Biology subjects

Seamans, J. K.

Publications and source records attributed to Seamans, J. K..

4 recordsLinked to original sources

bioRxiv2024

Neural basis of cognitive control signals in anterior cingulate cortex during delay discounting

Cognitive control involves allocating cognitive effort according to internal needs and task demands. The anterior cingulate cortex (ACC) is hypothesized to play a central role in this process. We investigated the neural basis of cognitive control in the ACC of rats performing an adjusting-amount delay discounting task, with a 4s or 8s delay between lever choice and reward. A reinforcement learning model indicated that decision making on this task can be guided by either a value tracking strategy, requiring a resource-based form of cognitive control or a delay-lever biased strategy requiring a resistance-based form of cognitive control. This was then tested in vivo by multiple single unit recordings and local field potentials acquired from male rats performing the task. On this task, the behavioral manifestation of resistance-based control is an excessive focus on delayed lever choices which was observed during a substantial portion of 4s but not 8s delay sessions. On a neural level, this was associated with an increase in Theta (6-12Hz) oscillations prior to delay choices which was present exclusively on 4s delay sessions. By contrast, evidence of a resource-based control signal was found in spike trains that closely tracked lever value prior to choice, and was far more prevalent on 8s delay sessions. These data provide candidate neural signatures of resource-based versus resistance-based forms of cognitive control. While mediated by distinct neural mechanisms, either form could be engaged by individual subjects under different task conditions.

neuroscience↗

bioRxiv2023

Reconfiguration of Behavioral Signals in the Anterior Cingulate Cortex based on Emotional State

Behaviours and their execution depend on the context and emotional state in which they are performed. The contextual modulation of behavior likely relies on regions such as the anterior cingulate cortex (ACC) that multiplex information about emotional/autonomic states and behaviours. The objective of the present study was to understand how the representations of behaviors by ACC neurons become modified when performed in different emotional states. A pipeline of machine learning techniques was developed to categorize and classify complex, spontaneous behaviors from video. This pipeline, termed HUB-DT, discovered a range of statistically separable behaviors during a task in which motivationally significant outcomes were delivered in blocks of trials that created 3 unique emotional contexts. HUB-DT was capable of detecting behaviors specific to each emotional context and was able to identify and segregate the portions of a neural signal related to a behaviour and to emotional context. Overall, [~]10x as many neurons responded to behaviors in a contextually dependent versus a fixed manner, highlighting the extreme impact of emotional state on representations of behaviors that were precisely defined based on detailed analyses of limb kinematics. This type of modulation may be a key mechanism that allows the ACC to modify behavioral output based on emotional states and contextual demands.

neuroscience↗

bioRxiv2019

Critical role of de novo LTD in the formation and maintenance of hippocampal CA1 place-cell fields

Synaptic plasticity mechanisms may help shape hippocampal place field representations of novel environments, yet direct evidence for how this occurs is lacking. Using multi-channel recordings in freely moving rats, we demonstrate that novelty exploration results in widespread de novo long-term depression (LTD) at hippocampal CA1 synapses in a pathway-specific manner, while blockade of LTD expression impairs the maintenance of newly formed place fields. This study therefore reveals an unrecognized role for LTD in the formation and maintenance of hippocampal place fields in novel environments.

neuroscience↗

bioRxiv2019

Dynamic changes in Anterior Cingulate Cortex ensembles mark the transition from exploration to exploitation

The ability to acquire knowledge about the value of stimuli or actions factors into simple foraging behaviors as well as complex forms of decision making. The anterior cingulate cortex (ACC) is thought to be involved in these processes, although the manner in which neural representations acquire value is unclear. Here we recorded from ensembles of ACC neurons as rats learned which of 3 levers was rewarded each day through a trial and error process. Action representations remained largely stable during exploration, but there was an abrupt, coordinated and differential change in the representation of rewarded and nonrewarded levers by ACC neurons at the point where the rat realized which lever was rewarded and began to exploit it. Thus, rather than a gradual, incremental process, value learning in ACC can occur in an all-or-none manner and help to initiate strategic shifts in forging behavior.

neuroscience↗