A "virtually minimal" visuo-haptic training of attention in severe traumatic brain injury.

BACKGROUND: Although common during the early stages of recovery from severe traumatic brain injury (TBI), attention deficits have been scarcely investigated. Encouraging evidence suggests beneficial effects of attention training in more chronic and higher functioning patients. Interactive technology may provide new opportunities for rehabilitation in inpatients who are earlier in their recovery. METHODS: We designed a "virtually minimal" approach using robot-rendered haptics in a virtual environment to train severely injured inpatients in the early stages of recovery to sustain attention to a visuo-motor task. 21 inpatients with severe TBI completed repetitive reaching toward targets that were both seen and felt. Patients were tested over two consecutive days, experiencing 3 conditions (no haptic feedback, a break-through force, and haptic nudge) in 12 successive, 4-minute blocks. RESULTS: The interactive visuo-haptic environments were well-tolerated and engaging. Patients typically remained attentive to the task. However, patients exhibited attention loss both before (prolonged initiation) and during (pauses during motion) a movement. Compared to no haptic feedback, patients benefited from haptic nudge cues but not break-through forces. As training progressed, patients increased the number of targets acquired and spontaneously improved from one day to the next. CONCLUSIONS: Interactive visuo-haptic environments could be beneficial for attention training for severe TBI patients in the early stages of recovery and warrants further and more prolonged clinical testing.

Treatment challenges with profound behaviour disturbance after traumatic brain injury: a case report.

BACKGROUND: Severe behavioural disturbances exhibited during the earliest stages of recovery from severe traumatic brain injury often limit the ability to provide standard care. Studies that focus on treatment options for inpatients with such behaviours are scarce. There is limited guidance on how to approach therapy that will maximize the patient's tolerance and participation and how to measure meaningful progress. CASE REPORT: This case study describes how the use of an innovative treatment approach to improve attention was beneficial in rehabilitation of a patient with severe traumatic brain injury whose profound behaviour disturbances substantially precluded participation in traditional therapies. The study shows how rehabilitation utilizing an interactive virtual reality-robotics environment that minimized distractions was associated with improved engagement in therapy, decreased disruptive behaviour during treatment and more sensitive measurement of progress. CONCLUSION: These results may be instructive in how technology can be used to modify therapy sessions to make them accessible to patients with profound behaviour disturbance and how meaningful progress can be measured even in the absence of gains in traditional metrics.

Tolerance of a virtual reality intervention for attention remediation in persons with severe TBI.

OBJECTIVE: To evaluate the feasibility of applying virtual reality and robotics technology to improve attention in patients with severe traumatic brain injury (TBI) in the early stages of recovery. METHODS: A sample of TBI patients (n=18, aged 19-73) who were receiving acute inpatient rehabilitation completed three-dimensional cancellation exercises over two consecutive days in an interactive virtual environment that minimized distractions and that integrated both visual and haptic (tactile) stimuli. Observations of behaviour during the intervention and of the instructions needed to encourage compliance were recorded. Performance data were compiled to assess improvement across three different treatment conditions. OUTCOMES: Fifteen of the 18 patients demonstrated tolerance of the virtual environment by completing the entire treatment protocol. Within-subjects comparisons of target acquisition time during treatment showed that a treatment condition that included haptic cues produced improved performance compared to a condition in which such cues were not provided. Separating out participants who were in post-traumatic amnesia showed that this group also demonstrated improvement in performance across trials despite their memory impairment. CONCLUSIONS: It is proposed that attention exercises using virtual environments are well-tolerated and engaging and that they could be beneficial for inpatients with severe TBI.

p66SHC promotes apoptosis and antagonizes mitogenic signaling in T cells.

Of the three Shc isoforms, p66Shc is responsible for fine-tuning p52/p46Shc signaling to Ras and has been implicated in apoptotic responses to oxidative stress. Here we show that human peripheral blood lymphocytes and mouse thymocytes and splenic T cells acquire the capacity to express p66Shc in response to apoptogenic stimulation. Using a panel of T-cell transfectants and p66Shc(-/-) T cells, we show that p66Shc expression results in increased susceptibility to apoptogenic stimuli, which depends on Ser36 phosphorylation and correlates with an altered balance in apoptosis-regulating gene expression. Furthermore, p66Shc blunts mitogenic responses to T-cell receptor engagement, at least in part by transdominant inhibition of p52Shc signaling to Ras/mitogen-activated protein kinases, in an S36-dependent manner. The data highlight a novel interplay between p66Shc and p52Shc in the control of T-cell fate.

Extensive temporally regulated reorganization of the lipid raft proteome following T-cell antigen receptor triggering.

Signalling by immunoreceptors is orchestrated at specific plasma membrane microdomains, referred to as lipid rafts. Here we present a proteomics approach to the temporal analysis of protein association with lipid rafts following T-cell antigen receptor (TCR) triggering. We show that TCR engagement promotes the temporally regulated recruitment of proteins participating in the TCR signalling cascade to lipid rafts. Furthermore, TCR triggering results in profound modifications in the composition of lipid rafts involving a number of proteins associated either directly or indirectly with both plasma and intracellular membranes. Raft-associated proteins can be clustered according to their temporal profile of raft association. The data identify lipid rafts as highly dynamic structures and reveal a dramatic impact of surface TCR triggering not only on components of the TCR signalling machinery but also on proteins implicated in a number of diverse cellular processes.

The p66Shc longevity gene is silenced through epigenetic modifications of an alternative promoter.

The mammal Shc locus encodes three overlapping isoforms (46, 52, and 66 kDa) that differ in the length of their N-terminal regions. p46/p52Shc and p66Shc have been implicated, respectively, in the cytoplasmic propagation of growth and apoptogenic signals. Levels of p66Shc expression correlate with life span duration in mice. p46Shc and p52Shc are ubiquitously expressed, whereas p66Shc is expressed in a cell lineage-specific fashion. However, the mechanisms underlying the regulation of Shc protein expression are unknown. Here we report the identification of two alternative promoters, driving the transcription of two mRNAs coding for p46/p52Shc and p66Shc. We show that treatment with an inhibitor of histone deacetylases or with a demethylating agent results in induction of p66Shc expression in cells that normally do not express this isoform but leaves the levels of the two other isoforms unchanged. Moreover, analysis of the methylation pattern of the p66Shc promoter in a panel of primary and immortalized human cells showed inverse correlation between p66Shc expression and methylation density of its promoter. These results identify histone deacetylation and cytosine methylation as the mechanisms underlying p66Shc silencing in nonexpressing cells.

F-actin dynamics control segregation of the TCR signaling cascade to clustered lipid rafts.

Following ligand binding the TCR segregates to plasma membrane microdomains, termed lipid rafts, characterized by a highly ordered lipid structure favoring partitioning of glycosyl phosphatidyl inositol-linked costimulatory receptors and acylated signaling molecules. Here we show that the inducible association of the TCR and key signaling proteins with lipid rafts is dependent on the actin cytoskeleton through a mechanism involving raft coalescence. Although lipid rafts are required for full activation of the TCR-dependent tyrosine phosphorylation cascade and sustained signaling, triggering of TCR-proximal events, including Fyn activation and a first wave of Vav phosphorylation, is independent of lipid rafts, while a second wave of raft-dependent Vav phosphorylation occurs after raft coalescence, as also supported by the finding that Vav is phosphorylated in response to lipid raft clustering by GM1 aggregation. The constitutive association found between Vav and the CD3zeta chain suggests a model whereby the TCR-associated signaling machinery initiates raft aggregation by promoting F-actin reorganization, which permits full activation of the tyrosine phosphorylation cascade, further reorganization of the actin cytoskeleton and sustained signaling, leading to cell activation.