Cost Associated with Geriatric Traumatic Brain Injury in Developing Countries: An Observational Study.

BACKGROUND: Traumatic brain injury (TBI) in the geriatric population is a serious public health problem and has a huge impact on mortality and morbidity. METHODS: A retrospective cohort study including patients aged above 65 admitted to a tertiary specialized trauma center, in the period from January 2016 to 31 December 2019. The data collected include patients' demographics, diagnosis, Glasgow Coma Scale (GCS) on arrival, length of stay, investigations, and type of surgery done. RESULTS: Total number of TBI cases in our study is 145. The most frequent single diagnosis was subdural hematoma (85). Subsequently, it was the costliest diagnosis with an average cost of 3569 USD per patient. Length of stay on average was 17.11 ± 41 hours, with the majority (109 patients) having nonprolonged hospital stay (<14 days). Most of those managed by observation have below-average costs compared to other patients (P < 0.001). Complete blood count was the highly requested test with a total cost 5070 $ in the study period. And head computed tomography had the highest total cost 58,864 $. 21 craniotomies and 30 burr holes were made with a total cost of 30,000 and 25,325 respectively. Patients with lower GCS (64.6%) have below-average hospitalization costs compared to those who got high GCS scores (P < 0.001). CONCLUSIONS: This study provides the first estimates of the financial burden of Geriatric TBI in the region, which signifies the importance of developing strategies to prevent TBIs and help in resource allocation and healthcare policy formation.

Glial cells have more important role in tDCS-induced brain activities rather than neurons.

Transcranial Direct Current Stimulation (tDCS) is a non-invasive and sub-threshold method for altering the excitability of neurons to achieve target conditions. Many clinical applications of tDCS are in progress including treatment of neurological disease. Despite the therapeutic and practical potentials of tDCS, the precise mechanism of its impact is still unclear to a large extent. The initial perspective about the effect of tDCS on synaptic plasticity was that electric stimulation of the brain degrades the threshold of neural firing, thus facilitating electrical transmission and improving conductivity between neurons and ultimately leading to changes in the processing of information. However, new results of some experimental studies have changed the initial perspective. Recently, calcium imaging has shown sudden calcium fluctuations, followed by a change in cortical metaplasticity under tDCS. These pieces of evidence pinpoint the important role of astrocytes in describing the effect of tDCS. Astrocytes are glial cells that are traditionally viewed with only a supportive and nutritional role, but recent research expresses that they are active and contribute to processing and regulating synaptic information. We hypothesize that considering astrocytes as an important player in tDCS effect instead of the direct effect on voltage membrane of neurons is closer to the reality of tDCS effect mechanism. This hypothesis is examined here based on the experimental evidence published so far, which indicates astroglia involvement in tDCS-induced activities and results of our proposed computational model.

An investigation into the effective role of astrocyte in the hippocampus pattern separation process: A computational modeling study.

A physiologically realistic three layer neuron-astrocyte network model is used to evaluate the biological mechanism in pattern separation. The innovative feature of the model is the use of a combination of three elements: neuron, interneuron and astrocyte. In the input layer, a pyramidal neuron receives input patterns from stimulus current, while in the middle layer there are two pyramidal neurons coupled with two inhibitory interneurons and an astrocyte. Finally, in the third layer, a pyramidal neuron produces the output of the model by integrating the output of two neurons from the middle layer resulting from inhibitory and excitatory connections among neurons, interneurons and the astrocyte. Results of computer simulations show that the neuron-astrocyte network within the hippocampal dentate gyrus can generate diverse, complex and different output patterns to given inputs. It is concluded that astrocytes within the dentate gyrus play an important role in the pattern separation process.

A biologically inspired neural model for visual and proprioceptive integration including sensory training.

Humans perceive the surrounding world by integration of information through different sensory modalities. Earlier models of multisensory integration rely mainly on traditional Bayesian and causal Bayesian inferences for single causal (source) and two causal (for two senses such as visual and auditory systems), respectively. In this paper a new recurrent neural model is presented for integration of visual and proprioceptive information. This model is based on population coding which is able to mimic multisensory integration of neural centers in the human brain. The simulation results agree with those achieved by casual Bayesian inference. The model can also simulate the sensory training process of visual and proprioceptive information in human. Training process in multisensory integration is a point with less attention in the literature before. The effect of proprioceptive training on multisensory perception was investigated through a set of experiments in our previous study. The current study, evaluates the effect of both modalities, i.e., visual and proprioceptive training and compares them with each other through a set of new experiments. In these experiments, the subject was asked to move his/her hand in a circle and estimate its position. The experiments were performed on eight subjects with proprioception training and eight subjects with visual training. Results of the experiments show three important points: (1) visual learning rate is significantly more than that of proprioception; (2) means of visual and proprioceptive errors are decreased by training but statistical analysis shows that this decrement is significant for proprioceptive error and non-significant for visual error, and (3) visual errors in training phase even in the beginning of it, is much less than errors of the main test stage because in the main test, the subject has to focus on two senses. The results of the experiments in this paper is in agreement with the results of the neural model simulation.

The effect of proprioceptive training on multisensory perception under visual uncertainty.

Most previous studies on multisensory integration concern mandatory integration. Moreover, no study has evaluated the effect of modality training on the result of integration. The purpose of this study is to evaluate the effect of training on visual-proprioceptive integration; i.e., we investigate the effect of proprioceptive modality training on the hand location estimation, when visual feedback exists. To achieve this goal, the effect of visual uncertainty on the estimation of hand position in visual-proprioceptive integration is studied in two groups: trained proprioception and untrained proprioception. The visual uncertainty is provided by an unpredictable spatial shift between visual and proprioceptive sensory feedbacks. The experiment was performed on nine subjects with trained proprioception and 11 subjects without proprioception training. The experiment had three phases: "familiarization", to draw participant's attention to a modality, "proprioception test", to estimate the hand position using only proprioception, and "vision-proprioception test", to investigate the effect of the visual uncertainty (bias) on hand position estimation. Our results indicate that: (i) modality training increases the subject reliance on the proprioceptive sensory information (i.e., bias decrement in sensory integration); and (ii) increasing the discrepancy between the modalities leads to more uncertainty (i.e., variance) in the estimation of hand position, but the variance of the final estimate is less than the variance of the proprioceptive estimate. This result confirms the theory that both senses contribute to the multisensory perception and in contrast to some studies, the dominant sense does not fully override the non-dominant one in the range of applied shift between the sensory sources.