Biology subjects

Petersson, P.

Publications and source records attributed to Petersson, P..

3 recordsLinked to original sources

bioRxiv2026

Rapid experience-dependent tuning of spinal and transcortical stretch reflexes supports goal-directed movement

The short-latency stretch reflex (SLR) is the fastest sensorimotor response in human limbs. The spinal SLR is traditionally viewed as automatic and resistant to rapid plasticity, while adaptive feedback is often attributed to transcortical mechanisms underlying the long-latency reflex. Using high-density surface electromyography (64-channel arrays) from the pectoralis major and posterior deltoid during an instructed-delay reaching task, we probed reflex gains with brief perturbations delivered during action preparation. Pre-perturbation muscle activity showed no systematic goal-directed change. After task familiarization and with sufficient preparation time, SLR gains decreased progressively (logarithmically) with experience when the planned movement was expected to stretch the homonymous muscle. This tuning occurred both with and without agonist muscle pre-loading and predicted the observed improvements in reaching performance. Early transcortical responses showed comparable tuning across load conditions. Our study shows that spinal feedback circuits can progressively adapt within a single session to support the performance of goal-directed movements. HighlightsO_LIThe short-latency stretch reflex adapts rapidly with experience in planned reaching C_LIO_LISpinal reflex tuning occurs with and without agonist muscle pre-loading C_LIO_LIReflex tuning evolves logarithmically and predicts reaching performance C_LIO_LIEarly transcortical reflex gains show comparable experience-dependent tuning C_LI

neuroscience↗

bioRxiv2024

Aberrant Neuronal Synchronization Associated with Cognitive Deficits in a Rodent Model of Childhood Cranial Irradiation

Cranial radiation can be a life-saving intervention in pediatric brain cancer therapy but often results in debilitating cognitive decline. To clarify the underlying mechanisms of these side-effects we have here recorded neurophysiological activity in distributed brain networks involved in decision-making and memory functions in adult rats exposed to cranial irradiation on postnatal day 21. Multi-structure local field potential (LFP) recordings revealed decreased power in irradiated animals in the 4-9 Hz frequency band. Additionally, a distinct slowing of the oscillatory activity was observed preceding erroneous choice in a decision-making task. Moreover, irradiated rats showed reduced dynamics and a fragmented pattern of inter-structural coherence across different phases of the task. Our results suggest that the cognitive deficits and reduced processing speed following irradiation of the juvenile brain arise as a consequence of changes in long-range functional connectivity, including thalamocortical circuits, causing abnormally slow and spatially fractionated patterns of coordinating LFP activity.

neuroscience↗

bioRxiv2022

Classic and dissociative psychedelics induce similar hyper-synchronous states in the cognitive-limbic cortex-basal ganglia system

The neurophysiological mechanisms behind the profound changes in perception and cognition induced by psychedelic drugs are not well understood. To identify neuronal activity specific to the psychedelic state, we here investigated the effects of classic psychedelics (LSD, DOI) and dissociative psychedelics (ketamine, PCP) on neuronal firing rates and local field potentials in several brain structures involved in cognitive processing in freely moving rats. The classic psychedelics had a net inhibitory effect on firing rates of putative interneurons and principal cells in all recorded regions. The dissociative psychedelics had a similar inhibitory effect on principal cells, but an opposite excitatory effect on interneurons in most regions. However, the inhibitory effect on principal cells was not specific to the psychedelic state, as similar inhibition occurred with a non-psychedelic psychotropic control (amphetamine). In contrast, both types of psychedelics dramatically increased the prevalence of high-frequency oscillations (HFOs) in local field potentials, while the non-psychedelic control did not. Further analysis revealed strong HFO phase locking between structures and very small phase differences corresponding to <1 ms delays. Such standing-wave behavior suggests local generation of HFOs in multiple regions and weak, fast coupling between structures. The observed HFO hypersynchrony is likely to have major effects on processes that rely on integration of information across neuronal systems, and it might be an important mechanism behind the changes in perception and cognition during psychedelic drug use. Potentially, similar mechanisms could induce hallucinations and delusions in psychotic disorders and would constitute promising targets for new antipsychotic treatments.

neuroscience↗