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At least 19 recordsLinked to original sources
PubMed2003

Distinct mechanisms for processing spatial sequences and pitch sequences in the human auditory brain.

Perception of the acoustic world requires the simultaneous processing of the acoustic patterns associated with sound objects and their location in space. In this functional magnetic resonance experiment, we investigated the human brain areas engaged in the analysis of pitch sequences and sequences of acoustic spatial locations in a paradigm in which both could be varied independently. Subjects were presented with sequences of sounds in which the individual sounds were regular interval noises with variable pitch. Positions of individual sounds were varied using a virtual acoustic space paradigm during scanning. Sound sequences with changing pitch specifically activated lateral Heschl's gyrus (HG), anterior planum temporale (PT), planum polare, and superior temporal gyrus anterior to HG. Sound sequences with changing spatial locations specifically activated posteromedial PT. These results demonstrate directly that distinct mechanisms for the analysis of pitch sequences and acoustic spatial sequences exist in the human brain. This functional differentiation is evident as early as PT: within PT, pitch pattern is processed anterolaterally and spatial location is processed posteromedially. These areas may represent human homologs of macaque lateral and medial belt, respectively.

Acoustic Stimulation↗
PubMed2006

Oculomotor and manual indexes of incidental and intentional spatial sequence learning during middle childhood and adolescence.

The goal of this study was to examine incidental and intentional spatial sequence learning during middle childhood and adolescence. We tested four age groups (8-10 years, 11-13 years, 14-17 years, and young adults [18+ years]) on a serial reaction time task and used manual and oculomotor measures to examine incidental sequence learning. Participants were also administered a trial block in which they were explicitly instructed to learn a sequence. Replicating our previous study with adults, oculomotor anticipations and response times showed learning effects similar to those in the manual modality. There were few age-related differences in the sequence learning indexes during incidental learning, but intentional learning yielded differences on all indexes. Results indicate that the search for regularities and the ability to learn a sequence rapidly under incidental conditions are mature by 8 to 10 years of age. In contrast, the ability to learn a sequence intentionally, which requires cognitive resources and strategies, continues to develop through adolescence.

Adolescent↗
PubMed2005

Predicting protein interaction sites from residue spatial sequence profile and evolution rate.

This paper proposes a novel method that can predict protein interaction sites in heterocomplexes using residue spatial sequence profile and evolution rate approaches. The former represents the information of multiple sequence alignments while the latter corresponds to a residue's evolutionary conservation score based on a phylogenetic tree. Three predictors using a support vector machines algorithm are constructed to predict whether a surface residue is a part of a protein-protein interface. The efficiency and the effectiveness of our proposed approach is verified by its better prediction performance compared with other models. The study is based on a non-redundant data set of heterodimers consisting of 69 protein chains.

Algorithms↗
PubMed1989

Prefrontal cortex and spatial sequencing in macaque monkey.

1. Single neuron activity was recorded from the prefrontal cortex of two macaque monkeys during the performance of a task involving spatial sequencing. The monkeys faced a panel displaying a central fixation point and three fixed targets (two lateral and one above the point of fixation). In the first phase of each trial, the three targets were turned on in random order: in the second phase, the animal had to press each target, still lighted, in the order of their illumination. Thus, successful performance of the task depended strongly on temporal memory. The animals were fitted with DC-EOG electrodes. 2. Three hundred and two task-related neurons were recorded in the superior arcuate area and caudal part of sulcus principalis. Among the cells whose pattern of activity appeared to be related to the sequencing task, five classes were distinguished: Visual tonic (VT), fixation, context, saccade related and visual phasic cells. In addition, a small number of cells appeared to be related to other aspects of the behavior, but not to the sequencing task. Our present analysis concentrates on two groups of sequencing task-related cells (VT and context cells). 3. The VT cells (35/302-11.5%) were recorded exclusively from the superior arcuate area. All VT cells increased their firing rate (sustained activation) during fixation of the central fixation point (FP) following onset of one of the three targets used, specific for a given cell (directional or spatial selectivity). In one group of VT cells, a shift in the eye position towards the specific peripheral target resulted in the return of the cells' firing rate to the pre-trial level. In the other group of VT cells, reset of the firing rate to pre-trial level was not related to the onset of fixation of the peripheral target. Sustained activation of the VT cells depended also on the sequential order of illumination of the specific target (temporal selectivity). In twenty-four cells (68.5% of VT cells) sustained activation was observed when the target came first in the sequence. Onset of the target in the second or third rank elicited either no response or only a short lasting phasic activation. In the remaining eleven cells (31.5% of VT cells), sustained activation was only observed when the target came second in a given sequence. The firing of the VT cells was correlated with the animals' performance of the task.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2002

Concurrent learning of temporal and spatial sequences.

In a serial reaction time task, stimulus events simultaneously defined spatial and temporal sequences. Responses were based on the spatial dimension. The temporal sequence was incidental to the task, defined by the response-to-stimulus intervals in Experiment 1 and stimulus onset asynchronies in Experiment 2. The two sequences were either of equal length and correlated or of unequal length. In both experiments, spatial learning occurred regardless of sequence length condition. In contrast, temporal learning occurred only in the correlated condition. These results suggest that timing is an integrated part of action representations and that incidental learning for a temporal pattern does not occur independently from the action. Interestingly, sequence learning was enhanced in the correlated condition, reflecting the integration of spatial-temporal information.

Analysis of Variance↗
PubMed1997

Learning spatial sequences in unilateral neglect.

Brain-damaged patients with unilateral spatial neglect ignore aspects of the world located on the side opposite their lesion. In the present study we examined the performance of unilateral neglect patients (UN) on an SRT task in which a hybrid repeating sequence (21313) was used. We analyzed the patients' performance for each location separately as a function of the target's location in the trial preceding the response. The UN patients were severely limited in their learning of the sequence when compared to normal controls. In particular, they appeared to learn unique associations (21 and 13) but not ambiguous ones (31 and 32). We discuss two possible explanations for this phenomenon. The first is that UN patients show a deficit similar to that of normal subjects in dual task situations. The second is that the learning deficit is unique to spatial processing impairments of UN patients and is not directly related to research with normal population. We outline future research that may distinguish between these two explanations.

Attention↗
PubMed2005

The effect of old age on supra-span learning of visuo-spatial sequences under incidental and intentional encoding instructions.

Recent findings [Turcotte, Gagnon, & Poirier, 2005. The effect of old age on the learning of supra-span sequences. Psychology and Aging, 20, 251-260.] indicate that incidental learning of visuo-spatial supra-span sequences through immediate serial recall declines with old age (Hebb's paradigm). In this study, we examined whether strategies induced by awareness of the repeated sequence might explain age differences. Young (18-35 years old) and older (65-80 years old) participants underwent either incidental or intentional learning instructions. Results indicated that older adults demonstrated reduced learning of the repeated sequence under both incidental and intentional instructions. In comparison, young adults showed superior learning of the repeated sequence in both conditions but intentional instructions triggered faster and greater learning in this age group. The results strongly indicated that knowledge of the repeated sequence enhanced learning only in the group of young adults. Older adults were unable to translate the knowledge of the repetition into elaborate strategies that would increase recall of the repeated sequence. Other findings suggest that incidental learning in young adults was mediated by both non-conscious and conscious recollection processes.

Adolescent↗
PubMed1995

Activity in the caudate nucleus of monkey during spatial sequencing.

1. There are indications that the execution of behavioral sequences involves the basal ganglia. In this study we examined the role of the caudate nucleus in the construction, storage, and execution of spatial plans. 2. Two monkeys (Macaca mulatta) were trained to perform sequences of saccades and arm movements. The animals had to remember the order of illumination, variable from one sequence to another, of three fixed spatial targets. After a delay, they had to visually orient toward, and press each target in the same order. Six different sequences were executed on the basis of the order of illumination of the targets. Single cell activity was recorded from the four caudate nuclei of the two monkeys. 3. Neural activity was analyzed in each sequence during 10 different periods: the instruction period in which the targets were illuminated, the three orientation periods toward the different targets, the three postsaccadic periods, and the three periods of target pressing. Statistical comparisons were made to detect differences between the different sequences with respect to activity in each period (sequence specificity). 4. A total of 2,100 neurons were studied, of which 387 were task related. The task-related cells were found in both the head and the body of the caudate nucleus. 5. During central fixation, anticipatory activity (n = 81) preceded onset of specific events. Four groups were considered: 1) neurons (n = 46) anticipating offset of the central fixation point, 2) neurons (n = 7) anticipating the illumination of any target, regardless of its spatial position or order of presentation (rank), 3) neurons (n = 17) anticipating the illumination of the first target, regardless of its spatial position, and 4) neurons (n = 11) anticipating the illumination of a given target, regardless of its rank. 6. Phasic visual responses to target onset were observed in 48 cells. The cells responded primarily to the contralateral and upper targets. In a majority (n = 35), visual responses were modulated by the rank of the target(s). Many cells (n = 20) responded only if the corresponding target was first; other cells responded only if the target was second or if it had complex time relationships with the other targets. 7. The responses of the cells to the same instruction stimuli repeated twice in a row, and under the condition that the animal did not behaviorally use the first instruction in between, were tested. More than one-third of the tested cells (n = 14) did not respond, or responded very weakly, to the second instruction.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2005

Implicit learning of non-spatial sequences in schizophrenia.

Recent studies have reported abnormal implicit learning of sequential patterns in patients with schizophrenia. Because these studies were based on visuospatial cues, the question remained whether patients were impaired simply due to the demands of spatial processing. This study examined implicit sequence learning in 24 patients with schizophrenia and 24 healthy controls using a non-spatial variation of the serial reaction time test (SRT) in which pattern stimuli alternated with random stimuli on every other trial. Both groups showed learning by responding faster and more accurately to pattern trials than to random trials. Patients, however, showed a smaller magnitude of sequence learning. Both groups were unable to demonstrate explicit knowledge of the nature of the pattern, confirming that learning occurred without awareness. Clinical variables were not correlated with the patients' learning deficits. Patients with schizophrenia have a decreased ability to develop sensitivity to regularly occurring sequences of events within their environment. This type of deficit may affect an array of cognitive and motor functions that rely on the perception of event regularity.

Adult↗
PubMed1993

Neural activity in the caudate nucleus of monkeys during spatial sequencing.

Single cell activity was recorded from the monkey caudate nucleus. The animal had to execute motor and oculomotor sequences based on memorized information. In each trial, the monkey had to remember the order of illumination of three fixed spatial targets. After a delay, the animal had to press the targets in the same sequence. The "task-related" cells were activated by onset of the targets and on execution of saccades or arm movements. In a majority of cells, activation did not depend only on the retinal position of the stimuli or on the spatial parameters of gaze and arm movements, but was contingent on the particular sequence in which the targets were illuminated or the movements were performed.

Animals↗
PubMed2000

Temporal and spatial sequence expression of cytokeratin K19 in cultured human keratinocyte.

The unique cytokeratin K19 specifically expresses in simple epithelial cells, basal cells of non-keratinized stratified squamous epithelium, epidermal cells during the embryonic stage and squamous carcinoma cells, but it is not expressed in adult epidermis. Interestingly, when epidermal cells are cultured in vitro, K19 is re-expressed in the supra-basal layer. K19 expression was used as a marker for epidermal cell growth and differentiation. In order to clarify the temporal and spatial sequential expression in cultured keratinocyte, two-stage human keratinocyte culture systems were used to examine K19 expression in keratinocytes in a proliferation and differentiation stages through immunoblotting and immunohistochemistry assay. According to our results, K19 was not expressed in cultured human keratinocytes in the proliferation stage but was re-expressed in keratinocytes three days after the cultured medium was changed to a differentiation medium. Immunohistochemical observation revealed that K19 was persistently expressed in the supra-basal layer of cultured keratinocytes during first three weeks of culturing, but none was detectable in the basal cell layer. When keratinocytes were cultured with an "inserted cultured dish," K19 was persistently expressed in all layers of keratinocytes nourished by medium both from an inner chamber and an outer chamber. The different expression of K19 in these two different culture systems seemed to indicate that down regulation of K19 expression in keratinocyte was related to the direction of medium supply.

Cell Differentiation↗
PubMed1978

Temporal and spatial sequence of anterograde degeneration in the cochlear nerve fibers of the cat. A light microscopic study.

This study deals with anterograde degeneration in the cochlear nerve fibers following cochlear lesions. The observations are based on 2-mum thick sections of material embedded in resin according to procedures used in electron microscopy and stained with toluidine blue. Among the various operative approaches used in this study, sparing of the modiolus afforded the least local reaction and furnished the material best suited for anterograde degneration studies in this nerve only 2 mm long. The anterograde degeneration of the cochlear nerve is characterized by segmental swelling of myelinated nerve fibers followed by shrinkage of the axoplasm and collapse of the distended myelin sheaths. The swelling, which begins at the nodal-paranodal region of the axon, is preceded by accumulation in the cytoplasm of granular organelles, presumably mitochondria and lysosomes. The portions of the cochlear fibers situated in the nerve root, i.e., within the cochlear nuclei and including the axon terminals, follow essentially the same pattern of degeneration as those in the peripheral portion of the nerve. Both peripherally and centrally degenerative changes occur first in the basal, high frequency fibers and centrally degenerative changes occur first in the basal, high frequency fibers and progress to the apical, low frequency fibers. The difference between the two extremes in the onset of degeneration is, approximately, 24 hours. Once initiated, however, the pace of degeneration is the same along the whole fiber spectrum.

Animals↗
PubMed2006

Microstimulation of frontal cortex can reorder a remembered spatial sequence.

Complex goal-directed behaviors extend over time and thus depend on the ability to serially order memories and assemble compound, temporally coordinated movements. Theories of sequential processing range from simple associative chaining to hierarchical models in which order is encoded explicitly and separately from sequence components. To examine how short-term memory and planning for sequences might be coded, we used microstimulation to perturb neural activity in the supplementary eye field (SEF) while animals held a sequence of two cued locations in memory over a short delay. We found that stimulation affected the order in which animals saccaded to the locations, but not the memory for which locations were cued. These results imply that memory for sequential order can be dissociated from that of its components. Furthermore, stimulation of the SEF appeared to bias sequence endpoints to converge toward a location in contralateral space, suggesting that this area encodes sequences in terms of their endpoints rather than their individual components.

Animals↗
PubMed1983

Effects of spinal tractotomy on spatial sequence recognition in macaques.

Five Macaca speciosa monkeys were trained to discriminate between the order of two tactile stimulus presentations (proximal-distal vs. distal-proximal) to the lateral calf. Psychophysical thresholds for tactile sequence recognition were obtained by varying the distance between the spots stimulated. Stabilized preoperative thresholds for stimulation on the lateral calf averaged 10.4 mm, which is comparable to point localization thresholds for sequential contact of the proximal limbs of humans. Complete interruption of the ipsilateral fasciculus gracilis produced elevations of thresholds within the first 3 postoperative weeks to an average of 3.6 times the control values. With training over 6 postoperative months, normal discrimination recovered. In contrast to the effects of dorsal column (DC) lesions, interruption of the lateral and ventral columns ipsilaterally or contralaterally produced no deficit or a mild and transient deficit. Monkeys with isolation of either the ipsilateral dorsolateral column (ILC) or the contralateral ventral quadrant (CVQ) exhibited substantial and enduring deficits. Thresholds were elevated an average of 5 times the control values, and recovery was not observed or was incomplete after months of training. In contrast, isolation of the ipsilateral dorsal column produced little or no threshold elevation. The results of isolating lesions complement the series of primary lesions to each cord sector, showing that spatiotactile sequence recognition for the hindlimb is served more critically by the dorsal columns than by the lateral columns.

Animals↗
PubMed1998

[Neuronal activity of monkey dorso-lateral premotor cortex during tasks of figure recognition guided motor sequence vs memorized spatial motor sequence].

In the last 2-3 decades the role of the premotor cortex (PM) of monkey in memorized spatial sequential (MSS) movements has been amply investigated. However, it is as yet not known whether PM participates in the movement sequence behaviour guided by recognition of visual figures (i.e. the figure-recognition sequence, FRS). In the present work three monkeys were trained to perform both FRS and MSS tasks. Postmortem examination showed that 202 cells were in the dorso-lateral premotor cortex. Among 111 cells recorded during the two tasks, more than 50% changed their activity during the cue periods in either task. During the response period, the ratios of cells with changes of firing rate in both FRS and MSS were high and roughly equal to each other, while during the image period, the proportion in the FRS (83.7%) was significantly higher than that in the MSS (66.7%). Comparison of neuronal activities during same motor sequence of two different tasks showed that during the image periods PM neuronal activities were more closely related to the FRS task, while during the cue periods no difference could be found. Analysis of cell responses showed that the neurons with longer latency were much more in MSS than in FRS in either cue or image period. The present results indicate that the premotor cortex participates in FRS motor sequence as well as in MSS and suggest that the dorso-lateral PM represents another subarea in function shared by both FRS and MSS tasks. However, in view of the differences of PM neuronal responses in cue or image periods of FRS and MSS tasks, it seems likely that neural networks involved in FRS and MSS tasks are different.

Animals↗
PubMedDate not supplied

Memory for temporal order of new and familiar spatial location sequences: role of the medial prefrontal cortex.

Rats with medial prefrontal cortex or sham control lesions were tested on an eight-arm radial maze task to examine memory for the temporal order of a variable and a constant sequence of spatial locations as a function of temporal distance. During the study phase of each trial, rats were allowed to visit each of eight arms once in an order that was randomly selected or fixed for that trial. The test phase required the rats to choose which of two arms occurred earlier in the sequence of arms visited during the study phase. The arms selected as test arms varied according to temporal distance (0, 2, 4, or 6) or the number of arms that occurred between the two test arms in the study phase. For the variable sequences based on new information, control rats showed an increasing temporal distance function. Relative to control rats, medial prefrontal cortex-lesioned rats displayed a temporal order memory deficit across all distances. For the constant sequence based on familiar information, control rats performed well across all distances. Relative to controls, the medial prefrontal cortex-lesioned rats displayed a performance deficit. The results support the idea that the medial prefrontal cortex contributes to mnemonic operations associated with temporal order for new and familiar spatial location information.

Analysis of Variance↗
PubMed2026

Spatial proximity sequencing maps developmental dynamics in the germinal center.

Spatial profiling of proteins and protein interactions facilitates understanding of cell functions within tissues and is essential for studies in signaling, immunity, and cancer. We present spatial proximity sequencing (Sprox-seq) for simultaneous profiling of surface proteins, protein complexes, and mRNAs, recording the tissue location of each molecule. Sprox-seq profiled 32 proteins, 528 pairwise interactions, and thousands of mRNAs with spatial resolution across human tonsils and germinal centers. Mapping tissue-wide protein interactions recapitulated RNA-defined tissue architecture but also revealed higher interaction complexity in the light zone. Protein-interaction trajectories uncovered a B cell state transition distinct from that inferred by RNA. Integrated protein-complex and mRNA analysis related spatially enriched complexes with mitotic pathways. Sprox-seq captured cell-cell interactions, such as B cell-follicular dendritic cell interactions mediated by the receptor complex VLA-4-VCAM1. Sprox-seq provides a spatially resolved multi-modal view of cell states and an integrated study of protein and cellular interactions across tissues.

Humans↗