Differences between Dorsal and Ventral Striatum in the Sensitivity of Tonically Active Neurons to Rewarding Events
نویسندگان
چکیده
Within the striatum, cholinergic interneurons, electrophysiologically identified as tonically active neurons (TANs), represent a relatively homogeneous group in terms of their functional properties. They display typical pause in tonic firing in response to rewarding events which are of crucial importance for reinforcement learning. These responses are uniformly distributed throughout the dorsal striatum (i.e., motor and associative striatum), but it is unknown, at least in monkeys, whether differences in the modulation of TAN activity exist in the ventral striatum (i.e., limbic striatum), a region specialized for processing of motivational information. To address this issue, we examined the activity of dorsal and ventral TANs in two monkeys trained on a Pavlovian conditioning task in which a visual stimulus preceded the delivery of liquid reward by a fixed time interval. We found that the proportion of TANs responding to the stimulus predictive of reward did not vary significantly across regions (58%-80%), whereas the fraction of TANs responding to reward was higher in the limbic striatum (100%) compared to the motor (65%) and associative striatum (52%). By examining TAN modulation at the level of both the population and the individual neurons, we showed that the duration of pause responses to the stimulus and reward was longer in the ventral than in the dorsal striatal regions. Also, the magnitude of the pause was greater in ventral than dorsal striatum for the stimulus predictive of reward but not for the reward itself. We found similar region-specific differences in pause response duration to the stimulus when the timing of reward was less predictable (fixed replaced by variable time interval). Regional variations in the duration and magnitude of the pause response were transferred from the stimulus to reward when reward was delivered in the absence of any predictive stimulus. It therefore appears that ventral TANs exhibit stronger responses to rewarding stimuli, compared to dorsal TANs. The high proportion of responsive neurons, combined with particular response features, support the notion that the ventral TAN system can be driven by specific synaptic inputs arising from afferent sources distinct from those targeting the dorsal TAN system.
منابع مشابه
Encoding by synchronization in the primate striatum.
Information is encoded in the nervous system through the discharge and synchronization of single neurons. The striatum, the input stage of the basal ganglia, is divided into three territories: the putamen, the caudate, and the ventral striatum, all of which converge onto the same motor pathway. This parallel organization suggests that there are multiple and competing systems in the basal gangli...
متن کاملDiabetes Mellitus Type1 and Neuronal Degeneration in Ventral and Dorsal Hippocampus
Background and Objectives: Studies have documented the morhplogical, neurochemical and functional difference between the dorsal and ventral zones of hippocampus. The aim of this study was to assess the effects of chronic diabetes mellitus type1 on ventral and dorsal zones of hippocampus. Methods: Experimental diabetes was induced by stereptozotocin at a dose of 60 mg/kg. At the end of 8 wee...
متن کاملPutative Cholinergic Interneurons in the Ventral and Dorsal Regions of the Striatum Have Distinct Roles in a Two Choice Alternative Association Task
The striatum consists of GABAergic projection neurons and various types of interneurons. Despite their relative scarcity, these interneurons play a key role in information processing in the striatum. One such class of interneurons is the cholinergic tonically active neurons (TANs). In the dorsal striatum, TANs are traditionally considered to be responsive to events of motivational significance....
متن کاملEnhance Your Chance with the TANs: Tonically Active Neurons Support Learning in the Ventral Striatum
The striatum is crucial for the correct learning and control of goal-directed behavior and habitual actions. Here in this issue of Neuron, Atallah et al. (2014) show that both reinforcement-based learning and control parameters are reflected in the neural activity of the ventromedial striatum.
متن کاملInfluence of spatial information on responses of tonically active neurons in the monkey striatum.
Previous studies have demonstrated that tonically active neurons (TANs) in the primate striatum play an important role in the detection of rewarding events. However, the influence of the spatial features of stimuli or actions required to obtain reward remains unclear. Here, we examined the activity of TANs in the striatum of monkeys trained to make spatially directed movements elicited by visua...
متن کامل