Emotion recognition impairment in traumatic brain injury compared with schizophrenia spectrum: similar deficits with different origins.

The aim of our study was to identify the common and separate mechanisms that might underpin emotion recognition impairment in patients with traumatic brain injury (TBI) and schizophrenia (Sz) compared with healthy controls (HCs). We recruited 21 Sz outpatients, 24 severe TBI outpatients, and 38 HCs, and we used eye-tracking to compare facial emotion processing performance. Both Sz and TBI patients were significantly poorer at recognizing facial emotions compared with HC. Sz patients showed a different way of exploring the Pictures of Facial Affects stimuli and were significantly worse in recognition of neutral expressions. Selective or sustained attention deficits in TBI may reduce efficient emotion recognition, whereas in Sz, there is a more strategic deficit underlying the observed problem. There would seem to be scope for adjustment of effective rehabilitative training focused on emotion recognition.

Speeded manual responses to unseen visual stimuli in hemianopic patients: what kind of blindsight?

Blindsight, i.e., unconscious visually guided behaviour triggered by stimuli presented to a cortically blind hemifield, has been typically found either by using direct (forced choice) or indirect (interhemispheric) methods. However, one would expect to find blindsight also in fast responses to suddenly appearing visual stimuli, a reminiscence of evolutionary ancient adaptive behaviour. In this study we provide preliminary evidence of this form of blindsight by using a conservative method for assessing blindsight based on a comparison between the cumulative probability functions (CPFs) of simple reaction times to blind and intact field stimuli. Furthermore, in two patients with blindsight we provided evidence that their above-chance unconscious responses were likely to be triggered by the intact hemisphere.

Targeted isometric force impulses in patients with traumatic brain injury reveal delayed motor programming and change of strategy.

The capability of quickly (as soon as possible) producing fast uncorrected and accurate isometric force impulses was examined to assess the motor efficiency of patients with moderate to severe traumatic brain injury (TBI) and good motor recovery at a clinical evaluation. Twenty male right-handed patients with moderate to severe TBI and 24 age-matched healthy male right-handed controls participated in the study. The experimental task required subjects to aim brief and uncorrected isometric force impulses to targets visually presented along with subjects' force displays. Both TBI patients and controls were able to produce force impulses whose mean peak amplitudes varied proportionally to the target load with no detectable group difference. Patients with TBI, however, were slower than controls in initiating their responses (reaction times [RTs] were longer by 125 msec) and were also slower during the execution of their motor responses, reaching the peak forces requested 23 msec later than controls (time to peak force: 35% delay). Further, their mean dF/dt (35 kg/sec) was slower than that of controls (53 kg/sec), again indicating a 34% impairment with respect to controls. Overall, patients with TBI showed accurate but delayed and slower isometric force impulses. Thus, an evaluation taking into account also response time features is more effective in picking up motor impairments than the standard clinical scales focusing on accuracy of movement only.

An investigation of prospective memory functions in people with traumatic brain injury using Virtual Week.

Prospective memory (PM) refers to memory for future intentions and is critically linked to independent living. Previous laboratory research has shown that people who have sustained a traumatic brain injury (TBI) have difficulties with PM, but few of these have used measures of PM that closely represent the types of PM activities that occur in everyday life. One measure that incorporates more ecologically valid tasks, and which also allows systematic investigation of different PM task parameters (regular, irregular, and event and time based), is Virtual Week. Consequently, in the present study, Virtual Week was administered to participants with TBI (n = 18) and demographically matched controls (n = 18). Consistent with considerable prior literature, the results indicated that people with TBI had significant difficulties executing PM tasks, with these deficits more pronounced for time-based than for event-based tasks. These data point to there being a relatively global PM deficit in people with TBI. Of particular interest was the finding that the magnitude of TBI impairment was consistent across regular and irregular tasks. Because the key distinction between these tasks is that they place low and high demands on retrospective memory, respectively, these data suggest that failures of retrospective memory are not the major cause of TBI-related impairment in PM. The implications of these results for the assessment and rehabilitation of PM impairment in people with TBI are discussed.

Time discrimination in traumatic brain injury patients.

Time management skills are required for most daily activities. Traumatic brain injury (TBI) patients often present with cognitive dysfunction, but few studies have investigated temporal impairment. The aim of the present study was to assess temporal abilities in TBI patients using a time discrimination task. Twenty-seven TBI patients (ages = 18-60 years) and 27 controls (ages = 20-60 years) were asked to discriminate between two time intervals presented sequentially. The standard intervals were 500 ms or 1,300 ms long followed by a comparison stimulus that was 25% shorter or longer than the standard one. Participants were also asked to perform two tasks to assess attention, speed-of-processing (the Stroop task), and working memory (the n-back task) abilities. The TBI patients were less accurate than the controls on the time discrimination task and showed greater time-order error effects. In fact, TBI patients pressed the "short" key more times when the standard time interval was 500 ms and the "long" key more times when the standard interval was 1,300 ms. Significant correlations were found between time discrimination, working memory, and speed of processing in both TBI and controls when the standard time interval was 1,300 ms. Attention appeared to be involved in different ways in the two groups. Working memory and speed of processing were involved in time processing only in TBI patients when the standard time interval was 500 ms. These data lend additional support to the notion that two different systems are responsible for elaborating time durations shorter or longer than a second.

Implicit olfactory abilities in traumatic brain injured patients.

To investigate implicit olfactory abilities in a group of anosmic traumatic brain injured (TBI) patients, an olfactomotor priming paradigm was administered. A group of matched normosmic/mildly microsmic TBI patients and a group of neurologically healthy participants served as controls. For all the groups, an interference effect was evident on the peak velocity of grip aperture when participants grasped a large target preceded by a "small" odor. The present results suggest that some form of implicit olfactory processing is preserved in TBI patients even when diagnosed as anosmic on the basis of explicit olfactory testing.

Narrative discourse in anomic aphasia.

Anomic aphasia is a disturbance affecting lexical retrieval. Nonetheless, persons with this disorder may also experience difficulties in the construction of coherent narratives. Whether this symptom is a sign of a macrolinguistic difficulty per se or reflects the lexical disorder is still an open debate. In order to analyze the effect of the lexical impairment on macrolinguistic processing, we compared the narrative skills of a group of ten participants with chronic anomic aphasia with those of ten healthy control individuals matched for age and educational level. The anomic participants produced narratives with lowered speech rate, reduced mean length of utterance, fewer grammatically well-formed sentences, more semantic paraphasias. The macrolinguistic analysis showed that they also produced more errors of cohesion and global coherence and fewer lexical information units. Interestingly, their levels of thematic selection were normal. A bivariate correlational analysis showed a strong correlation between the production of errors of cohesion and production of complete sentences, and between production of errors of global coherence and lexical information units. These correlations showed that aspects related to lexical retrieval may affect macrolinguistic processing during the construction of a narrative. Indeed, it is suggested that lexical deficits lead to two main consequences: First, patients with anomia frequently interrupt the utterances they are producing and this reduces the levels of sentence completeness and the overall degree of cohesion across the utterances; Second, they use strategies to cope with the lexical impairment and produce a quantity of lexical fillers and repetitions that, clustered in utterances, reduce the levels of global coherence.

Time-based prospective memory in severe traumatic brain injury patients: the involvement of executive functions and time perception.

Prospective memory (PM) is the ability to remember to perform a future action at a specified later time, which is investigated through the use of event-based and time-based tasks. Prior investigations have found that PM is impaired following traumatic brain injury (TBI). However, there is limited information regarding the cognitive functions that mediate TBI and PM performance. Thus, this study investigated time-based PM in TBI patients, and the relationship among time-based PM, time perception, and executive functions. To accomplish this objective, 18 severe TBI patients and 18 healthy matched controls performed a time-based PM task, a time reproduction task, and two executive functions (Stroop and n-back) tasks. While both groups increased their monitoring frequency close to the target time, TBI patients monitored more and were less accurate than healthy controls at the target time confirming the time-based PM dysfunction in these patients. Importantly, executive functions, particularly inhibition and updating abilities, were strongly related to time-based PM performance; both time perception and executive functions are involved in time-based prospective memory in controls, whereas, only executive functions appear to be involved in TBI time-based prospective memory performance.

'Moving' a paralysed hand: bimanual coupling effect in patients with anosognosia for hemiplegia.

Selective neurological impairments can shed light on different aspects of motor cognition. Brain-damaged patients with anosognosia for hemiplegia deny their motor deficit and believe they can still move the paralysed limb. Here we study, for the first time, if the anomalous subjective experience that their affected hand can still move, may have objective consequences that constrain movement execution with the opposite, intact hand. Using a bimanual motor task, in which anosognosic patients were asked to simultaneously trace out lines with their unaffected hand and circles with their paralysed hand, we found that the trajectories of the intact hand were influenced by the requested movement of the paralysed hand, with the intact hand tending to assume an oval trajectory (bimanual coupling effect). This effect was comparable to that of a group of healthy subjects who actually moved both hands. By contrast, brain-damaged patients with motor neglect or actual hemiplegia but no anosognosia did not show this bimanual constraint. We suggest that anosognosic patients may have intact motor intentionality and planning for the plegic hand. Rather than being merely an inexplicable confabulation, anosognosia for the plegic hand can produce objective constraints on what the intact hand does.

The cognitive rehabilitation of limb apraxia in patients with stroke.

Apraxia is a higher level motor deficit that occurs when processing a goal-directed action. The apraxic deficit can manifest itself in absence of sensory input deficits or motor output deficits, neglect, frontal inertia or dementia. According to a clinical classification still largely in use, there are two main forms of limb apraxia: ideomotor (IMA) and ideational (IA), observed when a patient is required to imitate a gesture or use an object, respectively. In the present review, we examined only the cognitive treatments of both types of limb apraxia of a vascular aetiology. Despite the high prevalence of limb apraxia caused by left brain damage, and the fact that apraxia has been known for over a century, the literature regarding its rehabilitation is still very limited. This is partly due to the nature of the recovery from the deficit, and in part to the automatic-voluntary dissociation. Here we review those treatments that have proved most successful in helping patients to recover from limb apraxia.

Inferential reasoning: comparison of patients with schizophrenia and patients with traumatic brain injury.

We investigated the cognitive processes underlying inferential reasoning, comparing performance of patients suffering from schizophrenia with that of patients with brain injury in an attempt to understand the nature of the social impairments in schizophrenia. Inferential reasoning on mental and physical states and second-order false belief attribution were assessed in healthy controls, in patients with schizophrenia and in brain trauma patients with predominantly ventromedial prefrontal cortex or dosolateral prefrontal cortex lesions. Our finding that ventromedial prefrontal areas are involved in general inferential reasoning casts further light on the neural structures implicated in socio-cognitive impairments in schizophrenia.

Neuropsychiatric disorders in persons with severe traumatic brain injury: prevalence, phenomenology, and relationship with demographic, clinical, and functional features.

OBJECTIVE: To characterize neuropsychiatric symptoms in a large group of individuals with severe traumatic brain injury (TBI) and to correlate these symptoms with demographic, clinical, and functional features. METHODS: The Neuropsychiatric Inventory (NPI), a frequently used scale to assess behavioral, emotional, and motivational disorders in persons with neurological diseases, was administered to a sample of 120 persons with severe TBI. Controls were 77 healthy subjects. RESULTS: A wide range of neuropsychiatric symptoms was found in the population with severe TBI: apathy (42%), irritability (37%), dysphoria/depressed mood (29%), disinhibition (28%), eating disturbances (27%), and agitation (24%). A clear relationship was also found with other demographic and clinical variables. CONCLUSION: Neuropsychiatric disorders constitute an important part of the comorbidity in populations with severe TBI. Our study emphasizes the importance of integrating an overall assessment of cognitive disturbances with a specific neuropsychiatric evaluation to improve clinical understanding and treatment of persons with TBI.

Improving language without words: first evidence from aphasia.

The pervasiveness of word-finding difficulties in aphasia has motivated several theories regarding management of the deficit and its effectiveness. Recently, the hypothesis was advanced that instead of simply accompanying speech gestures participate in language production by increasing the semantic activation of words grounded in sensory-motor features, hence facilitating retrieval of the word form. Based on this assumption, several studies have developed rehabilitation therapies in which the use of gestures reinforces word recovery. Until now, however, no studies have investigated the beneficial effects of gesture observation in word retrieval. Here, we report whether a different modality of accessing action-motor representation interacts with language by promoting long lasting recovery of verb retrieval deficits in aphasic patients. Six aphasic participants with a selective deficit in verb retrieval participated in an intensive rehabilitation training that included three daily sessions over two consecutive weeks. Each session corresponded to a different rehabilitation procedure: (1) "action observation", (2) "action observation and execution", and (3) "action observation and meaningless movement". In the four participants with lexical phonologically based disturbances, significant improvement of verb retrieval was found only with "action observation" and "action observation and execution". No significant differences were present between the two procedures. Moreover, the follow-up testing revealed long-term verb recovery that was still present two months after the two treatments ended. In support of a multimodal representation of action, these findings univocally demonstrate that gestures interact with the speech production system, inducing long-lasting modification at the lexical level in patients with cerebral damage.

Attentional distractor interference may be diminished by concurrent working memory load in normal participants and traumatic brain injury patients.

A reduction in congruency effects under working memory (WM) load has been previously described using different attentional paradigms (e.g., Kim, Kim, & Chun, 2005; Smilek, Enns, Eastwood, & Merikle, 2006). One hypothesis is that different types of WM load have different effects on attentional selection, depending on whether a specific memory load demands resources in common with target or distractor processing. In particular, if information in WM is related to the distractors in the selective attention task, there is a reduction in distraction (Kim et al., 2005). However, although previous results seem to point to a decrease in interference under high WM load conditions (Kim et al., 2005), the lack of a neutral baseline for the congruency effects makes it difficult to differentiate between a decrease in interference or in facilitation. In the present work we included neutral trials in the task introduced by Kim et al. (2005) and tested normal participants and traumatic brain injury patients. Results support a reduction in the processing of distractors under WM load, at least for incongruent trials in both groups. Theoretical as well as applied implications are discussed.

Theory of Mind in patients with ventromedial or dorsolateral prefrontal lesions following traumatic brain injury.

PRIMARY OBJECTIVE: Previous studies on patients with traumatic brain injuries (TBI) and diffuse brain damages have reported selective deficits in mental states reasoning or 'Theory of Mind' (ToM). The goal of the current study is to investigate the fundamental role of the prefrontal cortex in two ToM components: inferential reasoning and social perception. RESEARCH DESIGN: Selective cognitive impairments following a TBI provide crucial evidence for assessing competing models of specific aspects of the cognitive system. METHOD AND PROCEDURE: This study compared the performance of patients with predominantly focal lesions in the ventromedial (n = 11) or dorsolateral prefrontal cortex (n = 7) with matched controls (n = 20). All subjects performed two ToM tasks: the Eyes Test and the Faux-pas Test. RESULTS: It was found that both groups of patients performed equally poorly on the Eyes Test, but only patients with predominantly lesions in the ventromedial cortex performed poorly on the Faux-pas test. The group effects on ToM tasks could not be reduced to differences in the global severity of brain injuries. CONCLUSIONS: These results provide evidence supporting some current models of the fractionation of the mind-reading system and support the claim that the ventromedial cortex plays a fundamental role in inferential reasoning.

Dual task performance and post traumatic brain injury.

PRIMARY OBJECTIVE: To determine if people with traumatic brain injury (TBI) display deficits in dual tasking ability. RESEARCH DESIGN: Observational and correlational research design used, to identify and describe the nature of dual task impairment in people with TBI. METHODS AND PROCEDURES: Eighty-six people with TBI were assessed using a new standardized paper-and-pencil assessment of dual tasking ability and a number of other neuropsychological tests assessing attention, executive functioning and memory. MAIN OUTCOME AND RESULTS: Twenty-three out of the 86 people with TBI (26.74%) performed below the cut-off for normal performance, suggesting that only one quarter of the TBI sample assessed had deficits in attentional control. CONCLUSIONS: Deficits in task co-ordination are not a necessary consequence of TBI.

Verbal commands help the execution of endogenous movements in anarchic hand.

Patients with anarchic hand (AH) syndrome exhibit involuntary but seemingly purposeful controlesional upper limb movements. Here we report on the case of a patient (AC) presenting with a right AH following a left medial frontal lesion. Previous literature indicated that endogenous movements, particularly in the presence of distractors, are impaired in AH, whereas exogenous movements are spared. In this study we examined exogenous and endogenous (or sequential) movements using a new experimental procedure. Our main aim was to investigate whether the ability to perform sequential movements improves under verbal command as anecdotally observed in patients with AH. Results showed that the performance of AC's right AH was impaired in sequential tasks and that this impairment was improved by verbal command. The observed reduction in errors in sequential tasks under external verbal command was coupled with a compensatory increase in response times.

Selective impairment of self body-parts processing in right brain-damaged patients.

To investigate whether the processing of the visual appearance of one's own body, that is the corporeal self is a unified or modular function we submitted eight right brain-damaged (RBD) patients and a group of fourteen age-matched neurologically healthy subjects, to a visual matching-to-sample task testing for corporeal self processing. If corporeal self processing is a unique function (i.e., body- and face-parts are processed by the same network), patients impaired in self body-parts (i.e., showing no self-advantage) should be impaired also in self face-parts; alternatively, if corporeal self processing is a modular function (i.e., body- and face-parts are processed by different networks), patients impaired in self body-parts should be unimpaired in self face-parts, unless the face-module is also damaged by the lesion. Results showed that healthy participants were more accurate in processing pictures representing their own as compared to other people's body- and face-parts, showing the so-called self-advantage. The patients' findings revealed a simple dissociation, in that patients who were impaired in the processing of self-related body-parts showed a preserved self-advantage when processing self-related face-parts, thus providing initial evidence of a modular representation of the corporeal self.