Investigating the functional neuroanatomy of concrete and abstract word processing through direct electric stimulation (DES) during awake surgery.

Neuropsychological, neuroimaging and electrophysiological studies demonstrate that abstract and concrete word processing relies not only on the activity of a common bilateral network but also on dedicated networks. The neuropsychological literature has shown that a selective sparing of abstract relative to concrete words can be documented in lesions of the left anterior temporal regions. We investigated concrete and abstract word processing in 10 patients undergoing direct electrical stimulation (DES) for brain mapping during awake surgery in the left hemisphere. A lexical decision and a concreteness judgment task were added to the neuropsychological assessment during intra-operative monitoring. On the concreteness judgment, DES delivered over the inferior frontal gyrus significantly decreased abstract word accuracy while accuracy for concrete words decreased when the anterior temporal cortex was stimulated. These results are consistent with a lexical-semantic model that distinguishes between concrete and abstract words related to different neural substrates in the left hemisphere.

Management of psychogenic non-epileptic seizures: a multidisciplinary approach.

The International League against Epilepsy (ILAE) proposed a diagnostic scheme for psychogenic non-epileptic seizure (PNES). The debate on ethical aspects of the diagnostic procedures is ongoing, the treatment is not standardized and management might differ according to age group. The objective was to reach an expert and stakeholder consensus on PNES management. A board comprising adult and child neurologists, neuropsychologists, psychiatrists, pharmacologists, experts in forensic medicine and bioethics as well as patients' representatives was formed. The board chose five main topics regarding PNES: diagnosis; ethical issues; psychiatric comorbidities; psychological treatment; and pharmacological treatment. After a systematic review of the literature, the board met in a consensus conference in Catanzaro (Italy). Further consultations using a model of Delphi panel were held. The global level of evidence for all topics was low. Even though most questions were formulated separately for children/adolescents and adults, no major age-related differences emerged. The board established that the approach to PNES diagnosis should comply with ILAE recommendations. Seizure induction was considered ethical, preferring the least invasive techniques. The board recommended looking carefully for mood disturbances, personality disorders and psychic trauma in persons with PNES and considering cognitive-behavioural therapy as a first-line psychological approach and pharmacological treatment to manage comorbid conditions, namely anxiety and depression. Psychogenic non-epileptic seizure management should be multidisciplinary. High-quality long-term studies are needed to standardize PNES management.

False alarms during recognition of famous people from faces and voices in patients with unilateral temporal lobe resection and normal participants tested after anodal tDCS over the left or right ATL.

Data gathered in the field of the experimental social psychology have shown that it is more difficult to recognize a person through his/her voice than through his/her face and that false alarms (FA) are produced more in voice than in face recognition. Furthermore, some neuropsychological investigations have suggested that in patients with damage to the right anterior temporal lobe (ATL) the number of FA could be higher for voice than for face recognition. In the present study we assessed FA during recognition of famous people from faces and voices in patients with unilateral ATL tumours and in normal participants tested after anodal transcranial direct current stimulation (tCDS), over the left or right ATL. The number of FA was significantly higher in patients with right than in those with left temporal tumours on both face and voice familiarity. Furthermore, lesion side did not differentially affect patient's sensitivity or response criterion when recognizing famous faces, but influenced both these measures on a voice recognition task. In fact, in this condition patients with right temporal tumours showed a lower sensitivity index and a lower response criterion than those with left-sided lesions. In normal subjects, the greater right sided involvement in voice than in face processing was confirmed by the observation that right ATL anodal stimulation significantly increased voice but only marginally influenced face sensitivity. This asymmetry between face and voice processing in the right hemisphere could be due to the greater complexity of voice processing and to the difficulty of forming stable and well-structured representations, allowing to evaluate if a presented voice matches or not with an already known voice.

Present day's standards in microsurgery of low-grade gliomas.

Low-grade gliomas are slow growing intrinsic lesions that induces a progressive functional reshaping of the brain. Surgical removal of these lesions requires the combined efforts of a multidiscipinary team of neurosurgeon, neuroradiologist, neuropsychologist, neurophysiologist, and neurooncologists that all together contribute in the definition of the location, extension, and extent of functional involvement that a specific lesion has induced in a particular patient. Each tumor has induced particular and specific changes of the functional network, that varies among patients. This requires that each treatment plan should be tailored to the tumor and to the patient. When this is reached, surgery should be accomplished according to functional and anatomical boundaries, and has to aim to the maximal resection with the maximal patient functional preservation. This can be reached at the time of the initial surgery, depending on the functional organization of the brain, or may require additional surgeries, eventually intermingled with adjuvant treatments. The use of so called brain mapping techniques extend surgical indications, improve extent of resection with greater oncological impact, minimization of morbidity and increase in quality of life. To achieve the goal of a satisfactory tumor resection associated with the full preservation of the patients abilities, a series of neuropsychological, neurophysiological, neuroradiological and intraoperative investigations have to be performed. In this chapter, we will describe the rationale, the indications and the modality for performing a safe and rewarding surgical removal of low-grade gliomas by using these techniques, as well as the functional and oncological results.

Defective recognition and naming of famous people from voice in patients with unilateral temporal lobe tumours.

Twenty-nine patients who underwent surgery for a temporal glioma, either in the left (16 patients) or right (13 patients) hemisphere, were administered standardized tests of unknown voice discrimination (UVD) and of famous voice recognition (VO-REC), which included tasks of familiarity evaluation, semantic identification and naming of famous voices. The UVD consisted of twenty stimuli, in which two audio files were consecutively presented; the subject was requested to judge whether the voices belonged to the same or different persons. In the VO-REC, patients were requested to recognize the voices of 40 very well known people; these voices were intermingled with the voices of 20 unknown people for a familiarity check, followed by identification and naming of persons recognized as familiar. We aimed at verifying the effect of laterality and intra-temporal site of lesion on familiarity assessment, false alarms, identification and naming of familiar people. As for the effect of lesion side, our results showed that patients with right temporal gliomas were significantly more impaired in voices discrimination and produced more false alarms than patients with a left glioma, who, in turn, were significantly more impaired in name retrieval than patients with a right temporal glioma. The high number of false alarms in patients with a right temporal glioma suggests that familiarity judgment was impaired. Regarding the neuroanatomical correlates of these different patterns of impairment, MRI data suggested that: (a) UVD disorders are due to lesions involving the whole right anterior temporal lobe and extending to lateral portions of the temporal and frontal lobes; (b) familiarity judgments (testified by an increased number of false alarms) are impaired in lesions restricted to the right anterior temporal lobe; (c) name retrieval deficits are found only in patients with left temporal lesions. UVD disorders were interpreted, at least in part, as due to an impairment of executive functions, resulting from a disconnection of the right temporal lobe from the frontal lobe control. A partly unexpected finding was that some patients with a right temporal tumour had a normal performance in famous voice recognition and identification, in spite of having severe voice discrimination disturbances. These unexpected results, in agreement with previous observation made in the visual (face) modality, are inconsistent with strictly hierarchical models of voice processing.

The time course of idiom processing.

Recent neuropsychological and neurophysiological studies have suggested that the neural correlates of idiom processing are predominantly located in the left Brodmann's area (BA) 22 and, to some extent, in the prefrontal cortex. The present study explores the temporal dynamics of left prefrontal and temporal cortex in idiom processing by using repetitive transcranial magnetic stimulation (rTMS) in normal subjects. Forty-five opaque highly familiar idioms and 45 literal sentences were used. Forty-three subjects completed 5 blocks of 18 trials (9 idioms, 9 literal sentences) corresponding to 4 stimulation conditions (left prefrontal, left temporal, vertex, no-stimulation baseline). Each subject was assigned to one of three groups, which differed in the timing of stimulation delivery. A selective impairment in accuracy for idioms was found when rTMS was applied to the prefrontal and temporal cortex 80ms after picture presentation, confirming the role of these regions in this task. Moreover, rTMS to the prefrontal cortex, but not to the temporal cortex, continued to affect the performance with idiomatic sentences at the later time of 120ms. The results seem to suggest that the prefrontal region is involved in both the retrieval of the figurative meaning from semantic memory and the monitoring of the response by inhibiting alternative interpretations when a picture-matching task is used.

Testing idiom comprehension in aphasic patients: the effects of task and idiom type.

Idiom comprehension in 15 aphasic patients was assessed with three tasks: a sentence-to-picture matching task, a sentence-to-word matching task and an oral definition task. The results of all three tasks showed that the idiom comprehension in aphasic patients was impaired compared to that of the control group, and was significantly affected by the type of task and type of idiom. Whilst performance on the oral definition and sentence-to-picture matching tasks was similarly impaired, the patients performed significantly better on the sentence-to-word matching task. The results confirm the relevance of task and idiom type in drawing conclusions about figurative language interpretation in brain-damaged patients.

Slowly progressive aphasia: a four-year follow-up study.

This paper reports the long-term follow-up of GC, a patient with primary progressive aphasia of the fluent type. GC presented at onset with an anomia characterized by sparing of first letter knowledge, that applied mainly to proper names and living categories. No semantic deficits were observed in the first stage of the disease, and MRI showed a left temporal lobe atrophy with a gradient from the pole to the posterior regions, the latter being less involved. We now report the clinical evolution of GC from the 2nd to the 4th year of disease. As the disease progressed, the anomia became more severe and the phenomenon of first letter sparing was no longer detectable. Also semantic knowledge was gradually affected and, eventually, was dramatically lost. However, no other cognitive deficits were seen at the last examination. By that time, the temporal atrophy shown by MRI was bilateral, although still more evident on the left side.

Transient left-sided alien hand with callosal and unilateral fronto-mesial damage: a case study.

A patient who showed a transient left alien hand after a subarachnoid haemorrhage, due to a ruptured aneurysm of the anterior communicating artery, is described. No left agraphia and left apraxia could be found. A CT-scan including coronal sections showed a right medial frontal hypodensity and different ischaemic lesions in the anterior part of the corpus callosum. The possible anatomic site of the lesion responsible for the permanent form of alien hand is discussed.

Proper name anomia: a case with sparing of the first-letter knowledge.

In this article we describe the case of GC, a woman affected by severe proper name anomia due to progressive brain atrophy that mainly affected the left temporal pole. Proper name comprehension and semantic knowledge about the people she was unable to name were normal. GC showed a sparing of initial letter knowledge of proper names, while other phonological characteristics were not equally available. At a later stage of her illness, the naming impairment began to affect common names as well as proper names, though at a lesser extent. Whereas there was no category effect between names of animate and inanimate stimuli, we observed a relative sparing of first letter knowledge selectively for animate categories, although less marked than with proper names. This case is discussed within the theoretical framework of two-stage models of name production. Knowledge of the initial letter of proper names supports the psychological reality of the "phonological address" as a preliminary stage of the production of this class of names. Moreover, the qualitative similarity between errors observed with proper names and with names of animate objects suggests that the production of names belonging to these classes may conform, at least in part, to analogous algorithms.

Language and verbal memory after right hemispheric stroke: a clinical-CT scan study.

The performances on language and verbal memory tests of 26 right-hemisphere damaged subjects (RHD) have been compared with normal controls and 11 non-aphasic left-hemisphere damaged subjects. While phonological and syntactic performance was unimpaired, a small subgroup of RHD patients, with CT scan evidence of subcortical lesion, was mildly impaired in naming tasks. The performance of RHD patients on free recall was characterized by a reduced recency effect. The implications of these findings for theories about the participation of the right hemisphere in linguistic functions are discussed.

Unawareness of disease following lesions of the right hemisphere: anosognosia for hemiplegia and anosognosia for hemianopia.

Unawareness of motor and visual-field defects was investigated in 97 right brain-damaged subjects. Both kinds of anosognosia were found to be double-dissociated from more elementary neurological disorders and from personal and extra-personal neglect. The relationships between anosognosia and unilateral neglect are discussed and allusion is made to the implications concerning the neurological organization of higher control functions.

Parkinson's disease patient's behaviour in a covered maze learning task.

A computerized maze task was constructed that allowed only partial vision of the maze structure and produced measurements for separate analysis of cognitive processes described as impaired in Parkinson's disease. Eighteen patients suffering from mild Parkinson's disease and 18 individually matched normal controls were investigated. Baseline task response times were found to be identical for both groups. Differences between patients' and controls' performance could be related to (a) a response bias in Parkinson patients that favoured repetition of the previous action and slowed down shifting and (b) an impairment of multistep plan generation. It is speculated that the response bias reflects the disinhibition of cortico-thalamo-cortical reverberation loops which results from striatal dopamine depletion.

Improvement of left visuo-spatial hemineglect by left-sided transcutaneous electrical stimulation.

The effects of transcutaneous electrical stimulation on left visuo-spatial hemineglect, assessed by a visuo-motor exploratory task (letter cancellation), were investigated in patients with right hemisphere lesions. In Experiment 1 left neck stimulation temporarily improved the deficit in 13 out of 14 patients (93%), while stimulation of the right neck had no positive effects, worsening exploratory performance in nine patients (64%). Experiment 2 showed that left neck stimulation temporarily improved neglect also when head movements were prevented by a chin-rest. In Experiment 3, stimulation of both the left hand and left neck had comparable positive effects on visuo-spatial hemineglect. These results are interpreted in terms of: (1) non-specific activation of the right hemisphere, contralateral to the stimulation side; (2) specific directional effects of left somatosensory stimulation on the egocentric co-ordinates of extra-personal space, which in neglect patients are distorted towards the side of the brain lesion.

The phonological loop as a language learning device.

A relatively simple model of the phonological loop (A. D. Baddeley, 1986), a component of working memory, has proved capable of accommodating a great deal of experimental evidence from normal adult participants, children, and neuropsychological patients. Until recently, however, the role of this subsystem in everyday cognitive activities was unclear. In this article the authors review studies of word learning by normal adults and children, neuropsychological patients, and special developmental populations, which provide evidence that the phonological loop plays a crucial role in learning the novel phonological forms of new words. The authors propose that the primary purpose for which the phonological loop evolved is to store unfamiliar sound patterns while more permanent memory records are being constructed. Its use in retaining sequences of familiar words is, it is argued, secondary.

Patterns of lateralization and performance levels for verbal and spatial tasks in congenital androgen deficiency.

The effects of congenital deficiency of gonadal hormones on verbal and spatial performance and on the establishment of hemispheric asymmetries were investigated in a group of patients with idiopathic hypogonadotropic hypogonadism. The patients showed a left hemispheric advantage for verbal material and were mildly impaired, mainly on tasks involving a short-term memory load, in comparison with a matched control group. These results do not indicate a specific role of gonadal hormones on the establishment of hemispheric asymmetries. Lack of exposure during brain development results in a decrease in memory functions which is not specific for verbal or spatial material.

Dual-task performance in dysexecutive and nondysexecutive patients with a frontal lesion.

Patients with defined frontal lobe lesions were assigned to 1 of 2 groups based on whether they showed a behaviorally assessed dysexecutive syndrome or were behaviorally normal. All participants were tested on dual-task performance and on 2 tasks assumed to measure frontal lobe function, the Wisconsin Card Sorting Test and verbal fluency. The dysexecutive group differed significantly from the nondysexecutive in showing impaired capacity for dual-task coordination, but there were no significant differences on the Wisconsin Card Sorting Test and verbal fluency. Results are interpreted in terms of a multicomponent central executive, whose function is linked to, but not coterminous with, the operation of the frontal lobes.

Transient retrograde amnesia associated with impaired naming of living categories.

A ease of pure retrograde amnesia following mild head injury is reported. The patient, who also showed a deficit in verbal fluency and a living/non-living dissociation in naming during the amnesic period, recovered progressively in about ten days post-trauma. Both a psychogenic and an organic origin could be taken into account. A mechanism (no matter if psychogenic or organic) can be hypothesized, which produces a functional inhibition also involving performances that are unlikely to be affected by psychological factors.

Preserved vocabulary acquisition in Down's syndrome: the role of phonological short-term memory.

We report the study of a 23-year-old Italian girl, FF, with Down's syndrome (trisomy 21). FF showed a remarkably good developmental acquisition of Italian language and vocabulary and was able to learn English and French, although the latter with less proficiency. FF showed an entirely preserved function of the phonological short-term store and articulatory rehearsal components of verbal short-term memory. By contrast, she was impaired in a wide range of tasks assessing verbal and non-verbal reasoning, visuo-spatial perception and memory, and verbal long-term memory. These findings, in line with evidence from brain-damaged patients, normal subjects and children, suggest that phonological short-term memory plays a crucial role in vocabulary acquisition, which may occur in the presence of substantial deficits of general intelligence and episodic memory.

Perseveration in two aphasic patients.

In this paper we report the perseverative behavior of two aphasic patients, AB and MT. They were submitted to a standardized Language Examination and to verbal and nonverbal tasks designed to elicit perseveration. Some of the features pointed out in the literature were not confirmed. Perseveration was not semantically related to the target; a correct response did not have any special status; in many instances the perseveration had not been produced as a correct response and could reappear immediately or after many stimuli; the production of two consecutive correct responses did not inhibit the spontaneous recurrences and could again be followed by the perseveration of a previous wrong response. Perseveration did not set in in the same circumstances for the two patients: in AB it set in when the patient was unable to find the correct response; MT, on the contrary, while knowing the correct response, was unable to change her perseverative behavior from one response to the other. For both patients, however, it seems as if no inhibitory system stops pre-existing motor or verbal behavior.