Valentina Galetto

Narrative Language in Traumatic Brain Injury.

Persons with traumatic brain injury (TBI) often show impaired linguistic and/or narrative abilities. The present study aimed to document the features of narrative discourse impairment in a group of adults with TBI. 14 severe TBI non-aphasic speakers (GCS<8) in the phase of neurological stability and 14 neurologically intact participants were recruited for the experiment. Their cognitive, linguistic and narrative skills were thoroughly assessed. The group of non-aphasic individuals with TBI had normal lexical and grammatical skills. However, they produced narratives with increased errors of cohesion and coherence due to the frequent interruption of ongoing utterances, derailments and extraneous utterances that made their discourse vague and ambiguous. They produced a normal amount of thematic units (i.e. concepts) in their narratives. However, this information was not correctly organized at micro- and macrolinguistic levels of processing. A Principal Component Analysis showed that a single factor accounted for the production of global coherence errors, and the reduction of both propositional density at the utterance level and proportion of words that conveyed information. It is hypothesized that the linguistic deficits observed in the participants with TBI may reflect a deficit at the interface between cognitive and linguistic processing rather than a specific linguistic disturbance.

Cognitive correlates of narrative impairment in moderate traumatic brain injury.

Traumatic brain injuries (TBIs) are often associated with communicative deficits. The incoherent and impoverished language observed in non-aphasic individuals with severe TBI has been linked to a problem in the global organization of information at the text level. The present study aimed to analyze the features of narrative discourse impairment in a group of adults with moderate TBI (modTBI). 10 non-aphasic speakers with modTBI and 20 neurologically intact participants were recruited for the experiment. Their cognitive, linguistic and narrative skills were thoroughly assessed. The persons with modTBI exhibited normal phonological, lexical and grammatical skills. However, their narratives were characterized by lower levels of Lexical Informativeness and more errors of both Local and Global Coherence that, at times, made their narratives vague and ambiguous. Significant correlations were found between these narrative difficulties and the production of both perseverative and non-perseverative errors on the WCST. These disturbances confirm previous findings which suggest a deficit at the interface between cognitive and linguistic processing rather than a specific linguistic disturbance in these patients.

Concomitant use of transcranial direct current stimulation and computer-assisted training for the rehabilitation of attention in traumatic brain injured patients: Behavioral and neuroimaging results

Divided attention (DA), the ability to distribute cognitive resources among two or more simultaneous tasks, may be severely compromised after traumatic brain injury (TBI), resulting in problems with numerous activities involved with daily living. So far, no research has investigated whether the use of non-invasive brain stimulation associated with neuropsychological rehabilitation might contribute to the recovery of such cognitive function. The main purpose of this study was to assess the effectiveness of 10 transcranial direct current stimulation (tDCS) sessions combined with computer-assisted training; it also intended to explore the neural modifications induced by the treatment. Thirty-two patients with severe TBI participated in the study: 16 were part of the experimental group, and 16 part of the control group. The treatment included 20’ of tDCS, administered twice a day for 5 days. The electrodes were placed on the dorso-lateral prefrontal cortex. Their location varied across patients and it depended on each participant’s specific area of damage. The control group received sham tDCS. After each tDCS session, the patient received computer-assisted cognitive training on DA for 40’. The results showed that the experimental group significantly improved in DA performance between pre- and post-treatment, showing faster reaction times (RTs), and fewer omissions. No improvement was detected between the baseline assessment (i.e., 1 month before treatment) and the pre-training assessment, or within the control group. Functional magnetic resonance imaging (fMRI) data, obtained on the experimental group during a DA task, showed post-treatment lower cerebral activations in the right superior temporal gyrus (BA 42), right and left middle frontal gyrus (BA 6), right postcentral gyrus (BA 3) and left inferior frontal gyrus (BA 9). We interpreted such neural changes as normalization of previously abnormal hyperactivations.

Severity effects on discourse production after TBI

Abstract Persons with traumatic brain injury (TBI) often experience macrolinguistic (i.e., pragmatic and discourse) difficulties. However, it is still not clear whether these difficulties are related to their cognitive impairments and little research has investigated communication abilities across the severity spectrum of TBI. This study compared the cognitive profile and narrative performance of persons with mild-to-moderate TBI, individuals with severe TBI and healthy control participants by adopting a multilevel procedure for discourse analysis. The results showed both severity-dependent and severity-independent effects on the participants’ cognitive and narrative skills. A series of correlational analyses and two Principal Component Analyses confirmed the articulated nature of their narrative impairments and the complex interplay between cognitive and discourse difficulties in both groups of patients. The results from this study suggest that trauma severity influences the gravity of some of the symptoms observed in persons with TBI. At the same time, however, they highlight the cognitive nature of their narrative difficulties.

Neuroplastic Changes Induced by Cognitive Rehabilitation in Traumatic Brain Injury: A Review

Background. Cognitive deficits are among the most disabling consequences of traumatic brain injury (TBI), leading to long-term outcomes and interfering with the individual’s recovery. One of the most effective ways to reduce the impact of cognitive disturbance in everyday life is cognitive rehabilitation, which is based on the principles of brain neuroplasticity and restoration. Although there are many studies in the literature focusing on the effectiveness of cognitive interventions in reducing cognitive deficits following TBI, only a few of them focus on neural modifications induced by cognitive treatment. The use of neuroimaging or neurophysiological measures to evaluate brain changes induced by cognitive rehabilitation may have relevant clinical implications, since they could add individualized elements to cognitive assessment. Nevertheless, there are no review studies in the literature investigating neuroplastic changes induced by cognitive training in TBI individuals. Objective. Due to lack of data, the goal of this article is to review what is currently known on the cerebral modifications following rehabilitation programs in chronic TBI. Methods. Studies investigating both the functional and structural neural modifications induced by cognitive training in TBI subjects were identified from the results of database searches. Forty-five published articles were initially selected. Of these, 34 were excluded because they did not meet the inclusion criteria. Results. Eleven studies were found that focused solely on the functional and neurophysiological changes induced by cognitive rehabilitation. Conclusions. Outcomes showed that cerebral activation may be significantly modified by cognitive rehabilitation, in spite of the severity of the injury.

Evaluation of the effectiveness of transcranial direct current stimulation (tDCS) and psychosensory stimulation through DOCS scale in a minimally conscious subject

ABSTRACT The aim of our study was to assess the effectiveness of transcranial direct current stimulation (tDCS) on alertness improvement in a patient in a minimally conscious state (MCS) by means of disorders of consciousness scale combined with psycho-sensory stimulation. The effects of tDCS on muscle hypertonia through the Ashworth scale were also examined. tDCS was performed through a two-channel intra-cephalic stimulator. After stimulation, the patient followed a psychosensory stimulation training. Results pointed out an increase in DOCunit score, as well as an increase in alertness maintenance and an improvement in muscle hypertonia, although a MCS state persisted.

Recovering two languages with the right hemisphere

Converging evidence suggests that the right hemisphere (RH) plays an important role in language recovery from aphasia after a left hemisphere (LH) lesion. In this longitudinal study we describe the neurological, cognitive, and linguistic profile of A.C., a bilingual who, after a severe traumatic brain injury, developed a form of fluent aphasia that affected his two languages (i.e., Romanian and Italian). The trauma-induced parenchymal atrophy led to an exceptional ventricular dilation that, gradually, affected the whole left hemisphere. A.C. is now recovering both languages relying only on his right hemisphere. An fMRI experiment employing a bilingual covert verb generation task documented the involvement of the right middle temporal gyrus in processes of lexical selection and access. This case supports the hypothesis that the RH plays a role in language recovery from aphasia when the LH has suffered massive lesions.

How does language change after an intensive treatment on imitation

ABSTRACT The main aim of our study was to investigate the role of imitation in improving word-finding difficulties in a group of aphasic subjects. For this purpose, we designed software based on the computerised program described by Lee et al. (2010). Seven subjects with aphasia resulting from a brain injury were enrolled in the study. A battery of tests was administered to participants one month before the treatment (T0) and immediately before its beginning (T1) with the aim of detecting their language difficulties. In the period between T0 and T1 sessions, participants underwent traditional logopaedic and neuropsychological rehabilitation. The treatment lasted 45 days with 90-minute sessions per day and it was personalised in terms of difficulty for each of the subjects. During every session the task required participants to carefully observe and then imitate six actors while pronouncing aloud a series of words and sentences describing a set of items. The results showed a significant improvement in the whole sample and in all the analysed measures only between T1 and T2 (post-training evaluation), while, as expected, no improvement was registered between T0 and T1. Such outcomes are consistent with research showing the key role played by imitation in the word retrieval process following aphasia.