Biology subjects

Etemadi, L.

Publications and source records attributed to Etemadi, L..

3 recordsLinked to original sources

bioRxiv2022

Profound impact of hippocampal output on the interpretation of tactile input patterns in SI neurons

Due to continuous state variations in neocortical circuits, individual SI neurons in vivo display a variety of intracellular response types to repeated presentations of the exact same tactile input pattern. The specific intracellular response obtained depends on a time-evolving combination of the specific input with the current neocortical state. To manipulate the internal cortical state, we here used brief electrical stimulation of the output region of the hippocampus, which preceded the delivery of specific tactile afferent input patterns to digit 2 of the anesthetized rat. We find that hippocampal output had a diversified and remarkably strong impact on the specific set of intracellular response types each SI neuron displays to each given tactile input pattern. The findings show that hippocampal output can profoundly impact the state-dependent interpretation of tactile inputs in SI neurons and hence influence their perception, potentially with affective and semantic components.

neuroscience↗

bioRxiv2021

Remote cortical perturbation dynamically changes the network solutions 1 to given tactile inputs in neocortical neurons

The neocortex is a widely interconnected neuronal network. All such networks have a connectivity structure, which limits the possible combinations of neuronal activations across it. In this sense, the network can be said to contain solutions, i.e., for each given external input the cortex may yield a specific combination of neuronal activations/output. If the cortex has a variety of states, a given input could result in a range of possible outputs. There will also be a vast range of outputs that are not possible due to the network structure. Here we use intracellular recordings in SI neurons to show that remote intracortical electrical perturbation can impact such constraints on the responses to given tactile input patterns. Whereas each given tactile input pattern induced a wide set of preferred response states, when combined with cortical perturbation they induced response states that did not otherwise occur. The findings indicate that the physiological network structure can dynamically change as the state of any given cortical region changes, thereby enabling a very rich, multifactorial, perceptual capability.

neuroscience↗

bioRxiv2020

Effects of working memory load and CS-US intervals on delay eyeblink conditioning

BackgroundEyeblink conditioning is used in many different species to study motor learning and make inferences about cerebellar function. However, considerable discrepancies in performance between different species combined with evidence that awareness of stimulus contingencies affects performance indicates that eyeblink conditioning in part reflects activity in non-cerebellar regions. This questions whether eyeblink conditioning can be used as a pure measure of cerebellar function in humans. MethodsHere we explored two ways to reduce non-cerebellar influences on performance in eyeblink conditioning: (1) using a short interstimulus interval, and (2) having participants do working memory tasks during the conditioning. Data were analyzed, and the influence of the interstimulus interval and working memory tasks was assessed using a linear mixed effects model. ResultsOur results show that subjects trained with a short interstimulus interval (150ms and 250ms) produce few conditioned responses after 100 trials. For subjects trained with a longer interstimulus interval (500ms), those who did working memory tasks produced fewer conditioned responses and had a more gradual learning curve - more akin to those reported in the animal literature. ConclusionsOur results suggest that having subjects perform working memory tasks during eyeblink conditioning can be a viable strategy to reduce non-cerebellar interference in the learning.

neuroscience↗