The Anatomical and Functional Heterogeneity of the Mediodorsal Thalamus

Georgescu, Ioana Antoaneta; Popa, Daniela; Zăgrean, Leon

doi:10.3390/brainsci10090624

Cited by 39 publications

(29 citation statements)

References 120 publications

(197 reference statements)

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“…Using tetrode recording in free-moving mice, Lee et al (2011) showed that the tonic firing frequency of MD neurons positively correlates with the extent of fear extinction. In addition, enhancing tonic firing of MD neurons facilitated fear extinction, whereas burst-evoking stimulation suppressed extinction, indicating that distinct firing modes of MD neurons might bidirectionally modulate salience of fear-associated cue ( Lee et al, 2011 ; Georgescu et al, 2020 ).…”

Section: Connectivity Profiles Of Thalamic Nucleimentioning

confidence: 98%

“…Anatomically, the MD receives modulatory input from the midbrain and brainstem and forms a reciprocal connection with the frontal cortex ( Russchen et al, 1987 ; Mitchell, 2015 ; Collins et al, 2018 ). Single MD neurons receive convergence of small cortical inputs and project to multiple cortices across multiple layers ( Rubio-Garrido et al, 2009 ; Kuramoto et al, 2017 ; Georgescu et al, 2020 ). Schmitt et al (2017) proposed that the MD sustains rule representations in the PFC.…”

Section: Connectivity Profiles Of Thalamic Nucleimentioning

confidence: 99%

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The Contribution of Thalamic Nuclei in Salience Processing

Zhou

Zhu

Hou

et al. 2021

Front. Behav. Neurosci.

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The brain continuously receives diverse information about the external environment and changes in the homeostatic state. The attribution of salience determines which stimuli capture attention and, therefore, plays an essential role in regulating emotions and guiding behaviors. Although the thalamus is included in the salience network, the neural mechanism of how the thalamus contributes to salience processing remains elusive. In this mini-review, we will focus on recent advances in understanding the specific roles of distinct thalamic nuclei in salience processing. We will summarize the functional connections between thalamus nuclei and other key nodes in the salience network. We will highlight the convergence of neural circuits involved in reward and pain processing, arousal, and attention control in thalamic structures. We will discuss how thalamic activities represent salience information in associative learning and how thalamic neurons modulate adaptive behaviors. Lastly, we will review recent studies which investigate the contribution of thalamic dysfunction to aberrant salience processing in neuropsychiatric disorders, such as drug addiction, posttraumatic stress disorder (PTSD), and schizophrenia. Based on emerging evidence from both human and rodent research, we propose that the thalamus, different from previous studies that as an information relay, has a broader role in coordinating the cognitive process and regulating emotions.

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Section: Connectivity Profiles Of Thalamic Nucleimentioning

confidence: 98%

Section: Connectivity Profiles Of Thalamic Nucleimentioning

confidence: 99%

The Contribution of Thalamic Nuclei in Salience Processing

Zhou

Zhu

Hou

et al. 2021

Front. Behav. Neurosci.

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“…However, feedback projections from the PFC to the MD appear to mediate cognitive performance (Bolkan et al, 2017), and the MD may very well play a more active, continuous role than this view would imply. Furthermore, poly-synaptic feedback loops from the PFC to the striatum could also play a role, as the basal ganglia innervate the MD (Georgescu et al, 2020). Disconnection designs do not provide sufficient selectivity to dissociate these possibilities.…”

Section: Discussionmentioning

confidence: 99%

“…One promising candidate region is the mediodorsal nucleus (MD) of the thalamus. Neuroanatomically, the MD shares dense, reciprocal projections with the PFC across species (Alcaraz et al, 2016;Georgescu et al, 2020;Ray & Price, 1993). Functionally, the MD plays a role in cognitive functions (Markowitsch, 1982;Peräkylä et al, 2017), although finding a robust, cross-species behavioral assay to test its role in cognition has been difficult (Brito et al, 1982;Mitchell & Chakraborty, 2013).…”

Section: Introductionmentioning

confidence: 99%

Communication between the mediodorsal thalamus and prelimbic cortex regulates timing performance in rats

Cremers

et al. 2021

Preprint

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Predicting when future events will occur and adjusting behavior accordingly is critical to adaptive behavior. Despite this, little is known about the brain networks that encode time and how this ultimately impacts decision-making. One established finding is that the prefrontal cortex (PFC) and its non-human analogues (e.g., the rodent prelimbic cortex; PL) mediate timing. This provides a starting point for exploring the networks that support temporal processing by identifying areas that interact with the PFC during timing tasks. For example, substantial work has explored the role of frontostriatal circuits in timing. However, other areas are undoubtedly involved. The mediodorsal nucleus of the thalamus (MD) is an excellent candidate region. It shares dense, reciprocal connections with PFC-areas in both humans and non-human species and is implicated in cognition. However, causal data implicating MD-PFC interactions in cognition broadly is still sparse, and their role in timing specifically is currently unknown. To address this, we trained male rats on a time-based, decision-making task referred to as the 'peak-interval' procedure. During the task, presentation of a cue instructed the rats to respond after a specific interval of time elapsed (e.g., tone-8 seconds). We incorporated two cues; each requiring a response after a distinct time-interval (e.g., tone-8 seconds / light-16 seconds). We tested the effects of either reversibly inactivating the MD or PL individually or functionally disconnecting them on performance. All manipulations caused a comparable timing deficit. Specifically, responses showed little organization in time, as if primarily guided by motivational systems. These data expand our understanding of the networks that support timing and suggest that MD-PL interactions specifically are a core component. More broadly, our results suggest that timing tasks provide a reliable assay for characterizing the role of MD-PL interactions in cognition using rodents, which has been difficult to establish in the past.

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“…This effect might occur due to the failure of several structures, such as the motor cortex, brainstem, and spinal cord, to exert proper inhibition of the movements. A decreased capacity of the globus pallidus to inhibit the thalamus can subsequently hyperactivate the medial and prefrontal cortical regions and decrease the activity in the primary motor cortex (41,42).…”

Section: Asymmetries In Focal Dystoniamentioning

confidence: 99%

Reduced Interhemispheric Coherence in Cerebellar Kainic Acid-Induced Lateralized Dystonia

et al. 2020

Self Cite

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The execution of voluntary muscular activity is controlled by the primary motor cortex, together with the cerebellum and basal ganglia. The synchronization of neural activity in the intracortical network is crucial for the regulation of movements. In certain motor diseases, such as dystonia, this synchrony can be altered in any node of the cerebello-cortical network. Questions remain about how the cerebellum influences the motor cortex and interhemispheric communication. This research aims to study the interhemispheric cortical communication between the motor cortices during dystonia, a neurological movement syndrome consisting of sustained or repetitive involuntary muscle contractions. We pharmacologically induced lateralized dystonia to adult male albino mice by administering low doses of kainic acid on the left cerebellar hemisphere. Using electrocorticography and electromyography, we investigated the power spectral densities, cortico-muscular, and interhemispheric coherence between the right and left motor cortices, before and during dystonia, for five consecutive days. Mice displayed lateralized abnormal motor signs, a reduced general locomotor activity, and a high score of dystonia. The results showed a progressive interhemispheric coherence decrease in low-frequency bands (delta, theta, beta) during the first 3 days. The cortico-muscular coherence of the affected side had a significant increase in gamma bands on days 3 and 4. In conclusion, lateralized cerebellar dysfunction during dystonia was associated with a loss of connectivity in the motor cortices, suggesting a possible cortical compensation to the initial disturbances induced by cerebellar left hemisphere kainate activation by blocking the propagation of abnormal oscillations to the healthy hemisphere. However, the cerebellum is part of several overly complex circuits, therefore other mechanisms can still be involved in this phenomenon.

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The Anatomical and Functional Heterogeneity of the Mediodorsal Thalamus

Cited by 39 publications

References 120 publications

The Contribution of Thalamic Nuclei in Salience Processing

The Contribution of Thalamic Nuclei in Salience Processing

Communication between the mediodorsal thalamus and prelimbic cortex regulates timing performance in rats

Reduced Interhemispheric Coherence in Cerebellar Kainic Acid-Induced Lateralized Dystonia

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