Binaural integration of melodic patterns

It has been argued that there is a limit to the rate at which we can switch attention between ears in monitoring auditory information. Listeners identified melodic configurations formed by rapid sequences of tones. When these sequences were presented binaurally, excellent performance was obtained. Yet when the component tones of the melody were distributed between the ears, performance was largely nullified when a drone (i.e., a lower constantfrequency tone) was presented to the ear opposite that receiving the melody component. This improvement in performance cannot be attributed to processing the harmonic relationships between melody and drone, since when, instead, the drone was presented to the same ear as the melody component, performance was at chance. Onset-offset asynchronies between the drone and melody components resulted in performance levels between those where the drone and melody components were synchronous and those where the melody switched between ears without an accompanying drone. It is argued that difficulties in binaural integration are due not to processing limitations, but to a mechanism that is invoked under certain conditions to prevent confusion in monitoring individual sound sources.     

Competition between two memory traces for long-term recognition memory

Previous studies investigating the processes which underlie memory consolidation focused almost exclusively on isolated learning events. Here I studied the competition of two similar memory traces for consolidation non-conditioned recognition memory in adult male C57BL/6JOlaHsd mice using the olfactory cues based social discrimination procedure. My results show that the interference phenomena that cause forgetting are time-dependent, and that retroactive interference can be discriminated from proactive interference. Furthermore, both types of interference can be suppressed by subcutaneous anisomycin treatment immediately after presentation of the interference stimulus. These findings imply that interference phenomena, which result from the competition of two similar memory traces for long-term recognition memory, are related to the progress of memory consolidation and linked to protein synthesis.     

Auditory and visual memory in musicians and nonmusicians

Numerous studies have shown that musicians outperform nonmusicians on a variety of tasks. Here we provide the first evidence that musicians have superior auditory recognition memory for both musical and nonmusical stimuli, compared to nonmusicians. However, this advantage did not generalize to the visual domain. Previously, we showed that auditory recognition memory is inferior to visual recognition memory. Would this be true even for trained musicians? We compared auditory and visual memory in musicians and nonmusicians using familiar music, spoken English, and visual objects. For both groups, memory for the auditory stimuli was inferior to memory for the visual objects. Thus, although considerable musical training is associated with better musical and nonmusical auditory memory, it does not increase the ability to remember sounds to the levels found with visual stimuli. This suggests a fundamental capacity difference between auditory and visual recognition memory, with a persistent advantage for the visual domain.     

A programmable tone generator for presenting melodic and harmonic patterns in music research

This report describes the design of a programmable tone generator, a digitally controlled system for generating complex tones. The PTG will provide sequential series of single tones or simultaneously sounding two- and three-tone groups over a four-octave range. Programming of the PTG is accomplished by paper tape using a digital, binary configuration. The current version will interface with Grason-Stadler Series 1200 equipment.     

The role of cortical cholinergic pre- and post-synaptic receptors in taste memory formation

A number of studies have implicated cholinergic activity in the mediation of learning and memory processes. However, the specific role of muscarinic receptors in memory formation mechanisms is less known. The aim of the present study is to evaluate the effects of muscarinic antagonist M2 presynaptic receptor, AFDX-116 (0.5mM) and M1 and M3 post-synaptic receptor pirenzepine (100mM), as well as a non-selective muscarinic antagonist, scopolamine (136mM), in the insular cortex (IC) during acquisition and retrieval of conditioned taste aversion (CTA). In addition, we evaluate the effects of those antagonists in cortical ACh release by in vivo microdialysis and the effects on the induction of in vivo LTP in the BLA-IC projection. The results showed that the cortical microinjections of scopolamine and pirenzepine, but not AFDX-116, produced significant disruption in the acquisition of CTA, without effects during retrieval. Microinjections of scopolamine and AFDX-116 produced significant cortical ACh release, while infusions of pirenzepine did not produce any release. Application of scopolamine and pirenzepine diminished induction of LTP in the BLA-IC projection, but not AFDX-116, as compared with vehicle. The induction of BLA-CI LTP seems to be modulated by post-synaptic muscarinic acetylcholine receptors and not by pre-synaptic muscarinic receptors. These results suggest a differential involvement of cholinergic receptors during acquisition and retrieval of aversive memory formation, as well as a differential role of muscarinic receptors in the biochemical and electrophysiological processes that may underlay aversive memory.     

Visual search for changes in scenes creates long-term,incidental memory traces

Humans are very good at remembering large numbers of scenes over substantial periods of time. But how good are they at remembering changes to scenes? In this study, we tested scene memory and change detection two weeks after initial scene learning. In Experiments 1–3, scenes were learned incidentally during visual search for change. In Experiment 4, observers explicitly memorized scenes. At test, after two weeks observers were asked to discriminate old from new scenes, to recall a change that they had detected in the study phase, or to detect a newly introduced change in the memorization experiment. Next, they performed a change detection task, usually looking for the same change as in the study period. Scene recognition memory was found to be similar in all experiments, regardless of the study task. In Experiment 1, more difficult change detection produced better scene memory. Experiments 2 and 3 supported a “depth-of-processing” account for the effects of initial search and change detection on incidental memory for scenes. Of most interest, change detection was faster during the test phase than during the study phase, even when the observer had no explicit memory of having found that change previously. This result was replicated in two of our three change detection experiments. We conclude that scenes can be encoded incidentally as well as explicitly and that changes in those scenes can leave measurable traces even if they are not explicitly recalled.     

The role of auditory memory traces in attention to frequency

Three cued signal detection experiments demonstrated a role for auditory memory traces in frequency selectivity. The extent to which the cue predicted the signal frequency affected the size of the advantage for signals at the cue frequency over those at distant frequencies when the cue-signal gap was 10 sec but not when it was 1 sec. Detection of occasional signals presented at uncued frequencies was enhanced when they matched the frequency of cues from recent trials. With "relative" cues, which were usually followed by signals at the musical fifth above the cue frequency, performance on occasional signals at the cue frequency was enhanced relative to other unexpected frequencies. These results suggest that, regardless of the listener's expectations and intentions, the detectability of a signal is enhanced if its frequency matches an existing memory trace. One form of voluntary attention to frequency may involve maintaining traces that would otherwise slowly decay.     

Event-related brain potentials reflect traces of echoic memory in humans

In sequences of identical auditory stimuli, infrequent deviant stimuli elicit an event-related brain potential component called mismatch negativity (MMN). MMN is presumed to reflect the existence of a memory trace of the frequent stimulus at the moment of presentation of the infrequent stimulus. This hypothesis was tested by applying the recognition-masking paradigm of cognitive psychology. In this paradigm, a masking sound presented shortly before or after a test stimulus diminishes the recognition memory of this stimulus, the more so the shorter the interval between the test and masking stimuli. This interval was varied in the present study. It was found that the MMN amplitude strongly correlated with the subject’s ability to discriminate between frequent and infrequent stimuli. This result strongly suggests that MMN providesa measure for a trace of sensory memory, and further, that with MMN, this memory can be studied without performance-related distortions.     

Preferences for scale structure in melodic sequences

Most Western music is tonal; that is, pitch organization can largely be described in terms of scales or keys. A considerable amount of research has been conducted on the role played by scale in perceiving notes and melodies. The present article points out a potentially important distinction between scale structure (the set permitted pitch intervals between notes) and mode (the assignment of a special salience or centrality to particular notes within the scale structure). Four experiments are described that investigated the judgment of adult Western listeners for melodies that approximated to scale structure in differing degrees but that were random in other respects. We found that musicians and nonmusicians gave higher ratings of preference and adjudged musicality to melodies containing increased numbers of consecutive notes conforming to scale structure. A significant exception to this rule was the least scalar type of sequence, which received ratings as high as the fully scalar sequences. This exception occurred because subjects identified scale structure not only in groups of contiguous notes but also in groups of discontiguous notes that formed a coherent "stream" as long as the number of notes intervening corresponded to a standard temporal grouping, or meter, such as is commonly found in Western music.     

A framework for local cortical oscillation patterns

Oscillations are a pervasive feature of neuronal activity in the cerebral cortex. Here, we propose a framework for understanding local cortical oscillation patterns in cognition: two classes of network interactions underlying two classes of cognitive functions produce different local oscillation patterns. Local excitatory-inhibitory interactions shape neuronal representations of sensory, motor and cognitive variables, and produce local gamma-band oscillations. By contrast, the linkage of such representations by integrative functions such as decision-making is mediated by long-range cortical interactions, which yield more diverse local oscillation patterns often involving the beta range. This framework reconciles different cortical oscillation patterns observed in recent studies and helps to understand the link between cortical oscillations and the fMRI signal. Our framework highlights the notion that cortical oscillations index the specific circuit-level mechanisms of cognition.     

Ordering our world: The quest for traces of temporal organization in autobiographical memory

An experiment examined the idea, derived from the Self Memory System model (Conway & Pleydell-Pearce, 2000), that autobiographical events are sometimes tagged in memory with labels reflecting the life era in which an event occurred. The presence of such labels should affect the ease of judgments of the order in which life events occurred. Accordingly, 39 participants judged the order of two autobiographical events. Latency data consistently showed that between-era judgments were faster than within-era judgments, when the eras were defined in terms of either: (a) college versus high school, (b) academic quarter within year, or (c) academic year within school. The accuracy data similarly supported the presence of a between-era judgment effect for the college versus high school dichotomy.     

Rate and structure in memory for auditory patterns

Musically knowledgeable listeners heard auditory patterns based on sets of six (Study 1) or eight tones (Study 2). In the first study, listeners ordered events from patterns generated by hierarchical rule trees and which possessed different pitch space and time structures: one type (nondistance nested) was more likely to produce auditory streaming than the other (distance nested). In the second study, different listeners reconstructed pitch intervals contained in one of eight patterns. Patterns differed according to (1) levels of pitch distance occur), (2) levels of pattern contour (two), and (3) rate (two). In both studies, fast patterns with many large pitch distances were more difficult to recollect. Listeners in the second study telided to “telescope” pitch distances. Most difficult were those rapid sequences with large patch intervals combined into a changing contour (nondistance nested); these patterns streamed. A third study replicated effects due to differences in pitch distances observed in Study 2. Results were interpreted in terms of a rhythmic theory of memory.     

Acquisition of novel traces in short-term implicit memory: Priming for nonwords and new associations

McKone (1995) reported a short-lived repetition priming effect (up to 8 sec and three intervening items), superimposed on long-term priming. In lexical decision and naming, decay of this short-term implicit memory was faster for pseudowords than for words, suggesting an explanation in terms of transient activation of preexisting lexical representations. Here, we present two cases where, in contrast, preexperimental familiarity did not affect short-term priming, indicating acquisition of novel traces. Experiment 1 determined repetition priming in same-different judgments to lowercase-uppercase pairs for words, and for nonwords with three levels of wordlikeness. Across lags of 0, 1, and 6 intervening items (2-14 sec), short-term priming was the same for all stimuli, even random letter strings. Experiments 2 and 3 assessed priming in a double lexical decision task for old associations (orange-apple) and new associations (cigar-errand). Short-term priming for the association was equal in both cases.     

Glucocorticoid involvement in memory formation in a rat model for traumatic memory

Contextual fear conditioning under training conditions involving high stressor intensities has been proposed as an animal model for traumatic memories. The strength of memory for this task has been related to the intensity of the conditioning stressor and post-training corticosterone values. However, administration of a glucocorticoid receptor (GR) antagonist only attenuated memory for this task in rats conditioned at a moderate shock intensity (0.4 mA), but failed to influence conditioning in rats trained at a high shock intensity (1 mA). Here, we further questioned whether interfering with glucocorticoid action at the time of training might be effective in influencing contextual fear conditioning in rats trained under different shock intensities. Rats were subcutaneously injected with the glucocorticoid synthesis inhibitor metyrapone (50, 100 mg/kg) 90 min before being trained in the contextual fear conditioning task, at either 0.4 or 1 mA shock intensities. The results showed that metyrapone, in a dose-dependent manner: (i) attenuated long-term expression of contextual fear conditioning, both in 0.4- and 1 mA-trained rats; and (ii) efficiently prevented increased plasma corticosterone concentration. In addition to further supporting a facilitating role of glucocorticoids in memory consolidation, these findings suggest a critical involvement of these hormones in the formation of traumatic memories.     

Differential effects of repetition on pre- and postcategorical memory traces

The effect of list repetition on immediate recall for aurally presented nine-letter lists was studied under two conditions. In the first, a redundant stimulus item was presented as the tenth item in each list, while the suffix was not included in a control condition. As in previous research (Crowder & Morton, 1969), the stimulus suffix selectively interfered with recall at the terminal presentation serial positions, indicating the presence of precategorical acoustic storage. Repetition had a nonselective effect on performance. This result and an analysis of acoustic errors support the inference that qualitative differences in the memory code may lead to differences in other functional properties of the memory trace, such as responsiveness to repetition.