Spatial Processing Functions Research Articles

Changes in Metabolic Activity and Gait Function by Dual-Task Cognitive Game-Based Treadmill System in Parkinson's Disease: Protocol of a Randomized Controlled Trial.

Balance and gait impairments, and consequently, mobility restrictions and falls are common in Parkinson’s disease (PD). Various cognitive deficits are also common in PD and are associated with increased fall risk. These mobility and cognitive deficits are limiting factors in a person’s health, ability to perform activities of daily living, and overall quality of life. Community ambulation involves many dual-task (DT) conditions that require processing of several cognitive tasks while managing or reacting to sudden or unexpected balance challenges. DT training programs that can simultaneously target balance, gait, visuomotor, and cognitive functions are important to consider in rehabilitation and promotion of healthy active lives. In the proposed multi-center, randomized controlled trial (RCT), novel behavioral positron emission tomography (PET) brain imaging methods are used to evaluate the molecular basis and neural underpinnings of: (a) the decline of mobility function in PD, specifically, balance, gait, visuomotor, and cognitive function, and (b) the effects of an engaging, game-based DT treadmill walking program on mobility and cognitive functions. Both the interactive cognitive game tasks and treadmill walking require continuous visual attention, and share spatial processing functions, notably to minimize any balance disturbance or gait deviation/stumble. The ability to “walk and talk” normally includes activation of specific regions of the prefrontal cortex (PFC) and the basal ganglia (site of degeneration in PD). The PET imaging analysis and comparison with healthy age-matched controls will allow us to identify areas of abnormal, reduced activity levels, as well as areas of excessive activity (increased attentional resources) during DT-walking. We will then be able to identify areas of brain plasticity associated with improvements in mobility functions (balance, gait, and cognition) after intervention. We expect the gait-cognitive training effect to involve re-organization of PFC activity among other, yet to be identified brain regions. The DT mobility-training platform and behavioral PET brain imaging methods are directly applicable to other diseases that affect gait and cognition, e.g., cognitive vascular impairment, Alzheimer’s disease, as well as in aging.

Adult neurogenesis promotes efficient, nonspecific search strategies in a spatial alternation water maze task

Goal-directed navigation requires learning strategies that are efficient and minimize costs. In some cases it may be desirable to flexibly adjust behavioral responses depending on the cues that vary from one episode to the next. In others, successful navigation might be achieved with inflexible, habit-like responses that reduce cognitive load. Adult neurogenesis is believed to contribute to the spatial processing functions of the hippocampus, particularly when behavioral flexibility is required. However, little is known about the role of neurogenesis in spatial navigation when goals are unpredictable or change repeatedly according to certain rules. We hypothesized that neurogenesis is necessary in a spatial navigation task that involves different patterns of reinforcement. Intact and neurogenesis-deficient rats were trained to escape to one of two possible platform locations in a spatial water maze. The platform either repeated in the same location for all trials in a day, alternated between two locations across trials, or randomly moved between the two locations. Neurogenesis selectively enhanced escape performance in the alternating condition, but not by improving platform choice accuracy. Instead, neurogenesis-intact rats made fewer search errors and developed an efficient habit-like strategy where they consistently swam to a preferred location. If the platform was not present, they proceeded to the other possible location. In contrast, neurogenesis-deficient rats were indecisive and navigationally less-efficient. Thus, in conditions where goals follow a predictable spatiotemporal pattern, adult neurogenesis promotes the adoption of navigation strategies that are spatially nonspecific but, nonetheless, accurate and efficient.

Perirhinal cortex involvement in allocentric spatial learning in the rat: Evidence from doubly marked tasks.

It has recently been suggested that the different cortices of the medial temporal lobe support a mixture of object and spatial processing functions, challenging the anterior model that emphasized a strict functional differentiation between regions. However, for some structures, the perirhinal cortex (Prh) for example, a number of studies using lesion methods have shown a profound deficit exclusively in tasks involving object learning but not allocentric spatial learning. It may be that the learning paradigms used in previous studies have not been sensitive enough to detect a possible allocentric deficit in Prh-lesioned animals. To examine whether Prh lesions critically affect allocentric spatial learning, experimental and control rats were trained in two doubly marked navigation tasks. In experiment 1, the use of either one of two different memory systems, allocentric versus egocentric, made it possible to locate the goal arm in a four-arm radial maze. In experiment 2, rats had to choose between an allocentric versus a S-R/habit strategy, both of which predicted the location of the goal arm. Results showed that both experimental and control animals learned both navigation tasks well, reaching the same level of performance at the end of training. However, a probe test performed 1 day after the learning ended revealed that Prh-damaged animals learned both tasks predominantly using a non-allocentric strategy. Specifically, in lesioned subjects the percentage of egocentric correct responses (experiment 1) and the percentage of habit-based correct responses (experiment 2) was significantly higher than in the control rats. On the other hand, in both experiments, control rats in the probe test presented a significantly higher number of allocentric correct responses than the lesioned subjects. These results clearly suggest that Prh is normally needed for using allocentric strategies in order to solve a navigation problem. © 2017 Wiley Periodicals, Inc.

The different durations of methamphetamine abuse influenced abusers’ spatial processing function

Objective To investigate the effects of different durations of methamphetamine abuse on spatial cognitive processing. Methods The mental rotation task was used to evaluate the spatial processing function of 35 methamphetamine abusers and 30 healthy subjects. The methamphetamine abusers are divided into 2 groups according to their abuse durations, group 1 contains 16 abusers with an average duration of 1 year and group 2 contains 19 abusers with an average duration of 3 years. Participants were asked to judge the right hand/food or the left hand/food of the experimental stimuli at difference angles. The reaction time (RT) and the accurate rate (AR) of the mental rotation task were recorded. Results Compared with the control group, RT of group 1 methamphetamine abusers was longer at the angle of 0°((1469±318)ms) and 180°((1718±412)ms) (P<0.05), RT of group 2 was longer at the angle of 0°((1466±243)ms), 60°((1497±294)ms) and 180°((1708±288)ms) (P<0.05). And the AR of methamphetamine abusers was higher at every angle (P<0.05). Conclusion Long-term dependence on methamphetmine can damage the abuser's spatial processing function. Key words: Methamphetamine dependence; Spatial processing function; Mental rotation; Defect

Temporal associations for spatial events: The role of the dentate gyrus

Previous research suggests that the dorsal dentate gyrus (DG) hippocampal subregion mediates spatial processing functions. However, a novel role for the DG in temporal processing for spatial information has begun to emerge based on the development of a computational model of neurogenesis. According to this model, adult born granule cells in the DG contribute to a temporal associative integration process for events presented closer in time. Currently, there is a paucity of behavioral evidence to support the temporal integration theory. Therefore, we developed a novel behavioral paradigm to investigate the role of the dDG in temporal integration for proximal and distal spatial events. Male Long-Evans rats were randomly assigned to a control group or to receive bilateral intracranial infusions of colchicine into the dDG. Following recovery from surgery, each rat was tested on a cued-recall of sequence paradigm. In this task, animals were allowed to explore identical objects placed in designated spatial locations on a cheeseboard maze across 2 days (e.g., Day 1: A and B; Day 2: C and D). One week later, animals were given a brief cue (A or C) followed by a preference test between spatial location B and D. Control animals had a significant preference for the spatial location previously paired with the cue (the temporal associate) whereas dDG lesioned animals failed to show a preference. These findings suggest that selective colchicine-induced dDG lesions are capable of disrupting the formation of temporal associations between spatial events presented close in time.

Gateways of ventral and dorsal streams in mouse visual cortex.

It is widely held that the spatial processing functions underlying rodent navigation are similar to those encoding human episodic memory (Doeller et al., 2010). Spatial and nonspatial information are provided by all senses including vision. It has been suggested that visual inputs are fed to the navigational network in cortex and hippocampus through dorsal and ventral intracortical streams (Whitlock et al., 2008), but this has not been shown directly in rodents. We have used cytoarchitectonic and chemoarchitectonic markers, topographic mapping of receptive fields, and pathway tracing to determine in mouse visual cortex whether the lateromedial field (LM) and the anterolateral field (AL), which are the principal targets of primary visual cortex (V1) (Wang and Burkhalter, 2007) specialized for processing nonspatial and spatial visual information (Gao et al., 2006), are distinct areas with diverse connections. We have found that the LM/AL border coincides with a change in type 2 muscarinic acetylcholine receptor expression in layer 4 and with the representation of the lower visual field periphery. Our quantitative analyses also show that LM strongly projects to temporal cortex as well as the lateral entorhinal cortex, which has weak spatial selectivity (Hargreaves et al., 2005). In contrast, AL has stronger connections with posterior parietal cortex, motor cortex, and the spatially selective medial entorhinal cortex (Haftig et al., 2005). These results support the notion that LM and AL are architecturally, topographically, and connectionally distinct areas of extrastriate visual cortex and that they are gateways for ventral and dorsal streams.

Cerebellar information processing and visuospatial functions

Although there are consistent reports of altered visuospatial abilities in subjects with cerebellar pathologies, and although experimental evidence indicates the importance of this part of the brain in spatial processing, the role of the cerebellum in this area remains elusive. In the present essay, experimental and clinical studies from our group, focussing relations between cerebellum and visuospatial functions are reviewed. Explorative behaviour, visuospatial abilities and sequential spatial processing functions are analyzed to focus cerebellar involvement in spatial data processing. Reviewed evidence enlightens the importance of the cerebellum for scanning sensory data to extract relevant spatial information and for the acquisition of spatial-related procedures. This hypothesis is discussed within the general framework of cerebellar involvement in cognition.

Hippocampal memory system function and the regulation of cocaine self-administration behavior in rats

There is considerable interest in elucidating neurocognitive mechanisms of cocaine addiction. This report focuses on the hippocampal memory system. Using food reward, two cognitive tasks were examined after lidocaine inactivation of the dorsal (dSUB) or ventral (vSUB) subiculum, the primary hippocampal output regions in rats. These tasks were conducted to first identify functionally relevant stereotaxic coordinates within the hippocampal memory system, in order to then examine its role in regulating drug-seeking and drug-taking behavior studied under a contextually discriminable FI 5-min(FR5:S) second-order schedule of cocaine and brief stimulus delivery. Inactivation of the dSUB and vSUB with 10 μg lidocaine impaired hippocampal-dependent win-shift performance. Amygdalar-dependant conditioned cue preference, used as a test for behavioral specificity of lidocaine, was not affected following inactivation of either site. Inactivation of the dSUB with 100 μg lidocaine significantly reduced drug-seeking and drug-taking behavior studied during the cocaine self-administration maintenance phase. Following extinction, inactivation of neither the dSUB nor vSUB influenced reinstatement of drug-seeking behavior induced by drug-paired cues presented alone or with a cocaine priming injection. The impairments in win-shift performance are consistent with the spatial processing functions of the dSUB and vSUB, and the reduction in drug-taking behavior is consistent with the non-spatial temporal processing functions of the dSUB. The lack of an effect of dSUB and vSUB inactivation on reinstatement of drug-seeking behavior may relate to the fact that the contextual associations with cocaine were well-practiced at the time of cue reinstatement testing, and therefore, drug-seeking behavior was likely regulated by nonhippocampal-dependent mechanisms.