Using image analysis techniques to analyze figure-copying performance of patients with visuospatial neglect and control groups

Figure copying is often used to detect visuospatial neglect (VSN) in brain-damaged patients. We describe algorithms that enable the computation of parameters for describing figure-copying performance. The researcher can readily implement these algorithms on a computer using image analysis software, and they provide information on goodness-of-fit, relative to a standard model, as well as on dynamic aspects of subjects’ performance in completing figure copies. To demonstrate the clinical utility of these algorithms, preliminary results from a group of right-hemisphere brain-damaged patients, some of whom have VSN, are compared with those for age-matched controls.     

Confrontation naming impairment in dementia

In tone languages pitch variations (tones) serve to distinguish the lexical meanings of words. This study was conducted to examine the extent and nature of impairment in the perception of tones by aphasic patients who were monolingual speakers of Thai, a tone language which has five contrastive tones (mid, low, falling, high, rising). Six subjects participated in the study: two Broca aphasics, one transcortical motor aphasic, one conduction aphasic, one right brain-damaged nonaphasic, and one normal control. Three sets of stimuli (two real-speech, one synthetic-speech) were presented for identification, each set containing five Thai words minimally distinguished by tone. Results of the perception tests indicated that the performance of all four left brain-damaged aphasics differed significantly from that of the normal control, while the performance of the right brain-damaged nonaphasic did not. The normal performance of the right brain-damaged nonaphasic patient on this tone identification task suggests that deficits in the perception of tone exhibited by left brain-damaged patients can be attributed specifically to pathology in the language dominant hemisphere rather than to a general brain-damage effect. No difference in performance among the left brain-damaged patients could be attributed to a specific type of aphasic syndrome. The pattern of tonal confusions of the aphasics in comparison to that of normals suggests that their deficit is primarily quantitative rather than qualitative. Although two (mid, low) of the five tones accounted for a large percentage of the aphasics' errors, no uniform rank order of tones in terms of identifiability could be established across aphasic subjects, which suggests that their deficit is general to all five tones rather than selective to individual tones.     

Development of procedures for rating posed emotional expressions across facial, prosodic, and lexical channels.

A number of rating systems are available to evaluate emotional communication in a single modality. The main purpose of this study was to develop procedures to train human raters to evaluate posed expressions of emotion across three different channels of communication, i.e., facial, prosodic/intonational, and lexical/verbal. These procedures were used to evaluate posed emotional expressions produced by individuals with unilateral brain lesions from stroke. Posers in this preliminary report were two right brain-damaged, two left brain-damaged, and two normal control right-handed adults who were matched on demographic and neurological factors. Eight emotional expressions, both positive and negative, were produced in three channels and rated for intensity, pleasantness, and category accuracy. 15 normal adults served as raters, five per channel. The rating procedures were comparable across channels, with analogous properties, and yielded substantial interrater agreement. In this small sample of posers, it was observed that the expressions of the right brain-damaged group were rated as the least accurate and those of the left brain-damaged group as the most intense. When patterns of individual performance across the channels were examined, performance was quiet consistent for the normal controls yet variable for the right brain-damaged persons. These observations are in keeping with the notion that patients with right hemisphere pathology have difficulty in emotional communication. In summary, these findings suggest that comparison of emotional expressions across multiple channels is feasible.     

Story arrangement ability in right brain-damaged patients.

The purpose of the present study is to explore the role of an explicit expression of macrostructure in facilitating performance on a Story Arrangement Task. Subjects were presented with a series of sentences which they were required to arrange into a coherent paragraph. Half of the items were preceded by a theme sentence containing the framework or macrostructure of the paragraph, while the items without theme sentences required subjects to formulate their own macrostructure in a bottom-up fashion. Results of the study support the hypothesis that the presence of a theme sentence facilitates performance on the Story Arrangement Task for non-brain-damaged individuals (NBDs) and left brain-damaged patients (LBDs), but not for right brain-damaged patients (RBDs). This suggests that RBDs are impaired in their ability to recognize and benefit from explicit thematic statements in narratives. Other discourse-level deficits in RBDs are discussed in the light of these findings. The performance of LBDs on such tasks is also discussed.     

Perception and production of tone in aphasia

An acoustical and perceptual study of lexical tone was conducted to evaluate the extent and nature of tonal disruption in aphasia. The language under investigation was Thai, a tone language which has five lexical tones--mid, low, falling, high, and rising. Subjects included six left brain-damaged aphasics (two Broca's, one transcortical motor, one global, one conduction, one Wernicke), one right brain-damaged nonaphasic, one cerebellar dysarthric, and five normals. High-quality tape recordings of each subject's productions of a minimal set of five, monosyllabic Thai words were presented to 10 adult Thai listeners for identification. Results from the phonemic identification tests indicated that tone production is relatively spared in aphasic patients with unilateral left hemisphere lesions. The performance of the global aphasic, however, was considerably below normal. Patterns of tonal confusions further revealed that the performance of all aphasics, except the global, differed from that of normal speakers primarily in degree rather than in kind. Tonal contrasts were signaled at a high level of proficiency by the right brain-damaged and dysarthric patients. Acoustical analysis revealed that F0 contours associated with the five tones for all aphasics, except the global, were similar in overall shape as well as position in the tone space to those of normals. F0 contours for the right brain-damaged patient and the dysarthric also generally agreed with those of normals in terms of shape and position. F0 ranges of both aphasic and nonaphasic brain-damaged speakers were generally larger than those of normals for all five tones. The relationship between tone and vowel duration was generally similar to that of normals for all brain-damaged speakers. A comparison of aphasics' performance on tone perception (J. Gandour & R. Dardarananda, 1983, Brain and Language, 18, 94-114) and tone production indicated that, for the normal and right brain-damaged subjects, performance on the perception task was higher than on production, whereas the opposite was true for the aphasics. These data are brought to bear on issues related to tone production in aphasia, consonant and vowel production in aphasia, hemispheric specialization for tone production, intonation production in aphasia, relationship between speech perception and speech production, and tone production in dysarthria with cerebellar disease.     

Effects of left-hand preference on postinjury measures of distal motor ability

The relationship of preinjury left-hand dominance for motor performance to postinjury distal motor skills following penetrating brain wounds in patients without overt hemiplegia was examined. We studied 13 controls, 13 right-hemisphere brain-damaged patients, and 11 left-hemisphere brain-damaged patients on motor tasks measuring reaction time, strength, and coordination. Our results indicated that no persistent deficits were seen on distal motor tasks in left-handed adults who suffered a penetrating brain wound. These findings are compatible with the relative sparing of persistent neuropsychological deficits in left-handers following brain damage.     

Developing algorithms to enhance the sensitivity of cancellation tests of visuospatial neglect

We describe a set of algorithms that enhance the sensitivity of cancellation tests used in assessing visuospatial neglect. The algorithms can be readily implemented on a computer and can provide temporal and nontemporal data on strategies used during cancellation. We also present preliminary results from a group of 68 right-hemisphere brain-damaged patients and 12 age-matched control participants, which demonstrate the clinical significance of the measures we have defined.     

Facts, rules, and procedures in normal calculation: evidence from multiple single-patient studies of impaired arithmetic fact retrieval.

This article presents results from multiple single-case studies of brain-damaged patients with impairments in retrieval of arithmetic facts (i.e., "table" facts such as 8 x 7 = 56). The results provide a basis for exploring the types of knowledge implicated in simple arithmetic performance, the internal representations for the various knowledge types, the processes operating upon these representations, and the ways in which the representations or processes may be disrupted by brain damage.     

Cognitive representations and processes in arithmetic: inferences from the performance of brain-damaged subjects.

In this article, we present data from two brain-damaged patients with calculation impairments in support of claims about the cognitive mechanisms underlying simple arithmetic performance. We first present a model of the functional architecture of the cognitive calculation system based on previous research. We then elaborate this architecture through detailed examination of the patterns of spared and impaired performance of the two patients. From the patients' performance we make the following theoretical claims: that some arithmetic facts are stored in the form of individual fact representations (e.g., 9 x 4 = 36), whereas other facts are stored in the form of a general rule (e.g., 0 x N = 0); that arithmetic fact retrieval is mediated by abstract internal representations that are independent of the form in which problems are presented or responses are given; that arithmetic facts and calculation procedures are functionally independent; and that calculation algorithms may include special-case procedures that function to increase the speed or efficiency of problem solving. We conclude with a discussion of several more general issues relevant to the reported research.     

The interleaving of actions in everyday life multitasking demands

It has been argued that executive tests should capture central aspects of executive functions in everyday life such as initiating and monitoring parallel actions in low-structured environments (so-called multitasking; see Burgess, 2000). We present a cooking task in order to assess executive function impairments in brain-damaged patients, which focuses on a central feature of multitasking, the interleaving of tasks (Burgess, 2000). Behavioural performance of 21 brain-damaged patients (stroke, traumatic brain injury) and of a group of matched controls was analysed on the basis of a standardized protocol. In comparison to controls, the patients explored less, were less successful in monitoring their actions and corrected errors less efficiently. Interleaving of actions was observed less frequently in patients, with respect to both cooking itself as well as to subordinate goals (e.g., cleaning up). Interleaving proved efficient, as it was associated with less time to complete the task. Patients' scores in the cooking task correlated with performance in both the Behavioural Assessment of the Dysexecutive Syndrome (BADS) Zoo Map Test and the BADS Six Elements Test, but not with tests of attention, verbal memory, or figural fluency, thus demonstrating convergent and discriminant validity. In summary, our task demonstrates that cooking can provide a valid testing ground for assessing a central aspect of everyday multitasking demands, namely, the interleaving of actions.     

Exploring the impact of plasticity-related recovery after brain damage in a connectionist model of single-word reading

The effect of retraining a damaged connectionist model of single-word reading was investigated with the aim of establishing whether plasticity-related changes occurring during the recovery process can contribute to our understanding of the pattern of dissociations found in brain-damaged patients. In particular, we sought to reproduce the strong frequency × consistency interactions found in surface dyslexia. A replication of Plaut, McClelland, Seidenberg, and Patterson’s (1996) model of word reading was damaged and then retrained, using a standard backpropagation algorithm. Immediately after damage, there was only a small frequency × consistency interaction. Retraining the damaged model crystallized out these small differences into a strong dissociation, very similar to the pattern found in surface dyslexic patients. What is more, the percentage of regularization errors, always high in surface dyslexics, increased greatly over the retraining period, moving from under 10% to over 80% in some simulations. These results suggest that the performance patterns of brain-damaged patients can owe as much to the substantial changes in the pattern of connectivity occurring during recovery as to the original premorbid structure. This finding is discussed in relation to the traditional cognitive neuropsychological assumptions of subtractivity and transparency.     

Disorders of classificatory activity in aphasia

Two nonverbal tasks of classificatory activity ("class inclusion" and "class intersection") were administered to 46 aphasics, 28 normal controls, 19 nonaphasic left-brain-damaged and 17 right-hemisphere-damaged patients in order to study if aphasic patients are more impaired than nonaphasic brain-damaged patients on these two tasks of elementary logic and if a relationship exists within the aphasic patients between inability to perform the tasks of classifiactory activity and impairment of the semantic-lexical level of integration of language. Results were for the most part in line with expectations because aphasics scored worse than normal controls and nonaphasic brain-damaged patients (even if the difference reached the level of statistical significance only on the test of "class intersection") and within the aphasic patients the worst results were obtained by subjects presenting clear signs of semantic-lexical disintegration.     

Effects of right and left hemisphere damage on performance of the "Right Hemisphere Communication Battery"

A Hebrew adaptation of Gardner and Brownell's (1986) "Right Hemisphere Communication Battery" (HRHCB) was administered to 27 right brain-damaged (RBD) patients, 31 left brain-damaged (LBD) patients, and 21 age-matched normal controls. Both patient groups showed deficits relative to controls and overall there was no difference between the two patient groups. A factor analysis of patients' scores on the HRHCB yielded two interpretable factors, a verbal and a nonverbal one. These factors were not lateralized. Performance of patients on the HRHCB correlated significantly and positively with performance on most tests of basic language functions, measured with a Hebrew adaptation of the "Western Aphasia Battery" (HWAB) and with other cognitive functions measured with standardized neuropsychological tests. There were stronger correlations of HRHCB with subtests of the HWAB in LBD patients and with nonlanguage cognitive tests in RBD patients. In the LBD group, HRHCB subtests' scores correlated negatively with lesion extent in frontal and temporal perisylvian regions. Such localization was not observed in RBD patients. The results argue against selective right hemisphere (RH) involvement in the RHCB, alleged to measure pragmatic aspects of language use, and show, instead, bilateral involvement. The results also argue against a modular organization of these functions of language use, especially in the RH.     

Amer-Ind versus ASL: recognition and imitation in aphasic subjects

The imitation and recognition ability of brain-damaged and normal subjects was tested for 30 pairs of semantically matched ASL signs and corresponding Amer-Ind gestures. Subjects were rated according to severity and site of lesion. They were 6 nonaphasic, right-hemisphere brain-damaged subjects, 12 aphasic subjects, and 12 non-brain-damaged geriatric subjects. Results indicated that the Amer-Ind gestures were significantly easier to imitate and to recognize than the matched ALS signs. The relationships between these gestural abilities and severity of aphasia, site of lesion, Amer-Ind transparency ratings, and subjects' performance on a standardized aphasia test are outlined. The theoretical implications that concern the neural systems which mediate spoken and limb gestures are discussed.     

Phonological processing during silent reading in aphasic patients

In a task involving the detection of a predesignated letter during the silent reading of a series of passages, left-brain-damaged aphasic patients and right-brain-damaged patients showed patterns of performance consistent with those of normal individuals. Both of the brain-damaged groups were more likely to detect letters when they were pronounced in a typical way (e.g., g in "ago") than in an atypical way (e.g., g in "through"), suggesting the use of phonological recoding during silent reading. In addition, both of these groups were more likely to detect letters when they occurred in content than in function words, suggesting a differential processing of these word types. Possible differences in the strategies predominantly relied on for phonological recoding and for the differential processing of content and function words by different groups of patients are discussed.     

The Symbol Digit Modalities Test: a screening instrument for brain-damaged children

28 brain-damaged males ranging in age from 8 to 16 yr. were compared with 28 nondamaged matching controls on their Symbol Digit Modalities Test performance. The damaged group performed significantly more poorly, and 75% of the subjects scored more than .5 z score below their matched controls. The results suggest that this brief and objective test can be used to screen brain-damaged children when their performance is compared to that of a control group or the normative group.     

Methodological and theoretical issues in neuropsychological assessment

While there are philosophical and theoretical differences between neuropsychologists and behavior therapists, it is suggested that a significant reconciliation can be achieved in regard to assessment and treatment of the brain-damaged patient. While brain damage is often viewed as an irreversible disorder, there is evidence that substantial recovery of function can occur, particularly when adequate retraining is provided. There are practical and empirical considerations that suggest that neuropsychological tests are currently the best tools available for behavioral assessment of brain-damaged patients. However, the results of these tests can be used not only diagnostically but also to identify target behavioral deficits that may be rehabilitated through systematic retraining efforts. Such rehabilitation efforts can be optimally planned, implemented, and evaluated through an alliance between the neuropsychologist, who identifies the ability and deficit pattern, and the behavior therapist, who devises and evaluates the retraining program. It is possible that the successes of behavior therapy in numerous clinical and educational applications can be repeated in the cases of brain-damaged patients. However, such success would appear to be contingent on appreciation of the high degree of specificity often seen in neurological deficit patterns and the great complexities involved in the relationships between brain function and behavior.     

Voice onset time in aphasia: Thai. I. Perception

This study investigated left brain-damaged aphasic and right brain-damaged non-aphasic patients' ability to label synthetic speech continua differing in voice onset time (VOT) at three places of articulation. The language chosen for investigation was Thai, which exhibits 3 contrasting labial and apical stop categories (voiced, voiceless unaspirated, voiceless aspirated) and 2 contrasting velar stop categories (voiceless unaspirated, voiceless aspirated). Results of the labelling task indicated an impairment in VOT perception at all three places of articulation across clinical types of aphasia. Normal performance by the right brain-damaged patient indicated that deficits in VOT perception can be attributed to pathology specific to the language-dominant hemisphere. No relation was found between the aphasic patient's level of auditory language comprehension and his performance on the VOT perception task. It is suggested that the aphasics' impairment reflects a deficit in phonological processing at the linguistic level.     

Consequences of brain tumour resection on emotion recognition

Emotion processing impairments are common in patients undergoing brain surgery for fronto-temporal tumour resection, with potential consequences on social interactions. However, evidence is controversial concerning side and site of lesions causing such deficits. This study investigates visual and auditory emotion recognition in brain tumour patients with the aim of clarifying which lesion sites are related to impairments in emotion processing from different modalities. Thirty-four patients were evaluated, before and after surgery, on facial expression and emotional prosody recognition; voxel-based lesion–symptom mapping (VLSM) analyses were performed on patients’ post-surgery MRI images. Results showed that patients’ performance decreased after surgery in both visual and auditory modalities, but, in general, recovered 3 months after surgery. In facial expression recognition, left brain-damaged patients showed greater post-surgery deterioration than right brain-damaged ones, whose performance specifically decreased for sadness and fear. VLSM analysis revealed two segregated areas in the left hemisphere accounting for post-surgery scores for happy (fronto-temporo-insular region) and surprised (middle frontal gyrus and inferior fronto-occipital fasciculus) facial expressions. Our findings demonstrate that surgical removal of tumours in the fronto-temporal region produces impairment in facial emotion recognition with an overall recovery at 3 months, suggesting a partially different representation of positive and negative emotions in the left and right hemispheres for visually – but not auditory – presented emotions; moreover, we show that deficits in specific expression recognition are associated with discrete lesion locations.     

Assessment of weight-error derivative (WED) analysis

Often considered one of the more discriminating tests between normal and brain-damaged individuals, the Category Test has been described as a complex measure of new problem solving, logical analysis, concept formation, abstract reasoning, and mental efficiency. Since publication of a booklet format by DeFilippis and McCampbell in 1979, researchers have attempted to develop other versions to reduce time required for administration. The present study compared the sensitivity of the Short Category Test, Booklet Format with the Booklet Category Test. Subjects were 22 male veterans seen for comprehensive neuropsychological evaluation and were classified into a brain-damaged or a control group (ns =11) according to independent neurological or neuroradiological evidence. Comparison of performances based on T scores yielded no significant differences between the groups on either format. Analyses of performance based upon suggested raw score cut-offs for the tests, however, yielded a statistically meaningful difference, but caution is in order when using T scores derived from age- or education-based normative data to suggest the presence of brain dysfunction. Raw score cut-offs yielded valid differentiation of individual patients in both groups.