http://www.40hz.net/engel_2010_curr_opin.pdf

Beta-band oscillations--signalling the status quo?

Deficits in daytime performance due to sleep loss are experienced universally and associated with a significant social, financial, and human cost. Microsleeps, sleep attacks, and lapses in cognition increase with sleep loss as a function of state instability. Sleep deprivation studies repeatedly show a variable (negative) impact on mood, cognitive performance, and motor function due to an increasing sleep propensity and destabilization of the wake state. Specific neurocognitive domains including executive attention, working memory, and divergent higher cognitive functions are particularly vulnerable to sleep loss. In humans, functional metabolic and neurophysiological studies demonstrate that neural systems involved in executive function (i.e., prefrontal cortex) are more susceptible to sleep deprivation in some individuals than others. Recent chronic partial sleep deprivation experiments, which more closely replicate sleep loss in society, demonstrate that profound neurocognitive deficits accumulate over time in the face of subjective adaptation to the sensation of sleepiness. Sleep deprivation associated with disease-related sleep fragmentation (i.e., sleep apnea and restless legs syndrome) also results in neurocognitive performance decrements similar to those seen in sleep restriction studies. Performance deficits associated with sleep disorders are often viewed as a simple function of disease severity; however, recent experiments suggest that individual vulnerability to sleep loss may play a more critical role than previously thought.

/pdf/neurocognitive-consequences-of-sleep-deprivation-hg8oxdvlng.pdf

Neurocognitive Consequences of Sleep Deprivation

In this review, we consider the potential functional role of beta-band oscillations, which at present is not yet well understood. We discuss evidence from recent studies on top-down mechanisms involved in cognitive processing, on the motor system and on the pathophysiology of movement disorders that suggest a unifying hypothesis: beta-band activity seems related to the maintenance of the current sensorimotor or cognitive state. We hypothesize that beta oscillations and/or coupling in the beta-band are expressed more strongly if the maintenance of the status quo is intended or predicted, than if a change is expected. Moreover, we suggest that pathological enhancement of beta-band activity is likely to result in an abnormal persistence of the status quo and a deterioration of flexible behavioural and cognitive control.

Background In many patients with idiopathic Parkinson's disease, treatment with levodopa is complicated by fluctuations between an “off” period (also referred to as “off medication”), when the medication is not working and the motor symptoms of parkinsonism are present, and an “on” period, when the medication is causing improved mobility (also referred to as “on medication”), often accompanied by debilitating dyskinesias. In animal models of Parkinson's disease, there is overactivity in the subthalamic nucleus, and electrical stimulation of the subthalamic nucleus improves parkinsonism. We therefore sought to determine the efficacy and safety of electrical stimulation of the subthalamic nucleus in patients with Parkinson's disease. Methods We studied 24 patients with idiopathic Parkinson's disease in whom electrodes were implanted bilaterally in the subthalamic nucleus under stereotactic guidance with imaging and electrophysiologic testing of the location. Twenty were followed for at least 12 months. Clin...

https://www.nejm.org/doi/pdf/10.1056/NEJM199810153391603

Electrical Stimulation of the Subthalamic Nucleus in Advanced Parkinson's Disease

Researchers have wondered how the brain creates emotions since the early days of psychological science. With a surge of studies in affective neuroscience in recent decades, scientists are poised to answer this question. In this target article, we present a meta-analytic summary of the neuroimaging literature on human emotion. We compare the locationist approach (i.e., the hypothesis that discrete emotion categories consistently and specifically correspond to distinct brain regions) with the psychological constructionist approach (i.e., the hypothesis that discrete emotion categories are constructed of more general brain networks not specific to those categories) to better understand the brain basis of emotion. We review both locationist and psychological constructionist hypotheses of brain-emotion correspondence and report meta-analytic findings bearing on these hypotheses. Overall, we found little evidence that discrete emotion categories can be consistently and specifically localized to distinct brain regions. Instead, we found evidence that is consistent with a psychological constructionist approach to the mind: A set of interacting brain regions commonly involved in basic psychological operations of both an emotional and non-emotional nature are active during emotion experience and perception across a range of discrete emotion categories.

/pdf/the-brain-basis-of-emotion-a-meta-analytic-review-32zzrbb78z.pdf

The brain basis of emotion: A meta-analytic review

Long-term suppression of tremor by chronic stimulation of the ventral intermediate thalamic nucleus

Effect on parkinsonian signs and symptoms of bilateral subthalamic nucleus stimulation

In animal models of Parkinson''s disease (PD), it is postulated that the excessive output from the subthalamic nucleus (STN) plays a critical role Selective lesions or high frequency electrical stimulation of the STN can alleviate parkinsonian symptoms in MPTP-treated monkeys We decided to carry out STN stimulation in patients suffering from severe akinetic forms of PD After approval of the institutional ethical committee, we operated on a parkinsonian patient aged 51, suffering for 8 years from a strongly disabling akinetorigid form of PD, complicated by an on-off effect (Hœhn and Yahr stage 5 in the worst-off motor phase) Stereotactic surgery was done on one side under local anesthesia The theoretical target was chosen according to stereotactic atlases, based on ventriculographic landmarks such as anterior and posterior commissures (AC and PC) The final position of the chronic electrodes was optimized using electrophysiological recording and stimulation along with clinical assessment and surface EMG of agonist and antagonist muscles of the examined limbs A spontaneous increase in neuronal activity was recorded in an area located 2–4 mm under the level of the intercommissural plane, 10 mm from the midline, at middistance between AC and PC Within the same place, a 130-Hz stimulation induced acute and reversible akinesia alleviation mainly on the contralateral limbs, comparable to that obtained with dopaminergic drugs No dyskinesia, such as hemiballism, was induced by introduction of electrodes or by stimulation Then a long-term quadripolar DBS Medtronic electrode was inserted in this area Studies of the effects of chronic stimulation were extensively performed to determine the best spatiotemporal and electrical stimulation variables Then, 3 weeks after implantation, the electrodes were connected to implantable programmable Medtronic Itrel II stimulators A second patient has been operated since that time with excellent results so far Effects of chronic unilateral and then bilateral stimulation are being tested Mechanisms of stimulation which can induce similar effects to destruction of the same structure could be based on neuronal membrane blockade or on neural network jamming Nevertheless, the interest of stimulation versus neural grafts must be discussed in patients with highly disabling forms of PD

Acute and long-term effects of subthalamic nucleus stimulation in Parkinson's disease.

Impairment of cognitive executive functions previously has been suspected to occur in association with sleep apnea syndrome (SAS), as suggested by some neuropsychological studies. However, such functions have not been assessed directly. In the present study, 17 patients with SAS were evaluated with various focused frontal lobe-related tests in comparison with 17 normal controls. Such tasks explored attention, short-term memory spans, learning abilities, planning and programming capacities, categorizing activities and verbal fluency. Patients were found to have a significantly decreased ability to initiate new mental processes and to inhibit automatic ones, in conjunction with a tendency for preservative errors. They were also affected with deficits of verbal and visual learning abilities and had reduced memory spans. Such defects were further evaluated via logistic regression against two criteria of the severity of the disease: the number of apneas and hypopneas per hour of sleep and the level of nocturnal hypoxemia. Memory deficits were rather related to the former, whereas typical frontal lobe-related abnormalities seemed rather consistent with the latter. These findings are discussed in light of data from the literature concerning cognitive impairments described for patients with isolated daytime sleepiness versus hypoxemia, as illustrated in other pathological or physiological circumstances.

/pdf/deficits-of-cognitive-executive-functions-in-patients-with-1mzpe4fmwc.pdf

Perret J

Papers

Long-term suppression of tremor by chronic stimulation of the ventral intermediate thalamic nucleus

Effect on parkinsonian signs and symptoms of bilateral subthalamic nucleus stimulation

Acute and long-term effects of subthalamic nucleus stimulation in Parkinson's disease.

Deficits of cognitive executive functions in patients with sleep apnea syndrome.

Effects of the stimulation of the subthalamic nucleus in Parkinson disease