Search PubMed⌕ Search

Biomedical subjects

Kenneth M Heilman

Publications and source records attributed to Kenneth M Heilman.

At least 55 records · Page 3Linked to original sources
PubMed2004

Visual facial grasp.

Some patients with degenerative neurological diseases have a release of the vestibular-ocular reflex (VOR), as detected by passive head movement during visual fixation on a moving target ("doll's eyes"maneuver). However, a positive doll's eyes sign might be induced by other defects and the purpose of this article is to describe a new ocular sign of cortical dysfunction, the visual facial grasp. We observed three patients, one with progressive supranuclear palsy (PSP), another with probable Alzheimer's disease (AD) and a third with cortico-basal degeneration (CBD) all of whom appeared to demonstrate a release of the vestibulo-ocular reflex (VOR) with passive head movements. Whereas the patient with PSP, who was unable to inhibit the VOR regardless of the visual target used probably had a true release of the VOR, the patients with AD and CBD were able to inhibit this reflex when the visual target was the examiner's moving face. These two patients also exhibited spontaneous preference for visual fixation on the examiner's face and improvement in smooth pursuit when the examiner's face was the visual target. This clinical observation suggests that the deficits in these two patients with AD and CBD were related to the emergence of a primitive stimulus-bound behavior, the visual facial grasp.

Aged↗
PubMed2004

Verbal dichotic listening in developmental stuttering: subgroups with atypical auditory processing.

OBJECTIVE: The major aim of this study was to determine whether adults with persistent developmental stuttering have atypical auditory processing. BACKGROUND: Stuttering has been attributed to aberrant hemispheric dominance, and auditory processing deficits have been found in some adults who stutter. Dichotic listening, an indirect measure of auditory processing, has not been used to study auditory laterality in right- and left-handers who stutter. Because left-handers and people who stutter may have aberrant hemispheric dominance, it is important to examine auditory neural systems in right- and left-handed people who do and do not stutter. METHODS: Adults with persistent developmental stuttering (n = 18) and matched controls (n = 28) were studied by simultaneous binaural (dichotic) presentation of consonant-vowel stimuli in three attention conditions: nondirected attention, attention directed right, and attention directed left. Sex-handedness groups (stutter and control) included right-handed men and women and left-handed men, but not left-handed women because this stutter subgroup could not be recruited. To study ear advantage and auditory laterality, two dependent measures were examined: percent left and right ear responses and lateralization shift magnitude. Potential relationships between degree of handedness and dichotic listening measures were also examined. RESULTS: Matched controls and right-handed men who stutter had the expected right-ear advantage (REA) in the nondirected attention condition. In contrast, left-handed men who stutter had a left-ear advantage (LEA), and right-handed women who stutter did not have a lateral ear bias in the nondirected attention condition. Right-handed women who stutter had the greatest tendency to hear a sound that was not presented to either ear, and were relatively unable to selectively direct attention left or right. In contrast, left-handed men who stutter were able to shift attention to the left and right ear better than any other group. For the fluent control group, there were no significant relationships among degree of handedness and dichotic-listening variables. For the stutter group, degree of handedness was significantly related to percentage left and right ear response and to the lateralization shift magnitude. CONCLUSIONS: Left-handed men who stutter and right-handed women who stutter have atypical auditory processing but differ in important ways. The left-ear bias found in left-handed men who stutter in the nondirected attention condition suggests that their right temporal lobe may be important in perceiving speech, and, therefore, they have mixed dominance. These subjects were also better at shifting attention in both directions in comparison to all other groups; thus, the right hemisphere, which is dominant for shifting attention to both right and left space, may be activated. In contrast, the right-handed women who stutter had no ear bias in the nondirected attention condition, made more perceptual errors, and had difficulty shifting attention to the left and right. Although these results suggest that right-handed women who stutter have attentional deficits, the relationship between attentional disorders and stuttering remains to be elucidated. Because right-handed men who stutter were not different from controls, aberrant hemispheric dominance cannot fully account for stuttering. Unfortunately, left-handed women were not examined in this study. Therefore, these interesting sex-handedness effects found in left-handed men and right-handed women who stutter must be interpreted with caution.

Adult↗
PubMed2003

Ipsilateral neglect versus hemianopic compensation.

Hemianopic patients may make line bisection errors in the direction of contralesional space, which could represent functional compensation or might be due to ipsilateral neglect. The authors report a patient with stroke with left homonymous hemianopsia and contralesional (leftward) bias on the line bisection task while upright, lying on his left side, and sitting with head bent 90 degrees leftward. Because hemianopic compensation should map retinotopically and the patient consistently erred body-leftward, the authors conclude that his contralesional errors are consistent with ipsilateral neglect.

Brain↗
PubMed2003

Progressive affective aprosodia and prosoplegia.

The right frontal lobe is important for the expression of emotional prosody, emotional faces, and automatic speech. The authors describe a woman who presented with progressive expressive affective aprosodia, affective prosoplegia, amusia, and loss of automatic speech but with an intact ability to understand emotional prosody and faces as well as express and understand syntactic prosody. MRI showed predominant right frontal cortical atrophy. The authors suggest that this patient has a form of frontotemporal dementia, analogous to primary progressive aphasia but disrupting right frontal lobe-mediated functions.

Atrophy↗
PubMed2003

Callosal neglect.

BACKGROUND: According to the interhemispheric inhibition model of neglect, the uninjured hemisphere inhibits (via the corpus callosum) the injured hemisphere but the injured hemisphere can no longer inhibit the opposite hemisphere, which becomes hyperactive and produces an ipsilesional attentional bias. Alternatively, according to the compensation hypothesis, the uninjured hemisphere helps compensate for the damaged hemisphere, which is impaired in directing attention to contralateral stimuli. If the inhibition model of neglect is correct, callosal disconnection should reduce neglect. If the compensation model is correct, however, it may increase or induce neglect. PATIENT: A 32-year-old woman, at age 14 years, developed a right frontal astrocytoma and was treated with surgery and radiation but had a cardiopulmonary arrest secondary to aspiration. Subsequent imaging studies revealed damage to the frontal, parietal, and occipital regions of the right hemisphere and damage to the temporal region of the left hemisphere. After discharge, she was able to return to school and drive a car, without any evidence of neglect. About 10 years later, she developed complex partial and atonic seizures that were multifocal and medically intractable. She underwent a complete section of her corpus callosum at age 31 years. RESULTS: One year after the callosal section, she demonstrated (1) diminished spontaneous saccades to the left, hypometric leftward saccades, and left gaze impersistence; (2) left arm hemispatial limb akinesia; (3) unilateral spatial neglect; and (4) motor and cognitive impersistence. CONCLUSION: In patients with right hemisphere injury, callosal section may induce or enhance motor-intentional deficits and hemispatial neglect.

Adult↗
PubMed2003

Tolterodine and memory: dry but forgetful.

BACKGROUND: Anticholinergic drugs are known to produce or enhance cognitive deficits. Tolterodine tartrate is marketed as a bladder-selective anticholinergic drug that is reported to be free of significant cognitive adverse effects. OBJECTIVE: To describe a 46-year-old woman who had memory loss and abnormal memory test results that improved when she discontinued tolterodine therapy. RESULTS: While taking tolterodine, the patient's score on the delayed free recall portion of the Hopkins Verbal Learning Test-Revised was at the first percentile. One month after discontinuing tolterodine therapy, this test was administered a second time using an alternative form and she showed marked improvement scoring above the 75th percentile. CONCLUSIONS: Tolterodine therapy caused cognitive dysfunction in our patient. It is possible that cognitive dysfunction is a common result of tolterodine treatment, but in the absence of testing, remains undiagnosed. Alternatively, our patient may have had aberrant metabolism of this drug or an increased sensitivity as a result of incipient Alzheimer disease.

Benzhydryl Compounds↗
PubMed2003

Caloric stimulation in neglect: evaluation of response as a function of neglect type.

Contralesional neglect may be induced by either unawareness of contralesional stimuli (attentional neglect, AN) or failure to act in contralesional space (intentional neglect, IN). We examined whether contralesional cold caloric stimulation differentially affects AN versus IN. Patients with left-sided neglect (n = 16) from right-hemisphere lesions performed target cancellation and line bisection tasks. Using a video-based apparatus that reverses the right and left side of stimuli, patients with abnormal cancellation performance were divided into those with AN and those with IN. The 5 subjects with normal cancellation performance but rightward bisection bias were also separated into 2 neglect groups. Subjects performed cancellation or bisection tasks before and immediately after irrigation of the left auditory canal with ice water. Caloric stimulation induced brisk rightward nystagmus in all subjects. Subjects with AN cancelled more left-sided targets after stimulation than those with IN (p = .02). Whereas caloric stimulation significantly shifted bisection error leftward for both IN and AN groups (p < .0001), AN patients exhibited a greater magnitude of shift than the IN patients. While the basis for differential performance remains undefined, the data indicate that caloric stimulation influences AN more than IN.

Aged↗
PubMed2003

Mental object rotation in Parkinson's disease.

Deficits in visual-spatial ability can be associated with Parkinson's disease (PD), and there are several possible reasons for these deficits. Dysfunction in frontal-striatal and/or frontal-parietal systems, associated with dopamine deficiency, might disrupt cognitive processes either supporting (e.g., working memory) or subserving visual-spatial computations. The goal of this study was to assess visual-spatial orientation ability in individuals with PD using the Mental Rotations Test (MRT), along with other measures of cognitive function. Non-demented men with PD were significantly less accurate on this test than matched control men. In contrast, women with PD performed similarly to matched control women, but both groups of women did not perform much better than chance. Further, mental rotation accuracy in men correlated with their executive skills involving mental processing and psychomotor speed. In women with PD, however, mental rotation accuracy correlated negatively with verbal memory, indicating that higher mental rotation performance was associated with lower ability in verbal memory. These results indicate that PD is associated with visual-spatial orientation deficits in men. Women with PD and control women both performed poorly on the MRT, possibly reflecting a floor effect. Although men and women with PD appear to engage different cognitive processes in this task, the reason for the sex difference remains to be elucidated.

Aged↗
PubMed2003

Creative innovation: possible brain mechanisms.

This article reviews and develops some theories about the neurobiological basis of creative innovation (CI). CI is defined as the ability to understand and express novel orderly relationships. A high level of general intelligence, domain-specific knowledge and special skills are necessary components of creativity. Specialized knowledge is stored in specific portions of the temporal and parietal lobes. Some anatomic studies suggest that talented people might have alterations of specific regions of the posterior neocortical architecture, but further systematic studies are needed. Intelligence, knowledge and special skills, however, are not sufficient for CI. Developing alternative solutions or divergent thinking has been posited to be a critical element of CI, and clinical as well as functional imaging studies suggest that the frontal lobes are important for these activities. The frontal lobes have strong connections with the polymodal and supramodal regions of the temporal and parietal lobes where concepts and knowledge are stored. These connections might selectively inhibit and activate portions of posterior neocortex and thus be important for developing alternative solutions. Although extensive knowledge and divergent thinking together are critical for creativity they alone are insufficient for allowing a person to find the thread that unites. Finding this thread might require the binding of different forms of knowledge, stored in separate cortical modules that have not been previously associated. Thus, CI might require the co-activation and communication between regions of the brain that ordinarily are not strongly connected. The observations that CI often occurs during levels of low arousal and that many people with depression are creative suggests that alterations of neurotransmitters such as norepinephrine might be important in CI. High levels of norepinephrine, produced by high rates of locus coeruleus firing, restrict the breadth of concept representations and increase the signal to noise ratio, but low levels of norepinephrine shift the brain toward intrinsic neuronal activation with an increase in the size of distributed concept representations and co-activation across modular networks. In addition to being important in divergent thinking, the frontal lobes are also the primary cortical region that controls the locus coeruleus-norepinephrine system. Thus creative people may be endowed with brains that are capable of storing extensive specialized knowledge in their temporoparietal cortex, be capable of frontal mediated divergent thinking and have a special ability to modulate the frontal lobe-locus coeruleus (norepinephrine) system, such that during creative innovation cerebral levels of norepinephrine diminish, leading to the discovery of novel orderly relationships.

Animals↗
PubMed2003

Age-dependent recall bias for material of internal versus external origin.

OBJECTIVE: To learn whether young and aged subjects exhibit different recall biases for internally derived (Internal) versus externally supplied (External) material. BACKGROUND: Internally derived knowledge, prized by educators and therapists, can bring about dramatic behavioral change. Such information, seldom assessed on formal memory testing, may be preferentially recalled compared with external-origin material. Under some circumstances, however, subjects may demonstrate a recall advantage for externally supplied over internally generated material. METHOD: We compared Internal and External word recall in young and aged subjects with and without explicit intent to remember. RESULTS: Although overall the young and aged subjects recalled the same number of words, we did find a word-origin recall bias. This recall bias differed by age group (P = 0.005). When not instructed to remember words, the young subjects tended to remember more External words, while aged subjects remembered more Internal words. CONCLUSIONS: The differences in the brain mechanisms mediating Internal versus External recall bias are unknown. However, aging may modify an Internal-External memory bias.

Adult↗
PubMed2002

Is the middle between both halves?: midpoint location and segment size estimation in neglect.

BACKGROUND: Line bisection errors in neglect are attributed to perceptual size distortions. In order to compare the two segments of the line to determine if they are equal, one might first estimate the location of a midpoint that defines the two line segments to be compared. OBJECTIVES: The authors attempted to determine whether estimating a line's midpoint can be dissociated from comparing the two segments of this line, and if so, what the relative contribution of each of these tasks is to the perceptual bias in neglect. METHODS: The authors studied two patients with hemispatial neglect from right hemisphere lesions by asking them where bisection marks were placed on prebisected lines and whether the two adjacent line segments were equal. RESULTS: There was a stronger bias judging the position of the bisecting marks ("where" determination) than comparing the size of two adjacent line segments. CONCLUSIONS: These results suggest that perceptual size distortion of line segments alone cannot explain the subjects' line bisection bias, but postperceptual deficits in "where" computations may better account for their errors locating the midpoint. "Where" determinations might require more attentional capacity, depend more heavily on viewer-centered allocation of attention, and be mediated by the right hemisphere's "where" dorsal stream. In contrast, comparing the length of two segments might be mediated by the left hemisphere's "what" ventral stream.

Aged↗
PubMed2002

The contribution of an avoidance response to contralateral neglect.

Displacement of line bisection to the right of midline in a patient with a right hemisphere lesion has been attributed to either contralesional attentional or intentional hemispatial neglect. However, it has been suggested that patients with hemispheric lesions might also have an avoidance response, and the ipsilesional eye and hand deviation attributed to neglect might, at least in part, be related to this response. The authors report a patient with a net contralateral neglect produced by the combination of intention and avoidance factors.

Aged↗
PubMed2002

Progressive dementia and hypersomnolence with dream-enacting behavior: oneiric dementia.

BACKGROUND: Sleep disorders are associated with several types of degenerative dementias, including Alzheimer and prion diseases. Animal models have demonstrated abolition of rapid eye movement atonia, resulting in dream-enacting complex movements termed oneiric behavior, and patients with fatal familial insomnia may have vivid dreams that intrude on wakefulness. OBJECTIVE: To describe a new form of progressive dementia with hypersomnia and oneiric behavior. METHODS: Neuropsychological and polysomnographic studies of a middle-aged woman with a progressive dementia, excessive daytime sleepiness, and a vertical gaze palsy. RESULTS: Neuropsychological testing revealed decreased verbal fluency, impaired attention and working memory, amnesia, poor recall, and bradyphrenia with hypersomnia. Polysomnography revealed a rapid eye movement behavioral disorder with complete absence of slow wave sleep. Prion protein analysis did not reveal the mutation associated with fatal familial insomnia, and other diagnostic test findings were unrevealing. CONCLUSION: Our patient had a previously unreported syndrome of progressive dementia associated with rapid eye movement behavioral disorder and the absence of slow wave sleep.

Dementia↗