The posterior auditory field is the chief generator of prediction error signals in the auditory cortex

The auditory cortex (AC) encompasses distinct fields subserving partly different aspects of sound processing. One essential function of the AC is the detection of unpredicted sounds, as revealed by differential neural activity to predictable and unpredictable sounds. According to the predictive coding framework, this effect can be explained by repetition suppression and/or prediction error signaling. The present study investigates functional specialization of the rat AC fields in repetition suppression and prediction error by combining a tone frequency oddball paradigm (involving high-probable standard and low-probable deviant tones) with two different control sequences (many-standards and cascade). Tones in the control sequences were comparable to deviant events with respect to neural adaptation but were not violating a regularity. Therefore, a difference in the neural activity between deviant and control tones indicates a prediction error effect, whereas a difference between control and standard tones indicates a repetition suppression effect. Single-unit recordings revealed by far the largest prediction error effects for the posterior auditory field, while the primary auditory cortex, the anterior auditory field, the ventral auditory field, and the suprarhinal auditory field were dominated by repetition suppression effects. Statistically significant repetition suppression effects occurred in all AC fields, whereas prediction error effects were less robust in the primary auditory cortex and the anterior auditory field. Results indicate that the non-lemniscal, posterior auditory field is more engaged in context-dependent processing underlying deviance-detection than the other AC fields, which are more sensitive to stimulus-dependent effects underlying differential degrees of neural adaptation

Cerebellar interpositus nucleus exhibits time-dependent errors and predictive responses

Abstract Learning is a functional state of the brain that should be understood as a continuous process, rather than being restricted to the very moment of its acquisition, storage, or retrieval. The cerebellum operates by comparing predicted states with actual states, learning from errors, and updating its internal representation to minimize errors. In this regard, we studied cerebellar interpositus nucleus (IPn) functional capabilities by recording its unitary activity in behaving rabbits during an associative learning task: the classical conditioning of eyelid responses. We recorded IPn neurons in rabbits during classical eyeblink conditioning using a delay paradigm. We found that IPn neurons reduce error signals across conditioning sessions, simultaneously increasing and transmitting spikes before the onset of the unconditioned stimulus. Thus, IPn neurons generate predictions that optimize in time and shape the conditioned eyeblink response. Our results are consistent with the idea that the cerebellum works under Bayesian rules updating the weights using the previous history

Chronic adult‐onset of growth hormone/IGF‐I hypersecretion improves cognitive functions and LTP and promotes neuronal differentiation in adult rats

[Aim] Besides their metabolic and endocrine functions, the growth hormone (GH) and its mediated factor, the insulin‐like growth factor I (IGF‐I), have been implicated in different brain functions, including neurogenesis. Long‐lasting elevated GH and IGF‐I levels result in non‐reversible somatic, endocrine and metabolic morbidities. However, the subcutaneous implantation of the GH‐secreting (GH‐S) GC cell line in rats leads to the controllable over‐secretion of GH and elevated IGF‐I levels, allowing the experimental study of their short‐term effects on brain functions.[Methods] Adult rats were implanted with GC cells and checked 10 weeks later, when a GH/IGF‐I‐secreting tumour was already formed.[Results] Tumour‐bearing rats acquired different operant conditioning tasks faster and better than controls and tumour‐resected groups. They also presented better retentions of long‐term memories in the passive avoidance test. Experimentally evoked long‐term potentiation (LTP) in the hippocampus was also larger and longer lasting in the tumour bearing than in the other groups. Chronic adult‐onset of GH/IGF‐I hypersecretion caused an acceleration of early progenitors, facilitating a faster neural differentiation, maturation and integration in the dentate gyrus, and increased the complexity of dendritic arbours and spine density of granule neurons.[Conclusion] Thus, adult‐onset hypersecretion of GH/IGF‐I improves neurocognitive functions, long‐term memories, experimental LTP and neural differentiation, migration and maturation.This study was supported by a grant from the Junta de Andalucía (PI‐0302‐2012) to RL‐C and by grants from the Spanish Ministry of Economy and Competitiveness (BFU2014‐56692‐R and BFU2017‐82375‐R) and the Junta de Andalucía (BIO122) to AG and JMD‐G, and grants from the ISCIII‐Subdirección General de Evaluación y Fomento de la Investigación co‐funded with Fondos FEDER (PI16/00175) and the Nicolás Monardes program of the Andalusian Ministry of Health (C‐0015‐2014) to DAC.Peer reviewe

Gu?a r?pidas de consultor?a telef?nica m?dica y de enfermer?a

Gu?a de consulta para o persoal m?dico e de enfermar?a que desenvolve o seu traballo en centros de coordinaci?n telef?nica para a atenci?n ?s urxencias e ?s emerxencias sanitarias. Est? estruturada en 12 cap?tulos nos que describen os principais protocolos de actuaci?n para a asistencia ?s patolox?as m?is com?ns atendidas no ?mbito de urxencias extra hospitalarias.Gu?a de consulta para el personal m?dico y de enfermer?a que desarrolla su trabajo en centros de coordinaci?n telef?nica para la atenci?n a las urgencias y a las emergencias sanitarias. Est? estructurada en 12 cap?tulos en los que describen los principales protocolos de actuaci?n para la asistencia a las patolog?as m?s comunes atendidas en el ?mbito de urgencias extra hospitalarias