Seventh Annual Meeting of ISBN

June 30 – July 4, 1999

Santorini, Greece

ABSTRACTS

SYMPOSIUM I: SINGLE EVENT fMRI

SINGLE EVENT FMRI – A BRIEF OVERVIEW

Philip Servos, Department of Psychology, Wilfrid Laurier University, Waterloo, Ontario, Canada

Traditional functional magnetic resonance imaging (fMRI) studiesgenerate static maps of brain function. Technological advancements have made it possible to image single trials of perceptual and cognitive tasks with high temporal resolution — producing dynamic maps of brain function. In this symposium recent applications of event-related fMRI to questions about human memory, motor control, visual cognition, and auditory processing will bepresented. Limitations of the methods as well as the experimental avenues that may become possible several years in the future will also be discussed.

EVENT-RELATED FUNCTIONAL MRI: IMPLICATIONS FOR COGNITIVE PSYCHOLOGY

Mark D’Esposito, Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA

Functional magnetic resonance imaging (fMRI) has rapidly emerged as a powerful technique in cognitive neuroscience. I will describe and critique a new class of imaging experimental designs called event-related fMRI that exploit the temporal resolution of fMRI by modeling fMRI signal changes associated with behavioral trials as opposed to blocks of behavioral trials. Advantages of this method are the ability to randomize trial presentations and test for functional correlates of behavioral measures with greater power. We also discuss some more refined advantages of event-related fMRI designs. These include the abilities to I) directly examine the neural correlates of temporally dissociable components of behavioral trials (e.g., the delay period of a working memory task) and ii) test for differences in the onset time of neural activity evoked by different trial types. We argue that event-related fMRI designs overcome several limitations of blocked designs for testing hypotheses regarding the neural basis of behavior. As a result, event-related fMRI has the potential to address a number of cognitive neuroscience and psychology questions with a degree of inferential and statistical power not previously available.

SKETCHING THE FUNCTIONAL NEUROARCHITECTURAL BLUEPRINTS OF WORKING MEMORY WITH EVENT-RELATED FMRI

Brad Postle, Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA

Elucidation of the cognitive and neural architectures underlying human working memory has been an important focus of cognitive neuroscience for much of the past decade. Two conclusions that arise from this research are that working memory, a faculty that enables temporary storage and manipulation of information in the service of behavioral goals, can be viewed as neither a unitary, nor a dedicated system. For example, a review of the neuropsychological literature has confirmed that performance on tests of immediate serial recall for verbal and spatial stimuli (i.e., memory “span”), widely accepted as indices of working memory capacity, is not impaired by damage to the prefrontal cortex (PFC; ‘Esposito & Postle, in press), a fact that stands in apposition to the overwhelming evidence from functional neuroimaging research that working memory function is associated with PFC activation. I will present the results of event-related fMRI experiments testing several hypotheses about the functional architecture of working memory. Some of our work has demonstrated that the processes supporting the strictly mnemonic demands of a working memory task can be dissociated anatomically from the processes supporting the nonmnemonic control demands of the same task. Other experiments assess the dissociability of executive control processes contributing to working memory performance, and the response of PFC to different components of a working memory trial.

EVENT-RELATED fMRI IN MEMORY AND THOUGHT

John Gabrieli, Department of Psychology, Stanford University, Stanford, California, USA

Event-related fMRI studies provide a new tool for exploring brain-behavior relations via functional neuroimaging. I will report on two studies that exploited event-related fMRI in efforts to elucidate the neural bases of (1) the encoding of experience into long-term declarative memory and (2) integrative reasoning processes. In the first study, subjects studied color scenes while being scanned and later received a recognition memory test. Analyses revealed that the magnitudes of activation in parahippocampal and frontal regions during encoding correlated positively with subsequent recognition accuracy for specific scenes. In the second study, subjects performed reasoning tasks that involved one relation or two relations (the latter problems required integration of relations). The ability to use the subjects’ trial-by-trial response times permitted an analysis that was less prone to trial duration (or duty cycle) than blocked designs. These duty cycle differences can be especially large for reasoning problems that require long response periods and can vary considerably across problems of different complexity.

EVENT-RELATED fMRI OF THE AUDITORY CORTEX

Pascal Belin, Robert J. Zatorre, Rick Hoge, Alan C. Evans, & Bruce Pike Neuropsychology/Cognitive Neuroscience Unit and McConnell Brain Imaging Center, Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada

The event-related design was adapted to allow auditory fMRI studies minimally affected by the echo-planar noise artifact; a long time interval (TR=10 sec) between each cerebral volume acquisition was combined with stroboscopic acquisition of data, and event-related curves were reconstructed with a 1 sec resolution. Time-course of the cerebral hemodynamic response to a target auditory stimulus was measured in five individual subjects using this method. Clear bell-shaped event-related responses were observed bilaterally in all individuals in primary auditory cortex (A1) as well as in laterally extending secondary cortical fields. Group-average event-related curves attained their maxima (0.5-0.7%) 3 sec after stimulus onset in A1 (4 sec for more anterior and lateral regions of auditory cortex), and signal had returned to baseline level 6 sec after stimulus onset. The stroboscopic event-related method appeared effective in minimizing effects of the interaction between scanning noise and experimental auditory stimulation; it provides a new tool for exploring auditory function in human with high spatial and temporal resolution, while allowing presentation of auditory stimuli on a silent background.

FUNCTIONAL MAGNETIC RESONANCE IMAGING OF THE HUMAN BRAIN WITH HIGH TEMPORAL RESOLUTION

Wolfgang Richter, National Research Council, Winnipeg, Manitoba, Canada

Even though the first functional magnetic resonance imaging (fMRI) experiment was performed only a few years ago (in 1992), this method has become the premier tool to measure the function of the human brain. fMRI is noninvasive, and experiments can be performed on most clinical MRI machines. While fMRI has exquisite spatial resolution, it falls behind electrophysiological methods in temporal resolution, as it measures only a secondary effect of neuronal activity (the blood oxygen concentration). One focus of our research is to improve the temporal resolution such that sequential neuronal activity during a single cognitive task can be distinguished from simultaneous neuronal activity. We have developed a conceptually new method called time-resolved fMRI; in this method, the temporal resolution may be improved by an order of magnitude from traditional experiments. Time-resolved fMRI makes few assumptions to the hemodynamic response, but relies on a series of single-trial experiments. We have measured neuronal activity by this method in various cognitive and movement tasks. One example is Shepard and Metzler’s Mental Rotation task of spatial perception; we showed that cortical motor areas are active during the performance of this imagined rotation.

EXPLOITING TEMPORAL AND SPATIAL RESOLUTION IN FMRI. EXPERIENCES AT 4 TESLA

Ravi S. Menon, The John P. Robarts Research Institute, London, Ontario, Canada

A large body of research in human perception and cognition has been concerned with the segregation of mental events into their presumed hierarchical processing stages, the temporal aspect of such processing being termed ‘mental chronometry’. Advances in single-event functional magnetic resonance imaging (fMRI) have allowed the extraction of relative timing information between the onset of activity in different neural substrates as well as the duration of cognitive processing during a task, offering new opportunities in the study of human perception and cognition. Single-event fMRI studies have also facilitated increased spatial resolution in fMRI, allowing studies of columnar organization in humans. Important processes such as object recognition, binocular vision and other processes are thought to be organized at the columnar level; thus, these advances in the spatial and temporal capabilities of fMRI allow a new generation of cognitive and basic neuroscience studies to be performed, investigating the temporal and spatial relationships between these cortical sub-units. Such experiments bear a closer resemblance to single-unit or evoked-potential studies than to classical static brain activation maps and might serve as a bridge between primate electrophysiology and human studies. We will review the basic principles underlying these developments and give some examples.

PAPER SESSION I (Traditional)

THE EFFECT OF NOVEL H3-RECEPTOR ANTAGONISTS ON COGNITIVE FUNCTION IN RATS.

Muir, J.L. School of Psychology, Cardiff University, Wales U.K.

Recently, interest has developed in the therapeutic potential of histamine H3-receptor antagonists for the treatment of cognitive dysfunction in Alzheimer’s disease (AD), as histaminergic neurons appear to be largely spared in AD. We have now assessed the H3-antagonist strategy in rats using Ciproxifan, a compound enhancing histamine release in brain with increased potency than previous antagonists and Compound 421, a compound possibly even more potent. Lesion-induced impairments on attentional tasks (5-choice serial reaction time task and a vigilance paradigm) were significantly improved following administration of the histaminergic compounds. In contrast, such compounds were ineffective in improving the short term memory deficit observed in normal animals on the delayed nonmatching-to-position task. Therefore, the results at the present time suggest that these histaminergic antagonists may have a role in enhancing attentional function.

DISCONNECTING HIPPOCAMPAL PROJECTIONS TO THE ANTERIOR THALAMUS PRODUCES DEFICITS ON TESTS OF SPATIAL MEMORY IN RATS

John P. Aggleton, E. Clea Warburton, and Janice L. Muir, School of Psychology, Cardiff University, Wales, UK

A disconnection procedure tested whether projections from the hippocampus to the anterior thalamic nuclei, via the fimbria-fornix, form functional components of a spatial memory system. The behavioural effects of combined unilateral lesions of the anterior thalamic nuclei (AT) and fimbria-fornix (FX) were compared when they were either in contralateral hemispheres (AT-FX Contra) or the same hemisphere (AT-FX Ipsi). Other groups received bilateral FX lesions and SHAM surgeries. Experiment 1 found that the FX group was severely impaired on a spatial T-maze alternation task, but that both the AT-FX Ipsi and AT-FX Contra groups were mildly and comparably impaired. In Experiment 2 we tested whether spared crossed projections might have supported spatial performance in the AT-FX Contra group. We therefore combined the crossed lesion with transection of the hippocampal commissure. This combination of lesions (AT-FX Contra + Hpc Comm) produced a clear disruption of spatial memory performance in the water maze, T-maze, and radial arm maze that was signficantly greater than that produced by ipsilateral and contralateral AT-FX lesions alone. These results support the notion that disconnection of the anterior thalamic nuclei from their hippocampal inputs produces impairments on a range of spatial tasks, but indicates that there are an array of different routes that can subserve this function. These findings may have implications for the interactions of medial temporal lobe and medial diencephalic structures for a broader array of memory functions.

FORMAT-SPECIFICITY IN THE ORGANIZATION OF EPISODIC MEMORY FOR COMMON OBJECTS: DOES THE BRAIN TREAT PICTURES AND WORDS DIFFERENTLY?

Stephen Kohler, Cognitive Neuroscience Unit, Montreal Neurological Institute, McGill University, Montreal Canada.

In the present PET study, we examined brain activity related to processing of pictures and printed words in episodic memory. Our goal was to determine how the perceptual format of objects is reflected in the neural organization of episodic memory for common objects. We investigated this issue in relation to encoding and retrieval with a particular focus on medial temporal-lobe (MTL) structures. At encoding, participants saw pictures of objects or their written names and were asked to make semantic judgments. At retrieval, participants made yes-no recognition judgments in four different conditions. In two conditions, target items were pictures of objects previously encoded as pictures or as words. In two other conditions, target items were words denoting objects previously encoded as words or pictures. Our results indicate that right MTL structures are differentially involved in picture processing during encoding and recognition. A posterior MTL region showed higher activation in response to pictures than to words across all conditions. At retrieval, this region seems to play a role in ecphory processes that are driven by the perceptual input, i.e. the retrieval cue. We found suggestive evidence that another more anterior right MTL region is involved in accessing stored picture-specific information regardless of whether the retrieval cue is pictorial in nature. Our data indicate that left MTL structures contribute to picture processing only during encoding. Some regions in the left MTL showed an involvement in semantic encoding that is picture specific; others showed an involvement across pictures and words. Our results provide no evidence for format-specific activation related to processing of words in MTL regions. Although left MTL regions were found to be involved in semantic encoding of words, this involvement does not appear to be word-specific. These data provide support for the notion that there are not only differences in the memory contributions of MTL regions across but also within the two hemispheres.

THE OPPOSITE OF HM: ISOLATED RETROGRADE AMNESIA AFTER THALAMIC INFARCTION

Laurie Miller, Diana Caine, John Watson, Neuropsychology Unit, Royal Prince Alfred Hospital, University of Sydney, Sydney AUSTRALIA

Case JG is a 34 year-old, right handed man of average range intelligence who developed a dense retrograde amnesia for the whole of his life in conjunction with a bilateral (right>left) postero-medial thalamic infarction. In addition to an inability to recall or recognise his own autobiographical details, he displays severe deficits in the recognition of famous faces, famous names and well known events. Patchy memory for some more recent, pre-morbid world events and some autobiographical material suggests a partial reverse temporal gradient. Most aspects of JG’s anterograde memory, executive functioning, visual imagery, procedural memory and sematic knowledge remain completely intact. This extensive, isolated retrograde amnesia in the context of a well-defined neurological event and highly circumscribed lesion on MRI indicate a critical role for the postero-medial thalamus in the ability to search for cortically stored long-term memories.

CONTRIBUTION OF RETINOTOPIC CORTICAL AREAS TO PERCEPTUAL FILLING-IN

Peter De Weerd, University of Arizona, Dept. Psychology, Tucson AZ, USA..

Psychophysical experiments in humans show that a gray figure surrounded by a dynamic texture, presented away from fixation, becomes filled in with the surrounded texture after several seconds of observation. The time required for filling-in was predicted by the total length of the figure’s boundary in retinotopic visual areas. This suggested that the time required for perceptual filling-in reflects the time required for figure-ground segregation to fail, rather than a slow spread of the texture across the gray figure. In neurophysiological experiments, we correlated the responses of neurons in V2 and V3 with their receptive field (RF) contained within a gray square surrounded by texture with the reports of perceptual filling-in in human subjects, under identical stimulus conditions. The gray square elicited a limited response during the first few seconds of stimulus presentation, but activity then increased to reach a level comparable with that when the RF was physically filled in with the texture. These neuronal activity increases occurred when humans would report filling-in for the same stimulus. Taken together, the data suggest that the neural response increases in V2 and V3 reflect the interpolation of texture across the region occupied by the square figure, after figure-ground segregation failed due to prolonged stabilization of the image.

THE EFFECTS OF V4/TEO LESIONS ON RESPONSES OF MACAQUE AREA TE NEURONS TO TARGETS EMBEDDED IN DISTRACTERS.

G. Bertini, E.A. Buffalo, H. Thakar, B. Jagadeesh, P. De Weerd, R. Desimone and L.G. Ungerleider, Laboratory of Brain and Cognition, Laboratory of Neuropsychology, NIMH, Bethesda MD USA.

It has been shown that directed attention to a behaviorally relevant visual stimulus can overcome the distracting effects of other nearby stimuli, and physiological studies suggest that the critical attentional mechanisms are located in visual areas of the ventral processing pathway. This idea was previously tested in a behavioral study of monkeys with “mosaic” visuotopic lesions of extrastriate areas V4 and TEO, which lead to the hypothesis that the lesions interfered with mechanisms of selective attention that normally improve the neurons’ ability to discriminate between targets by suppressing the influence of the surrounding distracters. As a consequence, the next stage of processing in the ventral pathway, area TE, should receive information about target stimuli that is degraded by the presence of distracters. To test this, we recorded from TE neurons in one of the operated monkeys, while the animal attended to targets presented with and without surrounding distracters. Data from 25 neurons suggest that, in parallel with the behavioral results, the ability of TE neurons to discriminate between targets in the presence of distracters is significantly more impaired when stimuli are presented with the visual quadrants affected by the lesions than in the normal quadrant. These preliminary results are consistent with the hypothesis that V4 and TEO provide a substrate for integrating visual input with an attentional signal that biases the competition among stimuli in favour of those that are behaviorally relevant.

DEVELOPMENTAL CHANGE IN EARLY ERP COMPONENTS DURING FACE PROCESSING

Margot J. Taylor, CERCO – CNRS, Toulouse, France

In neurophysiological studies, a face-specific event-related potential (ERP) (N170) has been identified, largest at posterior temporal leads, which allows the investigation of very early stages of face processing and its development. Recent studies have noted an earlier peak (P120) which has also been suggested to be face-specific. Age-related changes in face processing are reported in the behavioural literature, but with disagreement as to the rate and extent of this development. We compared ERPs evoked by nine categories of stimuli including faces, inverted faces, phase-scrambled faces, eyes-only and flowers in 40 adults and 90 children (4-15yrs), recording from 29 scalp sites. In the adults, N170 latency and amplitude varied with stimulus type, consistent with the literature; P120 did not show the same specificity. The latency of N170 decreased with increasing age, but the rate of change with age differed with stimulus category. The greatest developmental change in latencies was seen with upright faces, and the least with eyes-only stimuli. The N170 amplitude increased with age for inverted faces and decreased with age for eyes; yet, regardless of age, eyes evoked the largest N170. P120 was recorded in children for the facial stimuli, but showed only decreases in latency with age. The topographical distribution of the N170 changed with age; the frontal positivity so evident in adults did not appear until mid teenage years, and only eyes showed a consistent R>L asymmetry. These results suggest that 1) the underlying neural bases associated with processing faces and eyes are different; 2) qualitative rather than quantitative shifts in processing of faces occur with age; and 3) that the P120 is not face-specific.

SYMPOSIUM II: TIMING IN THE BRAIN

MODERATOR: A. A. Benasich

This seminar will explore basic neural mechanisms that mediate temporal information processing in the nervous system and the temporal dynamics of behavior and brain activity. Research relating to serial order in neural activity, temporal vs. spatial timing cues, and the neural processing of time intervals relating to various cortical systems will be discussed. The papers presented will examine topics ranging from the functional structure seen in primary auditory cortex to the impact of processing in the tens of ms time domain on the emergence of language in infants to the role of the cerebellum as a critical neural structure associated with motor timing. Time and the timing of biological and psychological events have long been recognized as the implicit or background framework on which many of the integrative body functions and sensory processes depend. Understanding the role of timing to brain structure and function across and within modalities is critical to understanding how alterations in these functions affect cognition, language, and motor abilities. The talks will progress in a bottom-up fashion from basic cellular mechanisms to higher cognitive function.

FUNCTIONAL MODULES IN PRIMARY AUDITORY CORTEX: IMPLICATIONS FOR TEMPORAL AND SPECTRAL PROCESSING AND PLASTICITY

Heather L. Read, Monty A. Escabi, Lee M. Miller, Jeffery A. Winer and Christoph E. Schreiner, Keck Center for Integrative Neuroscience, UCSF San Francisco, CA, USA.

We describe a functional and anatomic modular structure in primary auditory cortex (AI). The extensive long-range cortical connections and functional subcircuitries we observe in AI are only found in cortices of highly evolved sensory systems (e.g. visual and auditory cortices of cats and primates). Topographic maps of excitatory bandwidths reveal multiple functional modules. Tracer injections into single modules reveal anatomic connections between modules with similar bandwidth properties. These functional and parallel subcircuitries may be important for the extraction of multiple waveforms from the complex auditory scene. The efficiency for extracting temporal versus spectral features from a given sound appears to vary with the bandwidth modules. More direct measures of temporal processing abilities are derived from the spectral temporal transfer functions (STRF) generated with reverse correlation to ripple noise and moving ripple noise stimuli. A brief comparison of STRFs observed at key points in the auditory pathway will be given as this proves an interesting illustration of how temporal information encoding strategies of the brain change from peripheral to central brain structures. Knowledge of these coding strategies could be used to predict the nature of cortical dysfunctions that would result from subcortical defects in temporal extraction or coding. Finally, topographic maps of characteristic frequency and the distribution of bandwidths change with experience and behavioral conditioning. We propose that the functional modules in AI are an important substrate for such plasticity.

AN ANIMAL MODEL FOR IMPAIRED AUDITORY TEMPORAL PROCESSING: RELEVANCE TO DEVELOPMENTAL LANGUAGE IMPAIRMENT

Matthew Clark and R. Holly Fitch, Biobehavioral Sciences Graduate Degree program, University of Connecticut, Storrs, CT, USA

Ongoing behavioral studies have shown that basic auditory processing deficits are highly correlated with impaired speech perception and disrupted language development in children (Tallal, Miller & Fitch,1993), yet the neurobiological substrates underlying these devastating effects are not clearly defined. Conversely, post mortem studies have shown anomalies in the cortex and thalamus of dyslexics (Galaburda et al., 1985,1994), yet direct behavioral correlates to these findings are inferred or retrospectively obtained. We recently integrated these important lines of research via an animal model. Specifically, we showed that adult male rats with developmental cortical malformations like those seen in dyslexic brains exhibit auditory processing deficits strikingly similar to those of language impaired children (Fitch et al., 1994; Fitch et al., 1997; Herman et al.,1997). More recently, we adapted an acoustic startle paradigm to incorporate gap detection and two-tone sequence discrimination tasks, and confirmed our prior findings (Clark et al., submitted). Thus we have an animal model linking known neural and behavioral correlates of developmental language disability, paired with an accurate and efficient auditory processing paradigm. While basic neuroscience research on developmental disabilities has been limited by constraints on the use of invasive procedures with children, coupled with the difficulties inherent to modeling language-related disabilities in animals, our animal model surmounts these difficulties on the premise that language difficulties in children can be associated with basic auditory processing deficits, and these in turn can be studied very effectively in rodents.

THE INFLUENCE OF EFFICIENT PROCESSING OF BRIEF AUDITORY TEMPORAL CUES ON LATER LANGUAGE DEVELOPMENT

April A. Benasich , Center for Molecular & Behavioral Neuroscience, Rutgers, The State University of New Jersey, Newark NJ, USA.

Links between impaired temporal processing abilities and language-based learning disabilities in older children and adults have been well documented. In my laboratory, we have demonstrated that auditory temporal processing (ATP) thresholds can be assessed in the first year of life using a technique comparable to that used in older children (Benasich & Tallal, 1993, 1996). I will discuss research designed to examine the role of temporal processing efficiency in infancy as a critical link to childhood language abilities. In a series of prospective longitudinal studies, we have examined the processing abilities thought to underlie complex sensory perception and emerging language in infants. As a result of these studies a prototype auditory temporal processing (ATP) assessment battery has been constructed that allows recording of consistent and reliable ATP thresholds in normal infants as well as infants at risk for developmental delays. We have demonstrated that we can identify those infants who are poor at processing rapid temporal cues in the auditory domain and that differences in infant discrimination of rapid auditory cues (a critical skill for decoding language) across these studies are strongly and reliably related to differences in language comprehension and production in toddlers. Thus, infants who are poorer processors appear to be the same infants who are at higher risk for language delays. Genetic family history, repeated otitis media episodes early in infancy and/or prematurity may contribute to this risk.

TIMING IN ATTENTIONAL PROCESSING

Marie T. Banich, Michael Milham, Alessandra Pasarotti, Paige Scalf, Kevin Spencer and Daniel Weissman, Dept. of Psychology, University of Illinois at Urbana-Champaign, Champaign, IL, USA.

In this talk I will discuss various ways in which attentional processes in the nervous system are modulated by timing. In the first part of my talk I will illustrate how modulation of attentional control by interhemispheric interaction varies with time. I will illustrate with both behavioral and ERP data, examining phenomena ranging from the effect of distractors on target detection to the attentional blink. In the second part of my talk I will discuss a neural network of attentional control as discerned from fMRI data of Stroop tasks and discuss how the activity of different components can be modified over time with learning and automaticity.

CEREBELLAR CONTRIBUTIONS TO TEMPORAL-MOTOR LEARNING

Virginia Penhune, Neuropsychology Unit, Montreal Neurological Institute, Montreal, Quebec, CANADA

In this talk I will present data from behavioral and PET activation studies demonstrating the possible role of the cerebellum in temporal-motor learning. These findings will be discussed in relation to theories of cerebellar participation in motor skill learning, and in motor and perceptual timing. In addition, the results of a behavioral study of temporal-motor learning will be presented, and the application of this paradigm to future PET and fMRI studies will be discussed.

PAPER SESSION II: (Traditional)

A NEURAL NETWORK FOR ATTENTIONAL CONTROL AS REVEALED BY fMRI STUDIES OF STROOP TASKS

Marie T. Banich, Michael P. Milham, RuthAnn Atchley, Neal J. Cohen, Andrew Webb, Tracey Wszalek, Arthur F. Kramer, Zhi-Pei Liang, Vikram Barad, Dan Gullett, Chiarg Shah & Colin Brown,, Dept. of Psychology, University of Illinois at Urbana-Champaign, Champaign, IL, USA

By using variants of the Stroop task we have illustrated the role of different cortical regions in attentional control. In particular, our work illustrates that prefrontal regions of the brain are most important for creating an attentional set or expectancy for the information to be attended, especially when the attended information is not likely to be processed automatically. In contrast, activity of parietal and extrastriate areas can be modulated by both attended and unattended information, at least when that unattended information is related to attentional expectancies. Finally, we propose (as have others – e.g., Paus et al., 1993) that the anterior cingulate is mainly involved in response selection.

ESTIMATING SAMPLE SIZE FOR FMRI EXPERIMENTS

John E. Desmond, Departments of Radiology & Psychology, Stanford University, Stanford, CA, USA

Determining statistical power in functional MRI experiments requires an estimation of effect size, which in turn requires estimates of expected signal change between experimental and control conditions as well as variability in that signal change. Variability in the signal change is comprised of both between-subject and within-scan variability. Estimation of these parameters and how these estimates can be used to generate power curves will be discussed. These analyses regard subjects as a random rather than fixed factor and are therefore appropriate for making inferences from the sample to the population. From these investigations it appears that a point of diminishing returns is achieved after approximately 200 frames/subject in a 1.5 T magnet. Further inferential power can be gained only by scanning additional subjects, and in order to detect subtle (0.5% – 0.75%) changes in signal using a random-effects approach, approximately 12-16 subjects are required. Supported by NIA (AG 12995) and NIAAA (AA10723).

CEREBRAL ORGAINZATION IN THE BILINGUAL BRAIN: A PET STUDY OF CHINESE-ENGLISH VERB GENERATION

D. Klein, B. Milner, R.J. Zatorre V. Zhao and J. Nikelski, Cognitive Neuroscience Unit/Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada

To address the question of language diversity and cerebral representation, regional cerebral blood flow (CBF) was measured by the H215O intravenous bolus method with inter- and intra-subject averaging, and co-registration of magnetic resonance and PET images in seven bilingual volunteer subjects (4 female, 3 male), all of whom had learned Mandarin as their native language (L1), but had acquired proficiency in English (L2) later in life (mean age at first exposure = 11.5 years). Two experimental tasks were each performed twice. Each involved generating a verb for a given noun in the L1 and then in the L2, with counterbalanced language presentation. In each condition the subjects were presented with a single word every 4.2-sec through insert earphones and were required to make a spoken response. Activation during the control task (repetition in L1 and in L2, respectively) was subtracted from each of the noun-verb generation tasks. In both the subtractions of L1 verb generation minus L1 repeat (Chinese) and L2 verb generation minus L2 repeat (English), the same constellation of regions that were active in previous lexical search and retrieval studies (left inferior frontal, dorsolateral frontal, temporal and parietal cortices, as well as right cerebellum) were noted, supporting our predictions for similar cerebral representation of L1 and L2, and suggesting a convergence and generality of findings across languages. Moreover, when we specifically compared verb generation for each of the two languages against one another [(L1 GEN — L1 REP) — (L2 GEN — L2 REP)], no significant differences emerged. Intra-subject analyses consistently yielded CBF increases in the left frontal cortex for all the individuals for both the L1 and the L2, although there was some degree of intra-subject variability in the extent and location of the increases within the frontal lobe. A comparison of the differences in the generation tasks yielded no spatial separation in the frontal peaks observed. Overall, our results reveal similar patterns of organization for L1 and L2 on tasks of word generation, even with acoustically distinct languages.

PAPER SESSION III: (Works in Progress)

SELECTIVE VISUAL DEFICITS AT AGES 10-20 YEARS FROM AN AMINO ACID IMBALANCE IN THE FIRST MONTH OF LIFE

Adele Diamond, Center for Developmental Cognitive Neuroscience, Eunice Kennedy Shriver Center, Waltham, MA, USA

Sibling pairs were tested. Both children had severely elevated blood phenylalanine (Phe) levels immediately after birth due to a genetic disorder (phenylketonuria [PKU]). For the older sibling of each pair, treatment to lower Phe levels began at 14 days of age on average; for younger siblings, the average age of treatment onset was 3 days. When the older siblings were 13 years of age and younger siblings were 11 years old on average, they were tested on contrast sensitivity as well as other visual psychophysical tests. Older siblings had significantly worse contrast sensitivity than their younger siblings. Contrast sensitivity usually improves with age; here we found the younger children performing better. We previously reported selective impairments in cognitive functions dependent on prefrontal cortex and in contrast sensitivity in children treated early and continuously for PKU. While the prefrontal cognitive deficits were related to current plasma Phe levels, the contrast sensitivity deficit was related to Phe levels during the first month of life, not to current Phe levels. These results suggest that excessive Phe levels during the first weeks of life even if subsequently lowered and maintained at lower levels, may cause irreparable damage to the visual system. It may be wise to alter the current practice and begin treatment for PKU within the first few days after birth.

STRESS, CORTISOL, AND COGNITIVE FUNCTION

Peggy J. Jennings & Amy W. Wagner, Psychology Department, University of Wyoming, Laramie, WY, USA

Elevated levels of cortisol, a stress hormone, may be associated with impaired attention and long-term memory. It has long been known that steroid hormones bind with intracellular receptors that affect neural function by altering genomic mechanisms. These genomic mechanisms require minutes to hours to alter neural and cognitive function. Recent evidence suggests that steroid action is not limited to these relatively long-term genomic mechanisms, but may also activate fast-acting membrane receptors. This study-in-progress is designed to uncover the relations between the time course of cortisol’s effects on neural function and the time course of altered cognitive processes. It seeks to dissociate the immediate effects of acutely elevated cortisol from the long-term effects. The immediate effects may alter attention processes, perhaps mediated by membrane receptor mechanisms. The long-term effects may impair memory processes, perhaps mediated by genomic mechanisms. The goal of presenting this work in progress is to discuss some preliminary findings and to work out some of the difficulties of linking the time-related effects of hormones with time-related cognitive processes.

PROGRAM

Wednesday, June 30

8:00 DINNER

Thursday, July 1

8:00 BREAKFAST

SYMPOSIUM: SINGLE EVENT fMRI

Chair: Philip Servos, Dept of Psychology, Wilfrid Laurier University, Waterloo, Ont, Canada

(Note **=Potential New Member)

9:00 Opening Remarks: Philip Servos

9:10 Event-Related Functional MRI: Implications for Cognitive Psychology

Mark DEsposito, Dept of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA

10:05 Sketching the Functional Neuroarchitectural Blueprints of Working Memory with Event-Related fMRI

Brad Postle, Dept of Neurology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA

11:05 COFFEE

11:25 Event-Related fMRI in Memory and Thought

John Gabrieli, Dept of Psychology, Stanford University, Stanford, CA, USA

1:00 LUNCH

2:00 Event-Related f MRI of the Auditory Cortex

Pascal Belin**, Robert Zatorre, Rick Hoge, Alan Evans, Bruce Pike, Neuropsychology/Cognitive Neuroscience Unit and McConnell Brain imaging Center, Montreal Neurological Institute, McGill University, Montreal, PQ, Canada

3:00 Functional Magnetic Resonance Imaging of the Human Brain with High Temporal Resolution

Wolfgang Richter**, National Research Council, Winnipeg, MA, Canada

4:00 COFFEE

4:20 Exploiting Temporal and Spatial Resolution in fMRI. Experiences at 4 Tesla

Ravi Menon**, The John P. Robarts Research Institute, London, Ont, Canada

8:00 DINNER

Friday, July 2

8:00 BREAKFAST

OPEN PAPER SESSION I (TRADITIONAL)

(Note **=Potential New Member)

9:00 THE EFFECT OF NOVEL H3-RECEPTOR ANTAGONISTS ON COGNITIVE FUNCTION IN RATS.

Janice L. Muir, School of Psychology, Cardiff University, Wales U.K.

9:20 DISCONNECTING HIPPOCAMPAL PROJECTIONS TO THE ANTERIOR THALAMUS PRODUCES DEFICITS ON TESTS OF SPATIAL MEMORY IN RATS

John P. Aggleton, E. Clea Warburton, and Janice L. Muir, School of Psychology, Cardiff University, Wales, UK

9:40 FORMAT-SPECIFICITY IN THE ORGANIZATION OF EPISODIC MEMORY FOR COMMON OBJECTS: DOES THE BRAIN TREAT PICTURES AND WORDS DIFFERENTLY?

Stephen Kohler, Cognitive Neuroscience Unit, Montreal Neurological Institute, McGill University, Montreal, PQ, Canada

10:00 THE OPPOSITE OF HM: ISOLATED RETROGRADE AMNESIA AFTER THALAMIC INFARCTION

Laurie Miller, Diana Caine, John D G Watson, Neuropsychology Unit , Royal Prince Alfred Hospital, University of Sydney, Sydney, NSW, Australia

10:20 COFFEE

10:50 CONTRIBUTION OF RETINOTOPIC CORTICAL AREAS TO PERCEPTUAL FILLING-IN

Peter De Weerd**, University of Arizona, Dept. Psychology, Tucson AZ.

11:10 THE EFFECTS OF V4/TEO LESIONS ON RESPONSES OF MACAQUE AREA TE NEURONS TO TARGETS EMBEDDED IN DISTRACTERS

G. Bertini**, E.A. Buffalo, H. Thakar, B. Jagadeesh, P. De Weerd, R. Desimone and L.G. Ungerleider, Laboratory of Brain and Cognition, Laboratory of Neuropsychology, NIMH, Bethesda MD USA

11:30 DEVELOPMENTAL CHANGE IN EARLY ERP COMPONENTS DURING FACE PROCESSING

Margot J. Taylor, CERCO – CNRS, Toulouse, France

11:50 TITLE?

Nathalie Ehrle**

1:00 LUNCH

AFTERNOON GROUP OUTING TO BE ANNOUNCED

PRESIDENTIAL ADDRESS

7:00

Dr. Apostolos Georgopoulos,

Brain Sciences Ctr, VA, Medical Ctr., Minneapolis, MN. USA

8:00 DINNER

Saturday, July 3

8:00 BREAKFAST

SYMPOSIUM: TIMING IN THE BRAIN

Chair: April Benasich, Center for Molecular and Behavioral Neuroscience, Rutgers, State University of New Jersey, Newark, NJ, USA

9:00 Opening Remarks

April Benasich

9:10 Timing in Attentional Processing

Marie T. Banich, Michael Milhan, Alessandra Pasarotti, Paige Scalf, Kevin Spencer, and Daniel Weissman

Dept of Psychology, University of Illinois at Urbana-Champaign, Champaign, IL, USA

9:45 Cerebellar Contributions to Temporal-Motor Learning

Virginia Penhune, Neuropsychology Unit, Montreal Neurological Institute, Montreal, PQ, Canada

10:20 COFFEE

10:50 Animal Model for Impaired Auditory Temporal Processing: Relevance to Developmental Language Impairment

Matthew Clark and R. Holly Fitch, Biobehavioral Sciences University of Connecticut, Storrs, CT, USA

11:25 Functional Modules in Primary Auditory Cortex: Implications for Temporal and Spectral Processing and Plasticity

Heather l. Read, Monty A. Escabi, Lee M. Miller, Jeffery A. Winer, and Christoph E. Schrieiner, Keck Center for Integrative Neuroscience, UCSF, San Francisco, CA, USA

12:00 The Influence of Efficient Processing of Brief Auditory Temporal Cues on Later Language Development

April Benasich, Center for Molecular and Behavioral Neuroscience, Rutgers, State University of New Jersey, Newark, NJ, USA

1 PM LUNCH

AFTERNOON GROUP OUTING TO BE ANNOUNCED

8 PM DINNER

Sunday, July 4

8:00 BREAKFAST

OPEN PAPER SESSION II (TRADITIONAL)

9:00 A NEURAL NETWORK FOR ATTENTIONAL CONTROL AS REVEALED BY fMRI STUDIES

Marie T. Banich, Michael P. Milham, RuthAnn Atchley, Neal J. Cohen, Andrew Webb, Tracey Wszalek, Arthur F. Kramer, Zhi-Pei Liang, Vikram Barad, Dan Gullett, Chiarg Shih and Colin Brown, Dept of Psychology, University of Illinois at Urbana-Champaign, Champaign, IL, USA

9:20 ESTIMATING SAMPLE SIZE FOR fMRI EXPERIMENTS

John E. Desmond, Departments of Radiology and Psychology, Stanford University, Stanford, CA, USA

9:40 CEREBRAL ORGANIZATION IN THE BILINGUAL BRAIN: A PET STUDY OF CHINESE-ENGLISH VERB GENERATION

D. Klein, B. Milner, R.J. Zatorre V. Zhao and J. Nikelski, Cognitive Neuroscience Unit/Montreal Neurological Institute, McGill, University, Montreal, PQ, Canada

10:00 COFFEE AVAILABLE

OPEN PAPER SESSION III (WORKS IN PROGRESS)

10:05 SELECTIVE VISUAL DEFICITS AT AGES 10-20 YEARS FROM AN AMINO ACID IMBALANCE IN THE FIRST MONTH OF LIFE

Adele Diamond, Center for Developmental Cognitive Neuroscience, Eunice Kennedy Shriver Center, Waltham, MA, USA

10:25 STRESS, CORTISOL, AND COGNITIVE FUNCTION

Peggy J. Jennings & Amy W. Wagner, Psychology Department, University of Wyoming, Laramie, WY, USA

1:00 LUNCH