Long-term modification of cortical synapses improves sensory perception

Synapses and receptive fields of the cerebral cortex are plastic. However, changes to specific inputs must be coordinated within neural networks to ensure that excitability and feature selectivity are appropriately configured for perception of the sensory environment. Long-lasting enhancements and decrements to rat primary auditory cortical excitatory synaptic strength were induced by pairing acoustic stimuli with activation of the nucleus basalis neuromodulatory system. Here we report that these synaptic modifications were approximately balanced across individual receptive fields, conserving mean excitation while reducing overall response variability. Decreased response variability should increase detection and recognition of near-threshold or previously imperceptible stimuli, as we found in behaving animals. Thus, modification of cortical inputs leads to wide-scale synaptic changes, which are related to improved sensory perception and enhanced behavioral performance

MODIFICĂRI ÎN CONECTIVITATEA FUNCȚIONALĂ A STĂRII DE REPAUS ÎNTR-UN STUDIU FOLOSIND STIMULAREA NATURALISTICĂ

Naturalistic stimulation has had increasing influence on cognitive neuroscience in the last decade. Several studies have used naturalistic stimulation to investigate the connectivity dynamics under pathological condition or in healthy children for studying the developing brain. However, little is known about the connectivity changes during watching a movie in healthy, adult population. Our aim is to delineate the potential dynamic connectivity pattern of the healthy, mature brain during naturalistic movie watching compared to complete rest. In an observational case series, eleven healthy adult volunteers with no history of psychiatric or neurological illness underwent two magnetic resonance echo-planar imaging acquisitions. During the first acquisition they were asked to rest with their eyes closed and during the subsequent acquisition they watched a movie clip with slow human body movements. The Independent Component Analysis provided neural components which were further submitted to intra- and inter-network analyses. We found significantly increased intra-network connectivity during movie watching for the extrastriate visual and for the posterior visual networks. The inter-network analysis showed that for the extravisual and primary visual pair, the connectivity was lower during movie watching compared to rest condition. We also found significant uncoupling between the anterior Default Mode Network and the secondary somatosensory network during movie watching. These findings suggest greater visual network segregation during movie watching in order to support processing of complex stimuli. The decoupling of the secondary somatosensory network from the anterior Default Mode Network during movie watching suggest a somatosensory function segregation and its important role in processing information from observing the naturalistic movements of others. Brain imaging measures of major brain networks can contribute to early identification of risk for common psychiatric disorders hence facilitating preventive therapy.     Keywords: naturalistic stimulation , rest, conectivityStimularea naturalistică a avut o influență crescândă asupra neuroștiințelor cognitive în ultimul deceniu. Mai multe studii au folosit stimularea naturalistică pentru a investiga dinamica conectivității în condiții patologice sau la copiii sănătoși pentru studierea creierului în curs de dezvoltare. Cu toate acestea, se știe puțin despre schimbările de conectivitate în timpul vizionării unui film într-o populație adultă sănătoasă. Scopul nostru este de a delimita tiparul potențial de conectivitate dinamică a creierului sănătos și matur în timpul vizionării de filme ȋn mod natural, comparativ cu starea de repaus completă. Într-un studiu observaţional de gen serie de cazuri, unsprezece voluntari adulți sănătoși, fără antecedente de boli psihiatrice sau neurologice, au fost expuşi la două achiziții de imagistică eco-planară prin rezonanță magnetică. În timpul primei achiziții li s-a cerut să stea relaxaţi cu ochii închiși, iar în timpul achiziției ulterioare au urmărit un clip cu mișcări lente ale corpului uman. Analiza componentelor independente a furnizat componente neuronale care au fost ulterior supuse analizelor intra și inter-rețea. Am constatat o creștere semnificativă a conectivității intra-rețea în timpul vizionării filmelor pentru rețelele vizuale extrastriate și pentru rețelele vizuale posterioare. Analiza inter-rețea a arătat că, pentru perechea vizuală extrastriată și primară, conectivitatea a fost mai mică în timpul vizionării filmului comparativ cu starea de repaus. De asemenea, am constatat o decuplare semnificativă între nodul anterior al rețelei Default mode și rețeaua somatosenzorială secundară în timpul vizionării filmului. Aceste descoperiri sugerează o segregare vizuală mai mare a rețelei în timpul vizionării de filme, pentru a sprijini procesarea stimulilor complecşi. Decuplarea rețelei somatosenzoriale secundare de rețeaua Default mode anterioară în timpul vizionării filmului sugerează o segregare a funcției somatosenzoriale și rolul său important în procesarea informațiilor prin observarea mișcărilor naturale ale altor persoane. Investigarea imagistică a rețelelor majore ale creierului poate contribui la identificarea timpurie a riscului dezvoltării de tulburări psihiatrice, facilitând astfel prevenţia.   Cuvinte cheie: stimulare naturalistică, repaus, conectivitat

Role-play regulates positive emotions and prosocial attitudes

Role play is one of the core creative processes in theatrical performance. Play leads to positive emotions in both children and adults. Role-play, a distinctive type of play is used in several types of therapeutic interventions to increase social competence as well as for other benefits. The highly individualized use of role-play in psychotherapy, drama therapy and psychodrama is effective but not generalizable. In the present study we developed a standardized controlled procedure to promote role-play in 38 participants, and we monitored its impact on affect, anxiety, prosocial attitudes, and salivary oxytocin dynamics. Compared to the control condition where participants participated as selves, role-play significantly increased perceived levels of positive affect and prosocial attitudes and decreased self-reported levels of anxiety. Basal salivary oxytocin levels predicted gains in positive affect following the role-play procedure. Our study points to standardized role-play as a mean to reduce anxiety, and to increase sociability and positive affect. Possible mechanisms of how role-play induces the observed changes in affect and attitudes are discussed

Spike-timing-dependent ensemble encoding by non-classically responsive cortical neurons.

Neurons recorded in behaving animals often do not discernibly respond to sensory input and are not overtly task-modulated. These non-classically responsive neurons are difficult to interpret and are typically neglected from analysis, confounding attempts to connect neural activity to perception and behavior. Here, we describe a trial-by-trial, spike-timing-based algorithm to reveal the coding capacities of these neurons in auditory and frontal cortex of behaving rats. Classically responsive and non-classically responsive cells contained significant information about sensory stimuli and behavioral decisions. Stimulus category was more accurately represented in frontal cortex than auditory cortex, via ensembles of non-classically responsive cells coordinating the behavioral meaning of spike timings on correct but not error trials. This unbiased approach allows the contribution of all recorded neurons - particularly those without obvious task-related, trial-averaged firing rate modulation - to be assessed for behavioral relevance on single trials

Long-term modification of cortical synapses improves sensory perception.

Synapses and receptive fields of the cerebral cortex are plastic. However, changes to specific inputs must be coordinated within neural networks to ensure that excitability and feature selectivity are appropriately configured for perception of the sensory environment. We induced long-lasting enhancements and decrements to excitatory synaptic strength in rat primary auditory cortex by pairing acoustic stimuli with activation of the nucleus basalis neuromodulatory system. Here we report that these synaptic modifications were approximately balanced across individual receptive fields, conserving mean excitation while reducing overall response variability. Decreased response variability should increase detection and recognition of near-threshold or previously imperceptible stimuli. We confirmed both of these hypotheses in behaving animals. Thus, modification of cortical inputs leads to wide-scale synaptic changes, which are related to improved sensory perception and enhanced behavioral performance