Volume 5, Issue 4

Cognition and motor performance are essential components of human functioning. Recent research has provided evidence that these two domains are more interrelated than previously thought. This is a potentially important area of research with many questions that warrant further exploration and have practical implications to the field of neurological rehabilitation. In this review of literature we included animals and humans in healthy conditions as well as pathological conditions affecting the central nervous system. Our primary goal was to comprehensively review the relevant basic science and clinical literature on the effects of motor interventions on cognitive function and vice versa. We found more evidence supporting positive effects of exercise on cognition than effects of cognitive training on motor function. In addition, we examined the extent to which findings from animal literature have been or can be translated to humans. We found that, with the exception of one study in monkeys, most animal studies which investigate rodents are somewhat challenging to translate to human studies, independent of the intervention employed. It is difficult to find a human parallel to exercise in rodents, because both the voluntary and forced exercise paradigms used in rodents happen in a different context than humans. In addition it is difficult to find an animal parallel to cognitive training in humans, because the environmental enrichment intervention cannot be considered “purely” cognitive stimulation as it also involves sensory, motor and social components. We conclude the review by suggesting avenues for future research and intervention strategies.

The relevance of anatomical connectivity for understanding of the neural basis of language was recognized in the 19th century, and yet this topic has only recently become the subject of wider research interest. In this paper, I review recent findings on white matter tracts implicated in language: the arcuate fasciculus, superior longitudinal fasciculus, extreme capsule, uncinate fasciculus, middle longitudinal fasciculus, inferior longitudinal fasciculus, and inferior fronto-occipital fasciculus. The reviewed findings on these tracts were reported in studies that used a variety of methods, from post-mortem dissection and diffusion imaging to intraoperative electrostimulation with awake surgery patients. The emerging picture suggests that there is currently no consensus with regard to the exact number and identity of the tracts supporting language, their origins, trajectories, and terminations, as well as their functional interpretation.

Patients with amnestic mild cognitive impairment (aMCI) are at an increased risk of further deterioration and eventually developing Alzheimer’s disease (AD). Therefore, the identification of specific markers for this disease such as radiological markers is of great diagnostic and clinical significance. Our previous work has shown that magnetic resonance imaging (MRI) is a powerful tool to identify unique imaging features in patients with aMCI. Herein, we calculated the gray matter volume by structural magnetic resonance imaging (sMRI), and spontaneous low frequency fluctuations (LFF) using resting-state functional MRI (rs-fMRI) in 11 patients with aMCI and 22 normal control patients. Compared with the control group, patients with aMCI showed significant reduction of gray matter volume in the inferior frontal gyrus, inferior parietal lobule, anterior cingulated cortex, and insula and superior temporal gyrus. Patients with aMCI also showed significantly lower amplitudes of low-frequency fluctuations (ALFF) in the posterior cingulate cortex, precuneus, temporal gyrus and inferior parietal lobule when compared with the control group. However, in several other brain regions including the occipital lobe and cerebellum, the ALFF in patients with aMCI was significantly increased. The variation in ALFF between the two groups remained significant after adjustment for structural differences. Our results obtained in this pilot study are consistent with our previous finding and collectively show that patients with aMCI have abnormal MRI imaging findings. The pathological basis of these imaging features in patients with aMCI needs to be further explored.

Somatosensory pathways and cortices contribute to the control of human movement. In humans, non-invasive transcranial magnetic stimulation techniques to promote plasticity within somatosensory pathways and cortices have revealed potent effects on the neurophysiology within motor cortices. In this mini-review, we present evidence to indicate that somatosensory cortex is positioned to influence motor cortical circuits and as such, is an ideal target for plasticity approaches that aim to alter motor physiology and behavior in clinical populations.

Neuropsychological studies of patients with visuospatial neglect have shown differences in perceptual deficits for information in near space (i.e. near to the body) and information in far space. It has been suggested that among the many areas of the human brain, a number of areas are associated with a set of spatial maps specialized for visuospatial control related to this spatial distinction. This paper reviews how parietal cortex is thought to be involved in visuospatial neglect in relation to its control of visuospatial attention in the left and right visual fields and at different viewing distances. In particular, the importance of regions of the parietal cortex in the pathogenesis of neglect and in spatial attention and perception is discussed. Parietal cortex may control different distributions of attention across space by allocating specific attentional resources in near and far space while also showing attentional asymmetry across visual fields. Transcranial magnetic stimulation (TMS) as a technique offers the advantage of examining the direct behavioral effect of disruption of many of these areas with excellent temporal and spatial resolution. We discuss the use of TMS and the insights it may offer regarding the roles of these areas in neglect as well as normal visuospatial perception.

Offset neurons which respond to the termination of the sound stimulation may play important roles in auditory temporal information processing, sound signal recognition, and complex distinction. Two additional possible mechanisms were reviewed: neural inhibition and the intrinsic conductance property of offset neuron membranes. The underlying offset response was postulated to be located in the superior paraolivary nucleus of mice. The biological significance of the offset neurons was discussed as well.

Neuronal oscillations refer to periodic changes of neuronal activity. A prominent neuronal oscillation, especially in sensorimotor areas, is the beta-frequency-band (∼ 13–29 Hz). Sensorimotor beta oscillations are predominantly linked to motor-related functions such as preparation and/or execution of movements. In addition, beta oscillations have been suggested to play a role in long-range communication between multiple brain areas. In this review, we assess different studies that show that sensorimotor beta oscillations are additionally involved in the visual perception and imagery of biological movements. We propose that sensorimotor beta oscillations reflect a mechanism of attempted matching to internally stored representations of movements. We additionally, provide evidence that beta oscillations play a role for the integration of visual and sensorimotor areas to a functional network that incorporates perceptual components at specific spatial-temporal profiles and transmits information across different areas.

The Zagreb Collection of developing and adult human brains consists of approximately 1,300 brains of fetuses, children and adults that were collected following routine autopsies in the period from 1974 to 2014. The collection comprises brains of different normal developmental stages that may serve for investigation of normal human brain development. Previous studies on this material have led to several important contributions on human cortical development, such as the discovery of the transient fetal subplate zone. The Zagreb Collection, however, also contains approximately 100 brains with different anomalies including chromosomal aberrations such as Down syndrome. We have analyzed all the available material from the Zagreb Collection and identified 44 brains of fetuses and children with Down syndrome, 10 with Patau syndrome, 6 with Edwards syndrome as well as 7 holoprosencephalic, 7 hydrocephalic and 4 microcephalic brains. The largest part of the Collection is available for further research using modern genetic, immunocytochemical and imaging methods, especially magnetic resonance imaging. Furthermore, the histological slides from the Zagreb Collection are currently being digitally scanned and made available as virtual slides to general scientific audience. The Zagreb Collection represents unique and versatile resource for the future study of normal and abnormal human brain development.