Separate groups of dopamine neurons innervate caudate head and tail encoding flexible and stable value memories
Dopamine neurons are thought to be critical for reward value-based learning by modifying synaptic transmissions in the striatum. Yet, different regions of the striatum seem to guide different kinds of learning. Do dopamine neurons contribute to the regional differences of the striatum in learning? A...
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doaj-08ef28fd76b048dc94101336e3b9f85f2020-11-24T22:49:56ZengFrontiers Media S.A.Frontiers in Neuroanatomy1662-51292014-10-01810.3389/fnana.2014.00120117710Separate groups of dopamine neurons innervate caudate head and tail encoding flexible and stable value memoriesHyoung F Kim0Ali eGhazizadeh1Okihide eHikosaka2Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of HealthLaboratory of Sensorimotor Research, National Eye Institute, National Institutes of HealthLaboratory of Sensorimotor Research, National Eye Institute, National Institutes of HealthDopamine neurons are thought to be critical for reward value-based learning by modifying synaptic transmissions in the striatum. Yet, different regions of the striatum seem to guide different kinds of learning. Do dopamine neurons contribute to the regional differences of the striatum in learning? As a first step to answer this question, we examined whether the head and tail of the caudate nucleus of the monkey (Macaca mulatta) receive inputs from the same or different dopamine neurons. We chose these caudate regions because we previously showed that caudate head neurons learn values of visual objects quickly and flexibly, whereas caudate tail neurons learn object values slowly but retain them stably. Here we confirmed the functional difference by recording single neuronal activity while the monkey performed the flexible and stable value tasks, and then injected retrograde tracers in the functional domains of caudate head and tail. The projecting dopaminergic neurons were identified using tyrosine hydroxylase immunohistochemistry. We found that two groups of dopamine neurons in the substantia nigra pars compacta project largely separately to the caudate head and tail. These groups of dopamine neurons were mostly separated topographically: head-projecting neurons were located in the rostral-ventral-medial region, while tail-projecting neurons were located in the caudal-dorsal-lateral regions of the substantia nigra. Furthermore, they showed different morphological features: tail-projecting neurons were larger and less circular than head-projecting neurons. Our data raise the possibility that different groups of dopamine neurons selectively guide learning of flexible (short-term) and stable (long-term) memories of object values.http://journal.frontiersin.org/Journal/10.3389/fnana.2014.00120/fullmacaque monkeymicrocircuitDopamine NeuronNigrostriatal pathwaysubstantia nigra pars compactaobject value learning |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Hyoung F Kim Ali eGhazizadeh Okihide eHikosaka |
spellingShingle |
Hyoung F Kim Ali eGhazizadeh Okihide eHikosaka Separate groups of dopamine neurons innervate caudate head and tail encoding flexible and stable value memories Frontiers in Neuroanatomy macaque monkey microcircuit Dopamine Neuron Nigrostriatal pathway substantia nigra pars compacta object value learning |
author_facet |
Hyoung F Kim Ali eGhazizadeh Okihide eHikosaka |
author_sort |
Hyoung F Kim |
title |
Separate groups of dopamine neurons innervate caudate head and tail encoding flexible and stable value memories |
title_short |
Separate groups of dopamine neurons innervate caudate head and tail encoding flexible and stable value memories |
title_full |
Separate groups of dopamine neurons innervate caudate head and tail encoding flexible and stable value memories |
title_fullStr |
Separate groups of dopamine neurons innervate caudate head and tail encoding flexible and stable value memories |
title_full_unstemmed |
Separate groups of dopamine neurons innervate caudate head and tail encoding flexible and stable value memories |
title_sort |
separate groups of dopamine neurons innervate caudate head and tail encoding flexible and stable value memories |
publisher |
Frontiers Media S.A. |
series |
Frontiers in Neuroanatomy |
issn |
1662-5129 |
publishDate |
2014-10-01 |
description |
Dopamine neurons are thought to be critical for reward value-based learning by modifying synaptic transmissions in the striatum. Yet, different regions of the striatum seem to guide different kinds of learning. Do dopamine neurons contribute to the regional differences of the striatum in learning? As a first step to answer this question, we examined whether the head and tail of the caudate nucleus of the monkey (Macaca mulatta) receive inputs from the same or different dopamine neurons. We chose these caudate regions because we previously showed that caudate head neurons learn values of visual objects quickly and flexibly, whereas caudate tail neurons learn object values slowly but retain them stably. Here we confirmed the functional difference by recording single neuronal activity while the monkey performed the flexible and stable value tasks, and then injected retrograde tracers in the functional domains of caudate head and tail. The projecting dopaminergic neurons were identified using tyrosine hydroxylase immunohistochemistry. We found that two groups of dopamine neurons in the substantia nigra pars compacta project largely separately to the caudate head and tail. These groups of dopamine neurons were mostly separated topographically: head-projecting neurons were located in the rostral-ventral-medial region, while tail-projecting neurons were located in the caudal-dorsal-lateral regions of the substantia nigra. Furthermore, they showed different morphological features: tail-projecting neurons were larger and less circular than head-projecting neurons. Our data raise the possibility that different groups of dopamine neurons selectively guide learning of flexible (short-term) and stable (long-term) memories of object values. |
topic |
macaque monkey microcircuit Dopamine Neuron Nigrostriatal pathway substantia nigra pars compacta object value learning |
url |
http://journal.frontiersin.org/Journal/10.3389/fnana.2014.00120/full |
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