Lisa Bartha

Language Lateralization in Temporal Lobe Epilepsy: A Comparison between fMRI and the Wada Test

Summary:  Purpose: Recent studies have claimed that language functional magnetic resonance imaging (fMRI) can identify language lateralization in patients with temporal lobe epilepsy (TLE) and that fMRI‐based findings are highly concordant with the conventional assessment procedure of speech dominance, the intracarotid amobarbital test (IAT).

Basal Ganglia Lesions and the Theory of Fronto-Subcortical Loops: Neuropsychological Findings in Two Patients with Left Caudate Lesions

Basal ganglia lesions have a high prevalence for associated behavioural impairments. However, the exact pattern of cognitive impairments and its relationship to individual basal ganglia lesion have rarely been investigated by means of a detailed neuropsychological and lesion study. Furthermore, different mechanisms have been proposed as relevant for the observed cognitive deficits; among these, the hypothesis of fronto-subcortical loops (Alexander et al., 1986) has made predictions regarding the relationship between the damage of particular striato-frontal circuits and the resulting behavioural impairment which await clinical confirmation. We present a study of two subjects who suffered a MRI-documented focal left basal ganglia hematoma. The two patients differed in their lesions; in one patient (PJ) large parts of the caudate nucleus were destroyed whereas in the other (AS) mainly the pallidum and putamen were lesioned and the caudate suffered only minor damage. In the acute phase, the behavioural and neuropsychological abnormalities were similar in both cases and included mainly abulia, an impairment of executive and attentional functions, and a severe amnestic syndrome. After several months many functions were restored in AS, whereas PJ’s abilities remained largely defective. Based on these data and on previous case studies several conclusions are drawn. Left caudate lesions induce marked and long-lasting behavioural and neuropsychological impairments comprising predominantly drive, executive control, attention, and memory. The extent of lesion in the head of the caudate nucleus is the critical factor regarding the severity and the outcome of the syndrome, whereas damage to the putamen and pallidum is less crucial for cognitive functions. A subset of behavioural alterations, among them abulia, attentional and frontal-executive dysfunctions, can well be attributed to lesions of the anterior cingulate circuit and the dorsolateral-frontal circuit at the basal ganglia level. Other impairments, most importantly the prominent amnestic syndrome, are more difficult to interpret on the grounds of this hypothesis and may be related to other pathomechanisms.

Acute conduction aphasia: an analysis of 20 cases.

In this study, the linguistic performance of 20 patients with acute conduction aphasia (CA) is described. CA presented as a relatively homogeneous aphasic syndrome characterized by a severe impairment of repetition and fluent expressive language functions with frequent phonemic paraphasias, repetitive self-corrections, word-finding difficulties, and paraphrasing. Language comprehension as assessed by tests of auditory and reading comprehension was only mildly impaired, whereas most patients performed poorly on the Token Test. Verbal-auditory short-term memory was reduced in all patients except one and seems to play a role in associated cognitive deficits, such as impaired syntactic comprehension or reduced mental arithmetics. A follow-up examination of 12 patients showed that CA often resulted in a chronic language deficit. Lesion locations were the posterior temporal and inferior parietal lobe.

Medial temporal lobe activation during semantic language processing: fMRI findings in healthy left- and right-handers.

Medial temporal lobe (MTL) areas are well known to serve episodic memory functions; their contribution to semantic memory has been occasionally noticed but not studied in detail. In the present fMRI study, 35 right-handed and 35 left-handed healthy subjects performed a semantic decision paradigm during which subjects heard spoken concrete nouns designating objects and had to decide on whether these objects were available in the supermarket and cost lest then a certain amount of money. The control paradigm consisted of sequences of low and high tones where subjects had to decide whether a sequence contained two high tones. The resulting contrast activation of semantic decision versus tone decision involved neocortical temporal, parietal, and prefrontal areas. Additional significant, bilateral activations in the MTL, the hippocampal formation, and adjacent areas were found. The exact incidence and location of activation was studied in a single-subject analysis for all 70 subjects. At the chosen threshold of P<0.001, 94% of subjects showed activations in the MTL and inferior temporal lobe (ITL). Activations were found along the longitudinal axis of the MTL, including the hippocampal formation and the parahippocampal gyrus. In the ITL, parts of the fusiform and lingual gyri were activated. Activations were similar in right- and left-handers. We conclude from this study that the MTL and parts of the ITL can be added to the areas activated by semantic verbal memory processing.

Transcoding and calculation in aphasia

Aphasia may have deteriorating effects on several numerical skills, such as counting, reading numerals aloud, or writing them to dictation, as these abilities rely on intact language. However, aphasia also seems to have specific effects on the calculation system. Group studies, as well as single-case studies, point to the fact that language-impaired patients have particular difficulties in completing multiplication tasks, while other operations are less impaired. From a theoretical point of view, there is still a debate as to whether this association reflects a general psycholinguistic problem, the effect of aphasia on numerical cognition, or a deficit in non-specific resources underlying both number and language domains. In studies on number transcoding multi-route models have been proposed which parallel semantic and asemantic routes in alphabetical processing. Yet, the review of the empirical evidence suggests that these models still lack relevant theoretical specification.

Genital Automatisms: A Video‐EEG Study in Patients with Medically Refractory Seizures

Summary:  Purpose: Genital automatisms (GAs) are rare clinical phenomena during or after epileptic seizures. They are defined as repeated fondling, grabbing, or scratching of the genitals. The anatomic correlates of GAs have been discussed controversially. The aim of this investigation was to assess the localizing and lateralizing value of GAs.

Is math lateralised on the same side as language? Right hemisphere aphasia and mathematical abilities

The main purpose of the present study was to learn how mathematical abilities are located and develop in the brain with respect to language. Mathematical abilities were assessed in six right-handed patients affected by aphasia following a lesion to their non-dominant hemisphere (crossed aphasia) and in two left-handed aphasics with a right-sided lesion. Acalculia, although in different degrees, was found in all cases. The type of acalculia depended on the type of aphasia, following patterns that have been previously observed in the most common aphasias resulting from left hemisphere lesions. No sign of right hemisphere or spatial acalculia (acalculia in left lateralised right-handed subjects) was detected. These results suggest that, as a rule, language and calculation share the same hemisphere. A primitive computational mechanism capable of recursion may be the precursor of both functions.

Persistent Cognitive Deficits Associated with Lithium Intoxication: A Neuropsychological Case Description

We present the case of a 51-year-old patient with an acute lithium intoxication associated with several cognitive deficits. During the acute phase of intoxication the patient displayed general psychomotor slowing, dysarthric speech, mood changes, and incoherent discourse. Neuropsychological assessment revealed ideomotor apraxia, profound deficits of visuospatial processing, an impairment of memory and of frontal-executive functions. Other cognitive abilities, such as orientation, spontaneous speech, comprehension, naming, reading, writing, and working memory remained intact. An electroencephalogram revealed diffuse slowing with rhythmic trains, whereas MRI showed no cerebral abnormality. Follow-up examinations at 4 and 14 weeks with lithium levels in the normal range showed substantial recovery of memory abilities and executive functions, whereas praxis and visuoperceptual functions remained impaired, despite the fact that lithium was immediately withdrawn after the intoxication became manifest. We conclude that lithium intoxication may be associated with variable behavioural and cognitive impairments, some of them potentially persistent. Different from other case studies our findings suggest that lithium intoxication may cause a combined, multifocal functional impairment of subcortical and cortical neural mechanisms in both hemispheres.

Strategic learning in the rehabilitation of semantic knowledge

The aim of the present study was to evaluate the efficacy of a reorganisation approach in the rehabilitation of simple arithmetic deficits as an instance of disturbed semantic knowledge. We report the case of FS, who underwent targeted training to overcome specific difficulties with multiplication facts. The programme was based on the strategic use of his residual knowledge and explicit reference to the principles underlying simple arithmetic. The purpose of this approach was to facilitate the reacquisition process by reducing the number of facts to be memorised and inducing a meaningful organisation of this knowledge in memory. The positive outcome of the intervention speaks in favour of a reorganisation rationale in the rehabilitation of arithmetic skills, where the integration of declarative, procedural, and conceptual knowledge critically mediate the re-acquisition process.

Linguistic and neuropsychological deficits in crossed conduction aphasia. Report of three cases.

This study describes the linguistic and neuropsychological findings in three right-handed patients with crossed conduction aphasia. Despite the location of the lesion in the right hemisphere, all patients displayed a combination of linguistic deficits typically found in conduction aphasia following analogous damage to the left hemisphere. Associated cognitive deficits varied across the three patients. In addition, all cases showed deficits classically attributed to non-dominant hemisphere damage (visuoperceptual deficits and reduced figural memory). As a result, lesion-behaviour relationships in our study sample indicate both dominant and non-dominant qualities of the right hemisphere.