Physiological evidence for a trans-basal ganglia pathway linking extrastriate visual cortex and the superior colliculus

Pathways for Naturalistic Looking Behavior in Primate II. Superior Colliculus Integrates Parallel Top-down and Bottom-up Inputs

Volitional signals for gaze control are provided by multiple parallel pathways converging on the midbrain superior colliculus (SC), whose deeper layers output to the brainstem gaze circuits. In the first of two papers (Takahashi and Veale, 2023), we described the properties of gaze behavior of several species under both laboratory and natural conditions, as well as the current understanding of the brainstem and spinal cord circuits implementing gaze control in primate. In this paper, we review the parallel pathways by which sensory and task information reaches SC and how these sensory and task signals interact within SC's multilayered structure. This includes both bottom-up (world statistics) signals mediated by sensory cortex, association cortex, and subcortical structures, as well as top-down (goal and task) influences which arrive via either direct excitatory pathways from cerebral cortex, or via indirect basal ganglia relays resulting in inhibition or dis-inhibition as appropriate for alternative behaviors. Models of attention such as saliency maps serve as convenient frameworks to organize our understanding of both the separate computations of each neural pathway, as well as the interaction between the multiple parallel pathways influencing gaze. While the spatial interactions between gaze's neural pathways are relatively well understood, the temporal interactions between and within pathways will be an important area of future study, requiring both improved technical methods for measurement and improvement of our understanding of how temporal dynamics results in the observed spatiotemporal allocation of gaze.

A corticostriatal projection for sound-evoked and anticipatory motor behavior following temporal expectation

The ability to form predictions based on recent sensory experience is essential for behavioral adaptation to our ever-changing environment. Predictive encoding represented by neuronal activity has been observed in sensory cortex, but how this neuronal activity is transformed into anticipatory motor behavior remains unclear. Fiber photometry to investigate a corticostriatal projection from the auditory cortex to the posterior striatum during an auditory paradigm in mice, and pharmacological experiments in a task that induces a temporal expectation of upcoming sensory stimuli. We find that the auditory corticostriatal projection relays both sound-evoked stimulus information as well as predictive signals in relation to stimulus timing following rhythmic auditory stimulation. Pharmacological experiments suggest that this projection is required for the initiation of both sound-evoked and anticipatory licking behavior in an auditory associative-learning behavioral task, but not for the general recognition of presented auditory stimuli. This auditory corticostriatal projection carries predictive signals, and the posterior striatum is critical to the anticipatory stimulus-driven motor behavior.

Abnormal intrinsic functional network hubs in diabetic retinopathy patients

BACKGROUND

However, whether the whole-brain functional network hub changes occur in diabetic retinopathy patients remains unknown.

PURPOSE

The purpose of the study was to investigate the function network centrality and connectivity changes in diabetic retinopathy patients using the voxel-wise degree centrality method.

MATERIALS AND METHODS

Thirty-four diabetic retinopathy patients (18 male and 16 female) and 38 healthy controls (18 male and 20 female) closely matched in age, sex, and education were enrolled in the study. Graph theory-based network analysis was performed to investigate the degree centrality between two groups.

RESULTS

Compared with healthy controls, diabetic retinopathy patients had significantly higher degree centrality values in the pons and bilateral caudate and had significantly lower degree centrality values in the left lingual and right lingual, and right angular/middle occipital gyrus (MOG). Moreover, diabetic retinopathy patients exhibited increased functional connectivity between the bilateral lingual and right cerebellum lobe and right fusiform/bilateral caudate and increased functional connectivity between the right angular/MOG and bilateral anterior cingulum and right cuneus/bilateral precuneus and increased functional connectivity between the bilateral caudate and right lingual and right superior occipital gyrus. In contrast, diabetic retinopathy patients showed decreased functional connectivity between bilateral lingual and left lingual and right lingual and left superior occipital gyrus and decreased functional connectivity between the angular/MOG and right inferior occipital gyrus/right fusiform and left MOG/inferior occipital gyrus and decreased functional connectivity between the bilateral caudate and bilateral cerebellum crus1.

CONCLUSION

Our results highlight that reorganization of the hierarchy of the cortical connectivity network related to visual network.

Neural Circuit and Clinical Insights from Intraoperative Recordings During Deep Brain Stimulation Surgery

Observations using invasive neural recordings from patient populations undergoing neurosurgical interventions have led to critical breakthroughs in our understanding of human neural circuit function and malfunction. The opportunity to interact with patients during neurophysiological mapping allowed for early insights in functional localization to improve surgical outcomes, but has since expanded into exploring fundamental aspects of human cognition including reward processing, language, the storage and retrieval of memory, decision-making, as well as sensory and motor processing. The increasing use of chronic neuromodulation, via deep brain stimulation, for a spectrum of neurological and psychiatric conditions has in tandem led to increased opportunity for linking theories of cognitive processing and neural circuit function. Our purpose here is to motivate the neuroscience and neurosurgical community to capitalize on the opportunities that this next decade will bring. To this end, we will highlight recent studies that have successfully leveraged invasive recordings during deep brain stimulation surgery to advance our understanding of human cognition with an emphasis on reward processing, improving clinical outcomes, and informing advances in neuromodulatory interventions.

Perturbation-driven paradoxical facilitation of visuo-spatial function: Revisiting the 'Sprague effect'

The 'Sprague Effect' described in the seminal paper of James Sprague (Science 153:1544-1547, 1966a) is an unexpected paradoxical effect in which a second brain lesion reversed functional deficits induced by an earlier lesion. It was observed initially in the cat where severe and permanent contralateral visually guided attentional deficits generated by the ablation of large areas of the visual cortex were reversed by the subsequent removal of the superior colliculus (SC) opposite to the cortical lesion or by the splitting of the collicular commissure. Physiologically, this effect has been explained in several ways-most notably by the reduction of the functional inhibition of the ipsilateral SC by the contralateral SC, and the restoration of normal interactions between cortical and midbrain structures after ablation. In the present review, we aim at reappraising the 'Sprague Effect' by critically analyzing studies that have been conducted in the feline and human brain. Moreover, we assess applications of the 'Sprague Effect' in the rehabilitation of visually guided attentional impairments by using non-invasive therapeutic approaches such as transcranial magnetic stimulation (TMS) and transcranial direct-current stimulation (tDCS). We also review theoretical models of the effect that emphasize the inhibition and balancing between the two hemispheres and show implications for lesion inference approaches. Last, we critically review whether the resulting inter-hemispheric rivalry theories lead toward an efficient rehabilitation of stroke in humans. We conclude by emphasizing key challenges in the field of 'Sprague Effect' applications in order to design better therapies for brain-damaged patients.

Corticostriatal neurons in auditory cortex drive decisions during auditory discrimination

The neural pathways by which information about the acoustic world reaches the auditory cortex are well characterised, but how auditory representations are transformed into motor commands is not known. Here we have used a perceptual decision-making task to study this transformation. We directly demonstrate the role of corticostriatal projection neurones in auditory decisions by specifically manipulating the activity of these neurones in rats performing an auditory frequency discrimination task. Targeted Channelrhodopsin-2^1,2 (ChR2)-mediated stimulation of corticostriatal neurones during the task biased decisions in the direction predicted by the frequency tuning of the stimulated neurones, whereas archaerhodopsin-3³ (Arch)-mediated inactivation biased decisions in the opposite direction. Striatal projections are widespread in cortex and may provide a general mechanism for the control of motor decisions by sensory cortex.