scholarly journals Functional Organisation of the Mouse Superior Colliculus

2021 ◽  
Author(s):  
Thomas Wheatcroft ◽  
Aman B Saleem ◽  
Samuel G Solomon
Keyword(s):  
Superior Colliculus ◽  
Recent Work ◽  
Brain Areas ◽  
Functional Roles ◽  
Functional Organisation ◽  
Deep Layers ◽  
Convergence And Divergence ◽  
Small Change ◽  
And Control ◽  
Inputs And Outputs

The superior colliculus (SC) is a highly conserved area of the mammalian midbrain that is widely implicated in the organisation and control of behaviour. SC receives input from a large number of brain areas, and provides outputs to a large number of areas. The convergence and divergence of anatomical connections with different areas and systems provides challenges for understanding how SC contributes to behaviours. Recent work in mouse has provided large anatomical datasets, and a wealth of new data from experiments that identify and manipulate different cells within SC, and its inputs and outputs. These data offer an opportunity to better understand the functional roles of SC. However, some of the observations appear, at first sight, to be contradictory. Here we review this recent work and suggest a simple framework which can capture the observations, and that requires only a small change to previous models. Specifically, the functional organisation of SC can be explained by supposing that three largely distinct circuits support three largely distinct classes of behaviour - arrest, turning towards, and the triggering of escape or pursuit. These behavioural classes are supported by the optic, intermediate and deep layers respectively.

scholarly journals Widespread inhibitory projections from the interposed cerebellar nucleus

2021 ◽  
Author(s):  
Elena N. Judd ◽  
Samantha M. Lewis ◽  
Daniel G. Heck ◽  
Abigail L. Person
Keyword(s):  
Recent Work ◽  
Inferior Olive ◽  
Parallel Computations ◽  
Cerebellar Nucleus ◽  
Inhibitory Neurons ◽  
Functional Specificity ◽  
Functional Roles ◽  
Interposed Nucleus ◽  
Output Neurons ◽  
Inputs And Outputs

AbstractThe cerebellum consists of parallel parasagittal modules that contribute to diverse behaviors, spanning motor to cognitive. Recent work illustrating a role for the anterior interposed nucleus (IntA) in reach control in mice raised questions of its anatomical organization that could confer functional specificity. We employed intersectional cell- and projection- specific labeling methods to map IntA inputs and outputs. In contrast to long-standing dogma of primarily excitatory outputs and restricted inferior olive targeting inhibitory output, we found that inhibitory IntA neurons ramified widely within the brainstem, targeting both motor- and sensory-related nuclei, suggesting potential functional roles in disinhibitory control or predictive sensory cancellation. Using monosynaptic rabies tracing, we then found that excitatory output neurons receive fewer and more precisely organized inputs than inhibitory neurons, which may set them up for distinct computations. Together these data suggest IntA contains at least two distinct output circuits and promise advances in identifying parallel computations of the cerebellum.

scholarly journals Effects of Transcranial Ultrasound Stimulation on Trigeminal Blink Reflex Excitability

2021 ◽  
Vol 11 (5) ◽  
pp. 645
Author(s):  
Andrea Guerra ◽  
Edoardo Vicenzini ◽  
Ettore Cioffi ◽  
Donato Colella ◽  
Antonio Cannavacciuolo ◽  
...  
Keyword(s):  
Substantia Nigra ◽  
Superior Colliculus ◽  
Blink Reflex ◽  
Transcranial Ultrasound ◽  
Recovery Cycle ◽  
Brain Areas ◽  
Nucleus Raphe Magnus ◽  
Ultrasound Stimulation ◽  
Raphe Magnus ◽  
Interstimulus Intervals

Recent evidence indicates that transcranial ultrasound stimulation (TUS) modulates sensorimotor cortex excitability. However, no study has assessed possible TUS effects on the excitability of deeper brain areas, such as the brainstem. In this study, we investigated whether TUS delivered on the substantia nigra, superior colliculus, and nucleus raphe magnus modulates the excitability of trigeminal blink reflex, a reliable neurophysiological technique to assess brainstem functions in humans. The recovery cycle of the trigeminal blink reflex (interstimulus intervals of 250 and 500 ms) was tested before (T0), and 3 (T1) and 30 min (T2) after TUS. The effects of substantia nigra-TUS, superior colliculus-TUS, nucleus raphe magnus-TUS and sham-TUS were assessed in separate and randomized sessions. In the superior colliculus-TUS session, the conditioned R2 area increased at T1 compared with T0, while T2 and T0 values did not differ. Results were independent of the interstimulus intervals tested and were not related to trigeminal blink reflex baseline (T0) excitability. Conversely, the conditioned R2 area was comparable at T0, T1, and T2 in the nucleus raphe magnus-TUS and substantia nigra-TUS sessions. Our findings demonstrate that the excitability of brainstem circuits, as evaluated by testing the recovery cycle of the trigeminal blink reflex, can be increased by TUS. This result may reflect the modulation of inhibitory interneurons within the superior colliculus.

Auditory response properties of neurons in deep layers of cat superior colliculus

1983 ◽  
Vol 49 (3) ◽  
pp. 674-685 ◽  
Author(s):  
L. Z. Wise ◽  
D. R. Irvine
Keyword(s):  
Superior Colliculus ◽  
Free Field ◽  
Receptive Fields ◽  
Great Majority ◽  
Noise Burst ◽  
Preliminary Evidence ◽  
Excitatory Input ◽  
Response Properties ◽  
Deep Layers ◽  
Spatial Fields

1. The auditory responses of 207 single neurons in the intermediate and deep layers of the superior colliculus (SC) of barbiturate -or chloralose-anesthetized cats were recorded extracellularly. Sealed stimulating systems incorporating calibrated probe microphone assemblies were employed to present tone- and noise-burst stimuli. 2. All acoustically activated neurons responded with onset responses to noise bursts. Of those neurons also tested with tonal stimuli, approximately 30% were unresponsive over the frequency range tested (0.1-40 kHz), while the others had higher thresholds to tones than to noise. 3. Details of frequency responsiveness were obtained for 55 neurons; 21 were broadly tuned, while 34 were sharply tuned with clearly defined characteristic frequencies (CFs). All sharply tuned neurons had CFs greater than or equal to 10 kHz. 4. The majority of neurons (81%) responded with latencies in the range 8-20 ms; only 11% of neurons had latencies greater than 30 ms. 5. Binaural response properties were examined for 165 neurons. The great majority (79%) received monaural excitatory input only from the contralateral ear (EO). However, most EO cells were binaurally influenced, the contralateral response being either inhibited (EO/I; 96 of 131 units) or facilitated (EO/F; 33 of 131 units) by simultaneous ipsilateral stimulation. Small subgroups were monaurally excited by either ear (EE cells; 8%) or were unresponsive monaurally but responded strongly to binaural stimulation (OO/F cells; 7%). 6. EO/I, EO/F, and OO/F neurons showed characteristic forms of sensitivity to interaural intensity differences (IIDs). The IID functions of EO/I neurons would be expected to produce large contralateral spatial receptive fields with clearly defined medial borders, such as have been described in studies of deep SC neurons employing free-field stimuli. 7. Preliminary evidence suggests a possible topographic organization of IID sensitivity in deep SC, such that the steeply sloping portion of the function (corresponding to the medial edge of the receptive field) is shifted laterally for EO/I neurons located more caudally in the nucleus. 8. The auditory properties of deep SC neurons are compared with previous reports and implications for the organization of auditory input are considered. The binaural properties and auditory spatial fields of deep SC neurons suggest that any representation of auditory space in this structure is unlikely to be based on restricted spatial fields.

The impact of higher-order state and control effects on local relational reasoning

2012 ◽  
Vol 22 (4-5) ◽  
pp. 477-528 ◽  
Author(s):  
DEREK DREYER ◽  
GEORG NEIS ◽  
LARS BIRKEDAL
Keyword(s):  
Recent Work ◽  
Possible Worlds ◽  
Higher Order ◽  
Local State ◽  
Relational Reasoning ◽  
Logical Relation ◽  
Game Semantics ◽  
And Control ◽  
The Impact ◽  
Order State

AbstractReasoning about program equivalence is one of the oldest problems in semantics. In recent years, useful techniques have been developed, based on bisimulations and logical relations, for reasoning about equivalence in the setting of increasingly realistic languages—languages nearly as complex as ML or Haskell. Much of the recent work in this direction has considered the interesting representation independence principles enabled by the use of local state, but it is also important to understand the principles that powerful features like higher-order state and control effects disable. This latter topic has been broached extensively within the framework of game semantics, resulting in what Abramsky dubbed the “semantic cube”: fully abstract game-semantic characterizations of various axes in the design space of ML-like languages. But when it comes to reasoning about many actual examples, game semantics does not yet supply a useful technique for proving equivalences.In this paper, we marry the aspirations of the semantic cube to the powerful proof method of step-indexed Kripke logical relations. Building on recent work of Ahmed et al. (2009), we define the first fully abstract logical relation for an ML-like language with recursive types, abstract types, general references and call/cc. We then show how, under orthogonal restrictions to the expressive power of our language—namely, the restriction to first-order state and/or the removal of call/cc—we can enhance the proving power of our possible-worlds model in correspondingly orthogonal ways, and we demonstrate this proving power on a range of interesting examples. Central to our story is the use of state transition systems to model the way in which properties of local state evolve over time.

Why is lived experience important for market stewardship? A proposed framework for why and how lived experience should be included in stewarding disability markets

2021 ◽  
Author(s):  
Ariella Meltzer ◽  
Helen Dickinson ◽  
Eleanor Malbon ◽  
Gemma Carey
Keyword(s):  
Lived Experience ◽  
Knowledge Production ◽  
Policy Research ◽  
Market Forces ◽  
Research Knowledge ◽  
Key Points ◽  
People With Disability ◽  
And Control ◽  
Insight Into ◽  
Inputs And Outputs

Background: Many countries use market forces to drive reform across disability supports and services. Over the last few decades, many countries have individualised budgets and devolved these to people with disability, so that they can purchase their own choice of supports from an available market of services.Key points for discussion: Such individualised, market-based schemes aim to extend choice and control to people with disability, but this is only achievable if the market operates effectively. Market stewardship has therefore become an important function of government in guiding markets and ensuring they operate effectively.The type of evidence that governments tend to draw on in market stewardship is typically limited to inputs and outputs and has less insight into the outcomes services do or do not achieve. While this is a typical approach to market stewardship, we argue it is problematic and that a greater focus on outcomes is necessary.Conclusions and implications: To include a focus on outcomes, we argue that market stewards need to take account of the lived experience of people with disability. We present a framework for doing this, drawing on precedents where people with disability have contributed lived experience evidence within other policy, research, knowledge production and advocacy contexts.With the lived experience evidence of people with disability included, market stewardship will be better able to take account of outcomes as they play out in the lives of those using the market and, ultimately, achieve greater choice and control for people with disability.<br />Key messages<br /><ul><li>Market stewardship is key to guiding quasi-markets, including in the disability sector;</li><br /><li>Evidence guiding market stewardship is often about inputs and outputs only;</li><br /><li>It would be beneficial to also include lived experience evidence from people with disability;</li><br /><li>We propose a framework for the inclusion of lived experience evidence in market stewardship.</li></ul>

Glutamate-like immunoreactivity in the cat superior colliculus and visual cortex: Further evidence that glutamate is the neurotransmitter of the corticocollicular pathway

1997 ◽  
Vol 14 (1) ◽  
pp. 27-37 ◽  
Author(s):  
Chang-Jin Jeon ◽  
Michael K. Hartman ◽  
R. Ranney Mize
Keyword(s):  
Visual Cortex ◽  
Superior Colliculus ◽  
Optical Density ◽  
Retrograde Tracing ◽  
Biochemical Studies ◽  
Deep Layers ◽  
Dense Band ◽  
Cat Superior Colliculus ◽  
Made In ◽  
In Cells

AbstractBiochemical studies provide evidence that the pathway from visual cortex to the superior colliculus (SC) utilizes glutamate as a neurotransmitter. In the present study, we have used immunocytochemistry, visual cortex lesions, and retrograde tracing to show directly by anatomical methods that glutamate or a closely related analog is contained in corticocollicular neurons and terminals. A monoclonal antibody directed against gamma-L-glutamyl-L-glutamate (gamma glu glu) was used to localize glutamate-like immunoreactivity in both the superior colliculus (SC) and visual cortex (VC). Unilateral lesions of areas 17–18 were made in four cats to determine if gamma glu glu labeling was reduced in SC by this lesion. WGA-HRP was injected into the SC of 10 additional cats in order to determine if corticocollicular neurons were also labeled by the gamma glu glu antibody. A distinctive dense band of gamma glu glu immunoreactivity was found within the deep superficial gray and upper optic layers of SC where many corticotectal axons are known to terminate. Both fibers and cells were labeled within the band. Immunoreactivity was also found in cells and fibers throughout the deep layers of SC. Measures of total immunoreactivity (i.e. optical density) in the dense band were made in sections from the SC both ipsilateral to and contralateral to the lesions of areas 17–18. A consistent reduction in optical density was found in both the neuropil and in cells within the dense band of the SC ipsilateral to the lesion. A large percentage of all corticocollicular neurons that were retrogradely labeled by WGA-HRP also contained gamma glu glu. These results provide further evidence that the corticocollicular pathway in mammals is glutamatergic. The results also suggest that visual cortex ablation alters synthesis or storage of glutamate within postsynaptic SC neurons, presumably as a result of partial deafferentation.

scholarly journals Metacognitive Computations for Information Search: Confidence in Control

2021 ◽  
Author(s):  
Lion Schulz ◽  
Stephen M. Fleming ◽  
Peter Dayan
Keyword(s):  
Recent Work ◽  
Information Search ◽  
Information Seeking ◽  
Critical Role ◽  
Monitoring And Control ◽  
Metacognitive Monitoring ◽  
Extra Information ◽  
And Control

The metacognitive sense of confidence can play a critical role in regulating decisionmaking. In particular, a lack of confidence can justify the explicit, potentially costly, instrumental acquisition of extra information that might resolve the underlying uncertainty. Recent work has suggested a statistically sophisticated tapestry behind the information governing both the making and monitoring of choices. Here, we extend this tapestry to reveal extra richness in the use of confidence for controlling information seeking. We thereby highlight how different models of metacognition can generate diverse relationships between action, confidence, and information search. More broadly, our work shows how crucial it can be to treat metacognitive monitoring and control together.

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