Gerstmann syndrome without aphasia: a longitudinal study

A case of "pure" and complete Gerstmann syndrome resulting from a focal vascular lesion in the posterior parietal area of the left hemisphere and not associated with aphasic disorder or general mental impairment is described. The initial symptom presentation of this patient supported the concept of the autonomous nature of the Gerstmann aggregate but longitudinal findings suggested that these symptoms did not in fact represent a coherent syndrome.     

Phonemic imperception in aphasia

This study investigated characteristics of 14 aphasics with impaired phoneme discrimination identified from a population of 100 patients with left hemisphere lesions. All patients with impaired phoneme discrimination were significantly impaired in aural comprehension, but many showed intact sound recognition and some showed normal reading comprehension. Defects in phoneme discrimination were typically seen in the acute stage of aphasia resulting from stroke; and in most instances, defects in phoneme discrimination were no longer apparent 4 months postonset. All patients who recovered normal phoneme discrimination also made significant improvement in aural comprehension. The findings support the concept that some aural comprehension defects result from a specific disturbance in phoneme discrimination.     

Preservation of orthographic knowledge in aphasia

A simple untimed lexical decision task was designed to test implicit letter recognition in aphasic patients. Half of the nonwords used in this task were orthographically regular pronounceable pseudowords, and half were orthographically irregular unpronounceable letter strings. Twenty-five randomly chosen aphasic patients with mild to severe degrees of aphasia participated in the study. Although only six of the patients performed the lexical decision task successfully, all 25 demonstrated the ability to distinguish orthographically regular from irregular letter strings and, by implication, the ability to recognize and make use of the identities of written letters.     

Reconstructive retrieval deficits in Broca's aphasia

Anterior aphasic patients' ability to utilize the phonemic and/or semantic features of verbal material for retention purposes was investigated. In the first experiment, patients were asked to either detect word repetitions, phoneme repetitions, or rhymes in a list of items. The aphasics performed well on word and phoneme repetition detection but below both normals and amnesic Korsakoffs on rhyme detection. In the second experiment the patients were instructed to analyze either the physical, phonemic, or semantic features of words they were later asked to recognize. Aphasics were differentially affected (as were normals) by these instructions: semantic feature analysis resulted in the best performance, followed by phonemic feature analysis. It was concluded that anterior aphasics can analyze, recirculate, and even store the phonemic features of words, but find difficulty in reconstructing the originally presented item from these features.     

Psychometric and CT scan measurements in a case of crossed aphasia in a dextral

A case of crossed aphasia with lesion deep to the right supramarginal gyrus was studied to determine (1) if this patient behaved similar to patients with the same lesion site in the left hemisphere, (2) if visuospatial deficits were present, and (3) if the CT scan asymmetries were similar to those of other right-handers. Speech and language skills were similar to those patients with similar lesions in the left hemisphere. Visuospatial and arithmetic deficits were similar to those described after right-hemisphere and left-hemisphere damage. CT scan asymmetries were atypical. These results provide behavioral and neuroradiological confirmation of atypical hemispheric dominance.     

Picture-naming in aphasia

The distribution of picture-naming errors for Broca's aphasics (n = 9), Wernicke's aphasics (n = 9), conduction aphasics (n = 9), frontal anomics (n = 7), and posterior anomics (n = 9) was examined to determine the diagnostic power of error types in picture-naming. Negated responses were associated with Broca's aphasia, whole-part errors ("hose" for nozzle) were associated with frontal anomia, and poor phonemic cuing was associated with Wernicke's aphasia. In addition, the relative distribution of the three most prominent naming errors-phonemic errors, semantic errors, and multiword circumlocutions-tended to distinguish the two anomic subgroups from the other aphasia subgroups. Anomic aphasics produced the fewest phonemic errors and the most multiword circumlocutions; this pattern suggests minimal word-production difficulty in anomic aphasia relative to the other aphasia syndromes. Despite such group differences, the overall picture indicates that there is considerable similarity among aphasia syndromes in terms of picture-naming behavior.     

The relationship of limb apraxia severity to motor and language deficits

Ipsilateral motor and symbolic/linguistic skills were examined in normals and three left hemisphere damaged groups with no, mild, or moderate-severe limb apraxia. When the two apraxic groups were pooled they demonstrated poorer response inhibition and reading relative to the nonapraxic group. There were no significant group differences on motor or language tasks when the three brain damaged groups were separately compared. These results indicate there is a limited relationship between limb apraxia and some motor and linguistic skills, but the relationship was not greater for motor than linguistic skills.     

Quantitative CT scan studies in aphasia. I. Infarct size and CT numbers

Infarct si?e (number of 1-mm² pixels in the lesion) on CT scans of 30 aphasia patients was obtained with a semiautomated computer program. The mean number of lesion pixels present per slice containing lesion was approximately 500 for mild aphasias (transcortical motor and conduction), 700 for Wernicke's, 1000 for Broca's, 1500 for mixed, and 2000 for globals. These differences were significant for $\text{11}\text{15}$ of the group pairwise comparisons. When lesion locus was controlled for in the anterior/posterior plane, 73–100% of the aphasia patients were correctly classified as to type of aphasia by a discriminant analysis utilizing only the number of lesion pixels present on two CT slices. Different slice combinations were used for different aphasia group comparisons. There was a significant correlation between severity of aphasia and lesion size. There was a significant correlation between lesion size and the CT numbers in the lesion. This type of analysis may be useful to predict the prognosis for recovery potential in aphasics who have CT scans performed at 2 months poststroke.     

The nature of the phonological disorder in conduction aphasia

Sequences of attempts to name pictured objects were used to examine phonological dysfunction in three diagnostic subgroups of aphasia. A prevalence of "phonologically-oriented sequences" (i.e., those sequences that contained only attempts with a phonological resemblance to the target word) was found to be a diagnostic criterion for conduction aphasia. When compared to a group of Broca's (n = 7) and Wernicke's (n = 5) aphasics, all the conduction aphasics (n = 6) produced proportionately more of such phonologically-oriented sequences on a picture naming test. An examination of the phonologically-oriented sequences produced by the conduction aphasics indicates that speech production in conduction aphasia involves dysfunction at an early stage of sound-encoding. The theoretical implications of this view are discussed.     

The US preexposure phenomenon in the conditioned suppression paradigm: A role for conditioned situational stimuli

Four experiments evaluated possible associative and nonassociative accounts of the retardation in the acquisition of conditioned suppression produced by repeated prior exposure to an electric shock US. Associative interference resulting from conditioning of situational stimuli during preexposure to shock was suggested by the findings that signaling the occurrence of high-intensity shock with a discrete nontarget CS during the preexposure phase reduced the magnitude of the retardation effect compared to an unsignaled shock preexposure treatment (Experiments 1 and 4), nonreinforced presentations of putatively conditioned situational stimuli prior to conditioned suppression training reduced the magnitude of the retardation effect (Experiment 2), and the magnitude of the retardation effect was directly related to the intensity of preexposure shock (Experiment 3). Nonassociative interference was suggested by the finding that signaling the occurrence of low-intensity shock with a discrete nontarget CS during the preexposure phase did not reduce the magnitude of the retardation effect compared to an unsignaled shock preexposure treatment (Experiment 4). It was suggested that associative and nonassociative mechanisms govern the US preexposure phenomenon obtained in the conditioned suppression paradigm, and their relative contribution depends upon the intensity of shock.     

Lateral-frontal slow potential shifts preceding language acts in deaf and hearing adults

Slow potential EEG shifts (SPSs) recorded over Broca's area and the paired contralateral site preceding cued language acts have been reported to identify the language-dominant hemisphere. A contingent negative variation paradigm SPS method was applied to the comparative study of 10 hearing adults and of 10 adult prelingually deaf persons whose first learned language was American Sign Language. Volunteers performed both language and non-language acts in both oral and manual expressive modes. The hearing group showed no lateralized SPS, failing to replicate previous reports. The deaf group showed a nonsignificant trend opposite in laterality to that of hearing groups in previous reports.     

The role of the right hemisphere in the apprehension of complex linguistic materials

To secure information on which aspects of linguistic functioning might be mediated by the nondominant hemisphere, a test battery assessing sensitivity to narrational and humorous materials was administered to a population of right-hemisphere-damaged patients, as well as relevant control groups of normal, aging, and aphasic individuals. While elementary linguistic functioning was adequate, the right-hemisphere-injured groups exhibited consistent difficulties in respecting the boundaries of a fictive entity, assessing the plausibility of elements within a story or joke, selecting the appropriate punch line for a joke, and integrating elements of a story into a coherent narrative. Certain elements—specifically emotional content and noncanonical facts injected into a narrative—also posed characteristic difficulties for these patients. The results suggest that, in contrast to the other populations, right-hemisphere patients exhibit special difficulties in processing complex linguistic entities and in utilizing the surrounding context as they assess linguistic messages.     

Speech prosody in Broca's aphasia

Because speech prosody is thought to be impaired in Broca's aphasia, we conducted three experiments using Broca's aphasics and nonneurological control subjects in order to determine to what extent this statement is accurate. Using three acoustic measures of speech prosody—sentence-final fundamental frequency (F₀) fall, F₀ declination, and sentence-final lengthening—we found that some aspects of prosody were spared while others were abnormal. All Broca's aphasics, regardless of degree of impairment, exhibited sentence-final F₀ fall. F₀ declination was present in simple sentences but was absent over longer domains; moreover, the amount of declination was correlated with the degree of linguistic impairment. Sentence-final lengthening was clearly absent in Broca's aphasia; in fact, sentence-terminal words were actually shorter than their sentence-initial and medial counterparts.     

Surprise but not coherence: Sensitivity to verbal humor in right-hemisphere patients

Verbal humor deficits were investigated in right-hemisphere-damaged patients. It was hypothesized that the appreciation of jokes presupposes two elements: sensitivity to the surprise element entailed in the punch line of a joke and apprehension of the coherence which results when the punch line has been integrated with the body of the joke. The possible dissociation between these elements was tested by asking subjects to select from four alternatives the appropriate ending to a joke. Right-hemisphere patients exhibited a selective attraction to endings which contained an element of surprise but which were not otherwise coherent with the body of the joke. This finding suggests that right-hemisphere patients have difficulty in integrating content across parts of a narrative and confirms the psychological reality of the proposed distinction between the surprise and coherence elements of humor processing.     

Olfactory dysfunction in man: anatomical and behavioral aspects

We reviewed studies examining the olfaction of patients with brain damage for the purpose of discerning correlations between disordered structure and function. Patient samples included those with neurological disorders and neurosurgical interventions and recording of spontaneous or elicited neuronal activity. Brain areas involved in olfaction include the olfactory bulbs, the orbitofrontal and medial temporal cortices, the thalamus, and the amygdala. Despite recent advances in olfactory anatomy, understanding of how these structures are related to olfactory detection, discrimination, and recognition continues to be limited. Inadequate localization of brain lesions and lack of comprehensive behavioral assessment have thus far prevented a detailed account of the organization of olfaction in the human brain.     

Item-specific and relational encoding effects in children's recall and recognition memory for words

This study tests the hypothesis that children's deficiency in encoding itemspecific and relational information in episodic events contributes to age differences in recall and recognition. In two experiments, grade school children and college adults were presented with word triplets varying in categorical relatedness. The processing of the item-specific and relational information in the triplets was independently manipulated. Experiment 1 assessed cued recall, and Experiment 2 assessed recognition of both the central target and incidental contextual members of each triplet. The results showed that the processing manipulations had independent and different effects on recall and recognition, on memory for the members of the different kinds of triplets, on the use of the retrieval cues, and on memory for target and incidental words. Developmental differences were found in both recall and recognition, and of both target and incidental words, that varied with triplet type and the processing manipulations and that were attributable to differences in the encoding of item-specific and relational information in the triplets. The discussion contrasts alternative accounts of children's encoding deficiency, and suggests that the distinction between automatic, age-invariant, and strategic age-sensitive encoding processes needs to be redrawn.     

Aphasics' selective deficits in appreciating grammatical agreements

This study attempted to dissociate in aphasic patients different aspects of grammatical capacity. Subjects were asked to evaluate sentences containing violations of agreements between pronouns and verbs. Agreements which are considered primarily structural in nature were violated (e.g., a surface object case like “them” placed in a surface subject sentential slot) while other violated agreements seemed to involve both structural and semantic information (e.g., lack of agreement between a pronoun and a verb in terms of the number of people performing the act). These violations were couched in one of three types of sentential frames which varied in terms of syntactic complexity (e.g., active declarative vs. passive syntactic voices). The results revealed that Broca's aphasics found agreement violations difficult to detect in complex syntactic frames. They were quite successful at detecting even violations of the largely structural “case” type of agreement, however, when couched in simpler syntactic frames. Fluent aphasics encountered more difficulty detecting violations of agreements involving both semantic and structural information than agreements which were primarily structural in nature, that is, regardless of the syntactic frame. These unique performance profiles suggest that Broca's aphasics may be agrammatic only with respect to certain aspects of a sentence's structure, and that fluent aphasics may also experience some selective—but different—grammatical deficits.