Prefrontal-hippocampal functional connectivity encodes recognition memory and is impaired in intellectual disability.

Down syndrome (DS) is the most common form of intellectual disability. The cognitive alterations in DS are thought to depend on brain regions critical for learning and memory such as the prefrontal cortex (PFC) and the hippocampus (HPC). Neuroimaging studies suggest that increased brain connectivity correlates with lower intelligence quotients (IQ) in individuals with DS; however, its contribution to cognitive impairment is unresolved. We recorded neural activity in the PFC and HPC of the trisomic Ts65Dn mouse model of DS during quiet wakefulness, natural sleep, and the performance of a memory test. During rest, trisomic mice showed increased theta oscillations and cross-frequency coupling in the PFC and HPC while prefrontal-hippocampal synchronization was strengthened, suggesting hypersynchronous local and cross-regional processing. During sleep, slow waves were reduced, and gamma oscillations amplified in Ts65Dn mice, likely reflecting prolonged light sleep. Moreover, hippocampal sharp-wave ripples were disrupted, which may have further contributed to deficient memory consolidation. Memory performance in euploid mice correlated strongly with functional connectivity measures that indicated a hippocampal control over memory acquisition and retrieval at theta and gamma frequencies, respectively. By contrast, trisomic mice exhibited poor memory abilities and disordered prefrontal-hippocampal functional connectivity. Memory performance and key neurophysiological alterations were rescued after 1 month of chronic administration of a green tea extract containing epigallocatequin-3-gallate (EGCG), which improves executive function in young adults with DS and Ts65Dn mice. Our findings suggest that abnormal prefrontal-hippocampal circuit dynamics are candidate neural mechanisms for memory impairment in DS.

Postnatal environmental enrichment enhances memory through distinct neural mechanisms in healthy and trisomic female mice.

Stimulating lifestyles have powerful effects on cognitive abilities, especially when they are experienced early in life. Cognitive therapies are widely used to improve cognitive impairment due to intellectual disability, aging, and neurodegeneration, however the underlying neural mechanisms are poorly understood. We investigated the neural correlates of memory amelioration produced by postnatal environmental enrichment (EE) in diploid mice and the Ts65Dn mouse model of Down syndrome (trisomy 21). We recorded neural activities in brain structures key for memory processing, the hippocampus and the prefrontal cortex, during rest, sleep and memory performance in mice reared in non-enriched or enriched environments. Enriched wild-type animals exhibited enhanced neural synchrony in the hippocampus across different brain states (increased gamma oscillations, theta-gamma coupling, sleep ripples). Trisomic females showed increased theta and gamma rhythms in the hippocampus and prefrontal cortex across different brain states along with enlarged ripples and disrupted circuit gamma signals that were associated with memory deficits. These pathological activities were attenuated in their trisomic EE-reared peers. Our results suggest distinct neural mechanisms for the generation and rescue of healthy and pathological brain synchrony, respectively, by EE and put forward hippocampal-prefrontal hypersynchrony and miscommunication as major targets underlying the beneficial effects of EE in intellectual disability.

Fear in action: Fear conditioning and alleviation through body movements.

Fear memories enhance survival especially when the memories guide defensive movements to minimize harm. Accordingly, fear memories and body movements have tight relationships in animals: Fear memory acquisition results in adapting reactive defense movements, while training active defense movements reduces fear memory. However, evidence in humans is scarce because their movements are typically suppressed in experiments. Here, we tracked adult participants' body motions while they underwent ecologically valid fear conditioning in a 3D virtual space. First, with body motion tracking, we revealed that distinct spatiotemporal body movement patterns emerge through fear conditioning. Second, subsequent training to actively avoid threats with naturalistic defensive actions led to a long-term (24 h) reduction of physiological and embodied conditioned responses, while extinction or vicarious training only transiently reduced the responses. Together, our results highlight the role of body movements in human fear memory and its intervention.

Serotonin 5-HT1A, 5-HT2A and dopamine D2 receptors strongly influence prefronto-hippocampal neural networks in alert mice: Contribution to the actions of risperidone.

Atypical antipsychotic drugs (APDs) used to treat positive and negative symptoms in schizophrenia block serotonin receptors 5-HT2AR and dopamine receptors D2R and stimulate 5-HT1AR directly or indirectly. However, the exact cellular mechanisms mediating their therapeutic actions remain unresolved. We recorded neural activity in the prefrontal cortex (PFC) and hippocampus (HPC) of freely-moving mice before and after acute administration of 5-HT1AR, 5-HT2AR and D2R selective agonists and antagonists and atypical APD risperidone. We then investigated the contribution of the three receptors to the actions of risperidone on brain activity via statistical modeling and pharmacological reversal (risperidone + 5-HT1AR antagonist WAY-100635, risperidone + 5-HT2A/2CR agonist DOI, risperidone + D2R agonist quinpirole). Risperidone, 5-HT1AR agonism with 8-OH-DPAT, 5-HT2AR antagonism with M100907, and D2R antagonism with haloperidol reduced locomotor activity of mice that correlated with a suppression of neural spiking, power of theta and gamma oscillations in PFC and HPC, and reduction of PFC-HPC theta phase synchronization. By contrast, activation of 5-HT2AR with DOI enhanced high-gamma oscillations in PFC and PFC-HPC high gamma functional connectivity, likely related to its hallucinogenic effects. Together, power changes, regression modeling and pharmacological reversals suggest an important role of 5-HT1AR agonism and 5-HT2AR antagonism in risperidone-induced alterations of delta, beta and gamma oscillations, while D2R antagonism may contribute to risperidone-mediated changes in delta oscillations. This study provides novel insight into the neural mechanisms for widely prescribed psychiatric medication targeting the serotonin and dopamine systems in two regions involved in the pathophysiology of schizophrenia.

Autoplastia Conjuntival en el Pterigium Primario / Conjunctival autoplasty in primarty pterygium

La autoplastia conjuntival (AC) y sus complicaciones posquirurgicas fueron estudiadas en 102 pacientes con pterigium primario durante un periodo de 8 meses. El granuloma conjuntival y la diplopia transitoria fueron las complicaciones encontradas. La frecuencia de recidiva fue del 4,9 por ciento. Como hallazgo observamos el avanzamiento conjuntival hacia la cornea y el edema del injerto. Resultados alentadores deben tenerse en cuenta en el tratamiento del pterigium primario y recidivante

Vitreo en la cámara anterior del ojo como complicación de la cirugía extracapsular de la catarata / Vitreous in the eye's anterior chamber as a complication for cataract extracapsular surgery

Se le estudiaron las compliaciones producidas, así como el redultado de la vitrectomía anterior realizada a un total de 53 ojos en pacientes operados mediante la técnica de extracción extracapsular del cristalino y complicados por ruptura de la cápsula posterior, con pérdida de vítreo, contacto de la hialoides con el endotelio, o bloque pupilar. Se dividieron en 4 grupos según el momento de realizada la cirugía anterior del vítreo. Las complicaciones encontradas incluyen: queratopatía permeabilidad de los vasos del iris, hipertensión ocular, deformidad pupilar, bloqueo pupilar, edema macular quístico y desprendimiento de retina. Los mejores resultados fueron encontrados en el grupo de ojos tratados con vitrectomía inmediata con equipo de vitrectomía; todos tuvieron visión final de 0,5 o mayor y hubo resultados menos favorables en los ojos tratados con vitrectomía tardía (AU)

Autoplastia Conjuntival en el Pterigium Primario / Conjunctival autoplasty in primarty pterygium

La autoplastia conjuntival (AC) y sus complicaciones posquirúrgicas fueron estudiadas en 102 pacientes con pterigium primario durante un período de 8 meses. El granuloma conjuntival y la diplopia transitoria fueron las complicaciones encontradas. La frecuencia de recidiva fue del 4,9 por ciento. Como hallazgo observamos el avanzamiento conjuntival hacia la córnea y el edema del injerto. Resultados alentadores deben tenerse en cuenta en el tratamiento del pterigium primario y recidivante(AU)

Utilidad de la lente de contacto blanda terapéutica en afecciones corneales / Usefulness of the therapeutic soft contact lens in corneal diseases

Se estudiaron 88 pacientes con enfermedades corneales a los que se les indicó lente de contacto blanda terapéutica permasoft. La queratopatía bullosa fue la más frecuente y beneficiada con su uso. La úlcera corneal con hipopion, la neovascularización y la aparición de infiltrados corneales asépticos fueron las complicaciones encontradas, las cuales mejoraron al retirar la lente (AU)