Biomedical subjects

B Milner

Publications and source records attributed to B Milner.

At least 37 records · Page 2Linked to original sources

PubMed1994

Capacity of visual short-term memory after unilateral frontal or anterior temporal-lobe resection.

The effect of unilateral temporal- or frontal-lobe lesions on the capacity of short-term memory for a single pattern was explored; this measure has been designated pattern span. Pattern span was assessed under different delays and with and without distraction. Both the passage of time and presence of distraction decreased pattern span for all subject groups. Right anterior temporal lobectomy did not result in an impairment in pattern span in any condition, whereas right frontal-lobe excisions were associated with impaired span in all conditions. It is suggested that this deficit represents a decreased ability to encode the more complex patterns under a time constraint.

Adolescent↗

PubMed1994

The effect of presentation rate on the comprehension and recall of speech after anterior temporal-lobe resection.

Twenty-two patients who had undergone unilateral anterior resection of either the left (LT) or right (RT) temporal lobe and 13 normal control (NC) subjects were tested on a lexical-decision task and a story-memory task. Stimuli were presented aurally, and, in the latter task, at five different speech rates ranging from 125 words per minute (wpm) to 325 wpm. Memory for stories in the LT group was not abnormally sensitive to the effect of increasing rate, although it was inferior to that of the NC group at all speeds. This argues against the hypothesis that the verbal memory deficit evident after LT resection is partially attributable to an abnormally slow processing of verbal information. But LT subjects were impaired at judging the lexicality of words and nonwords presented aurally, suggesting that the left anterior temporal region plays a special role in the processing of speech sounds.

Adult↗

PubMed1994

Right-hippocampal contralateral-hand effect in the recall of spatial location in the tactual modality.

The recall of spatial location in the tactual modality was investigated in 53 patients with unilateral temporal lobectomy, one patient with bilateral hippocampal damage and 23 normal control subjects. Using only active touch, blindfolded subjects had to locate the position of a map pin within a circular space and then recall its position after a 12- or 24-sec delay. Left temporal-lobe patients (N = 23) were found to perform normally as were right temporal-lobe patients with removals that did not exceed the pes of the hippocampus (N = 22). In contrast, right temporal-lobe patients with large hippocampal excision (N = 8) were impaired on the 24-sec (but not at the 12-sec) delay condition. When performance of the two hands was compared, no difference was found for the left-temporal, right-temporal-small-hippocampal-removal and normal control groups. In contrast, for the right temporal-large-hippocampal-removal group performance on the hand contralateral to the side of temporal lobectomy (left hand) was impaired, whereas right-hand performance in this group was normal. The patient with bilateral hippocampal damage was inferior to the most impaired patient with unilateral temporal lobectomy. These findings suggest that the right and left medial-temporal regions differ in their functional relationships to cerebral areas mediating tactual processing, intact right medial-temporal structures being involved in tactuo-spatial retention bimanually while left medial-temporal structures serve a more specific role confined to the contralateral (right) hand.

Adolescent↗

PubMed1994

Verbal recall and recognition as a function of depth of encoding in patients with unilateral temporal lobectomy.

The hypothesis that impairment in cognitive organization is a significant causal factor in the verbal memory impairment known to follow left anterior temporal (LT) lobectomy was tested by assessing verbal recall and recognition as a function of depth of encoding in 20 patients with LT lobectomy (19 in the recognition condition), 20 patients with right temporal lobectomy and 20 normal control subjects. Subjects first made decisions regarding either the physical, phonemic or semantic aspects of 48 words. After the encoding phase, a free recall test was given, followed by a recognition test. As expected, the verbal memory of the LT group was impaired in both the recall and recognition conditions. However, the LT group followed the pattern of the other two groups in recalling and recognizing more words which had been subjected to semantic analysis. These findings do not support the hypothesis that a disruption in the normal relationship between cognitive organization and memory contributes to the memory impairment following LT lobectomy. In contrast the verbal recall of the LT group failed to follow the pattern of the other two groups in that it did not benefit from phonemic encoding. Taken together, these findings support the notion that left anterior temporal-lobe cortical structures are more specialized for the evocation of the sound of a word than for those processes that underlie the recall of semantically encoded verbal material.

Adult↗

PubMed1994

Genetic mapping of the BRCA1 region on chromosome 17q21.

Chromosome 17q21 harbors a gene (BRCA1) associated with a hereditary form of breast cancer. As a step toward identification of this gene itself we developed a number of simple-sequence-repeat (SSR) markers for chromosome 17 and constructed a high-resolution genetic map of a 40-cM region around 17q21. As part of this effort we captured genotypes from five of the markers by using an ABI sequencing instrument and stored them in a locally developed database, as a step toward automated genotyping. In addition, YACs that physically link some of the SSR markers were identified. The results provided by this study should facilitate physical mapping of the BRCA1 region and isolation of the BRCA1 gene.

Base Sequence↗

PubMed1993

The criterion-related validity of the Childhood Autism Rating Scale and the Autism Behavior Checklist.

The present study sought to examine the relationship between two popular instruments for screening autistic children: the Childhood Autism Rating Scale (CARS) and the Autism Behavior Checklist (ABC). The sample included 77 individuals. The records of 48 subjects contained firm diagnoses of autism, while the suggestion of autism was found in the remaining records. Correlations between the two scales ranged from -.16 to .73 (median = .39). The validity coefficient between the two total scores was .67. Using cutoff scores recommended by the authors, an analysis of the sensitivity of the two instruments was conducted. The CARS correctly identified 98% of the autistic subjects; it identified 69% of the possibly autistic as autistic. The ABC correctly identified 88% of the autistic subjects, while it identified 48% of those subjects considered possibly autistic as autistic. A phi coefficient was computed to estimate the degree of relationship between the nominal classifications produced by the two instruments. A moderate relationship was found (r phi = .54). Implications of the results are discussed.

Adolescent↗

PubMed1993

Strategic search and retrieval inhibition: the role of the frontal lobes.

Recall of words from categorised lists was examined in 77 patients and 12 normal control subjects. In Experiment 1, both left temporal-lobe excisions that included the hippocampus (LTH) and left frontal-lobe removals (LF) impaired free recall, but the LF group performed normally when encoding and retrieval strategies were supplied. In Experiment 2, experimentally induced interference during cued recall abnormally hampered performance for the LF, but not for the LTH group. Subsequent removal of the interfering cues resulted in improved performance for the LF group. Thus, the integrity of the left frontal lobe seems indispensable for normal strategic retrieval and for the suppression of potentially interfering items in verbal memory.

Adolescent↗

PubMed1993

Memory for different aspects of complex visual scenes after unilateral temporal- or frontal-lobe resection.

Delayed recognition memory for different aspects of complex visual scenes was examined in 65 patients with unilateral temporal- or frontal-lobe excisions and 15 normal control subjects. Right anterior temporal lobectomy, irrespective of the extent of hippocampal removal, impaired memory for figurative detail (the visual characteristics of the objects in a scene) and spatial composition (the arrangement of the filled and unfilled space in a scene). In contrast, only patients with right temporal-lobe lesions that included extensive hippocampal removal were impaired at detecting changes in the spatial location of specific objects. A subsequent study provided no evidence that right temporal lobectomy impairs the immediate recognition of these types of visual information, suggesting that the impairments observed after a delay represent a failure of retention or retrieval rather than of encoding.

Adolescent↗

PubMed1992

The multidisciplinary management of a family with epithelial ovarian cancer.

OBJECTIVE: To describe the management of a family with an inherited predisposition to ovarian and breast cancer. Particular attention is paid to the problems of contraception, screening, prophylactic surgery and hormone replacement therapy. SETTING: The multidisciplinary Grampian Familial Epithelial Ovarian Cancer Study Group. SUBJECTS: 162 members of a family extending over five generations. In the third generation, five of the 10 women died with epithelial ovarian cancer. Three women in generation IV have developed pre-menopausal breast cancer. There are now 78 family members in the fifth generation aged between 2 and 22 years. INTERVENTIONS: Counselling of female family members is started at the age of 18 years. The combined oral contraceptive pill is advocated to suppress ovulation. Gynaecological follow-up after the age of 28 includes yearly pelvic examination, transvaginal ultrasonography and serum CA125 estimation. Laparoscopy with peritoneal cytology is indicated if any part of this yearly assessment is abnormal. Prophylactic oophorectomy is advised between the ages of 35 and 40 years after the family is complete. In generation IV, 20 of the 29 women have undergone prophylactic oophorectomy. Oestrogen hormone replacement therapy with a cyclical progestogen is recommended after prophylactic oophorectomy. Breast cancer screening starts at the age of 25 and involves annual clinical breast examination augmented by mammography and breast ultrasound. CONCLUSIONS: Only by the careful questioning and recording of family history, including at least third degree relatives (cousins), will similar groups with familial ovarian/breast cancer be identified. When predisposing genes are characterized it will be possible to identify carriers within the family and concentrate clinical effort on them while offering appropriate reassurance to those with decreased risk.

Adult↗

PubMed1991

Frontal-lobe contribution to recency judgements.

Three recency-discrimination tasks (involving concrete words, representational drawings and abstract paintings) were administered to 117 patients who had undergone unilateral cortical removals, and to 20 normal control subjects. Frontal or anterior temporal-lobe excision did not impair simple item recognition, and neither left nor right anterior-temporal lobectomy affected recency judgements on any task. In contrast, excisions that encroached on the mid-lateral frontal cortex impaired verbal recency judgements, the deficit being mild after right frontal lobectomy. Patients with right frontal-lobe removals showed the greatest impairment in recency discrimination on the two pictorial tests. The results provide evidence for hemispheric specialization related to the nature of the stimulus material and some support for a functional role for the left mid-lateral frontal cortex in verbal recency judgements.

Adolescent↗

PubMed1991

Does left temporal lobectomy adversely affect the rate at which verbal material can be processed?

Fifty-three patients with unilateral temporal- or right frontal-lobe excision and 12 normal control (NC) subjects read words, sentences and stories presented at slow, normal or fast reading rates. No group differences were noted for the number of errors committed when reading single words or sentences. The left temporal-lobe group with large hippocampal excisions made more mistakes than the NC group when identifying false statements about the stories, but this increased error-rate occurred irrespective of the rate of stimulus presentation. These findings suggest that the critical feature affecting recall of stories after left temporal lobectomy is not the rate at which the information is presented but, rather, the amount of information that must be retained.

Adolescent↗

PubMed1991

Right temporal-lobe contribution to global visual processing.

The performance of 92 patients with unilateral temporal- or frontal-lobe excisions and 35 normal control subjects was tested under two experimental conditions (global, local) of a Stroop-type reaction-time task, employing either hierarchically structured letters or abstract designs as stimuli. In the local condition, subjects were asked to focus their attention on the small forms and to ignore the large form, whereas they were instructed to do the reverse in the global condition. The results showed that, in the local condition, the patients with right temporal-lobe lesions were less affected than the other groups by interference from the global aspect of the stimulus. This reduced sensitivity to the overall configuration of the stimulus was unrelated to the extent of hippocampal removal or to the presence of visual-field defects. These findings support the hypothesis that the human right temporal neocortex contributes to the global processing of visual information.

Adolescent↗

PubMed1991

The frontal cortex and memory for temporal order.

Patients with unilateral frontal- or temporal-lobe excisions and normal control subjects made relative-recency decisions about objects presented sequentially. Several objects within each series were presented in the context of actions to be performed using them, such as "squeeze the sponge", whereas others had only to be named. Both left and right frontal-lobe groups were impaired on order judgements for named items, but their performance was normal for action items. The results suggest that providing salient and distinctive items, involving meaningful actions and multimodal cues, helps compensate for deficits in memory for temporal information associated with frontal-lobe damage.

Adolescent↗

PubMed1991

Role of the right temporal lobe in visual-cue learning during repeated pattern discriminations.

The ability to acquire visual cues for discriminating between two targets against a background of visually similar items was examined in 64 patients with unilateral temporal- or frontal-lobe excisions and 20 normal control subjects. The subjects were tested on two versions (letters and abstract designs) of a visual cue-learning task that was an adaptation and extension of RABBITT's (Am. J. Psychol. 80, 1-13, 1967) visual-search paradigm. For both versions, the material consisted of two packs of cards, each containing a different set of background letters or designs. Subjects were required to sort the cards into two piles according to which of two targets was present on the card. On the letter task, all groups took longer to sort when the background letters were changed after three learning trials. With abstract designs, patients with right temporal-lobe lesions failed to show this interference effect after three learning trials, but they, like other groups, did so after six. This slowness in learning was related neither to the extent of hippocampal removal nor to visual-field defects. It is argued that the right temporal neocortex plays a role in incremental learning of visual cues during repeated pattern discriminations.

Adolescent↗

PubMed1991

Contribution of the right frontal lobe to the encoding and recall of kinesthetic distance information.

Sixty-two patients with unilateral temporal- or frontal-lobe excisions and 16 normal control subjects were tested on a kinesthetic task, which required the monitoring of peripheral feedback in order to duplicate the distance of examiner-defined arm movements. Temporal lobectomy did not interfere with performance. Patients with left frontal-lobe or small right frontal-lobe excisions also performed normally, whereas those with large right frontal-lobe removals were impaired, the deficit being equal for the two arms. The results point to an important role played by the right frontal lobe in the monitoring of kinesthetic feedback both during the presentation of the movements and during the recall attempt.

Adolescent↗

PubMed1991

Recall of the end-position of examiner-defined arm movements by patients with frontal- or temporal-lobe lesions.

Sixty-three patients with unilateral temporal- or frontal-lobe excisions and 14 normal control subjects were tested on a kinesthetic task in which they had to recall the end-position of arm movements determined by the examiner. Patients with left frontal-lobe or small right frontal-lobe excisions performed normally, whereas patients with temporal-lobe excisions that included extensive removal of the hippocampus performed poorly, but only after a delay during which an interpolated task was carried out. Subjects with large right frontal-lobe removals were impaired in delayed recall, and the presence of an interpolated task did not exacerbate the impairment, which was equal for the two arms. The results point to an important role played by the right frontal lobe in the maintenance of kinesthetic-location cues over time, but not in their initial encoding.

Adolescent↗

PubMed1990

The role of the left hippocampal region in the acquisition and retention of story content.

Thirteen normal control subjects and 62 patients who had undergone either a unilateral temporal or a unilateral frontal lobectomy learned the content of a short prose passage to a strict criterion. Compared to other subject, patients with left temporal-lobe excision took longer to learn the story content and, within this group, the slowest rate noted was for patients with extensive removal from the hippocampal region. When retention of the material was tested after a 20 min delay, only the group with large excisions from the left hippocampus and/or parahippocampal gyrus was impaired. This finding of abnormally rapid forgetting of material learned to criterion highlights the role of the left hippocampal region in the long-term maintenance of verbal information presented in a context.

Adolescent↗

PubMed1990

The relationship of working memory to the immediate recall of stories following unilateral temporal or frontal lobectomy.

Patients undergoing unilateral temporal lobectomy were tested preoperatively for working memory capacity, sentence comprehension, and rapid-naming ability, and were retested on these same measures 3 to 5 days and 2 weeks postoperatively. Immediate recall of stories was assessed twice only: preoperatively, and 2 weeks postoperatively. The left temporal-lobe group demonstrated transient deficits in working memory capacity, sentence comprehension, and rapid-naming ability over the 2 week postoperative period. No significant group differences in working memory capacity were evident two weeks after operation, even though the story recall of the left temporal-lobe group was impaired. A second experiment, with additional patients, explored the possible contribution of the hippocampus and of the frontal lobes to performance on these same tasks. Extent of hippocampal excision did not affect performance differentially on any task. Story recall was impaired following left temporal lobectomy, whereas left frontal lobectomy impaired sentence comprehension and rapid-naming ability. These results indicate a double dissociation of verbal deficits 2 weeks after left temporal- and left frontal-lobe excisions.

Adolescent↗