Biomedical subjects

S L Schandler

Publications and source records attributed to S L Schandler.

At least 19 recordsLinked to original sources

PubMed2001

Somatotopy of the motor cortex after long-term spinal cord injury or amputation.

Certain brain-computer interface (BCI) methods use intrinsic signals from the motor cortex to control neuroprosthetic devices. The organization of the motor pathways in those populations likely to use neuroprosthetic devices, therefore, needs to be determined; there is evidence that following disease or injury the representation of the body in the motor cortex may change. In this study, functional MRI measures of somatotopy following spinal cord injury (SCI) showed evidence of changes in limb representations in the motor cortex. Subjects with chronic SCI had unusual cortical patterns of activity when attempting to move limbs below their injury; amputees showed a more normal somatotopy. The functional reorganization may affect optimal implanted electrode placements for invasive BCI methods for these different populations.

Adult↗

PubMed2001

Frontal lobe functioning in adolescents with attention deficit hyperactivity disorder.

A prominent hypothesis regarding the etiology of attention deficit hyperactivity disorder (ADHD) is that its presence and magnitude reflect frontal lobe dysfunction. Past tests of this hypothesis have been inconsistent. The present study examined frontal lobe functioning in adolescents with ADHD. A sample of 10 ADHD adolescents and 10 controls between the ages of 12 and 17 served as participants for the study. The control group was matched on age (within six months) and gender. This study aided in clarifying past contradictory studies by using clearly defined criteria to determine ADHD, a representative age range of participants, carefully selected tests, and a control task. The two measures that were administered to assess frontal lobe functioning were the Wisconsin Card Sorting Test and the Stroop Color and Word Test. The Purdue Pegboard was used as a control measure that did not assess frontal lobe functioning. The findings indicate that the ADHD group performed significantly worse on the following: color score, color/word score, and interference score of the Stroop Color and Word Test; percent of perseverative responses, percent of perseverative errors, and number of completed categories of the Wisconsin Card Sorting Test. No differences were found on the Purdue Pegboard task.

Adolescent↗

PubMed1996

Visuospatial information processing in intoxicated, recently detoxified, and long-term abstinent alcoholics.

Visuospatial information processing has been shown to be particularly sensitive to acute alcohol intoxication and chronic alcohol abuse. This study extended previous studies by determining if recently detoxified alcoholics recover visuospatial processing after long-term abstinence. If visuospatial function returns to the level displayed by intoxicated alcoholics, then the deficit displayed by recently detoxified alcoholics may represent a short-term adjustment due to the removal of alcohol. However, if the visuospatial deficit remains in long-term abstinent alcoholics, then the superior processing of the intoxicated alcoholic could reflect a normalization of processing produced by alcohol ingestion. Twenty active and 40 recovering alcoholic male volunteers participated. The active alcoholics were seen intoxicated at the time of admission into a 21-day alcohol detoxification and treatment program. Of the recovering alcoholics, 20 were designated as recently detoxified alcoholics and had just completed the same treatment program. The remaining 20 long-term abstinent alcoholics had completed alcohol treatment several years previously with no relapse. Participants selected were similar in general demographic status, alcohol treatment histories, and psychomotor ability. Two main effects emerged from the results: First, the intoxicated alcoholics displayed visuospatial learning that was superior to the learning of alcoholics recently detoxified or abstinent for several years; a second principal finding was nearly identical visuospatial learning displayed by recently detoxified and long-term abstinent alcoholics.

Adult↗

PubMed1996

Changes in the P300 component of the tactile event-related potential following spinal cord injury.

Previous studies have demonstrated that significant changes in action or behaviour (function) and morphology occur in the deafferentated and the adjacent somatosensory cortex after amputation or experimental spinal cord injury. These studies have shown changes in somatotopic mappings and somatosensory perception as well as altered evoked responses. The purpose of the present study was to examine the potential effect of these changes on cognitive processes using the tactile P300 event-related potential (ERP) in a spinal cord injured (SCI) population. The P300 ERP has been associated with more complex cognitive functioning such as selective attention, memory, and stimulus evaluation rather than earlier sensory processing of stimuli. Three groups consisting of healthy control, paraplegic, and tetraplegic subjects participated in a transcutaneous electrical stimulation 'oddball' task. Results indicate that all groups were successful in maintaining target counts and produced significantly larger P300 amplitudes with longer latencies to target trials compared to non-target trials. The SCI groups, however, produced P300 ERPs for both targets and non-targets that were significantly reduced in amplitude compared to the control group. In the case of the tetraplegia patients, the P300 was almost abolished. No differences in latency of the P300 was observed between any of the groups.

Adolescent↗

PubMed1996

Problem solving and coping strategies in persons with spinal cord injury who have and do not have a family history of alcoholism.

Recovery from spinal cord injury (SCI) requires substantial coping by the patient. The coping process reflects both physical adjustment to permanent biological changes and psychological acceptance of these changes and their limitations to function. A history of family alcoholism appears as one prominent factor in persons with SCI. This factor is associated with several personality characteristics that could directly influence adjustment to the injury. As an initial exploration of this premise, the present study examined the relationship between family history of alcoholism and coping processes in SCI patients. Ninety volunteer subjects were selected from inpatient and outpatient populations of a Veterans Affairs spinal cord injury service. Based on structured interviews and responses to a standardized questionnaire, one group of 45 subjects, designated Family History Positive (FHP), were from families in which the father and at least one other second generation relative were alcoholics. The 45 Family History Negative (FHN) subjects were from families with no alcoholism subjects were from families with no alcoholism history. Once assigned to a group, subjects completed the Ways of Coping Questionnaire. Compared to subjects with no family alcoholism history, FHP subjects reported significantly more use of constructive coping strategies as measured by the Ways of Coping Questionnaire, but their alcohol use and anti-social behaviors indicated that they were less effective in actual coping behaviors. Persons with SCI and a family history of alcoholism reported utilization of coping methods that differ from those used by patients with SCI and no family alcoholism history. From the perspective of treatment and rehabilitation, this finding suggests the need to consider different therapeutic approaches for these groups.

Adaptation, Psychological↗

PubMed1996

Sensory detection and pain thresholds in spinal cord injury patients with and without dysesthetic pain, and in chronic low back pain patients.

In an effort to understand the mechanisms involved in dysesthetic pain syndrome (DPS) in spinal cord injury (SCI) patients, four groups of 13 subjects each--SCI subjects with DPS, SCI subjects without pain, chronic low back pain subjects, and control subjects--were examined for sensory detection and pain thresholds at forearm, neck, and rostral trunk areas. Results indicated that the SCI pain group had significantly lower pain thresholds at all skin sites, compared to the SCI no-pain and chronic low back pain groups, and at the rostral trunk skin site, compared to the control group. The SCI pain group also showed a lower sensory detection threshold at the rostral trunk skin site than did the SCI no-pain group. Equally important, the SCI no-pain group had detection and pain thresholds significantly higher than those of the control group. The results suggest fundamental differences in somatosensory processing when DPS is or is not a consequence of SCI.

Adult↗

PubMed1995

Auditory P3 event related potentials (ERP) and brainstem auditory evoked responses (BAER) after spinal cord injury in humans.

Previous studies have observed altered somatotopic sensory fields after experimental deafferentation in animals as well as enhanced somatosensory evoked potentials and altered cortical motor pathways following spinal cord injury (SCI) in humans. These observations indicate that cortical reorganization may occur subsequent to SCI. In earlier work, we have observed attenuated amplitudes for both tactile P3 and auditory N1/P2 orienting event-related potentials (ERP) in spinal cord injured groups. These results suggest that the reorganization process may have functional perceptual and cognitive consequences. In an effort to determine if deafferentation affects the P3 ERP using stimuli other than somatosensory, we measured brain activity from central recording sites during an auditory "oddball" task. Additionally, we obtained brainstem auditory evoked responses (BAER) in order to assess subcortical primary auditory pathways as well. Results show that the SCI groups produced significantly attenuated N1/P2 complexes and P3 when compared to controls. Also, the quadriplegic group exhibited increased latencies of the P3 at frontal and central sites. There were no differences between groups in BAER results. These findings suggest that primary subcortical auditory information processing stages remain intact after SCI although later stages may be significantly altered.

Adult↗

PubMed1995

Spatial learning deficits in preschool children of alcoholics.

When compared with nonalcoholics, chronic alcoholics and their children show significant deficits in the processing of visuospatial information. The literature supports two possible explanations of a visuospatial processing deficit in the child of an alcoholic (COA) when compared with the child of a nonalcoholic (NCOA). Either the COA may suffer cognitive disruptions produced by personal and social development within an alcoholic family, or the COA may inherit or very early develop alterations in central nervous system substrates of neurocognitive operations. The present study was designed to continue our examinations of visuospatial information processing differences and the source of these differences in COAs. An evaluation of very young subjects not only assisted in providing a more complete view of visuospatial processing across the COA's life span, but also helped explain why the deficit occurs. Thirty matched male and female preschool children, aged 35.8-51.6 months, served as participants. Fifteen children were COAs from families in which the biological father and two other relatives had an alcoholism history. The other group of 15 children were NCOAs. Each child performed a visuospatial learning task similar to the task used in previous studies of older COAs. The visuospatial learning performance of the preschool COAs was inferior to that displayed by preschool NCOAs. The patterns of correct, error, and nonresponses emitted by the preschool COAs and the interrelationships of these data closely resembled the data from our previous studies of older children, adolescent, and adult COAs.(ABSTRACT TRUNCATED AT 250 WORDS)

Attention↗

PubMed1995

Incidence and characteristics of spinal cord injured patients with a family history of alcoholism.

OBJECTIVE: Of the many factors that affect the occurrence of and rehabilitation from spinal cord injury, alcohol use and abuse are particularly prominent. Persons with a family history of alcoholism are at greater risk for alcohol abuse and alcoholism. Preliminary data show a much higher than normal proportion of these persons in the spinal cord injured population. If these data are reliable, they may show that family history of alcoholism is a premorbid or comorbid factor to the occurrence of accidents that results in catastrophic injuries. Our investigation represented an evaluation of this premise. METHOD: Male volunteer subjects (N = 100) were selected from inpatient and outpatient populations of a Veterans Affairs spinal cord injury service. Subjects received a comprehensive interview and completed two standardized questionnaires and a general information form designed to evaluate their past and present use of alcohol and the use of alcohol by their parents and relatives. RESULTS: The incidence (45%) of spinal cord injured patients with a family history of alcoholism was over four times that found in the general population. Spinal cord injured subjects with a family history of alcoholism reported significantly more problems with alcohol before, at the time of, and after their injury. CONCLUSIONS: The data suggest a relationship between the predisposition to alcoholism and accidents that result in catastrophic injury.

Accidents↗

PubMed1994

Coping with ambiguity in multi-ethnic children of alcoholics.

Visual field dependence in 292 multi-ethnic adult children of alcoholics (ACAs) and nonalcoholics (NACAs) was assessed, using the Hidden Figures Test (Ekstrom, French, & Harmon, 1976). There were no differences among ethnic groups, but ACAs achieved a significantly lower percentage of correct answers and more incorrect answers and attempted more questions relative to NACAs. These findings suggest that ACAs' visuospatial deficits are not related to ethnic and cultural factors.

Adaptation, Psychological↗

PubMed1993

Two-point discrimination thresholds in spinal cord injured patients with dysesthetic pain.

We questioned whether deafferentation following SCI would result in an increase in somatic sensitivity possibly due to cortical reorganization. Dysesthetic pain syndrome (DPS) below the level of a spinal cord injury (SCI) is a common complication. We hypothesized that DPS patients would show increased cortical reorganization because of high levels of sensory stimulation following injury. Sixteen dysesthetic pain SCI patients, 15 SCI patients without pain, and 16 control subjects were examined for two-point discrimination thresholds (2PDT) of the forearm, neck, and spine. The SCI pain group had significantly smaller 2PDTs than either SCI no pain or control groups, particularly over the neck and spine. The SCI pain group had a significant inverse correlation between perceived degree of pain (visual analogue scale) and 2PDT in the spinal skin area. The findings indicate that SCI patients with severe DPS have a higher sensitivity to somatosensory stimuli, particularly in skin areas with projections to primary somatosensory cortex areas adjacent to the deafferentated region. The increase in 2PDT may be due to an increase in the size of the somatosensory cortical areas allotted to the corresponding skin areas.

Adult↗

PubMed1993

An exploration of the interaction between variation in wavelength and time perception.

The interaction of color wavelength and perception was evaluated during two experiments. The first study used a time-estimation task which included controls for both stimulus duration and frequency. The second study required production of duration using the same colors and three time periods to be reproduced by the participant according to stimulus cues. Based upon previous research, it was hypothesized that exposure to long-wavelength stimuli would yield shorter time estimations than exposure to short-wavelength stimuli. The results supported the assumption that stimuli of different color wavelengths differentially alter perception and psychological activation; however, the effects were not related to systematic alterations of wavelength.

Adult↗

PubMed1992

Event-related brain potentials during orienting to auditory and visual stimulation in spinal cord injured humans.

In intact humans, deprivation of somatosensory and kinesthetic sensations result in significant alterations in perception and information processing. There have been very few studies to discover if the loss of sensation with spinal cord injury (SCI) in humans affects perceptual operations. We hypothesized that the SCI participant would either exhibit arousal, perceptual, and information processing alterations similar to experimentally sensory deprived subjects (who provide the closest human analogue), or that the somatosensory cortex would show reorganization for the processing of other modalities of stimulation. The subjects consisted of 16 paraplegic, 13 quadriplegic, and 22 non SCI controls. Subjects received an auditory orienting task consisting of a 500 Hz tone presented 20 times each at 66, 75, 88, and 101 db and a visual orienting task incorporating light flashes of 115, 123, 131, and 140 lux presented 20 times each. EEG information processing data were recorded from C3 and C4 for 100 msec prior to and 500 msec post stimulation. Information processing variables, analyzed as event-related potentials, indicated that the somatosensory cortex of SCI groups had a flattened response to auditory stimulation. The control group had a significantly larger P2 component. We concluded that these data signified that the somatosensory cortex did not reorganize function in response to chronic deafferentation nor was the SCI subject hyperresponsive to stimulation.

Acoustic Stimulation↗

PubMed1992

Activation, attention, and visuospatial learning in adults with and without a family history of alcoholism.

While recent evidence shows visuospatial information processing deficits to be present in chronic alcoholics, it remains unclear whether such deficits are present prior to alcohol abuse in persons at risk for developing alcoholism. If present, it is also unclear whether the information processing mechanisms underlying these deficits are the same in alcoholics and persons at risk for alcoholism. This study investigated visuospatial information processing psychophysiological activation in adults with and without a family history of alcoholism. Thirty matched nonalcoholics served as participants. Fifteen persons were from families in which at least one biologic parent and one other relative had a history of alcoholism. Another group of 15 persons had no family history of alcoholism. In addition to displaying atypical patterns of learning-contingent physiological activation, participants with a family history of alcoholism displayed visuospatial learning that was significantly poorer than persons with no family history of alcoholism. The learning and physiological activation displayed by the participants with a family history of alcoholism were similar to those displayed by previously studied alcoholics using a similar learning task. The data suggest that visuospatial learning deficits may reflect an antecedent to, rather than a consequence of, chronic alcohol abuse.

Adult↗

PubMed1991

Spatial learning deficits in adult children of alcoholic parents.

This study investigated whether the visuospatial deficits displayed by chronic alcoholics are present in persons at risk for alcoholism. Participants were 34 matched social drinkers, half of whom were children of alcoholic parents and half of whom had no family alcoholism history. Ss with a family history of alcoholism displayed visuospatial learning that was significantly poorer than that displayed by Ss with no family alcoholism history. The learning patterns displayed by those with a family alcoholism history were similar to those displayed by previously studied detoxified alcoholics and young children of alcoholics using a similar learning task. Data suggest that visuospatial learning deficits may reflect an antecedent to rather than a consequence of chronic alcohol abuse.

Adult↗

PubMed1991

Rasch analysis of functional assessment scales: an example using pain behaviors.

Functional assessments associated with rehabilitation frequently rely on scoring systems based upon a limited set of categorical values, arranged in order and intended to represent an underlying performance continuum. Making sense of data generated by these scales is a challenge well met by the Rasch measurement model, which allows detailed investigation of how individuals are likely to perform on a given occasion and indicates whether changes in performance occur in orderly patterns over repeated occasions. Additionally, the Rasch measurement model allows study of the quality of measurement and the degree to which the scoring adequately reflects the underlying, but not directly measurable, continuum. Data gathered at admission and discharge from 330 patients attending a rehabilitation program for chronic low back pain were evaluated using the Rasch measurement model, and the results were contrasted with those from the best available nonparametric technique, ridit analysis.

Back Pain↗

PubMed1989

Spatial learning of visual 'nonsense figures' during experimental ethanol intoxication.

The interaction of alcohol and visuospatial learning was evaluated during two experimental sessions. During one session, participants were experimentally intoxicated to obtain a blood alcohol concentration of at least 0.10%. During another session, a nonalcohol placebo was administered. The learning task consisted of a paired-associate paradigm requiring participants to learn the distinct spatial positions of 6 visually presented "nonsense shapes." The visuospatial learning of participants in the placebo condition was generally superior to their learning while intoxicated. However, intercorrelations of performance measures indicated that the relation between alcohol ingestion and performance differences across conditions was not linear.

Adult↗

PubMed1988

Event-related brain potentials in intoxicated and detoxified alcoholics during visuospatial learning.

Event-related potentials and visuospatial learning performance were examined to understand the effects of chronic alcohol use on complex information processing. A total of 18 alcoholic male in-patients in an alcohol treatment program served as participants. Nine persons were seen at time of admission to the program while intoxicated (mean BAC = 18.0 mg/dl). The second group of nine persons was seen detoxified after 4 weeks in the treatment program. Learning consisted of a paired-associate paradigm requiring participants to learn the distinct spatial positions of six, randomly presented "nonsense" shapes. The visuospatial learning performance of the intoxicated alcoholics was superior to that of the detoxified alcoholics. Evaluation of event-related potentials during the visuospatial learning task indicated that while both groups displayed greater right hemisphere amplitudes of P3, P2, N1, and N2-P3 components, the amplitudes of the latter three components were significantly greater in the intoxicated alcoholics. The overall results suggest that compared to the intoxicated alcoholic, the detoxified alcoholic may suffer a disruption in attentional mechanisms related to visuospatial information processing, providing support for a theory that alcohol ingestion serves to balance information processing in the chronic alcoholic.

Adult↗