance.

Male offspring of Sprague-Dawley dams were injected with 25 micrograms of ACTH4-10 or the vehicle on days 2 through 7 postpartum. Peptide treated animals exhibited a marked motor response to the peptide injection. Adrenal weights of these animals were consistently heavier than littermate controls in both the developing and adult animals. ACTH4-10 treated neonates exhibited significantly poorer learning performance in the shuttle box and were slower to acquire the reversal learning problem of a visual discrimination task under light shock levels. In addition, these animals also exhibited an exaggerated startle response and a stronger thigmotaxis response in the open field than controls. These results indicate that exposing the developing nervous system to relatively high levels of ACTH4-10 can produce marked long-term effects on behavior.

Acoustic Stimulation↗
PubMed1986

Persisting subsensitivity of the striatal dopamine system after fetal exposure to beta-endorphin.

Fetal exposure of rats to beta-endorphin during the third trimester, either alone or with alpha-MSH, resulted in mild developmental delay and significant decreases in striatal dopamine receptor density (subsensitivity) persisting through maturity. The apparent paradoxical down-regulation of dopamine receptors in the presence of beta-endorphin was consistent with fetal exposure to dopamine receptor antagonists and synthesis inhibitors. These findings suggest biophysical properties of receptors which are unique to fetal development including loss of plasticity after exposure to antagonists. Permanent, down-regulation of the striatal dopamine system may be one mechanism underlying delayed development after fetal exposure to beta-endorphin which may accompany hypoxia. Even though there were no statistically significant differences between males and females in density of the dopamine receptor, the behavioral profile after peptide treatment was sexually demorphic. Behaviorally, female rats appeared sensitized to perinatal alpha-MSH and males to alpha-endorphin.

Animals↗
PubMed1985

The relationship of endogenous ACTH levels to visual-attentional functioning in patients with congenital adrenal hyperplasia.

The within subject experimental approach of either doubling cortisone medication dose or withdrawing steroid treatment for 36 hr preceding behavioral testing was found to induce corresponding significantly elevated or suppressed plasma ACTH levels, as measured by radioimmunoassay, in six of eight adults diagnosed as having congenital adrenal hyperplasia (CAH). During the session characterized by elevated ACTH levels, the CAH patients exhibited significantly reduced median reaction times on the Sternberg Item Recognition Task. Their response pattern was suggestive of facilitated visual attentional functioning and/or overt motor response capacity rather than alteration of simple cognitive processing. Moreover, Sternberg performance was significantly correlated with endogenous ACTH levels but not with levels of plasma cortisol or cortisone replacement medication. This enhancement of performance paralleled a previous finding of improved performance on the Sternberg paradigm by normal adults following exogenous administration of ACTH 4-10 (Ward et al., 1979). Further analysis of the Sternberg performance suggests that other variables such as mineralocorticoid treatment, type of CAH impairment, and sex may act to moderate the degree of ACTH-related facilitation on this task. Performance on other visual and verbal attention and memory tasks, found earlier to be sensitive indices of exogenous administration of ACTH 4-10 and related fragments, was not significantly altered by manipulation of endogenous ACTH levels in these CAH patients.

Adolescent↗
PubMed1985

Paradoxical excitement to sedative-hypnotics in mentally retarded clients.

The relationships among "paradoxical" excitement to sedative--hypnotic medication, self-injurious behavior, and perinatal trauma were evaluated. Mentally retarded patients were classified as either paradoxical or normal responders to sedative-hypnotics. Paradoxical responders to these medications have a lower MA, a history of perinatal trauma, self-injurious behavior (SIB), and aggressive behavior when compared to normal responders. These findings confirmed and extended previous reports that a type of SIB may be indexed by paradoxical response to sedative-hypnotics. Results also suggested that perinatal trauma may be of etiological importance in the development of SIB. Because perinatal trauma or fetal distress results in excessive levels of B-endorphin, in utero, an impaired endogenous opiate system may be a critical factor maintaining a syndrome of SIB. Thus, these data may indicate psychopharmacological markers of SIB that may have both treatment and etiological significance.

Adolescent↗