A toolbox for studying cortical physiology in primates

Lesioning and neurophysiological studies have facilitated the elucidation of cortical functions and mechanisms of functional recovery following injury. Clinical translation of such studies is contingent on their employment in non-human primates (NHPs), yet tools for monitoring and modulating cortical physiology are incompatible with conventional NHP lesioning techniques. To address these challenges, we developed a toolbox demonstrated in seven macaques. We introduce the photothrombotic method to induce focal cortical lesions alongside a quantitative model for the design of lesion profiles based on experimental needs. Large-scale (~5 cm2) vascular and neural dynamics can be monitored and lesion induction can be validated in vivo with optical coherence tomography angiography and our electrocorticographic array, the latter of which also enables testing stimulation-based interventions. By combining optical and electrophysiological techniques in NHPs, we can enhance our understanding of cortical functions, investigate functional recovery mechanisms, integrate physiological and behavioral findings, and develop treatments for neurological disorders.

Cognitive and Emotional Mapping With SEEG

Mapping of cortical functions is critical for the best clinical care of patients undergoing epilepsy and tumor surgery, but also to better understand human brain function and connectivity. The purpose of this review is to explore existing and potential means of mapping higher cortical functions, including stimulation mapping, passive mapping, and connectivity analyses. We examine the history of mapping, differences between subdural and stereoelectroencephalographic approaches, and some risks and safety aspects, before examining different types of functional mapping. Much of this review explores the prospects for new mapping approaches to better understand other components of language, memory, spatial skills, executive, and socio-emotional functions. We also touch on brain-machine interfaces, philosophical aspects of aligning tasks to brain circuits, and the study of consciousness. We end by discussing multi-modal testing and virtual reality approaches to mapping higher cortical functions.

Single-Pulse TMS to the Temporo-Occipital and Dorsolateral Prefrontal Cortex Evokes Lateralized Long Latency EEG Responses at the Stimulation Site

IntroductionTranscranial magnetic stimulation (TMS)–evoked potentials (TEPs) allow for probing cortical functions in health and pathology. However, there is uncertainty whether long-latency TMS-evoked potentials reflect functioning of the targeted cortical area. It has been suggested that components such as the TMS-evoked N100 are stereotypical and related to nonspecific sensory processes rather than transcranial effects of the changing magnetic field. In contrast, TEPs that vary according to the targeted brain region and are systematically lateralized toward the stimulated hemisphere can be considered to reflect activity in the stimulated brain region resulting from transcranial electromagnetic induction.MethodsTMS with concurrent 64-channel electroencephalography (EEG) was sequentially performed in homologous areas of both hemispheres. One sample of healthy adults received TMS to the dorsolateral prefrontal cortex; another sample received TMS to the temporo-occipital cortex. We analyzed late negative TEP deflections corresponding to the N100 component in motor cortex stimulation.ResultsTEP topography varied according to the stimulation target site. Long-latency negative TEP deflections were systematically lateralized (higher in ipsilateral compared to contralateral electrodes) in electrodes over the stimulated brain region. A calculation that removes evoked components that are not systematically lateralized relative to the stimulated hemisphere revealed negative maxima located around the respective target sites.ConclusionTEPs contain long-latency negative components that are lateralized toward the stimulated hemisphere and have their topographic maxima at the respective stimulation sites. They can be differentiated from co-occurring components that are invariable across different stimulation sites (probably reflecting coactivation of peripheral sensory afferences) according to their spatiotemporal patterns. Lateralized long-latency TEP components located at the stimulation site likely reflect activity evoked in the targeted cortex region by direct transcranial effects and are therefore suitable for assessing cortical functions.

Clinical neuropsychological pathology profile of Moyamoya disease

The goal of this study is to discover and describe the clinical qualities of higher cortical functions in a young Moyamoya patient with acute brain ischemia. We assessed the recovery of higher cortical functions for the period from March 2019 to January 2020. This paper presents the individual patients medical history and the neuropsychological evaluation conducted during the patients rehabilitation in January 2020.

Infants can outperform adults in pitch and timbre perception

Adults perceive pitch with fine precision, an ability ascribed to cortical functions that are also important for speech and music perception. Infants display neural immaturity in the auditory cortex, suggesting that pitch discrimination may improve throughout infancy. In three experiments, we tested the limits of pitch and timbre perception in 66 infants and 44 adults. Contrary to expectations, we found that infants surpassed adults in detecting subtle changes in pitch in the presence of random variations in timbre, and vice versa. The results indicate high fidelity of pitch and timbre coding in infants, implying that fully mature cortical processing is not necessary for accurate discrimination of these features. The surprising superiority of infants over adults may reflect a developmental trajectory for learning natural statistical covariations between pitch and timbre that improves coding efficiency in adults, but results in degraded perceptual acuity when expectations for such covariations are violated.

The features of psychopathology and cognitive impairments in various variants of the psychoorganic syndrome

Mental disorders and cognitive impairments are more or less inherent in most organic brain diseases. The psychoorganic syndrome is the consequence and one of the fundamental manifestations of such diseases. The article discusses the results of the analysis of the features of psychopathology and neurocognitive symptom complex in patients with psychoorganic syndrome of different aetiologies, with an assessment of impairments of higher cortical functions depending on the variant of the psycho-organic syndrome.

Neurorehabilitation in cognitive disorders in patients with neurosurgical brain pathology

Background. Neurosurgical pathology of the brain is an urgent problem of modern medicine. Existing models of cognitive rehabilitation are based on neuropsychological correction. The literature does not contain enough information about the effect of medical and physiotherapeutic techniques on higher nervous activity.Objective. To assess the effect of neurorehabilitation in cognitive impairment in patients with neurosurgical brain pathology.Design and methods. The dynamics of cognitive impairment was studied in 165 neurosurgical patients (72 men, 93 women, average age 52.82 ± 14.79 years) at the second stage of rehabilitation. The severity of the deficit of higher cortical functions was assessed upon admission and after 30 days in the rehabilitation department. Roschina test, MMSE, FAB, HDRS were used to detect depression.Results. When analyzing the dynamics of indicators for scoring higher cortical functions, it was found that in all groups of patients, cognitive rehabilitation led to positive results.Conclusion. The combined use of neuropsychological, medical and physiotherapeutic techniques can significantly improve the results of rehabilitation treatment.