Cortex-Wide Dynamics of Intrinsic Electrical Activities: Propagating Waves and Their Interactions.

Cortical circuits generate patterned activities that reflect intrinsic brain dynamics that lay the foundation for any, including stimuli-evoked, cognition and behavior. However, the spatiotemporal organization properties and principles of this intrinsic activity have only been partially elucidated because of previous poor resolution of experimental data and limited analysis methods. Here we investigated continuous wave patterns in the 0.

Neural surprise in somatosensory Bayesian learning.

Tracking statistical regularities of the environment is important for shaping human behavior and perception. Evidence suggests that the brain learns environmental dependencies using Bayesian principles. However, much remains unknown about the employed algorithms, for somesthesis in particular.

Sensory Response of Transplanted Astrocytes in Adult Mammalian Cortex In Vivo.

Glial precursor transplantation provides a potential therapy for brain disorders. Before its clinical application, experimental evidence needs to indicate that engrafted glial cells are functionally incorporated into the existing circuits and become essential partners of neurons for executing fundamental brain functions. While previous experiments supporting for their functional integration have been obtained under in vitro conditions using slice preparations, in vivo evidence for such integration is still lacking.

Bimodal stimulus timing-dependent plasticity in primary auditory cortex is altered after noise exposure with and without tinnitus.

Central auditory circuits are influenced by the somatosensory system, a relationship that may underlie tinnitus generation. In the guinea pig dorsal cochlear nucleus (DCN), pairing spinal trigeminal nucleus (Sp5) stimulation with tones at specific intervals and orders facilitated or suppressed subsequent tone-evoked neural responses, reflecting spike timing-dependent plasticity (STDP). Furthermore, after noise-induced tinnitus, bimodal responses in DCN were shifted from Hebbian to anti-Hebbian timing rules with less discrete temporal windows, suggesting a role for bimodal plasticity in tinnitus.

Cortical EEG components that reflect inverse effectiveness during visuotactile integration processing.

Multisensory integration is required to interpret information from multiple senses and then produce the appropriate behavioral output. Inverse effectiveness, a phenomenon in which weaker stimuli induce greater activation of multisensory neurons than do stronger stimuli, is an essential component of multisensory integration. The superior colliculus is especially abundant in multisensory neurons with properties of inverse effectiveness.

Short-term cortical plasticity associated with feedback-error learning after locomotor training in a patient with incomplete spinal cord injury.

Background And Purpose: For rehabilitation strategies to be effective, training should be based on principles of motor learning, such as feedback-error learning, that facilitate adaptive processes in the nervous system by inducing errors and recalibration of sensory and motor systems. This case report suggests that locomotor resistance training can enhance somatosensory and corticospinal excitability and modulate resting-state brain functional connectivity in a patient with motor-incomplete spinal cord injury (SCI).

Case Description: The short-term cortical plasticity of a 31-year-old man who had sustained an incomplete SCI 9.

[The clinical diagnosis and treatment of blood-blister-like cerebral aneurysms in supra-clinoid segment of internal carotid artery].

Objective: To study the clinical characteristics, surgical principles and treatment options of blood-blister-like cerebral aneurysms in supra-clinoid segment of internal carotid artery.

Methods: Twelve blood-blister-like aneurysms were retrospectively studied including 4 open-surgery cases and 8 endovascular-treated cases from November 2008 to December 2012. Patients comprised 8 female and 4 male patients, whose mean age was 46.

[The analysis of intracranial aneurysms undergoing surgical treatment].

Objective: To study the surgical principles and treatment options of intracranial aneurysms.

Methods: One hundred and thirty nine patients with intracranial aneurysms were retrospectively studied, including 80 open-surgery cases and 59 endovascular-treated cases from January to December in 2009. Open surgical methods included clipping, trapping or wrapping and interventional methods included simple coiling or stent-assisted coiling.

Quantitative analysis and biophysically realistic neural modeling of the MEG mu rhythm: rhythmogenesis and modulation of sensory-evoked responses.

Variations in cortical oscillations in the alpha (7-14 Hz) and beta (15-29 Hz) range have been correlated with attention, working memory, and stimulus detection. The mu rhythm recorded with magnetoencephalography (MEG) is a prominent oscillation generated by Rolandic cortex containing alpha and beta bands. Despite its prominence, the neural mechanisms regulating mu are unknown.

Neural correlates of tactile detection: a combined magnetoencephalography and biophysically based computational modeling study.

Previous reports conflict as to the role of primary somatosensory neocortex (SI) in tactile detection. We addressed this question in normal human subjects using whole-head magnetoencephalography (MEG) recording. We found that the evoked signal (0-175 ms) showed a prominent equivalent current dipole that localized to the anterior bank of the postcentral gyrus, area 3b of SI.

BOLD response during uncoupling of neuronal activity and CBF.

The widely used technique of functional magnetic resonance imaging (fMRI) based on the blood oxygenation level-dependent (BOLD) effect is a tool for the investigation of changes in local brain activity upon stimulation. The principle of measurement is based on the assumption that there is a strong coupling between changes in neural activity, metabolism, vascular response and oxygen extraction in the area under investigation. As fMRI is on the way to become a routine tool in clinical examinations, we wanted to investigate whether, generally and under a variety of conditions, there is a strong link between the BOLD signal and neural activity.

From postsynaptic potentials to spikes in the genesis of auditory spatial receptive fields.

Space-specific neurons in the owl's inferior colliculus respond only to a sound coming from a particular direction, which is equivalent to a specific combination of interaural time difference (ITD) and interaural level difference (ILD). Comparison of subthreshold postsynaptic potentials (PSPs) and spike output for the same neurons showed that receptive fields measured in PSPs were much larger than those measured in spikes in both ITD and ILD dimensions. Space-specific neurons fire more spikes for a particular ITD than for its phase equivalents (ITD +/- 1/F, where F is best frequency).

New devices to deliver somatosensory stimuli during functional MRI.

A new class of devices are described for improving investigation of somatosensory neuronal activation using fMRI. Dubbed magnetomechanical vibrotactile devices (MVDs), the principle of operation involves driving wire coils with small oscillatory currents in the large static magnetic field inherent to MRI scanners. The resulting Lorentz forces can be oriented to generate large vibrations that are easily converted to translational motions as large as several centimeters.

Generalisability of sensory gating during passive movement of the legs.

Movement-related gating of somatosensory evoked potentials in the upper limb is restricted mainly to nerve stimulation supplying the moved limb segment. In the lower limb, this principle may not be followed. Tibial nerve (stimulation at the knee) somatosensory evoked potentials (SEPs) and soleus H reflexes exhibit quite similar patterns of modulation during movement.

[Surgical treatment of thoraco-abdominal aneurysm. Indications and results].

Aortic replacement for thoraco-abdominal aneurysms remains a major challenge in vascular surgery. Related symptoms, maximal diameter > 6 cm, progression, aneurysm sac containing none or excentric thrombi and uncontrollable hypertension are factors in favour of surgery, if the general condition of the patient allows the operation. Patients with aneurysms < 5 cm maximal diameter, tube-size aneurysms, heavy calcification of the aortic wall, concentric thrombi within the aneurysmal sac and significant cardiopulmonary risks should be treated conservatively.

Assessing the evolution of the evoked potential average: a new color display method.

A new method to control the averaging process and to check the stability of evoked potential (EP) components is described. The principle of the method is based on the display of the consecutive averages of the EP after each stimulus in a color-coded picture. In this way the evolution of the process is visualised instead of only the last average.

[Physiology and physiopathology of somatic sensations studied in man by the method of evoked potentials].

The physiology of somatic sensation can be investigated noninvasively in man by recording the electric activity of peripheral nerves, spinal cord and brain. Since these responses have a small voltage, it is necessary to use electronic averaging methods for improving the signal-to-noise ratio. These methods are described and discussed, as well as principles of interpretation of somatosensory evoked potentials.

[Features of corticofugal effects of the motor area of the cortex on processing of heterogeneous afferentation in the parafascicular complex of the thalamus in the cat].

Evoked potentials to somatic and visual stimuli were recorded in the parafascicular complex (parafascicular nuclei--centrum medianum--Pf--CM) of the thalamus of cats anaesthetized by nembutal. Cooling of the motor cortex was also used. The influence of the motor cortex on processing of the visual and somatic afferent signals at the thalamic level was found to be direct but different by its character.

Spectro-temporal representations and time-varying spectra of evoked potentials. A methodological investigation.

Evoked potential waveforms are generally of a dynamic, transient character. Consequently, their spectral energy distribution cannot be adequately described by time-invariant representations, such as the power density spectrum. Obviously, a spectro-temporal description is needed.

Organization of the visceral afferent representation in the cerebral cortex.

In experiments on cats which had been narcotized with chloralose and immobilized with myo-relaxants, we have studied cerebral cortical responses to stimulation of the visceral system. A peculiarity of the visceral afferent representation is the fact that the convergence of visceral and dermomuscular impulses is achieved with predominance of somatic signals in the cortical zones of visceral representation, with the exception of the focus of maximal activity (FMA). A second peculiarity is the fact that the visceral afferent systems develop habituation to prolonged stimulation.