A counterpoint to Reitan's note on the history of clinical neuropsychology.
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Comment↗
Biomedical subjects
D W Loring
Publications and source records attributed to D W Loring.
The effects of lateralized temporal lobe dysfunction on formal and semantic word fluency.
Word fluency performance was studied in 32 patients with unilateral temporal lobe epilepsy (TLE) and 25 healthy dextral controls. Two word fluency tasks were administered conforming to either formal-based criteria or semantic-based criteria. Performance for TLE patients was assessed both pre-operatively and approximately 1 week following anterior temporal lobectomy. Both formal and semantic word fluency decreased regardless of resection laterality. Left TLE patients performed significantly worse at both pre- and post-operative assessments compared to the right TLE patients, while right TLE patients performed significantly poorer than controls on all verbal fluency criteria at pre- and post-operative assessments. In addition, both TLE and control groups produced significantly fewer formal and semantic words during the second 30-sec portion of each task. These findings are discussed in terms of temporal lobe contributions to word fluency production and lexical semantic processing.
Adult↗
Cerebral language lateralization: evidence from intracarotid amobarbital testing.
Cerebral language lateralization was investigated in 103 patients undergoing intracarotid amobarbital testing as part of their diagnostic work-up for epilepsy surgery. Inclusion criteria included adequate bilateral intracarotid amobarbital studies and no radiologic lesion in areas other than the temporal lobe. Language was evaluated with respect to strict presence or absence of language representation, in which a patient was considered to have bilateral language despite potentially having asymmetric language representation, and with respect to forced relative hemispheric dominance, in which a single side could be considered dominant despite bilateral language representation. Seventy-nine patients displayed exclusive left hemisphere language representation, two patients showed exclusive right hemisphere language representation, and 22 patients had language represented in each hemisphere. In the 22 patients with bilateral language, an asymmetry was present in 17 cases (13 L greater than R, 4 R greater than L). These data indicate that language restricted only to the right hemisphere is rare, and that in the absence of purely left hemisphere language, most patients exhibit bilateral representation. Previously reported incidence of exclusive right hemisphere language may be an artifact of dichotomizing a continuous variable.
Amobarbital↗
Hemispheric specialization for emotional expression: a reexamination of results from intracarotid administration of sodium amobarbital.
Emotional and behavioral responses to sodium amobarbital injection were examined in 44 epilepsy surgery candidates. Thirty-three emotional reactions occurred in 26 patients, 44% of the reactions following right hemisphere injection and 32% after injection of the left hemisphere. Among all patients examined, laughter/elated mood was statistically more frequent following right hemisphere injection while crying was statistically associated with left hemisphere injections. These observed effects were not related to amobarbital dose, sex, bilateral hemispheric inactivation (angiographic crossflow), general cognitive status, or side of seizure onset. These results support differing specialization of emotional expression in the right and left cerebral hemispheres and their subcortical connections.
Adolescent↗
Material specific learning during electrical stimulation of the human hippocampus.
Material specific learning was assessed during unilateral electrical stimulation of the hippocampus through intracerebrally implanted electrodes in 30 patients with unilateral temporal lobe epilepsy (TLE). Verbal learning significantly decreased in patients with right TLE after stimulation of the left, but not the right, hippocampus. No verbal learning impairment was observed in left TLE patients following stimulation of either hippocampus. Visuospatial memory performance significantly decreased following stimulation of the right hippocampus regardless of the side of seizure onset. Results suggest that the contralateral "nonepileptic" hippocampus does not assume the material specific mnestic functions of the dysfunctional hippocampus associated with longstanding epilepsy.
Analysis of Variance↗
The contribution of an imagery code to verbal memory.
Free recall for auditorially presented spatial information was examined in a patient with a large right cerebral infarction. Despite normal verbal memory at immediate and 30-minute conditions, the patient exhibited a significant loss in verbal recall at 24 hours and a more severe deficit in the recall of the spatial components of prose passages across all delayed recall conditions. These results suggest that although the verbal code is important early in the learning process, spatial imagery exerts an increasing influence over time. Thus, reliance upon a left hemispheric mediated verbal encoding process may only allow for partial integration of linguistic and visuospatial properties.
Adult↗
Crossed aphasia in a patient with complex partial seizures: evidence from intracarotid amobarbital testing, functional cortical mapping, and neuropsychological assessment.
We report a right-handed patient who became transiently aphasic following a right temporal lobectomy for control of intractable complex partial seizures. Preoperative intracarotid amobarbital testing revealed right-hemisphere language dominance, although bilateral language representation was present. Memory testing during unilateral electrical hippocampal simulation with depth electrodes indicated reliance on left-hemisphere mesial temporal lobe structures for verbal memory. Functional mapping for language during surgery established several right perisylvian regions that, when stimulated, produced speech arrest and/or paraphasic substitution. One-year follow-up neuropsychological assessment demonstrated an increase in verbal learning and decrease in visual memory, a pattern associated with patients who have undergone right temporal lobectomy. These data demonstrate that (1) right cerebral language dominance can be observed when ipsilateral seizure onset is present (2) verbal memory and language dominance are not necessarily linked, and (3) some reported cases of crossed aphasia may in fact have bilateral language representation.
Adult↗
Henry F. Campbell and the secretory nervous system.
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Autonomic Nervous System↗
Comparative cognitive effects of anticonvulsants.
We investigated the neuropsychological effects of carbamazepine, phenobarbital, and phenytoin in 15 partial complex epilepsy patients treated with each drug for 3 months, using a randomized double-blind, triple crossover design. Neuropsychological evaluation at the end of each treatment period included Digit Span, Selective Reminding Test, Digit Symbol, Finger Tapping, Grooved Pegboard, Choice Reaction Time, P3 evoked potential, and Profile of Mood States. Employing anticonvulsant blood levels and seizure frequencies as covariates, the only significant difference was for Digit Symbol. Performance with phenobarbital was significantly worse than with the other 2 anticonvulsants despite phenobarbital's having had the lowest overall blood levels. Our data show that patients receiving carbamazepine, phenobarbital, and phenytoin have comparable neuropsychological performance on most measures. The results suggest that the differential cognitive effects of anticonvulsants may be subtle.
Adult↗
The intracarotid amobarbital procedure as a predictor of memory failure following unilateral temporal lobectomy.
We investigated the efficacy of the intracarotid amobarbital procedure to accurately predict post-temporal lobectomy anterograde amnesia. We presented items at 2 separate times during amobarbital assessment; both early and late item recall were decreased during the injection contralateral to seizure onset indicating sensitivity to bilateral temporal lobe dysfunction. Ten patients for whom follow-up neuropsychological assessment was available failed either the early or late item recognition portions of their amobarbital evaluation ipsilateral to seizure onset, but had hippocampus included in the temporal lobectomy by virtue of satisfactory performance on other tests of hippocampal function. None of these 10 patients displayed postoperative anterograde amnesia, although there was a reduction in material-specific memory in some patients. These results indicate that relying solely on amobarbital memory testing to assess the functional ability of the contralateral temporal lobe to sustain global memory prior to temporal lobectomy may needlessly exclude patients from a viable therapeutic option.
Amnesia↗
Human hippocampal EEG: effects of behavioral activation.
We studied spectral components of human hippocampal EEG in relation to behavioral status in 19 patients with intractable complex partial seizures who had depth electrodes implanted into the anterior hippocampi as a part of their preoperative evaluations. Behavioral conditions included: eyes closed resting, eyes open resting, eyes open with a verbal task, and eyes open with a visuospatial task. Hippocampal EEG spectral power uniformly decreased during behavioral activation. EEG activation was quantitatively different among the 3 activated conditions, with the most prominent change occurring during the visuospatial task. The degree of EEG activation corresponded inversely with the site of epileptic focus during the verbal task. The results demonstrate the response of human hippocampal EEG to behavioral activation. The magnitude of EEG change may reflect the degree of functional activation of the given hippocampus.
Adult↗
Unilateral cerebral inactivation produces differential left/right heart rate responses.
We studied heart rate following unilateral hemispheric inactivation by intracarotid amobarbital in 25 patients undergoing preoperative evaluation for epilepsy surgery. Heart rate increased after left hemisphere inactivation, but decreased following right hemisphere inactivation. The results are consistent with differential left/right cerebral hemispheric effects on autonomic function, and appear related to functional and anatomic asymmetries in both the central and peripheral nervous systems.
Adolescent↗
Long-latency evoked potentials during aura of temporal lobe origin.
Long-latency evoked potentials recorded from scalp or scalp/sphenoidal electrodes have been shown to have diminished amplitude and power during interictal recordings on the side ipsilateral to an unilateral mesial temporal lobe (MTL) focus. We now report recordings of long-latency evoked potentials both during a prolonged aura and also on two seizure-free days. P3 amplitude and sphenoidal evoked potential (SpEP) spectral power in the scalp/sphenoidal channels were less, ipsilateral to the MTL focus. During the aura, the SpEPs had reduced power and reduced amplitude. However, the amplitude of the N2 component for the target averages in the CZ-A1A2 channel was markedly enhanced during the aura.
Adolescent↗
Anterograde memory for visuospatial arrays.
A new test was developed to assess direction of errors and hemispatial differences in anterograde memory for visuospatial arrays of abstract figures. After a series of learning trials, delayed recall of figure placement was obtained in 12 healthy dextral adults. Horizontal and vertical errors were measured for each figure. Mean directional error and mean absolute error were calculated for each subject in left and right hemispace for horizontal and vertical dimensions. Although no hemispatial effect was found for mean absolute error, hemispatial differences were present for mean directional error in both horizontal and vertical dimensions. Overall, horizontal deviations were medial, and vertical deviations were downward. However, these effects reached statistical significance only in right hemispace. The directional errors are believed to be due to an attentional shift toward proximal peripersonal space, in combination with attentional shifts from differential left/right cerebral activation.
Adult↗
Psychometric construction of the Rey-Osterrieth Complex Figure: methodological considerations and interrater reliability.
Formal scoring criteria for the standard 18 elements of the Rey-Osterrieth Complex Figure were developed and applied to reproductions of 87 healthy young adults. In addition, the effects of immediate recall on delayed performance was investigated. Results indicate (a) the formal scoring criteria can be reliably applied by independent raters; (b) 30-minute recall is significantly higher if immediate reproduction is included compared to 30-minute delay performance without immediate recall; (c) significantly fewer qualitative scoring errors are present at the 30-minute delay if immediate memory is previously assessed; and (d) in addition to an absence of decay over a 30-minute delay, performance significantly improves over this interval. These findings underscore the caution that must be exercised when making specific inferences from test scores alone based upon measures that were obtained in a variety of contexts employing unspecified scoring criteria.
Journal Article↗
The intracarotid amobarbital sodium procedure. False-positive errors during recognition memory assessment.
Memory performance during the intracarotid amobarbital sodium (Amytal sodium) procedure was examined in 40 patients as part of their diagnostic work-up as candidates for epilepsy surgery. Free recall was significantly better following right hemisphere injection although no left/right difference was present during recognition assessment. However, the occurrence of false-positive (FP) recognition errors was significantly more frequent following left hemisphere injection. In all conditions, no relationship to seizure focus was observed. Patients with FP errors displayed poorer delayed verbal memory during baseline neuropsychological assessment compared with patients without FP errors. Data indicate an inverse relationship between FP errors and recent verbal memory function, and they suggest that impaired memory rather than failure to suppress incorrect responses secondary to poor self-monitoring capacity is responsible for the generation of FP and intrusion errors.
Adult↗
Differential-handed response to verbal and visual spatial stimuli: evidence of specialized hemispheric processing following callosotomy.
Left- and right-hand responses were studied in a patient who had undergone complete corpus callosotomy to examine selective hemispheric processing employing free-field stimuli. Tests of verbal and visual spatial processing were presented, and multiple choice performances were obtained using both left and right hands. A double dissociation emerged, with superior left-handed performance on visual spatial tasks, and better right-handed performance on verbal tasks. In addition, the patient displayed hemispatial dyscalculia in which he solved written arithmetic problems disregarding free-field numerical information presented toward his left. Evidence of multimodality left-sided extinction was also present. Further, despite unilateral callosal apraxia, the left hand displayed superiority during a continuous performance task. These results demonstrate that specialized functions of the cerebral hemispheres may be observed for response output in the absence of restricted hemispheric input, and that components of the neglect syndrome may be seen following corpus callosotomy.
Adult↗
Differential cognitive effects of terfenadine and chlorpheniramine.
The H1-histamine antagonist, terfenadine, has been proposed to have reduced cognitive side effects. In the present study, the relative cognitive effects of terfenadine, 60 mg, chlorpheniramine maleate, 8 mg, and placebo were tested with a double-blind, randomized, three-period crossover design in 24 healthy adult subjects. The dependent variable was latency of the P3-evoked potential. The P3 is a cognitively evoked electroencephalographic response that is an objective and sensitive measure of sustained attention and cerebral processing speed. Disease and drug states that adversely affect the central nervous system can slow P3 latency. For example, the centrally active anticholinergic scopolamine slows cognitive processing speed and prolongs P3 latency. P3 latency (millisecond) means (+/- mean standard error) were pretreatment, 310 (+/- 1.7; placebo, 313 (+/- 3); terfenadine, 320 (+/- 3); and chlorpheniramine, 333 (+/- 3). The findings suggest that terfenadine may be particularly advantageous in patients who require alertness and intact cognitive abilities.
Adult↗