Spatial Memory for Context Reasoning in Object Detection

Modeling instance-level context and object-object relationships is extremely challenging. It requires reasoning about bounding boxes of different classes, locations \etc. Above all, instance-level spatial reasoning inherently requires modeling conditional distributions on previous detections. Unfortunately, our current object detection systems do not have any {\bf memory} to remember what to condition on! The state-of-the-art object detectors still detect all object in parallel followed by non-maximal suppression (NMS). While memory has been used for tasks such as captioning, they mostly use image-level memory cells without capturing the spatial layout. On the other hand, modeling object-object relationships requires {\bf spatial} reasoning -- not only do we need a memory to store the spatial layout, but also a effective reasoning module to extract spatial patterns. This paper presents a conceptually simple yet powerful solution -- Spatial Memory Network (SMN), to model the instance-level context efficiently and effectively. Our spatial memory essentially assembles object instances back into a pseudo "image" representation that is easy to be fed into another ConvNet for object-object context reasoning. This leads to a new sequential reasoning architecture where image and memory are processed in parallel to obtain detections which update the memory again. We show our SMN direction is promising as it provides 2.2\% improvement over baseline Faster RCNN on the COCO dataset so far.Comment: Draft submitted to ICCV 201

Stimulus-specific mechanisms of visual short-term memory

The retention of spatial information in visual short-term memory was assessed by measuring spatial frequency discrimination thresholds with a two-interval forced-choice task varying the time interval between the two gratings to be compared. The memory of spatial frequency information was perfect across 10-sec interstimulus intervals. Presentation of a “memory masker” grating during the interstimulus interval may interfere with short-term memory. This interference depends on the relative spatial frequency of the test and masker gratings, with maximum interference at spatial frequency differences of 1–1.5 octaves and beyond. This range of interference with short-term memory is comparable to the bandwidth of sensory masking or adaptation. A change of the relative orientation of test and masker gratings does not produce interference with spatial frequency discrimination thresholds. These results suggest stimulus-specific interactions at higher-level representations of visual form

Inhibition of Connexin43 hemichannels impairs spatial short-term memory without affecting spatial working memory

Astrocytes are active players in higher brain function as they can release gliotransmitters, which are essential for synaptic plasticity. Various mechanisms have been proposed for gliotransmission, including vesicular mechanisms as well as non-vesicular ones, for example by passive diffusion via connexin hemichannels (HCs). We here investigated whether interfering with connexin43 (Cx43) HCs influenced hippocampal spatial memory. We made use of the peptide Gap19 that blocks HCs but not gap junction channels and is specific for Cx43. To this end, we microinfused transactivator of transcription linked Gap19 (TAT-Gap19) into the brain ventricle of male NMRI mice and assessed spatial memory in a Y maze. We found that the in vivo blockade of Cx43 HCs did not affect the locomotor activity or spatial working memory in a spontaneous alternation Y maze task. Cx43 blockade did however significantly impair the spatial short-term memory in a delayed spontaneous alternation Y maze task. These results indicate that Cx43 HCs play a role in spatial short-term memory

A comprehensive investigation of memory impairment in attention deficit hyperactivity disorder and oppositional defiant disorder

We conducted a comprehensive and systematic assessment of memory functioning indrug-naïve boys with attention deficit hyperactivity disorder (ADHD) and oppositional defiant disorder (ODD). Boys performed verbal and spatial working memory (WM) component (storage and central executive) and verbal and spatial storage load tasks, and the spatial span, spatial executive WM, spatial recognition memory and verbal recognition memory tasks from the Cambridge Neuropsychological Test Automated Battery. Groups comprised: (a) ADHD only (N = 21); (b) ADHD+ODD (N = 27); (c) ODD only (N = 21); and (d) typically developing (TYP) boys (N = 26). Groups were matched for age (M = 9.7 years) and sex (all boys). Confirmatory factor analyses confirmed the presence of five factors: verbal functioning, spatial functioning, WM storage, WM central executive and long-term memory (LTM). All three clinical groups demonstrated impaired memory performance. Boys with ODD and ODD+ADHD but not ADHD alone performed poorly on verbal memory tasks, whilst all three clinical groups showed impaired performance on spatial memory tasks. All three clinical groups performed poorly on the storage and central executive WM factors and the LTM factor. ADHD and ODD are characterised by impaired performance storage and central executive WM tasks and LTM tasks. This is, we believe, the first report of impaired WM and LTM performance in ODD. This study suggests that verbal memory difficulties are more closely associated with ODD than ADHD symptoms and that combined ADHD+ODD represents a true comorbidity. The data also support a small but growing number of suggestions in the literature of impaired LTM in ADHD

The effect of spatial learning on the number of astrocytes in rat dentate gyrus

In this study, we evaluated the effect of spatial learning on the number of astrocytes in the rat dentate gyrus with Morris water maze. Fifteen male albino Wistar rats were divided into three groups as control, reference memory and working memory groups. Each group was consisted of 5 rats. After spatial learning, the brains were histologically examined; the slides were stained with phosphotungstic acid hematoxylin (PTAH) staining to show the astrocytes. We found significant difference in the number of astrocytes in dentate gyrus between control and reference memory groups, and between control and working memory groups as well. When compared two learning groups there was a significant difference in the number of astrocytes between them, being higher in the working memory group. We concluded that the number of astrocytes increased due to spatial learning and this increase can be affected to the period of learning. Our studies of spatial learning and effect of learning techniques (reference and working memory) showed that the technique that has longer period of learning has more effect on the number of astrocytes

Both symbolic and embodied representations contribute to spatial language processing: Evidence from younger and older adults

Building on earlier neuropsychological work, we adopted a novel individual differences approach to examine the relationship between spatial language and a wide range of both verbal and nonverbal abilities. Three new measures were developed for the assessment of spatial language processing: spatial naming, spatial verbal memory, and verbal comprehension in spatial perspective taking. Results from a sample of young adults revealed significant correlations between performance on the spatial language tasks and performance on both the analogous (non-spatial) verbal measures as well as on the (non-verbal) visual-spatial measures. Visual-spatial abilities, however, were more predictive of spatial language processing than verbal abilities. Furthermore, results from a sample of older adults revealed impairments in visual-spatial tasks and on spatial verbal memory. The results support dual process accounts of meaning, and provide further evidence of the close connection between the language of space and non-linguistic visual-spatial cognition

Insensitivity of visual short-term memory to irrelevant visual information

Several authors have hypothesised that visuo-spatial working memory is functionally analogous to verbal working memory. Irrelevant background speech impairs verbal short-term memory. We investigated whether irrelevant visual information has an analogous effect on visual short-term memory, using a dynamic visual noise (DVN) technique known to disrupt visual imagery (Quinn & McConnell, 1996a). Experiment 1 replicated the effect of DVN on pegword imagery. Experiments 2 and 3 showed no effect of DVN on recall of static matrix patterns, despite a significant effect of a concurrent spatial tapping task. Experiment 4 showed no effect of DVN on encoding or maintenance of arrays of matrix patterns, despite testing memory by a recognition procedure to encourage visual rather than spatial processing. Serial position curves showed a one-item recency effect typical of visual short-term memory. Experiment 5 showed no effect of DVN on short-term recognition of Chinese characters, despite effects of visual similarity and a concurrent colour memory task that confirmed visual processing of the characters. We conclude that irrelevant visual noise does not impair visual short-term memory. Visual working memory may not be functionally analogous to verbal working memory, and different cognitive processes may underlie visual short-term memory and visual imagery

Topological Schemas of Memory Spaces

Hippocampal cognitive map---a neuronal representation of the spatial environment---is broadly discussed in the computational neuroscience literature for decades. More recent studies point out that hippocampus plays a major role in producing yet another cognitive framework that incorporates not only spatial, but also nonspatial memories---the memory space. However, unlike cognitive maps, memory spaces have been barely studied from a theoretical perspective. Here we propose an approach for modeling hippocampal memory spaces as an epiphenomenon of neuronal spiking activity. First, we suggest that the memory space may be viewed as a finite topological space---a hypothesis that allows treating both spatial and nonspatial aspects of hippocampal function on equal footing. We then model the topological properties of the memory space to demonstrate that this concept naturally incorporates the notion of a cognitive map. Lastly, we suggest a formal description of the memory consolidation process and point out a connection between the proposed model of the memory spaces to the so-called Morris' schemas, which emerge as the most compact representation of the memory structure.Comment: 24 pages, 8 Figures, 1 Suppl. Figur

Differences in spatial memory recognition due to cognitive style

Field independence refers to the ability to perceive details from the surrounding context as a whole and to represent the environment by relying on an internal reference frame. Conversely, field dependence individuals tend to focus their attention on single environmental features analysing them individually. This cognitive style affects several visuo-spatial abilities including spatial memory. This study assesses both the effect of field independence and field dependence on performance displayed on virtual environments of different complexity. Forty young healthy individuals took part in this study. Participants performed the Embedded Figures Test for field independence or dependence assessment and a new spatial memory recognition test. The spatial memory recognition test demanded to memorize a green box location in a virtual room picture. Thereafter, during ten trials participants had to decide if a green box was located in the same position as in the sample picture. Five of the pictures were correct. The information available in the virtual room was manipulated. Hence, two different experimental conditions were tested: a virtual room containing all landmarks and a virtual room with only two cues. Accuracy and reaction time were registered. Analyses demonstrated that higher field independent individuals were related to better spatial memory performance in two landmarks condition and were faster in all landmark condition. In addition, men and women did not differ in their performance. These results suggested that cognitive style affects spatial memory performance and this phenomenon is modulated by environment complexity. This does not affect accuracy but time spent. Moreover, field dependent individuals are unable to organize the navigational field by relying on internal reference frames when few landmarks are available, and this causes them to commit more errors

Representation, space and Hollywood Squares: Looking at things that aren't there anymore

It has been argued that the human cognitive system is capable of using spatial indexes or oculomotor coordinates to relieve working memory load (Ballard, Hayhoe, Pook & Rao, 1997) track multiple moving items through occlusion (Scholl & Pylyshyn, 1999) or link incompatible cognitive and sensorimotor codes (Bridgeman and Huemer, 1998). Here we examine the use of such spatial information in memory for semantic information. Previous research has often focused on the role of task demands and the level of automaticity in the encoding of spatial location in memory tasks. We present five experiments where location is irrelevant to the task, and participants' encoding of spatial information is measured implicitly by their looking behavior during recall. In a paradigm developed from Spivey and Geng (submitted), participants were presented with pieces of auditory, semantic information as part of an event occurring in one of four regions of a computer screen. In front of a blank grid, they were asked a question relating to one of those facts. Under certain conditions it was found that during the question period participants made significantly more saccades to the empty region of space where the semantic information had been previously presented. Our findings are discussed in relation to previous research on memory and spatial location, the dorsal and ventral streams of the visual system, and the notion of a cognitive-perceptual system using spatial indexes to exploit the stability of the external world