讲座：Dr. Stewart Shipp，UCL
19
2014-11
实验室邀请了UCL Institute of Ophthalmology的Principal Associate Investigator，Dr. Stewart Shipp作学术报告，欢迎感兴趣的老师和同学来听。
报告时间：11月24日上午9:00
报告地点：脑成像中心308会议室（大会议室）
报告题目：Subcortical circuitry for attention
报告摘要：
The neural implementation of visual attention relies on the ability of the brain to allocate processing resources according to behavioural priority. Paradoxically, much of the cerebral cortex is rather specialised with regard to spatial and/or feature processing. It is subcortical structures such as the pulvinar where spatial and featural specialisation is less in evidence, that are more likely to represent the limited resource capable of switching from task to task .
The pulvinar could play such a role by regulating and facilitating transareal corticocortical communication. It has the broad connectivity profile to do this, and a likely mechanism would involve communication through phase coherence in oscillatory cycles. Essentially, “…incipient cortical networks compete with each other to recruit the same pulvinar circuits. If rival object networks tend to synchronize at different phases, it is necessary for one network to entrain a disproportionate share of thalamic elements to dominate, and maintain its long-term activity – corresponding to selective attention to that object” [1].
The talk will review this functional logic for the pulvinar, and contrast it to an attentional function for its thalamic partner in the visual system, the lateral geniculate nucleus.
[1] S. Shipp, The functional logic of cortico-pulvinar connections. Philos. Trans. R. Soc. Lond. B. Biol. Sci. 358, 1605-1624 (2003).
报告人简介：
Dr. Stewart Shipp has published in four of the key disciplines of neuroscience: anatomy/connectivity, neurophysiology, functional imaging and psychophysics, including single authored papers in the first and last of these, a relatively broad spread in terms of techniques. The common theme to this work is the relation between anatomical structure and function. The primary research publications detail the anatomy and physiology of segregated pathways through early visual areas and their links with the thalamus, in primates. In addition, a number of reviews (1-7) set out novel accounts of particular neural systems, assimilating a broad base of cross-disciplinary findings with the overt objective to significantly influence the general perception of the functionality of these systems. Other papers highlight particular roles for specific areas of visual cortex (8-10), or examine cognitive function in the light of basic brain circuitry (11, 12).
1. Zeki S & Shipp S (1988) The functional logic of cortical connections. Nature, 335: 311-317.
Summarised the interplay of forward, backward and lateral connectivity relating to segregation and integration of information processing in primate visual cortex.
2. Shipp S (2003) The functional logic of cortico-pulvinar connections. Philos Trans R Soc Lond B Biol Sci, 358: 1605-1624.
3. Shipp S (2004) The brain circuitry of attention. Trends Cogn Sci, 8: 223-230.
Suggested new functions for the thalamic pulvinar nucleus, based on a reinterpretation of the organization of its connections with cortex:-
a) as an element in a re-entrant pathway (from frontal cortex to colliculus to pulvinar to visual cortex) with a role in governing the locus of spatial attention;
b) as a remote hub for co-ordinating transcortical communication (essentially, rival cortical networks must compete to recruit pulvinar circuitry essential for establishing transcortical coherence of oscillatory activity).
4. Shipp S (2005)The importance of being agranular: a comparative account of visual and motor cortex. Philos Trans R Soc Lond B Biol Sci, 360: 797-814.
5. Adams RA, Shipp S & Friston KJ (2013) Predictions not commands: active inference in the motor system. Brain Struct Funct, 218: 611-643.
Both papers compare and contrast the organisation of visual and motor cortex, establishing common elements of hierarchical organization across these systems. The possession of hierarchy by the motor system is a necessary precursor for its functional interpretation in terms of predictive coding theory.
6. Shipp S, Adams RA & Friston KJ (2013) Reflections on agranular architecture: predictive coding in the motor cortex. Trends Neurosci, 36: p. 706-716.
Provides the first principled account of the functional origins of the ‘agranular’ architecture of motor cortex. The rationale arises from a detailed scheme for the implementation of predictive coding by identified components of intrinsic and extrinsic connectivity, in both visual and motor cortices. The operating principles are explained through reference to motor ‘mirror neurons’, with predictions for future research findings arising from predictive coding theory.
7. Shipp S (2015) The functional logic of corticostriatal projections – and associated oculomotor circuitry in the cortico-basal ganglia loop. Brain Structure & Function (in preparation).
The subcortical basal ganglia (BG) loop can be modelled as an action selection system that is subject to reward-based behavioural reinforcement. This paper will argue that the classical convergent or ‘funneling’ architecture of the BG rules against the fine, anatomically separate loops proposed by most models, but is ideal for motor plans of rival actions to compete dynamically. That is to say, rival action-plans compete to govern the oscillatory signaling of a shared return pathway (e.g. to frontal eye field, in the case of oculomotor control) in order to establish positive feedback by virtue of dynamically regulated effective connectivity.
8. Galletti C, Fattori P, Shipp S et al (1996) Functional demarcation of a border between areas V6 and V6A in the superior parietal gyrus of the macaque monkey. Eur J Neurosci, 8: 30-52.
9. Shipp S, Blanton M & Zeki S (1998) A visuo-somatomotor pathway through superior parietal cortex in the macaque monkey: cortical connections of areas V6 and V6A. Eur J Neurosci, 10: 3171-3193.
Established the identity and role of areas V6 (the ‘medial motion area’) and V6A as the primary source of visual guidance for motor control by dorsal premotor cortex.
10. Shipp S, Adams D, Moutoussis K & Zeki S (2009) Feature binding in the feedback layers of area V2. Cereb Cortex, 19: 2230-2239.
Proposes a solution to the conundrum known as the ‘binding problem’: how the brain retains an association between features of a given object (such as its colour, and direction of motion) that are processed along specialized divergent pathways, each lacking a full analysis of the global feature-set.
11. Hulme OJ, Whiteley L & Shipp S (2010) Spatially distributed encoding of covert attentional shifts in human thalamus. J Neurophysiol, 104: 3644-3656.
Uniquely, in the imaging literature, provides a comprehensive profile of nuclear activation by reference to a standard atlas of human thalamus. The subset of most activated nuclei forms a close match to the organisation of thalamic connections with the frontal eye field in Macaca.
12. Shipp S (2011) Interhemispheric integration in visual search. Neuropsychologia, 49: 2630-2647.
Reports the effect of display geometry (i.e. unilateral v bilateral search arrays) upon human search efficiency, and relates this to the presence/absence of interhemispheric connectivity in specific cortical and subcortical brain systems.
