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Naturally log-scaled quantities abound in the nervous system. Distributions of these quantities have non-intuitive properties, which have implications for data analysis and the understanding of neural circuits. Here, we review the log-scaled statistics of neuronal spiking and the relevant analytical probability distributions. Recent work using log-scaling revealed that interspike intervals of forebrain neurons segregate into discrete modes reflecting spiking at different timescales and are each well-approximated by a gamma distribution. Each neuron spends most of the time in an irregular spiking 'ground state' with the longest intervals, which determines the mean firing rate of the neuron. Across the entire neuronal population, firing rates are log-scaled and well approximated by the gamma distribution, with a small number of highly active neurons and an overabundance of low rate neurons (the 'dark matter'). These results are intricately linked to a heterogeneous balanced operating regime, which confers upon neuronal circuits multiple computational advantages and has evolutionarily ancient origins.

Introduction: Surgeons first became interested in Parkinson’s disease in the early part of the 20th century when surgical attempts were made to control the tremor of Parkinson’s disease. The “Golden Age” of surgery for Parkinson’s disease was in the 1950’s and 1960’s when stereotactic frames were available and very precise lesions within the basal ganglia could be accomplished with relative safety. Surgeons in Europe, North America and Asia all developed the field of “Functional and Stereotaxic Neurosurgery”. Patients with tremor, which does not respond to medical management, who are medically stable, are candidates for thalamic deep brain stimulation. The tremor must be disabling and interfere with activities of daily living such as eating, dressing and writing. Material and methods: The pre-operative evaluation of all Parkinsonian patients prior to bilateral subthalamic nucleus (STN) surgery includes neuropsychological testing to rule out dementia and extensive medical workup to be certain that the patients have adequate cardiorespiratory reserves to undergo the stressful period of the multiple surgical procedures. Our protocol, besides the above-mentioned testing, does include pre-operative videotaping of each patient in both the on and the off phase of their medication. We have chosen to use both MRI and CT scans for image guidance for our stereotactic procedures. Results and Discussion: Despite this being a very rigorous surgical endeavor for the patients, the benefit has been quite worth the effort. In our series, 2/3 of the patients would report a very significant benefit while 1/3 have had minor benefit from the deep brain stimulation system for Parkinson’s. Overall, we have seen a reduction in the need for Parkinsonian medications and a dramatic decrease in the incidence of dyskinesias in the patients who had them pre-operatively. After this initial programming period of 4-6 weeks, most patients reach a relative plateau with a lower dose of medicine and improved level of function. Gait has improved in almost all of the patients. There are two basic types of complications; those associated with surgery and those associated with stimulation itself. The surgical complication rate in our hands mirrors that of the existing literature. Conclusion: Deep brain stimulation is technically challenging but offers a significant potential to improve the quality of life for patients with Parkinson’s disease or disabling tremor.

We report two cases and review the literature concerning the importance of early magnetic resonance imaging (MRI) of the brain as a guide for the early diagnosis and treatment of acute disseminated encephalomyelitis (ADEM). A nonspecific term, ADEM refers to an acute disease that is postinfectious, parainfectious, postvaccinal, or of an unknown precipitating factor. Often when there is clinical suspicion of ADEM, MRI is not done before significant morbidity and mortality occur, despite the existence of adequate treatments. Primary care physicians should be aware of the importance of early MRI in ADEM.

Thalamic gating of sensory inputs to the cortex varies with behavioral conditions, such as sleep-wake cycles, or with different stages of anesthesia. Behavioral conditions in turn are accompanied by stereotypic spectral content of the EEG. In the rodent somatosensory system, the receptive field size of the ventral posteromedial thalamic nucleus (VPM) shrinks when anesthesia is deepened. Here we examined whether evoked thalamic responses are correlated with global EEG activity on a fine time scale of a few seconds. Trial-by-trial analysis of responses of VPM cells to whisker stimulation in lightly anesthetized rats indicated that increased EEG power in the delta band (1-4 Hz) was accompanied by a small, but highly significant, reduction in spontaneous and evoked thalamic firing. The opposite effect was found for the gamma EEG band (30-50 Hz). These significant correlations were not accompanied by an apparent change in the size of the receptive fields and were not EEG phase-related. The correlation between EEG and firing rate was observed only in neurons that responded to multiple whiskers and was higher for the non-principal whiskers. Importantly, the contributions of the two EEG bands to the modulation of VPM responses were to a large extent independent of each other. Our findings suggest that information conveyed by different whiskers can be rapidly modulated according to the global brain activity.

The aim of this study was to completely review the literature on cognitive and mood changes resulting from deep brain stimulation (DBS), and to examine the factors that might lead to these changes. DBS has been shown to improve motor symptoms in many movement disorders. Despite the widespread use of this technique, there are relatively few well controlled studies describing the potential cognitive, mood and behavioral consequences that may result from DBS. Additionally, the factors that may influence these changes have not been carefully studied.A complete survey of the articles exploring the effects of DBS on mood and cognition was performed. Each study identified was examined and categories of factors that may have influenced mood and cognition were noted. These factors included surgical target, number of patients studied, whether procedures were unilateral or bilateral, average age of patients, diagnosis, condition of the DBS during the study (on or off), pre-operative screening tests (e.g., dementia rating scale, mini mental state exam), and changes on mood and cognitive tests (categorized as no change, improved, or worsened). Studies were divided into evidence-based categories.There are many mood and cognitive changes that may result from DBS. Due to methodological limitations of existing studies there are important unanswered questions about cognitive and mood changes resulting from this type of surgery. The predominant amount of data regarding changes in mood and cognition with DBS is level 3 or case based evidence.There exists a paucity of well-controlled studies addressing the mood and cognitive changes that result from DBS. Carefully performed prospective studies may help us to understand the effects of DBS on mood and cognition.