After neurological/orthopedic trauma, functional performance needs to be improved by monitoring the load-bearing distribution between the lower extremities. This research focuses on measuring and controlling an active rehabilitation system to enhance functional improvement. As part of a related research study, we are also working on designing an Active Passive Trainer (APT) for physiotherapy treatment of children with cerebral palsy. The research investigates the influence of physiotherapy treatment on the patient through measurable biomechanical parameters.
We model the brainstem as two layers of purely excitatory and inhibitory cells, with a time delay in transmission of information between the layers. The response to a localized afferent impulse is a strong function of this inhibitory delay; at first showing increased amplification as the delay increases, but at larger delays showing increased convection away from the impulse location.These features are consistent with the function of the brainstem in regulating attentional levels. And have possible implications for the understanding of higher brain mechanisms.
We assume that individual neurons carry information mostly as indistinguishable parts of a multitude. This “continuum” picture takes many forms in the literature, notably the “groups” posited by Edelman and the theoretical basis for the mathematical description by Wilson and Cowan. It also postulates the correctness of the holographic theory of Pribram. One can consider first a wave of definite wavelength, determined, by the delay. Two regions of space separated by an integral number of wavelengths will always be in phase with each other, (i.e. they will both have a high fraction and a low fraction of active cells at the same time.) Because of the regularity, the exact location of the original stimulus will not change this fact. This reliably reproducible behavior makes this type of wave most suitable as a vehicle for memory recall, i.e. it could serve to reintegrate the distributed stored information postulated by Prideaux. The assumption of “widely distributed” connections in order to explain the synchronization of activity is no longer necessary if we recognize that the amplified wavelengths are always considerably longer than some “mean axonal length”. No matter how it is computed, the mathematics of wave dynamics shows that the favored wavelength always surpasses it. The variable delay controls the frequency, and thus the wavelength, analogously to the control of transmission and reception of radio waves, i.e. it functions as a “tuner “. Assuming the model has some relation to reality, the question is immediately raised as to the relationship of the wavelength to the semantic content of the corresponding memory. Before contending with this problem it is necessary to examine another question: If the waves are so regular and predictably dependent on the delay, how can one account for creativity? The answer lies in the condition for mutual reinforcement of the intra-layer and delayed interlayer signals. The product of frequency and delay is equal to ¼ at the smallest values of T, but the phase condition is also satisfied for ¾, and indeed for any odd multiple of ¼. All these possibilities are potentially present, but the system picks out the one with the largest amplification (growth rate). Since the amplification is initially exponential, the wave with the fastest growth soon dominates all others. As the delay increases, the growth rate forfT = ¾ begins to approach that for fT = ¼, and eventually surpasses it. Then the preferred frequency increases, discontinuously, i.e. another wave begins to dominate. In the range of delays in which this transition occurs, both waves are present, and there is considerable wave mixing. Similar transitions occur as the multiplier goes from three to five, and so on. Each of the two waves dominates in a different region of space. The boundary shifts position as T changes, favoring one wave over another, and thus expanding its region of domination. At the border, the activity can be more or less chaotic. Where this occurs thus depends on the delay, but the location also is random, since it is measured from the point of the initial disturbance, which is itself random. Synchronous activation occurs for different regions in an essentially indeterminate way. This might well be a description of original thought. What remains open, though, is a translation or “decoding” from activity waves to meaning. This is the function of this research.
Studies investigating the development and interruption of inter-regional communication in the brain and nervous system and how that relates to the optimization or efficient/inefficient communication between regions in sensory, motor, and cognitive interactions pre-, during and after interventions and the normal development of these interactions through the lifespan. The natural clinical vehicles for studying such issues include those situations highly associated with functional disconnectivities, a term based on our work in the early 1970’s, that principally include autistic spectrum and other developmental disorders as well as persistent vegetative, minimally conscious and comatose states. The natural consequence of this work in the real world is in neural engineering and rehabilitation for the handicapped. Specific current areas of investigation include: Optimization of dipole source localization in autistic spectrum disorder (examining coherence of inter-hemispheric function); Optimization of auditory function in developmental disabilities; Optimization of visual feature identification in developmental disabilities; Optimization of motor performance in developmental disabilities; Optimization of motor performance in elite athletes; Optimization of recovery of function for plotting the course of treatment over time in developmental disabilities; Optimization in language acquisition in autistic spectrum disorders; Optimization models of economic resource allocation in providing rehabilitation services for children.
Rafael Rodriguez-Rojas (Brain Imaging Group, International Center for Neurological Restoration, Havana, Cuba & The Abdus Salam International Centre for Theoretical Physics, Trieste, Italy), Karla Batista (Brain Imaging Group, International Center for Neurological Restoration, Havana, Cuba), Yasser Iturria (Neuroimaging Department, Cuban Neuroscience Center, La Habana, Cuba), Calixto Machado (Univ. of the Medical Sciences, Univ. of Havana Cuba), Gerry Leisman (Haifa University, Israel), Mauricio Chinchilla (Neurology Department, Hermanos Ameijeiras Hospital, Havana, Cuba), Philip DeFina (Neuroscience, Univ. Medical Sci. of Havana, Univ. Havana), Maylen Carballo (Brain Imaging Group, International Center for Neurological Restoration, Havana, Cuba) and Juan M. Morales (Brain Imaging Group, International Center for Neurological Restoration, Havana, Cuba)
Persistent vegetative states (PVS) and locked-in syndrome (LIS) are well-differentiated disorders of consciousness that can be reached after a localized brain injury in the brainstem. The relations of the lesion topography with the impairment in the whole-brain architecture and functional disconnections are poorly understood. We are examining individuals with both PVS and LIS and age-matched healthy volunteers using diffusion tensor imaging (DTI). Anatomical network is being modeled as a graph whose nodes are represented by 71 brain regions. Inter-region connections were quantified through Anatomical Connection Strength (ACS) and Density (ACD). Complex networks properties such as local and global efficiency and vulnerability were studied. Mass univariate testing was performed at every connection using network based statistic approach. LIS patients’ network show significant differences from controls in the brainstem-thalamus-frontal cortex circuitry, while PVS patients show a widespread disruption of anatomical connectivity in both hemispheres. Patients show a reorganization of network attributes, with decreased global and local efficiency, significantly more pronounced in PVS. Our results suggest that DTI-based network connectivity combined with graph theory is useful to study the long-range effect of confined injuries and the relationship to the degree of consciousness impairment, underlying PVS and LIS.
The project assesses EEG coherence assessment in a group of autistic children, compared to a control group, in three experimental conditions. The autistics demonstrated significant incremental coherence values for all EEG bands and for both hemispheres, compared with controls. Autistics demonstrated significantly higher intra-hemispheric long-range coherence in the left hemisphere compared to control participants. Moreover, autistics did not show significant differences between both hemispheres for the resting control condition. Autistic and control participants demonstrated significantly lower coherence values for the two experimental conditions, cartoon with audio (V-A), and without audio band (VwA), compared to the control condition. No significant differences were found for the control group comparing V-A vs. VwA conditions. Nonetheless, in autistics, the VwA, compared with the V-A condition tended to show lower coherence values in the right hemisphere. Autistics did not show these hemispheric coherence differences in the control condition. We conclude that EEG coherence assessment in the three experimental conditions significantly differentiates autistics from normal control participants, supporting the notion of distinct neural synchronization among different brain areas in autism. In the audio-muted condition autistics demonstrated significantly reduced coherence values in the right hemisphere associated with, we hypothesize, a lack of visual and auditory integration, lateralized to the right hemisphere.
New information about basal ganglia and cerebellar connections with the cerebral cortex has prompted a reevaluation of the role of the basal ganglia in cognition. We know that the relation between the basal ganglia and the cerebral cortical region allow for connections organized into discrete circuits. Rather than serving as a means for widespread cortical areas to gain access to the motor system, these loops reciprocally interconnect a large and diverse set of cerebral cortical areas with the basal ganglia. The properties of neurons within the basal ganglia or cerebellar components of these circuits resemble the properties of neurons within the cortical areas subserved by these loops. For example, neuronal activity within basal ganglia and cerebellar loops with motor areas of the cerebral cortex is highly correlated with parameters of movement, while neuronal activity within basal ganglia and cerebellar loops with areas of the prefrontal cortex is more related to aspects of cognitive function. Thus, individual loops appear to be involved in distinct behavioral functions. Studies of basal ganglia and cerebellar pathology support this conclusion. Damage to the basal ganglia or cerebellar components of circuits with motor areas of cortex leads to motor symptoms, whereas damage of the subcortical components of circuits with non-motor areas of cortex causes higher-order deficits. In this report, we review some of the new anatomical, physiological and behavioral findings that have contributed to a reappraisal of function concerning the basal ganglia and cerebellar loops with the cerebral cortex and apply it in clinical applications to obsessive-compulsive disorder, Tourette’s, and attention-deficit hyperactivity disorder as examples of how compromise at different points in the system may yield similar but different clinical results.
Attention deficit and hyperactivity disorder (ADHD) is the common syndrome affecting 3-20% of children and has become a significant public health problem. In previous researches it was revealed, that electric brain activity increases in anticipation of in frontal areas of children with ADHD as compared with non-ADHD children. The frontal lobes are concerned with the planning and execution of movement. These studies aim to investigate the dynamics of inattention, impulsivity and EEG during training of posture stability in those with ADHD and investigate central and biomechanical mechanisms for their correction.
Exposure to musical training in childhood has been studied extensively as models of neuroplasticity. The long-term training and continued practice of complex bi-manual motor sequences are highly associated with changes in brain structure and cortical motor maps compared with individuals without such training. We know that the anterior corpus callosum, with fibers connecting frontal motor regions and pre-frontal areas coordinating bimanual activity is larger in musicians who started training prior to age seven than in either controls. Additionally, auditory experiences during early postnatal development shape the functional neurology of auditory cortical representation resulting in increased functional areas of the auditory cortex. The developing brain is far more plastic than the adult brain explaining the results that we see in recovery of function after brain damage in childhood, neuronal connections are being continuously remodeled by experience, enrichment, and by performance on specific and complex movements during motor and cognitive learning. New skill acquisition, present to a much greater degree in childhood is highly associated with structural changes in the intra-cortical and subcortical networks in motor skill training. The relationship between music, visual, and spatial training on brain organization and plasticity are being studied with applications for solutions to the rehabilitation of the brain impaired.
Many neurological syndromes are associated with pathology of balance and gait. The use of Computerized Dynamic Posturography is common in the practice of Neurology, yet there are no published guidelines or accepted procedures for its use in a Functional Neurology Application. We are developing a reference guide specific to this technology applied to the testing of human balance, vestibular and balance testing, basic clinical evaluation of balance patients, applied to various clinical populations in particular Traumatic Brain Injured and Cerebral Palsied Children.