Encoding and Retrieval of Artificial Visuoauditory Memory Traces in the Auditory Cortex Requires the Entorhinal Cortex.

Encoding and retrieval of artificial visuoauditory memory traces in the auditory cortex requires the entorhinal cortex.

J Neurosci. 2013 Jun 12; 33(24): 9963-74
Chen X, Guo Y, Feng J, Liao Z, Li X, Wang H, Li X, He J

Damage to the medial temporal lobe impairs the encoding of new memories and the retrieval of memories acquired immediately before the damage in human. In this study, we demonstrated that artificial visuoauditory memory traces can be established in the rat auditory cortex and that their encoding and retrieval depend on the entorhinal cortex of the medial temporal lobe in the rat. We trained rats to associate a visual stimulus with electrical stimulation of the auditory cortex using a classical conditioning protocol. After conditioning, we examined the associative memory traces electrophysiologically (i.e., visual stimulus-evoked responses of auditory cortical neurons) and behaviorally (i.e., visual stimulus-induced freezing and visual stimulus-guided reward retrieval). The establishment of a visuoauditory memory trace in the auditory cortex, which was detectable by electrophysiological recordings, was achieved over 20-30 conditioning trials and was blocked by unilateral, temporary inactivation of the entorhinal cortex. Retrieval of a previously established visuoauditory memory was also affected by unilateral entorhinal cortex inactivation. These findings suggest that the entorhinal cortex is necessary for the encoding and involved in the retrieval of artificial visuoauditory memory in the auditory cortex, at least during the early stages of memory consolidation. HubMed – rehab

Obesity and worsening of chronic venous disease and joint mobility.

Phlebology. 2013 May 31;
Belczak CE, de Godoy JM, Belzack SQ, Ramos RN, Caffaro RA

OBJECTIVE: The aim of this study was to investigate a possible relationship between obesity and decreased mobility of the talocrural joint and in turn chronic venous disease. SUBJECTS AND METHODS: One hundred obese patients recruited at Hospital Santa Casa de Maringa, Parana were enrolled by order of arrival at the hospital in a randomized quantitative cross-sectional study. Inclusion criteria were patients with a body mass index above 30?kg/m(2) and the exclusion criteria were infectious conditions that would interfere with the assessment. Patients were graded according to the clinical, etiological, anatomical and pathophysiological classification. Talocrural goniometry was performed to assess the degree of mobility of the legs. The Kolmogorov-Smirnov normality test, Kruskal-Wallis test, Dunn’s Multiple comparison test and analysis of variance were used for statistical analysis tests with an alpha error of 5% being considered acceptable. RESULTS: The increase in body mass index is correlated to the reduction in joint mobility (Kruskal-Wallis test: p-value <0.0001) and increase in clinical, etiological, anatomical and pathophysiological classification is correlated to a decrease in joint mobility and the increase in age is associated with an increase in clinical, etiological, anatomical and pathophysiological classification (Kruskal-Wallis test: p-value <0.0001). CONCLUSION: Obesity is associated with deterioration in joint mobility and worsening of chronic venous disease. HubMed – rehab

Modular control of varied locomotor tasks in children with incomplete spinal cord injuries.

J Neurophysiol. 2013 Jun 12;
Fox EJ, Tester NJ, Kautz SA, Howland DR, Clark DJ, Garvan C, Behrman AL

A module is a functional unit of the nervous system that specifies functionally-relevant patterns of muscle activation. In adults, 4-5 modules account for muscle activation during walking. Neurologic injury alters modular control and is associated with walking impairments. The effect of neurologic injury on modular control in children is unknown and may differ from adults due to their immature and developing nervous systems. We examined modular control of locomotor tasks in children with incomplete spinal cord injuries (ISCIs) and control children. Five controls (8.6 ± 2.7 years) and five children with ISCIs (8.6 ± 3.7 years) performed treadmill walking, overground walking, pedaling, supine lower extremity flexion/extension, stair climbing, and crawling. Electromyograms (EMGs) were recorded in bilateral leg muscles. Non-negative matrix factorization was applied and the minimum number of modules required to achieve 90% of the “variance accounted for” (VAF) was calculated. On average, 3.5 modules explained muscle activation in the controls; whereas, 2.4 modules were required in the children with ISCIs. To determine if control is similar across tasks, the module weightings identified from treadmill walking were used to reconstruct the EMGs from each of the other tasks. This resulted in VAF values exceeding 86% for each child and each locomotor task. Our results suggest that 1) modularity is constrained in children with ISCIs; 2) for each child, similar neural control mechanisms are used across locomotor tasks. These findings suggest that interventions that activate the neuromuscular system to enhance walking also may influence the control of other locomotor tasks. HubMed – rehab

Event-related desynchronization reflects down-regulation of intracortical inhibition in human primary motor cortex.

J Neurophysiol. 2013 Jun 12;
Takemi M, Masakado Y, Liu M, Ushiba J

There is increasing interest in electroencephalogram (EEG)-based brain-computer interface (BCI) as a tool for rehabilitation of upper limb motor functions in hemiplegic stroke patients. This type of BCI often exploits EEG mu and beta oscillations recorded over the sensorimotor areas, and their event-related desynchronization (ERD) following motor imagery is believed to represent increased sensorimotor cortex excitability. However, it remains unclear whether the sensorimotor cortex excitability is actually correlated with ERD. Thus, we assessed the association of ERD with primary motor cortex (M1) excitability during motor imagery of right wrist movement. M1 excitability was tested by motor evoked potentials (MEPs), short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF) using transcranial magnetic stimulation (TMS). Twenty healthy participants were recruited. The participants performed 7 seconds of rest followed by 5 seconds of motor imagery, and received online visual feedback of the ERD magnitude of the contralateral hand M1 while performing the motor imagery task. TMS was applied to the right hand M1 when ERD exceeded predetermined thresholds during motor imagery. MEP amplitudes, SICI and ICF were recorded from the agonist muscle of the imagined hand movement. Results showed that the large ERD during wrist motor imagery was associated with significantly increased MEP amplitudes and reduced SICI, but no significant changes in ICF. Thus, ERD magnitude during wrist motor imagery represents M1 excitability. This study provides electrophysiological evidence that motor imagery task involving ERD may induce changes in corticospinal excitability similar to changes accompanying actual movements. HubMed – rehab

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