Perceiving an object and its context in different cultures: A cultural look at new look

Shinobu Kitayama, Sean Duffy, Tadashi Kawamura, and Jeff T. Larsen

Psychological Science 14:210-206 (2003)

In two studies, a newly devised test (framed-line test) was used to examine the hypothesis that individuals in Asian cultures are more capable of incorporating contextual information and those engaging in North American cultures are more capable of ignoring contextual information. On each trials, participants were presented with a square frame, within which was printed a vertical line. Participants were then shown another square frame of the same or different size and asked to draw a line that was identical to the first line in either absolute length (absolute task) or proportion to the height of the surrounding frame (relative task). The results supported the hypothesis: Whereas Japanese were more accurate in the relative task, Americans were more accurate in the absolute task. Moreover, when engaging in another culture, individuals tended to show the cognitive characteristic common in the host culture.

Culture shapes how we look at faces

Caroline Blais, Rachael E. Jack, Christoph Scheepers, Daniel Fiset, Roberto Caldara

POLS One 3(8):e3022

Face processing, among many basic visual skills, is thought to be invariant across humans. From as early as 1965, studies of eye movements have consistently revealed a systematic triangular sequence of fixation over the eyes and the mouth, suggesting that faces elicit a universal, biologically-determined information extraction pattern. Here we monitored the eye movements of Western Caucasian and East Asian observers while they learned, recognized, and categorized by race Western Caucasian and East Asian faces. Western Caucasian observers reproduced a scattered triangular pattern of fixations for faces and both races and across tasks. Contrary to intuition, East Asian observed focused more on the central region of the faces. These results demonstrate that face processing can no longer be considered as arising from a universal series of perceptual events. The strategy employed to extract visual information from faces differs across cultures.

The evolution of the arcuate fasciculus revealed with comparative DTI

James K Rilling, Matthew F Glasser, Todd M Preuss, Xiangyang Ma, Tiejun Zhao, Xiaoping Hu, and Timothy E J Behrens

Nature Neuroscience 11:426-428 (2008)

The arcuate fasciculus is a white-matter fiber tract that is involved in human language. Here we compared cortical connectivity in humans, chimpanzees and macaques (Macaca mulatta) and found a prominent temporal lobe projection of the human arcuate fasciculus that is much smaller or absent in nonhuman primates. This human specialization may be relevant to the evolution of language.

Cultural variation in eye movements during scene perception

Hannah Faye Chua, Julie E. Boland, and Richard E. Nisbett

PNAS 102:12629-12633 (2005)

In the past decade, cultural differences in perceptual judgment and memory have been observed: Westerners attend more to focal objects, whereas East Asians attend more to contextual information. However, underlying mechanisms for the apparent differences in cognitive processing styles have not been known. In the present study, we examined the possibility that the cultural differences arise from culturally different viewing patterns when confronted with a naturalistic scene. We measured the eye movements of American and Chinese participants while they viewed photography with a focal object on a complex background. In fact, the Americans fixated more on focal objects than did the Chinese, and the Americans tended to look at the focal objects more quickly. In addition, the Chinese made more saccades to the background than did the Americans. Thus, it appears that differences in judgment and memory may have their origins in differences in what is actually attended as people view a scene.

Sex differences in neural processing of language among children

Douglas D. Burman, Tali Bitan, James R. Booth

Neuropsychologia (in press)

Why females generally perform better on language tasks than males is unknown. Sex differences were here identified in children (age 9-15) across two linguistic tasks for words presented in two modalities. Bilateral activation in the inferior frontal and superior temporal gyri and activation in the left fusiform gyrus of girls was greater than boys. Activation in the left inferior frontal and fusiform regions of girls was also correlated with linguistic accuracy irregardless of stimulus modality, whereas correlation with performance accuracy in boys depended on the modality of word presentation (either visual or auditory association cortex). This pattern suggests that girls rely on a supramodal language network, whereas boys process visual and auditory words differently. Activation in the left fusiform region was additionally correlated with performance on standardized language tests in which girls performed better, additional evidence of its role in early sex differences for language.

Cue- versus probe-dependent prefrontal cortex activity during contextual remembering

Ian G. Dobbins and Sanghoon Han

Journal of Cognitive Neuroscience 18:1439-1452 (2006)

Functional neuroimaging comparisons of context and item memory frequently implicate the left prefrontal cortex (PFC) during the recovery of contextually specific memories. However, because cues and probes are often presented simultaneously, this activity could reflect operations involved in planning retrieval or instead reflect later operations dependent upon the memory probes themselves, such as evaluation of probe-evoked recollections. More importantly, planning related activity, wherein subjects reinstate details outlining the nature of desired remembrances, should occur in response to contextual memory cues even before retrieval probes are available. Using event-related functional magnetic resonance imaging, we tested this by dissociating cue- from probe-related activity during context memory for pictures. Cues forewarning contextual memory demands yielded more activity than those forewarning item memory in the left lateral precentral gyrus, midline superior frontal gyrus, and right frontopolar cortex. Thus, these anticipatory, cue-based activations indicated whether upcoming probe decisions would require contextually specific memories or not. In contrast, the left dorsolateral/midventrolateral and anterior ventrolateral PFC areas did not show differential activity until the probes were actually presented, demonstrating greater activity for context than for item memory probes. Direct comparison of proximal left PFC regions demonstrated qualitatively different response profiles across cue versus probe periods for lateral precentral versus dorsolateral regions. These results potentially isolate contextual memory-planning-related processes from subsequent processes such as the evaluation of recollections, which are necessarily dependent on individual probe features. They also demonstrate that contextual remembering recruits multiple, functionally distinct PFC processes.

Neural mechanisms mediating optimism bias

Tali Sharot, Alison M. Riccardi, Candace M. Raio, and Elizabeth A. Phelps

Nature 450:102-105 (2007)

Human expect positive events in the future even when there is no evidence to support such expectations. For example, people expect to live longer and be healthier than average, they underestimate their likelihood of getting a divorce, and overestimate their prospects for success on the job market. We examined how the brain generates this pervasive optimism bias. Here we report that this tendency was related specifically to enhanced activation in the amygdale and in the rostral anterior cingulate cortex when imagining positive future events relative to negative ones, suggesting a key role for areas involved in monitoring emotional salience in mediating the optimism bias. These are the same regions that show irregularities in depression, which has been related to pessimism. Across individuals, activity in the rostral anterior cingulate cortex was correlated with trait optimism. The current study highlights how the brain may generate the tendency to engage in the projection of positive future events, suggesting that the effective integration and regulation of emotional and autobiographical information supports the projection of positive future events in healthy individuals, and is related to optimism.

Neural events that underlie remembering something that never happened

Brian Gonsalves and Ken A. Paller

Nature Neuroscience 3:1316-1321 (2000)

We induced people to experience a false-memory illusion by first asking them to visualize common objects when cued with the corresponding word; on some trials, a photography of the object was presented 1800 ms after the cued word. We then tested their memory for the photographs. Posterior brain potentials in response to words at encoding were more positive if the corresponding object was later falsely remembered as a photography. Similar brain potentials during the memory test were more positive for true than for false memories. These results implicate visual imagery in the generation of false memories and provide neural correlates processing differences between true and false memories.

Augmenting mental chronometry: The P300 as a measure of stimulus evaluation time

Marta Kutas, Gregory McCarthy, and Emanuel Donchin

Science 197:792-795 (1977)

A technique for measuring the latency of the P300 component of event-related brain potentials on individual trials is described. Choice reaction times and the latency of P300 were compared under speed-maximizing and under accuracy-maximizing instructions. The choice stimuli required different levels of semantic categorization. The data support the proposition that the latency of P300 corresponds to stimulus evaluation time and is independent of response selection.

Source of dual-task interference: Evidence from human electrophysiology

Steven J. Luck

Psychological Science 9:223-227 (1998)

When an individual attempts to perform two tasks at the same time, the tasks often interfere with each other. This interference has been studied for several decades with the psychological refractory period paradigm, in which two targets that require independent responses are presented on each trial, separated by a variable delay period, interference typically takes the form of increased response times for the second target at short interstimulus delays. The present study used electrophysiological recordings to determine whether a specific index of perception and categorization (the P3 wave) is delayed in the same manner as response times. Although response times for the second target were found to be greatly delayed at short interstimulus interval, the P3 wave was not substantially delayed. This finding indicates that there was minimal interference during target identification and categorization and that the prolongation of response times in this paradigm primarily reflects a delay in a relatively late process such as response selection.

Time course of word identification and semantic integration in spoken language

Cyma Van Petten, Seana Coulson, Susan Rubin, Elena Plante, and Marjorie Parks

Journal of Experimental Psychology: Learning, Memory and Cognition 25:394-417 (1999)

The minimum duration signal necessary to identify a set of spoken words was established by the gating technique; most words could be identified before their acoustic offset. Gated words were used as congruent and incongruent sentence completions, and isolation points established in the gating experiment were compared with the time course of semantic integration evident in event-related brain potentials. Differential N400 responses to contextually appropriate and inappropriate words were observed about 200 ms before the isolation point. Semantic processing was evident before the acoustic signal was sufficient to identify the words uniquely. Results indicate that semantic integration can begin to operate with only partial, incomplete information about word identity. Influences of semantic constraint, word frequency, and rate of presentation are described.

Brain activity during speaking: From syntax to phonology in 40 milliseconds

Miranda van Turennout, Peter Hagoort, Colin M. Brown

Science 280:572-574 (1998)

In normal conversation, speakers translate thoughts into words at high speed. To enable this speed, the retrieval of distinct types of linguistic knowledge has to be orchestrated with millisecond precision. The nature of this orchestration is still largely unknown. This report presents dynamic measures of the real-time activation of two basic types of linguistic knowledge, syntax and phonology. Electrophysiological data demonstrate that during noun-phrase production speakers retrieve the syntactic gender of a noun before its abstract phonological properties. This two-step process operates at high speed: the data show that phonological information is already available 40 millisecond after syntactic properties have been retrieved.

A structural-functional basis for dyslexia in the cortex of Chinese readers

Wai Ting Siok, Zhendong Niu, Zhen Jin, Charles A. Perfetti and Li Hai Tan

PNAS 105:5561-5566 (2008)

Developmental dyslexia is a neurobiologically based disorder that affect ~5-17％ of school children and is characterized by a severe impairment in reading skill acquisition. For readers of alphabetic (e.g., English) language, recent neuroimaging studies have demonstrated that dyslexia is associated with weak reading-related activity in left temporoparietal and occipitotemporal regions, and this activity difference may reflect reductions in gray matter volume in these areas. Here, we find different structural and functional abnormalities in dyslexic readers of Chinese, a non-alphabetic language. Compared with normally developing controls, children with impaired reading in logographic Chinese exhibited reduced gray matter volume in a left middle frontal gyrus region previously shown to be important for Chinese reading and writing. Using functional MRI to study language-related activation of cortical regions in dyslexics, we found reduced activation in this same left middle frontal gyrus region in Chinese dyslexics versus controls, and there was a significant correlation between gray matter volume and activation in the language task in this same area. By contrast, Chinese dyslexics did not show functional or structural (i.e., volumetric gray matter) differences from normal subjects in the more posterior brain systems that have been shown to be abnormal in alphabetic-language dyslexics. The results suggest that the structural and functional basis for dyslexia varies between alphabetic and nonalphabetic languages.

A decrease in brain activation associated with driving when listening to someone speak

Marcel Adam Just, Timothy A. Keller and Jacquelyn Cynkar

Brain Research 1205:70-80 (2008)

Behavioral studies have shown that engaging in a secondary task, such as on talking on a cellular telephone, disrupts driving performance. This study used functional magnetic resonance imaging (fMRI) to investigate the impact of concurrent auditory language comprehension on the brain activity associated with a simulated driving task. Participants steered a vehicle along a curving virtual road, either undisturbed or while listening to spoken sentences that they judged as true or false. The dual-task condition produced a significant deterioration in driving accuracy caused by the processing of the auditory sentences. At the same time, the parietal lobe activation associated with spatial processing in the undisturbed driving task decreased by 37% when participants concurrently listened to sentences. The findings show that language comprehension performed concurrently with driving draws mental resources away from the driving and produced deterioration in driving performance, even when it does not require holding or dialing a phone.

Attending to the execution of a complex sensorimotor skill: Expertise differences, choking, and slumps

Rob Gray

Journal of Experimental Psychology: Applied 10:42-54 (2004)

A simulated baseball batting task was used to compare the relative effects of attending to extraneous information (tone frequency) and attending to skill execution (direction of bat movement) on performance and swing kinematics and to evaluate how these effects differ as a function of expertise. The extraneous dual task degraded batting performance in novices but had no significant effect on experts. The skill-focused dual task increased batting error and movement variability for experts but had no significant effect on novice. For expert batters, accuracy in the skill-focused dual task was inversely related to the current level of performance. Expert batters were significant more accurate in the skill-focused dual task when placed under pressure. These findings indicate that the attentional focus varies substantial across and within performers with different levels of expertise.

Reading senseless sentences: Brain potentials reflect semantic incongruity

Marta Kutas and Steven A. Hillyard

Science 207:203-205 (1980)

In a sentence reading task, words that occurred out of context were associated with specific types of event-related potentials. Word that were physically aberrant (larger than normal) elicited a late positive series of potentials, whereas semantically inappropriate words elicits a late negative wave (N400). The N400 wave may be an electrophysiological sign of the “reprocessing” of semantically anomalous information.

Amnesia is a deficit in relational memory

Jennifer D. Ryan, Robert R. Althoff, Stephen Whitlow, and Neal J. Cohen

Psychological Science 11:454-461 (2000)

Eye movements were monitored to assess memory for scenes indirectly (implicitly). Two eye movement-based memory phenomena were observed: (a) the repetition effect, a decrease in sampling of previously viewed scenes compared with new scenes, reflecting memory for those scenes, and (b) the relational manipulation effect, an increase in viewing of the regions where manipulations of relations among scene elements had occurred. In normal control subjects, the relational manipulation effect was expressed only in the absence of explicit awareness of the scene manipulations. Thus, memory representations of scenes contain information about relations among elements of the scenes, at least some of which is not accessible to verbal report. But amnesia patients with severe memory impairment failed to show the relational manipulation effect. Their failure to show any demonstrable memory for relations among the constituent elements of scenes suggests that amnesia involves a fundamental deficit in relational (declarative) memory processing.

The Neural correlates of conceptual and perceptual false recognition

Rachel J. Garoff-Eaton, Elizabeth A. Kensinger and Daniel L. Schacter

Learning & Memory 14:684-692 (2007)

False recognition, broadly defined as a claim to remember something that was not encountered previously, can arise for multiple reasons. Foe instance, a distinction can be made between conceptual false recognition (i.e., false alarms resulting from semantic or associative similarities between studied and tested items) and perceptual false recognition (i.e., false alarms resulting from physical similarities between studied and tested items). Although false recognition has been associated with frontal cortex activity, it is unclear whether this frontal activity can be modulated by the precise relationship between studied and falsely remembered items. We used event-related fMRI to examine the neural basis of conceptual compared with perceptual false recognition. Results revealed preferential activity in multiple frontal cortex regions during conceptual false recognition, which likely reflected increased semantic processing during conceptual (but not perceptual) memory errors. These results extend recent reports that different types of false recognition can rely on dissociable neural substrates, and they indicate that the frontal activity that is often observed during false compared with true recognition can be modulated by the relationship between studied and tested items.

Age-related changes in cognitive conflict processing: An event-related potential study

Ralph Mager, Alex H. Bullinger, Serge Brand, Maria Schmidlin, Heinz Sch¨arli, Franz M¨uller-Spahn, Robert St¨ormer, Michael Falkenstein

Neurobiology of Aging 28:1925-1935 (2007)

Cognitive tasks involving conflicting stimuli and responses are associated with an early age-related decline in performance. Conflict and conflict-induced interference can be stimulus- or response-related. In classical stimulus-response compatibility tasks, such as the Stroop task, the event-related potential (ERP) usually reveals a greater negativity on incongruent versus congruent trials which has often been linked with conflict processing. However, it is unclear whether this negativity is related stimulus- or response-related conflict, thus rendering the meaning of age-related changes inconclusive. In the present study, a modified Stroop task was used to focus on stimulus-related interference processes while excluding response-related interference. Since we intended to study work-relevant effects ERP and performance were determined in young (about 30 years old) and middle-aged (about 50 years old) healthy subjects (total n=80). In the ERP, a broad negativity developed after incongruent versus congruent stimuli between 350ms and 650ms. An age-related increase of the latency and amplitude of this negativity was observed. These results indicate age-related alterations in the processing of conflicting stimuli already in middle age.

Common and distinct neural substrates of attentional control in an integrated Simon and spatial Stroop task as assessed by event-related fMRI

Xun Liu, Marie T. Banich, Benjamin L. Jacobson, and Jody L. Tanabe

NeuroImage 22: 1097-1106 (2004)

The purpose of this experiment was to directly examine the neural mechanism of attentional control involved in the Simon task as compared to a spatial Stroop task using event-related fMRI. The Simon effect typically refers to the interference people experience when there is a stimulus-response conflict. The Stroop effect refers to the interference people experience when two attributes of the same stimulus conflict with each other. Although previous imaging studies have compared the brain activation for each of these tasks performed separately, none had done so in an integrated task that incorporates both types of interference, as was done in the current experiment. Both tasks activated brain regions that serve as a source of attentional control (dorsolateral prefrontal cortex) and posterior regions that are sites of attentional control (the visual processing stream-middle occipital and inferior temporal cortices). In addition, there were also specific brain regions activated to a significantly greater degree by one task and/or only by a single task. The brain regions significantly more activated by the Simon task were those sensitive to detection of response conflict, response selection, and planning (anterior cingulated cortex, supplementary motor areas, and precuneus), and visuospatial motor association areas. In contrast, the region significantly more activated by the Stroop task were those involved in biasing the processing toward the task-relevant attribute (inferior parietal cortex). These findings suggest that the interference effects of these two tasks are caused by different types of conflict (stimulus-response conflict for the Simon effect and stimulus-stimulus conflict for the Stroop effect) but both invoke similar sources of top-down modulation.

Not all false memories are created equal: The neural basis of false recognition

Rachel J. Garoff-Eaton , Scott D. Slotnick and Daniel L. Schacter

Cerebral Cortex 16:1645-1652 (2006)

False recognition, a type of memory distortion where one claims to remember something that never happened, can occur in response to items that are similar but not identical to previous seen items (i.e., related false recognition) or in response to novel items (i.e., unrelated false recognition). It is unknown whether these 2 types of memory errors arise from the same or distinct neural substrates. Using functional magnetic resonance, we compared the neural activity associated with true recognition, related false recognition, and unrelated false recognition for abstract shapes. True recognition and related false recognition were associated with similar patterns of neural activity, including activity in the prefrontal cortex, the parietal cortex, and the medial temporal lobe. By contrast, unrelated false recognition was associated with activity in language-processing regions. These results indicate that false recognition is not a unitary phenomenon, but rather can reflect the operation of 2 distinct cognitive and neural processes.

Stimulus context modulates competition in human extrastriate cortex

Diane M Beck and Sabine Kastner

Nature Neuroscience 8:1110-1116 (2005)

When multiple stimuli appear simultaneously in the visual field, they are not processed independently, but rather interact in a mutually suppressive way, suggesting that they compete for neural representation in visual cortex. The biased competition model of selective attention predicts that the competition can be influenced by both top-down and bottom-up mechanisms. Directed attention has been shown to bias competition in favor of the attended stimulus in extrastriate cortex. Here, we show that suppressive interactions among multiple stimuli are eliminated in extrastriate cortex when they are presented in the context of pop-out displays, in which a single item differs from the others, but not in heterogeneous displays, in which all items differ from each other. The pop-out effects seemed to originate in early visual cortex and were independent of attention top-down control, suggesting that stimulus context may provide a powerful influence on neural competition in human visual cortex.

Content-specificity of the neural correlates of recollection

C. Chad Woodruff, Jeffrey D. Johnson, Melina R. Uncapher, Michael D. Rugg

Neuropsychologia 43:1022–1032 (2005)

It is widely assumed that episodic retrieval (recollection) involves reinstatement of cortical activity engaged during the processing of an episode when it was initially experienced. It follows from this assumption that the cortical correlates of recollection should differ with the content of what is recollected, and that retrieval of different content should be associated with activity in functionally distinct cortical regions. The present experiment investigated these predictions. Subjects (N=17) studied a mixed list of words and pictures and were then presented with a test list comprised of words only. Test items were studied words, the names of studied pictures, and unstudied (new) words. Functional magnetic resonance images were acquired while the subjects made Remember/Know/New judgments to these words. Independent of study material, studied items endorsed as Remembered elicited greater activity than correctly classified unstudied items in several regions, including left frontal, left lateral parietal, and posterior cingulated cortex. In addition, Remembered items elicited greater activity in the right hippocampus and parahippocampal gyrus than items accorded Know judgments, replicating previous findings. Analysis of content-specific effects demonstrated a regional double-dissociation within left fusiform cortex; recollected words elicited greater activity than recollected pictures in lateral fusiform, whereas the reverse effect was evident in an anterior fusiform region. The lateral and anterior fusiform areas correspond closely to areas held to be functional specialized for the processing of visual words and pictures, respectively. Thus, the current findings support the cortical reinstatement hypothesis of episodic retrieval.

Recollection and the reinstatement of encoding-related cortical activity

Jeffrey D. Johnson and Michael D. Rugg

Cerebral Cortex 17:2507-2515 (2007)

The neural correlates of episodic memory retrieval (“recollection”) differ according to the type of information contained in the recollected episode. Such content-specific recollection effects have been hypothesized to reflect the reinstatement of processes or representations active during encoding. Using event-related functional magnetic resonance imaging, we evaluated this hypothesis by directly contrasting the neural activity elicited during the encoding and subsequent recollection of words studied with one of the 2 encoding tasks. Study words appearing on pictures of scenes required imaging the word’s referent at any location within the scene, whereas words appearing on a blank background required generating a sentence that incorporated the word. On a later memory test, the neural correlates of recollection were operationalized by contrasting the activity elicited during “remember” versus “know” responses. Recollected words from the “scene” task elicited activity in regions of left occipital cortex and anterior fusiform gyrus that overlapped regions where encoding-related activity was greater for the scene than sentence task. Conversely, activity elicited by words recollected from the “sentence” task overlapped with a region of ventromedial frontal cortex where encoding-related activity was greater for the sentence task. These content-specific associations between encoding- and recollection- related neural activity strongly support the reinstatement hypothesis of episodic retrieval.

A voice region in the monkey brain

Christopher I Petkov, Christoph Kayser, Thomas Steudel, Kevin Whittingstall, Mark Augath and Nikos K Logothetis

Nature Neuroscience 11:367-374

For vocal animals, recognizing species-specific vocalization is important for survival and social interactions. In human, a voice region has been identified that is sensitive to human voices and vocalizations. As this region also strongly responds to speech, it is unclear whether it is tightly associated with linguistic processing and is thus unique to humans. Using functional magnetic resonance imaging of macaque monkeys (Old World primates, Macaca mulatta) we discovered a high-level auditory region that prefers species-specific vocalizations over other vocalization and sounds. This region not only showed sensitivity to the “voice” of the species, but also to the vocal identity of conspecific individuals. The monkey voice region is located on the superior-temporal plane and belongs to an anterior auditory “what” pathway. These results establish functional relationships with the human voice region and support the notion that, for different primate species, the anterior temporal regions of the brain are adapted for recognizing communication signals from conspecifics.

Neural correlates of conceptual implicit memory and their contamination of putative neural correlates of explicit memory

Joel L. Voss and Ken A. Paller

Learning and Memory 14: 259-267 (2007)

During episodic recognition tests, meaningful stimuli such as words can engender both conscious retrieval (explicit memory) and facilitated access to meaning that is distinct from the awareness of remembering (conceptual implicit memory). Neuroimaging investigations of one type of memory are frequently subject to the confounding influence of the other type of memory, thus posing a serious impediment to theoretical advances in this area. We used minimalist visual shapes (squiggles) to attempt to overcome this problem. Subjective rating of squiggle meaningfulness varied idiosyncratically, and behavioral indications of conceptual implicit memory were evident only for stimuli given higher ratings. These effects did not result from perceptual-based fluency or from explicit remembering. Distinct event-related brain potentials were associated with conceptual implicit memory and with explicit memory by virtue of contrast based on meaningfulness ratings and memory judgments, respectively. Frontal potentials from 300 to 500 msec after the onset of repeated squiggles varied systematically with perceived meaningfulness. Explicit memory was held constant in this contrast, so these potentials were taken as neural correlates of conceptual implicit memory. Such potentials can contaminate putative neural correlates of explicit memory, in that they are frequently attributed to the expression of explicit memory known as familiarity. These findings provide the first neural dissociation of these two memory phenomena during recognition testing and underscore the necessity of taking both types of memory into account in order to obtain valid neural correlates of specific memory functions.

Validation neural correlates of familiarity

Ken A. Paller, Joel L. Voss and Stephan G. Boehm

TRENDS in Cognitive Sciences 11:243-250 (2007)

Familiarity is a pervasive memory phenomenon that occurs in its most basic form when someone recognizes a repeated stimulus without recollecting other aspects of the requisite prior learning episode. Theoretical controversy currently abounds with respect to both the cognitive and neural characteristics of familiarity. Here, we show that the extant data, particular brain-potential data, are insufficient for validating putative neural correlates of familiarity, and we outline strategies for making progress for this problem. Conceptual priming is an implicit-memory phenomenon that often occurs together with familiarity; experiments that conflate the two phenomena can be misleading. Avoiding this conflation is required to understand familiarity and to determine the extent to which the neurocognitive processes that support priming also drive familiarity..

Action-blindsight in healthy subjects after transcranial magnetic stimulation

Mark Schram Christensen, Lasse Kristiansen, James B. Rowe and Jens Bo Nielsen

PNAS 105:1353-1357 (2008)

Clinical cases of blindsight have shown that visually guided movements can be accomplished without conscious visual perception. Here, we show that blindsight can be induced in healthy subjects by using transcranial magnetic stimulation over the visual cortex. Transcranial magnetic stimulation blocked the conscious perception of a visual stimulus, but subjects still corrected an ongoing reaching movement in response to the stimulus. The data show that correction of reaching movements does not require conscious perception of a visual target stimulus, even in healthy people. Our results support previous results suggesting that an efference copy involved in movement correction, and this mechanism seems to be consistent even for movement correction without perception.

Objects are highlighted by spatial attention

A. Martı´nez, W. Teder-Sa¨leja¨rvi, M. Vazquez, S. Molholm, J. J. Foxe, D. C. Javitt, F. Di Russo, M. S. Worden and S. A. Hillyard

Journal of Cognitive Neuroscience 18:298-310 (2006)

Selective attention may be focused upon a region of interest within the visual surroundings, thereby improving the perceptual quality of stimuli at that location. It has been debated whether this spatially selective mechanism plays a role in the attentive selection of whole objects in a visual scene. The relationship between spatial and object-selective attention was investigated here through recording of event-related brain potentials (ERPs) supplemented with functional magnetic brain imaging (fMRI). Subjects viewed a display consisting of two bar-shaped objects and directed attention to sequences of stimuli (brief corner offsets) at one end of one of the bars. Unattended stimuli belonging to the same object as the attended stimuli elicited spatiotemporal patterns of neural activity in the visual cortex closely resembling those elicited by the attended stimuli themselves, albeit smaller in amplitude. This enhanced neural activity associated with object-selective attention was localized by use of ERP dipole modeling and fMRI to the lateral occipital extrastriate cortex. We conclude that object-selective attention shares a common neural mechanism with spatial attention that entails the facilitation of sensory processing of stimuli within the boundaries of an attended object. .

On the transmission of partial information: Inferences from movement-related brain potentials

Allen Osman, Michael G. H. Coles, Emanuel Donchin, Theodore R. Bashore and David E. Meyer

Journal of Experimental Psychology: Human Perception and Performance 18:217-232 (1992)

Results are reported from a new paradigm that uses movement-related brain potentials to detect response preparation based on partial information. The paradigm uses a hybrid choice-reaction go/nogo procedure in which decisions about response hand and whether to respond are based on separate stimulus attributes. A lateral asymmetry in the movement-related brain potential was found on nogo trials without overt movement. The direction of this asymmetry depended primarily on the signaled response hand rather hand on properties of the stimulus. When the asymmetry first appeared was influenced by the time required to select the signaled hand, and when it began to differ on go and nogo trials was influenced by the time to decide whether to respond. These findings indicate that both stimulus attributes were processed in parallel and that the asymmetry reflected preparation of the response hand that began before the go/nogo decision was completed.

Talking across time: Using reported speech as a communicative resource in amnesia

Melissa C. Duff, Julie Hengst, Daniel Tranel and Neal J. Cohen

Aphasiology 21:702-716 (2007)

Patients with amnesia may have more than pure memory deficits, as evidenced by reports of subtle linguistic impairments on formal laboratory tasks in the amnesia patients HM. However, little attention has been given to the impact of memory impairments on language use in regular, colloquial interactions. We analysed reported speech use by individuals with amnesia. Reported speech (RS), in which speakers represent thoughts/words from another time and/or place, requires management of two temporal frames, making it an interesting discourse practice in which to explore the impact of memory deficits on interactional of communication. This study: (1) documents frequency, type, and temporal contexts of reported speech used in discourse sample; (2) compares reported speech use by amnesic and comparison participants; (3) examines the interactional character of reported speech use in these discourse samples. Derived from a broader study of the discourse practices of individuals with amnesia, this study uses quantitative group comparisons and close discourse analysis to analyse reported speech episodes (RSEs) in interactional discourse samples between a clinician and each of 18 participants, 9 individuals with amnesia and 9 comparison participants (NC). Reported speech was used by all participants. However, significantly fewer RSEs were produced in amnesia sessions (273) than NC sessions (554). No significant group differences were observed for type or temporal domain. In addition, for the participant with amnesia, post-amnesia past RSEs differed qualitatively from the other RSEs in the data. These findings have important implications for understanding the interdependent relationship of memory and language, point to the value of examining interactional aspects of communication in the empirical study of brain-behaviour relationships, and reconceptualise interaction as a target in the remediation of functional communication following brain injury.

Development of shared information in communication despite hippocampal amnesia

Melissa C. Duff, Julie Hengst, Daniel Tranel and Neal J. Cohen

Nature Neuroscience 9:140-146 (2006)

This study investigated the ability of individuals with amnesia to acquire referential labels across a series of collaborative, dynamic interactions with a communication partner. Despite their inability to learn arbitrary relations in paired-associate learning, the amnesia patients showed remarkably robust collaborative learning across trials, at a rate equal to that of normal comparison subjects. The amnesic participants’ learning resulted in their arriving at labels for a set of abstract shapes (tangrams), thus facilitating rapid and efficient communication. The labels generated and used by the amnesics during interactions with their partners became simpler across trials, with most labels stabilizing long before the end of training and then being used consistently throughout; moreover, they endured long after the task had ended. These findings have important implications for understanding the memory system involved in semantic learning and in acquiring shared knowledge (‘common ground’) among communication partners, and the nature of hippocampal-dependent versus hippocampal-independent learning.

Superior auditory spatial tuning in conductors

Münte TF, Kohlmetz C, Nager W, Altenmüller E.
Nature 409:580 (2001)

This study provide evidence from brain-potential recordings that experienced professional conductors develop enhanced auditory localization mechanism in peripheral space..

Improved auditory spatial tuning in blind humans

Röder B, Teder-Sälejärvi W, Sterr A, Rösler F, Hillyard SA, Neville HJ.

Nature 400:162-166 (1999)

Despite reports of improved auditory discrimination capabilities in blind human and visually deprived animals, there is no general agreement as to the nature of pervasiveness of such compensatory sensory enhancements. Neuroimaging studies have pointed out differences in cerebral organization between blind and sighted humans, but the relationship between these altered cortical activation patterns and auditory sensory acuity remains unclear. Here we compare behavioral and electrophysiological indices of spatial tuning within central and peripheral auditory space in congenitally blind and normally sighted but blindfolded adults to test the hypothesis (raised by earlier studies of the effects of auditory deprivation on visual processing) that the effects of visual deprivation might be more pronounced for processing peripheral sounds. We find that blind participants displayed localization abilities that were superior to those of sighted controls, but only when attending to sounds in peripheral auditory space. Electrophysiological recordings obtained at the same time revealed sharper tuning of early spatial attention mechanism in the blind subjects. Differences in the scalp distribution of brain electrical activity between the two groups suggest a compensatory reorganization of brain areas in the blind that may contribute to the improved spatial resolution for peripheral sound sources.

Attention to central and peripheral visual space in a movement detection task. III.

Helen J. Neville and Donald Lawson

Brain Research 2:284-294(1987)

We employed event-related potentials (ERPs) and measures of signal detectability to compare attention to peripheral and central visual stimuli in normal hearing subjects who were born to deaf parents (HD Ss) and whose first language was American Sign Language (ASL). The results were compared with those obtained from normal hearing Ss and congenitally deaf Ss. in the same paradigm. Task performance and ERPs during attention to the foveal region were similar in the 3 groups. In contrast, with attention to the peripheral stimuli the deaf Ss displayed attention effects over the occipital regions of both hemispheres that were several times larger than those in the hearing and the HD Ss. However, both HD and deaf Ss displayed lateral asymmetries in behavior and ERPs that were opposite in direction to those of the hearing Ss. Whereas hearing Ss detected the direction of target motion better when it occurred in the left visual field, deaf and HD Ss performed better for right visual fields targets. Consistent with these results, the amplitude of the attention-related increases in the ERPs were larger from temporal and parietal regions of the right than the left hemisphere in hearing Ss, but were larger from the left than the right hemisphere in both HD and the deaf Ss. These results suggest that auditory deprivation and the acquisition of a visual language have marked and different effects on the development of cortical specialization in humans..