Cholinergic Behavior State-Dependent Mechanisms of Neocortical Gain Control: a Neurocomputational Study.

The embodied mammalian brain evolved to adapt to an only partially known and knowable world. The adaptive labeling of the world is critically dependent on the neocortex which in turn is modulated by a range of subcortical systems such as the thalamus, ventral striatum, and the amygdala. A particular case in point is the learning paradigm of classical conditioning where acquired representations of states of the world such as sounds and visual features are associated with predefined discrete behavioral responses such as eye blinks and freezing. Learning progresses in a very specific order, where the animal first identifies the features of the task that are predictive of a motivational state and then forms the association of the current sensory state with a particular action and shapes this action to the specific contingency. This adaptive feature selection has both attentional and memory components, i.e., a behaviorally relevant state must be detected while its representation must be stabilized to allow its interfacing to output systems. Here, we present a computational model of the neocortical systems that underlie this feature detection process and its state-dependent modulation mediated by the amygdala and its downstream target the nucleus basalis of Meynert. In particular, we analyze the role of different populations of inhibitory interneurons in the regulation of cortical activity and their state-dependent gating of sensory signals. In our model, we show that the neuromodulator acetylcholine (ACh), which is in turn under control of the amygdala, plays a distinct role in the dynamics of each population and their associated gating function serving the detection of novel sensory features not captured in the state of the network, facilitating the adjustment of cortical sensory representations and regulating the switching between modes of attention and learning.

Behavioral rehabilitation of the eye closure reflex in senescent rats using a real-time biosignal acquisition system.

In this paper the replacement of a lost learning function of rats through a computer-based real-time recording and feedback system is shown. In an experiment two recording electrodes and one stimulation electrode were implanted in an anesthetized rat. During a classical-conditioning paradigm, which includes tone and airpuff stimulation, biosignals were recorded and the stimulation events detected. A computational model of the cerebellum acquired the association between the stimuli and gave feedback to the brain of the rat using deep brain stimulation in order to close the eyelid of the rat. The study shows that replacement of a lost brain function using a direct bidirectional interface to the brain is realizable and can inspire future research for brain rehabilitation.

Effects of annual influenza vaccination on winter mortality in elderly people with chronic pulmonary disease.

BACKGROUND: Although there is a general agreement for the recommendation of the influenza vaccine to persons with chronic obstructive pulmonary disease (COPD), the magnitude of clinical effectiveness and benefit from the annual vaccination is controversial. We assessed the effects of annual influenza vaccination on winter mortality in older adults with COPD. METHODS: This prospective cohort study included 1298 Spanish community-dwelling individuals aged 65 years or older with a diagnosis of COPD followed from 1 January 2002 to 30 April 2005. The primary outcome was all-cause death during influenza periods (January-April). Multivariable Cox proportional hazard models adjusted by age, sex and comorbidity were used to evaluate vaccine effectiveness. RESULTS: Influenza vaccination was associated with a non-statistically significant 16% reduction in winter mortality among vaccinated COPD patients [unadjusted hazard ratio (HR): 0.84; 95% confidence interval (CI): 0.60-1.17]. Multivariable analysis showed that there was an insignificant trend towards a reduced mortality in the vaccinated group considering overall influenza periods 2002-2005 (adjusted HR: 0.76; 95% CI: 0.52-1.06; p=0.098). We estimated that, in the total COPD population, one death was prevented for every 187 annual vaccinations (95% CI: 62 to infinity). CONCLUSIONS: Our data suggest benefit from the influenza vaccination and support an annual vaccination strategy for elderly COPD patients.