Goal-directed and habitual control in the basal ganglia: implications for Parkinson's disease

Progressive loss of the ascending dopaminergic projection in the basal ganglia is a fundamental pathological feature of Parkinson's disease. Studies in animals and humans have identified spatially segregated functional territories in the basal ganglia for the control of goal-directed and habitual actions. In patients with Parkinson's disease the loss of dopamine is predominantly in the posterior putamen, a region of the basal ganglia associated with the control of habitual behaviour. These patients may therefore be forced into a progressive reliance on the goal-directed mode of action control that is mediated by comparatively preserved processing in the rostromedial striatum. Thus, many of their behavioural difficulties may reflect a loss of normal automatic control owing to distorting output signals from habitual control circuits, which impede the expression of goal-directed action. © 2010 Macmillan Publishers Limited. All rights reserved

Abnormal air righting behaviour in the spontaneously hypertensive rat model of ADHD

The spontaneously hypertensive rat (SHR) is the most commonly used model of attention-deficit hyperactivity disorder (ADHD), displaying the main symptoms of the disorder which are responsive to psychostimulant treatments. Research to date has focused on behavioural tests investigating functioning of the striatum or prefrontal cortex in these rats. However, there is now evidence that the superior colliculus, a structure associated with head and eye movements, may also be dysfunctional in ADHD. Therefore, the aim of this study was to investigate whether the SHR demonstrated impairment in collicular-dependent behaviour. To this end, we examined air righting behaviour, which has previously been shown to be modulated in a height-dependent manner reliant on a functional superior colliculus. We assessed SHR, Wistar Kyotos and Wistars on static righting and air righting at 50 and 10 cm drop heights. There were no differences in static righting, indicating that there were no gross motor differences that would confound air righting. Qualitative analysis of video footage of the righting did not reveal any changes previously associated with collicular damage, unique to the SHR. However, the SHR did show impairment in height-dependent modulation of righting in contrast to both control strains, such that the SHR failed to modulate righting latency according to drop height. This failure is indicative of collicular abnormality. Given that many rodent tests of attentional mechanisms involve head and eye orienting, which are heavily dependent on the colliculus, a collicular dysfunction has strong implications for the type of attentional task used in this strain

Maps as geomedial action spaces: considering the shift from logocentric to egocentric engagements

This paper considers some significant questions in geography and cognate fields about the roles of maps in the information age. Most maps are now digital products, offering immersive environments for user involvement. The increasingly networked digital distribution of geographic information in consumer-orientated cartographic representations leads to substantial changes how people individually and collaboratively experience and produce space and place. This article focuses on the ongoing metamorphosis arising through geobrowsing, the media-based flexible production of geographic knowledge through interactive maps. Drawing on work in media studies influenced by the so-called spatial turn-the rediscovering of geography-related questions in the social sciences and humanities, after modernism's claimed prioritization of time and history (Soja in Postmodern Geographies. The reassertion of space in critical social theory, London, 1989; Jameson in Postmodernism, or, the cultural logic of late capitalism, Duke University Press, Durham, 1991)-this paper develops a theoretical framework built on the dynamic networked geomedial action spaces concept to understand the changing roles of information age maps as imagined materialist spaces for the experience and production of space-ultimately a medial turn. Following this concept, maps change from offering static and noninteractive frames of geographic reference for the production of space and place and as geomedia support a veritable infinity of interactive and mapbased activities. Geobrowsing facilitates some new modes of geographic interactions that move from logocentric engagements with static maps to egocentric dynamic interactions with code-based elements of geomedial action spaces. Google Earth and similar geomedia facilitate maps that become intrinsic to a growing number of social action spaces and alter the experience and production of space and place

Human and Rodent Homologies in Action Control: Corticostriatal Determinants of Goal-Directed and Habitual Action

Recent behavioral studies in both humans and rodents have found evidence that performance in decision-making tasks depends on two different learning processes; one encoding the relationship between actions and their consequences and a second involving the formation of stimulus–response associations. These learning processes are thought to govern goal-directed and habitual actions, respectively, and have been found to depend on homologous corticostriatal networks in these species. Thus, recent research using comparable behavioral tasks in both humans and rats has implicated homologous regions of cortex (medial prefrontal cortex/medial orbital cortex in humans and prelimbic cortex in rats) and of dorsal striatum (anterior caudate in humans and dorsomedial striatum in rats) in goal-directed action and in the control of habitual actions (posterior lateral putamen in humans and dorsolateral striatum in rats). These learning processes have been argued to be antagonistic or competing because their control over performance appears to be all or none. Nevertheless, evidence has started to accumulate suggesting that they may at times compete and at others cooperate in the selection and subsequent evaluation of actions necessary for normal choice performance. It appears likely that cooperation or competition between these sources of action control depends not only on local interactions in dorsal striatum but also on the cortico-basal ganglia network within which the striatum is embedded and that mediates the integration of learning with basic motivational and emotional processes. The neural basis of the integration of learning and motivation in choice and decision-making is still controversial and we review some recent hypotheses relating to this issue