Basal ganglia function

Abstract: Manual therapy practitioners have positive results with a variety of neurologic conditions including, various types of generalized dystonia (idiopathic torsion dystonia), which typically starts in one part of the body and then spreads to other parts including the back, neck or arm. Clients with focal dystonia such as writer's cramp, blepharospasm, spasmodic torticollis, oro-facialmandibular dystonia and spasmodic dysphonia can also see a decrease in symptoms with manual therapy. Dystonia can be secondary to certain drugs (e.g. tardive dystonia), injuries of the brain, strokes and other insults to the basal ganglia. Manual therapy approaches that focus on improving the lymphatic and immune system function can help address these.

Keywords: Dystonia, spasmodic torticollis, basal ganglia, Integrative Manual Therapy, Matrix Energetics, Reiki, Craniosacral Therapy,

Burnham, K. (2013 ). "Dystonia and Creative Solutions." Nerve Whisperer Report 2013. [Full Text] https://www.academia.edu/17360057/Dystonia_and_Creative_Solutions

Abnormalities in frontostriatal circuitry potentially underlie the two core deficits in Autism Spectrum Disorder (ASD); social interaction and communication difficulties and restricted interests and repetitive behaviors. Whilst a few studies have examined connectivity within this circuitry in ASD, no previous study has examined both functional and structural connectivity within the same population. The present study provides the first exploration of both functional and structural frontostriatal connectivity in ASD. Twenty-eight right-handed Caucasian male ASD (17.28 ± 3.57 years) and 27 right-handed male, age and IQ matched controls (17.15 ± 3.64 years) took part in the study. Resting state functional connectivity was carried out on 21 ASD and control participants, and tractography was carried out on 22 ASD and 24 control participants, after excluding subjects for excessive motion and poor data quality. Functional connectivity analysis was carried out between the frontal cortex and ...

Abstract: A sense of balance, smooth controlled movements, such as walking are guided by the basal ganglia. The ability to recognize disgust in another person's face is also associated with the basal ganglia. People with a diagnosis of Huntington's disease lose both the ability to walk and move in a smooth controlled way and the ability to recognize disgust. Exercise and movement has been shown to light up the basal ganglia and slow the deterioration. Imagining something disgust also lights up the basal ganglia. Thesis based on client results: Spending a few minutes a day thinking about a disgusting food can light up, bring better blood flow and function to the basal ganglia, resulting in better movement and brain health.

Keywords: disgust, basal ganglia, disgust exercises, Huntington's disease, ataxia, walking, brain health

Burnham, Kimberly Burnham (2013). "Disgust Exercises for Balance: A Third Culture Kids Perspective on the World, Food and the Brain: Disgusting Foods, Beautiful Truth Poster Presentation." Poster Presentation accepted at the Neuroplasticity and Cognitive Modifiability Conference Jerusalem, Israel June 2013.: [Full Text]  https://www.academia.edu/17427646/Disgust_Exercises_for_Balance_A_Third_Culture_Kids_Perspective_on_the_World_Food_and_the_Brain_Disgusting_Foods_Beautiful_Truth_Poster_Presentation

Current models of flexible cognitive control emphasize the role of the prefrontal cortex. This region has been shown to control attention by biasing information processing in favor of task-relevant representations. However, the prefrontal cortex does not act in isolation. We used functional magnetic resonance imaging combined with nonlinear dynamic causal modeling to demonstrate that the basal ganglia play a role in modulating the top-down influence of the prefrontal cortex on visual processing in humans. Specifically, our results reveal that connectivity between the prefrontal cortex and stimulus-specific visual association areas depends on activity in the ventral striatopallidum, elicited by salient events leading to shifts in attention. These data integrate disparate literatures on top-down control by the prefrontal cortex and selective gating by the basal ganglia and highlight the importance of the basal ganglia for high-level cognitive control.

The basal ganglia (BG) have been functionally linked to emotional processing [Pell, M.D., Leonard, C.L., 2003. Processing emotional tone form speech in Parkinson's Disease: a role for the basal ganglia. Cogn. Affec. Behav. Neurosci. 3, 275-288; Pell, M.D., 2006. Cerebral mechanisms for understanding emotional prosody in speech. Brain Lang. 97 (2), 221-234].

Visual working memory (VWM) is a remarkable skill dependent on the brain's ability to construct and hold an internal representation of the world for later comparison with an external stimulus. The prefrontal cortex (PFC) and basal ganglia (BG) interact within a cortical and subcortical network supporting VWM. We used scalp electroencephalography in groups of patients with unilateral PFC or BG lesions to provide evidence that these regions play complementary but dissociable roles in VWM. PFC patients show behavioral and electrophysiological deficits manifested by attenuation of extrastriate attention and VWM-related neural activity only for stimuli presented to the contralesional visual field. In contrast, patients with BG lesions show behavioral and electrophysiological VWM deficits independent of the hemifield of stimulus presentation but have intact extrastriate attention activity. The results support a model wherein the PFC is critical for top-down intrahemispheric modulation of attention and VWM with the BG involved in global support of VWM processes. attention | electroencephalography | lesion | stroke E ven a seemingly simple action such as determining which of two bananas is riper requires us to compare real world visual information, such as the color of the banana you are currently looking at in the store, with your memory of the yellowness of the other banana you just put down. This relies in part on visual working memory (VWM), a remarkable ability wherein we construct and hold an internal model of a real-world visual stimulus that we then later compare against another stimulus. In essence, we construct and hold a model of the visual world and compare that model against subsequent inputs from the external world. VWM relies upon an intact and functioning prefrontal cortex (PFC), and damage to this region, such as from stroke, causes VWM impairments (1-3). However, cognitive processes do not localize to specific brain regions per se and a behavior as complex as VWM recruits a distributed network of cortical and subcortical structures (4-8), including the basal ganglia (BG) (9, 10) and visual extrastriate regions (11-13).

People with Parkinson’s disease (PD) experience motor symptoms that are affected by sensory information in the environment. Sensory attenuation describes the modulation of sensory input caused by motor intent. This appears to be altered in PD and may index important sensorimotor processes underpinning PD symptoms. We review recent findings investigating sensory attenuation and reconcile seemingly disparate results with an emphasis on task-relevance in the modulation of sensory input. Sensory attenuation paradigms, across different sensory modalities, capture how two identical stimuli can elicit markedly different perceptual experiences depending on our predictions of the event, but also the context in which the event occurs. In particular, it appears as though contextual information may be used to suppress or facilitate a response to a stimulus on the basis of task-relevance. We support this viewpoint by considering the role of the basal ganglia in task-relevant sensory filtering and the use of contextual signals in complex environments to shape action and perception. This perspective highlights the dual effect of basal ganglia dysfunction in PD, whereby a reduced capacity to filter task-relevant signals harms the ability to integrate contextual cues, just when such cues are required to effectively navigate and interact with our environment. Finally, we suggest how this framework might be used to establish principles for effective rehabilitation in the treatment of PD.

Behavioral and pharmacological evidence has shown a different and opposite role of the neuropeptide cholecystokinin (CCK) on the dopamine (DA) function in the caudal versus rostral part of the nucleus accumbens. Previous reports have speculated that the caudal region of the nucleus accumbens would receive CCKergic innervation from dopaminergic neurons of the mesencephalic ventral tegmental area, whereas the CCKergic input to the rostral accumbens would originate in non-dopaminergic neurons from extra-mesencephalic areas of the brain. In the present study, this issue was addressed using retrograde tracing techniques in conjunction with immunocytochemistry. Retrograde tracers were injected in the three compartments of the accumbens (i.e., rostral pole, core and septal shell). In summary, our results demonstrate that 1) the main CCKergic input of the accumbens originates in the ventral mesencephalon; 2) the rostral pole is equally innervated by CCK neurons projecting from both substantia nigra pars compacta and ventral tegmental area; 3) the primary source of CCK innervation of the accumbal core is the substantia nigra pars compacta; and 4) whereas the CCKergic input to the septal shell originates primarily in the ventral tegmental area. Additionally, our results also showed that most of the CCKergic neurons projecting to any of the accumbal compartments also produce dopamine. These data constitute the first neuroanatomical evidence for the differential effects of CCK on dopamine actions in the different regions of the nucleus accumbens.

Our sense of body position and movement independent of vision (i.e., proprioception) relies on muscle spindle feedback and is vital for performing motor acts. In this study, we first sought to elucidate age-related differences in the central processing of proprioceptive information by stimulating foot muscle spindles and by measuring neural activation with functional magnetic resonance imaging. We found that healthy older adults activated a similar, distributed network of primary somatosensory and secondary-associative cortical brain regions as young individuals during the vibration-induced muscle spindle stimulation. A significant decrease in neural activity was also found in a cluster of right putamen voxels for the older age group when compared with the younger age group. Given these differences, we performed two additional analyses within each group that quantified the degree to which age-dependent activity was related to (1) brain structure and (2) a behavioral measure of proprioceptive ability. Using diffusion tensor imaging, older (but not younger) adults with higher mean fractional anisotropy were found to have increased right putamen neural activity. Age-dependent right putamen activity seen during tendon vibration was also correlated with a behavioral test of proprioceptive ability measuring ankle joint position sense in both young and old age groups. Partial correlation tests determined that the relationship between elderly joint position sense and neural activity in right putamen was mediated by brain structure, but not vice versa. These results suggest that structural differences within the right putamen are related to reduced activation in the elderly and potentially serve as biomarker of proprioceptive sensibility in older adults. Hum Brain Mapp 00:000-000,

An associative learning task was employed in which, in separate blocks, reinforcement was limited to either correct or incorrect trials. Given the role of dopamine in reinforcement learning, we examined the effects of a dopamine (DA) agonist on performance and obtained genetic information to divide the participants based on two SNPs related to intrinsic DA levels, COMT and DRD2.
Participants learned to associate 16 abstract images with one of two response categories. Each trial had a 50% chance of being eligible for informative feedback. If ineligible, the response was followed by the feedback message “Unknown”. In the positive feedback condition, the feedback message “Correct” was displayed if the trial was eligible for feedback and the response was correct; otherwise the message “Unknown” was shown. Similarly, the message “Incorrect” was presented on eligible trials in the negative feedback condition when the answer was incorrect. In this manner, we separated positive and negative feedback-based learning. Participants were tested in two sessions in a double blind study. In one session participants ingested 1.25 mg of Bromocriptine (BR), a DA agonist; in the other session, they were given a placebo (PLAC).
On placebo, performance was more accurate in the positive condition (90%) than in the negative condition (83%). Overall, there was a Drug x Reinforcement Type interaction: BR resulted in a drop in accuracy for the positive condition and an increase in accuracy for negative condition. The reduction in performance from BR during positive reinforcement was similar for all alleles of COMT. In contrast, the benefit from BR during negative reinforcement was restricted to those individuals with higher levels of intrinsic DA (Val/Met or Met/MET alleles). For DRD2, the interaction of BR and reinforcement type was most pronounced in individuals with lower levels of intrinsic DA (A/A or A/G). These results suggest that individuals with higher DA levels in the frontal lobe may benefit in learning from negative feedback when DA signaling is increased, while individuals with lower striatal levels of DA may benefit in learning from both types of feedback with increased DA signaling.

Both perceptual inference and motor responses are shaped by learned probabilities. For example, stimulus-induced responses in sensory cortices and preparatory activity in premotor cortex reflect how (un)expected a stimulus is. This is in accordance with predictive coding accounts of brain function, which posit a fundamental role of prediction errors for learning and adaptive behaviour. We used fMRI and recent advances in computational modeling to investigate how (failures of) learned predictions about visual stimuli influence subsequent motor responses. Healthy volunteers discriminated visual stimuli that were differentially predicted by auditory cues. Critically, the predictive strengths of cues varied over time, requiring subjects to continuously update estimates of stimulus probabilities. This on-line inference, modeled using a hierarchical Bayesian learner, was reflected behaviourally: speed and accuracy of motor responses increased significantly with predictability of the stimuli. We used nonlinear dynamic causal modelling to demonstrate that striatal prediction errors are used to tune functional coupling in cortical networks during learning. Specifically, the degree of striatal trial-by-trial prediction error activity controls the efficacy of visuomotor connections and thus the influence of surprising stimuli on premotor activity. This finding substantially advances our understanding of striatal function and provides direct empirical evidence for formal learning theories that posit a central role for prediction error-dependent plasticity.

A network spanning prefrontal cortex and the basal ganglia (BG) have been implicated in an fMRI study in filtering information that gains access to visual working memory (WM). Specifically, bilateral middle frontal gyrus and the left BG were more active on trials in which distractors were present with trials compared to trials in which no distractors were presented. The lateralized activity in the BG suggests that filtering may be better when distractors are presented in the right visual field (RVF). We conducted a behavioral study to test this prediction. Participants were shown a display composed of 14 squares arranged in a circle centered at the fixation point. On each trial, red and yellow circles appeared in a subset of the squares. Prior to the memory display, one of two instruction cues had been presented. In the “red only” condition, participants had to remember only the locations that had red circles inside of them; they were to ignore the yellow circles (if present). In the “all” condition, participants were instructed to remember the locations of both the red and yellow circles. After a two-second delay, a question mark appeared in one location and participants indicated with a 2-AFC judgment whether the probed location had contained one of the circles in the working memory set. The memory display was presented for only 200 ms to minimize the utility of eye movements, and thus, keep the stimuli lateralized. Participants were consistently better on the memory test when locations in the left visual field were probed (80% vs. 78% overall accuracy). However, the visual field advantage was similar on filtering (4%) and non-filtering (4%) trials. While the results indicate there may be hemispheric (or visual field) differences in WM performance, the results failed to demonstrate any asymmetries in filtering effects. Further investigation is necessary to identify components of working memory that may account for the LVF advantage.

Neuro-evolution and computational neuroscience are two scientific domains that produce surprisingly different artificial neural networks. Inspired by the ``toolbox'' used by neuroscientists to create their models, this paper argues two main points: (1) neural maps (spatially-organized identical neurons) should be the building blocks to evolve neural networks able to perform cognitive functions and (2) well-identified modules of the brain for which there exists computational neuroscience models provide well-defined benchmarks for neuro-evolution.

To support these claims, a method to evolve networks of neural maps is introduced then applied to evolve neural networks with a similar functionality to basal ganglia in animals (i.e. action selection). Results show that: (1) the map-based encoding easily achieves this task while a direct encoding never solves it; (2) this encoding is independent of the size of maps and can therefore be used to evolve large and brain-like neural networks; (3) the failure of direct encoding to solve the task validates the relevance of action selection as a benchmark for neuro-evolution.

Successful goal pursuit involves repeatedly engaging self-control against temptations or distractions that arise along the way. Laboratory studies have identified the brain systems recruited during isolated instances of self-control, and ecological studies have linked self-control capacity to goal outcomes. However, no study has identified the neural systems of everyday self-control during long-term goal pursuit. The present study integrated neuroimaging and experience-sampling methods to investigate the brain systems of successful self-control among smokers attempting to quit. A sample of 27 cigarette smokers completed a go/ no-go task during functional magnetic resonance imaging before they attempted to quit smoking and then reported everyday self-control using experience sampling eight times daily for 3 weeks while they attempted to quit. Increased activation in right inferior frontal gyrus, pre-supplementary motor area, and basal ganglia regions of interest during response inhibition at baseline was associated with an attenuated association between cravings and subsequent smoking. These findings support the ecological validity of neurocognitive tasks as indices of everyday response inhibition.

Behavioral and pharmacological evidence has shown a different and opposite role of the neuropeptide cholecystokinin (CCK) on the dopamine (DA) function in the caudal versus rostral part of the nucleus accumbens. Previous reports have speculated that the caudal region of the nucleus accumbens would receive CCKergic innervation from dopaminergic neurons of the mesencephalic ventral tegmental area, whereas the CCKergic input to the rostral accumbens would originate in non-dopaminergic neurons from extra-mesencephalic areas of the brain. In the present study, this issue was addressed using retrograde tracing techniques in conjunction with immunocytochemistry. Retrograde tracers were injected in the three compartments of the accumbens (i.e., rostral pole, core and septal shell). In summary, our results demonstrate that 1) the main CCKergic input of the accumbens originates in the ventral mesencephalon; 2) the rostral pole is equally innervated by CCK neurons projecting from both substant...

Decision formation recruits many brain regions, but the procedure they jointly execute is unknown. Here we characterize its essential composition, using as a framework a novel recursive Bayesian algorithm that makes decisions based on spike-trains with the statistics of those in sensory cortex (MT). Using it to simulate the random-dot-motion task, we demonstrate it quantitatively replicates the choice behaviour of monkeys, whilst predicting losses of otherwise usable information from MT. Its architecture maps to the recurrent cortico-basal-ganglia-thalamo-cortical loops, whose components are all implicated in decision-making. We show that the dynamics of its mapped computations match those of neural activity in the sensorimotor cortex and striatum during decisions, and forecast those of basal ganglia output and thalamus. This also predicts which aspects of neural dynamics are and are not part of inference. Our single-equation algorithm is probabilistic, distributed, recursive, and parallel. Its success at capturing anatomy, behaviour, and electrophysiology suggests that the mechanism implemented by the brain has these same characteristics.

The metabolic syndrome (MetS) is a clustering of cardiovascular and cerebrovascular risk factors that are often comorbid with depressive symptoms. Individual components of the MetS also covary with the morphology of basal ganglia regions that are altered by depression. However, it remains unknown whether the covariation between the MetS and depressive symptomatology can be accounted for in part by morphological changes in the basal ganglia. Accordingly, we tested the hypothesis that increased depressive symptoms among individuals with the MetS might be statistically mediated by reduced gray matter volume in basal ganglia regions. The presence of the MetS was determined in 147 middle-aged adults using the criteria of the National Cholesterol Education Program, Adult Treatment Panel III. Basal ganglia volumes were determined on an a priori basis by automated segmentation of high-resolution magnetic resonance images. Depressive symptoms were assessed using the Patient Health Questionnaire. Even after controlling for demographic and other confounding factors, having the MetS and meeting more MetS criteria covaried with reduced globus pallidus volume. Meeting more MetS criteria and reduced pallidal volume were also related to depressive symptoms. Moreover, the MetS-depression association was statistically mediated by pallidal volume. In summary, reduced globus pallidus volume is a neural correlate of the MetS that may partly account for its association with depressive symptoms.

The basal ganglia appear to have a central role in reinforcement learning. Previous experiments, focusing on activity preceding movement execution, support the idea that dorsal striatal neurons bias action selection according to the expected values of actions. However, many phasically active striatal neurons respond at a time too late to initiate or select movements. Given the data suggesting a role for the basal ganglia in reinforcement learning, postmovement activity may therefore reflect evaluative processing important for learning the values of actions. To better understand these postmovement neurons, we determined whether individual striatal neurons encode information about saccade direction, whether a reward had been received, or both. We recorded from phasically active neurons in the caudate nucleus while monkeys performed a probabilistically rewarded delayed saccade task. Many neurons exhibited peak responses after saccade execution (77 of 149) that were often tuned for the direction of the preceding saccade (61 of 77). Of those neurons responding during the reward epoch, one subset showed direction tuning for the immediately preceding saccade (43 of 60), whereas another subset responded differentially on rewarded versus unrewarded trials (35 of 60). We found that there was relatively little overlap of these properties in individual neurons. The encoding of action and outcome was performed by largely separate populations of caudate neurons that were active after movement execution. Thus, striatal neurons active primarily after a movement appear to be segregated into two distinct groups that provide complimentary information about the outcomes of actions.