Generalized auditory same-different discrimination by pigeons.

Three pigeons were trained in a successive same/different (S/D) procedure using compound auditory stimuli (pitch/timbre combinations). Using a go/no-go procedure, pigeons successfully learned to discriminate between sequences of either all same (AAAA...or BBBB...) or all different (ABCD...) sequences consisting of 12 sounds. Both pitch and timbre were subsequently established as controlling dimensions. Transfer tests with novel stimuli revealed a generalized basis for the discrimination (novel pitch/timbre combinations, novel pitches, novel instruments, and complex natural & man-made sounds). These results indicate for the first time that pigeons can learn generalized same/different discriminations in a nondominant modality. When combined with earlier visual results, they support a qualitative similarity among birds and primates in their capacity to judge this type of fundamental stimulus relation across different modalities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cardiac orienting and auditory discrimination in 6-wk-old infants.

A series of 3 experiments with 32 6-wk-old infants studied heart rate and sucking in response to changes in acoustic stimuli. Exp I used a conventional discrete trials paradigm to present trains of synthetic speech syllables, Exp II used a no-delay paradigm to present nonspeech stimuli (tone frequencies). Overall analysis of cardiac data indicated that discriminative capacities in 6-wk-olds can be revealed by changes in heart rate and that this discrimination is better demonstrated using a no-delay (rather than a discrete trials) paradigm. It is suggested that direction of this rate change may provide information about differences in processing, since cardiac responses to changes in synthetic speech syllables was accelerative (possibly a defensive or startle reaction) while responses to changes in tone frequency were decelerative (possibly an orienting index). Findings reveal a consistent absence of sucking responses, indicating that heart rate responses to changes in acoustic stimulation can occur independently of sucking in 6-wk-olds. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rhinal cortex lesions produce mild deficits in visual discrimination learning for an auditory secondary reinforcer in rhesus monkeys.

Aspiration, but not neurotoxic, lesions of the amygdala impair performance on a visual discrimination learning task in which an auditory secondary reinforcer signals which of 2 stimuli will be reinforced with food. Because aspiration lesions of the amygdala interrupt projections of the rhinal cortex traveling close to the amygdala, it was hypothesized that damage to the rhinal cortex would severely impair learning in this task. Rhesus monkeys (Macaca mulatta) were trained to solve visual discrimination problems based on an auditory secondary reinforcer, were given lesions of the rhinal cortex or the perirhinal cortex alone, and were then retested. The monkeys displayed a reliable, albeit mild, deficit in postoperative performance. It is concluded that the aspiration lesions of the amygdala that produced a severe impairment did so because they interrupted connections of temporal cortical fields beyond the rhinal cortex that are also involved in learning in this task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Runway alternation and discrimination of mice with limbic lesions.

Trained 7 normal male HS mice (Norm), and 18 mice with septal (Sept) and cingulate-anterior limbic cortex lesions (Cing) in a straight-alley single-alternation task. Sept Ss performed significantly better than Norms, running faster on reinforced trials and slower on nonreinforced trials. Cing Ss performed as well as Norms. In a 2nd experiment with 64 Ss, Norm and Sept Ss learned a discrimination task using a food pellet or sound of a buzzer as a cue for either reinforced or nonreinforced trials. Sept Ss learned the food-cued task faster than Norms when nonreinforced trials were cued; Norms performed better when reinforced trials were cued with the buzzer. Results suggest that septal lesions enhance the cue value of food, and contradict the hypothesis that the septum is involved in response inhibition. (19 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Marginal and extramarginal cortical lesions and visual discrimination by cats.

75 mongrel cats learned a shape discrimination with 0, 1, or 2 irrelevant cues. They were then subjected to either sham operations, ablation of the marginal and splenial gyri, or lesions in the extramarginal (EM) cortex. The 32 EM cats comprised 4 groups, 3 with small (EM1), intermediate (EM2), large (EM3) decortications, and a 4th group with both EM lesions and heavy degeneration in the lateral geniculate nucleus (LGN). Ss with marginal or extensive extramarginal lesions were severely impaired in shape and size discrimination. Results show the following: (a) The errors made by marginal gyrus cases increased sharply as a function of the number of irrelevant cues present in shape discrimination training; no other group, including Group EM3, was affected by this variable. (b) Ss with extramarginal ablations and strong LGN degeneration were no more severely impaired than were Ss with comparable extramarginal damage and little or no LGN degeneration. While the nature of the 2 kinds of deficits remains unclear, they seem parallel to those following posterior cortical lesions in monkeys. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Olfactory discrimination in rats with anterior amygdala lesions.

In Exp I, 12 male rats with posterior lateral olfactory tract/anterior amygdala lesions or with control neocortical lesions were tested for retention of a preoperatively learned odor detection task and for learning on new odor discrimination problems. All Ss had perfect or near-perfect retention of the detection task, and there were no discernible differences between groups in learning on the new odor discrimination problems. In Exp II, an intensity-difference threshold for olfaction was determined in 4 male Long-Evans rats before and after similar lesions. There were no apparent differences between pre- and postoperative performances on this psychophysical test. Results indicate that lateral olfactory tract projections to the amygdala and posterior olfactory cortex are not essential for normal performance on simple olfactory discrimination tasks, although the more caudal projections of the olfactory bulb play an important role in the arousal and maintenance of certain species-typical behaviors. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temporal-order discrimination for selected auditory and visual stimulus dimensions

Thresholds for the discrimination of temporal order were determined for selected auditory and visual stimulus dimensions in 10 normal-adult volunteers. Auditory stimuli consisted of binary pure tones varying in frequency or sound pressure level, and visual stimuli consisted of binary geometric forms varying in size, orientation, or color. We determined the effect of psychophysical method and the reliability of performance across stimulus dimensions. Using a single-track adaptive procedure, Experiment 1 showed that temporal-order thresholds (TOTs) varied with stimulus dimension, being lowest for auditory frequency, intermediate for size, orientation, and auditory level, and longest for color. Test performance improved over sessions and the profile of thresholds across stimulus dimensions had a modest reliability. Experiment 2 used a double-interleaved adaptive procedure and TOTs were similarly ordered as in Experiment 1. However, TOTs were significantly lower for initially ascending versus descending tracks. With this method, the reliability of the profile across stimulus dimensions and tracks was relatively low. In Experiment 3, psychometric functions were obtained for each of the stimulus dimensions and thresholds were defined as the interpolated 70.7% correct point. The relative ordering of TOTs was similar to those obtained in the first two experiments. Non-monotonicities were found in some of the psychometric functions, with the most prominent being for the color dimension. A cross-experiment comparison of results demonstrates that TOTs and their reliability are significantly influenced by the psychophysical method. Taken together, these results support the notion that the temporal resolution of ordered stimuli involves perceptual mechanisms specific to a given sensory modality or submodality.     

Astereognosis. Tactile discrimination after localized hemispheric lesions in man

The specific object of this study was to determine which cortical areas have to be damaged or disconnected to cause an impairment of somatosensory discrimination (astereognosis). Ninety-three patients with verified unilateral and circumscribed lesions took part in a somatosensory two-alternative forced-choice discrimination of size and shape. The results failed to support earlier views of astereognosis. Only direct damage to or an undercutting of the anterior part of the middle third of the postcentral gyrus caused impairment of size and shape discrimination (astereognosis) contralateral to the lesion. When the hand is used for stereognostic discrimination, the integration of somatosensory impulse patterns into spatial information about the objects is believed to take place in the contralateral somatosensory hand area.     

Effects of the build-up and resetting of auditory stream segregation on temporal discrimination.

[Correction Notice: An erratum for this article was reported in Vol 34(6) of Journal of Experimental Psychology: Human Perception and Performance (see record 2008-16831-007). The year listed is incorrect. The article should have been dated 2008.] The tendency to hear a tone sequence as 2 or more streams (segregated) builds up, but a sudden change in properties can reset the percept to 1 stream (integrated). This effect has not hitherto been explored using an objective measure of streaming. Stimuli comprised a 2.0-s fixed-frequency inducer followed by a 0.6-s test sequence of alternating pure tones (3 low [L]-high [H] cycles). Listeners compared intervals for which the test sequence was either isochronous or the H tones were slightly delayed. Resetting of segregation should make identifying the anisochronous interval easier. The HL frequency separation was varied (0-12 semitones), and properties of the inducer and test sequence were set to the same or different values. Inducer properties manipulated were frequency, number of onsets (several short bursts vs. one continuous tone), tone:silence ratio (short vs. extended bursts), level, and lateralization. All differences between the inducer and the L tones reduced temporal discrimination thresholds toward those for the no-inducer case, including properties shown previously not to affect segregation greatly. Overall, it is concluded that abrupt changes in a sequence cause resetting and improve subsequent temporal discrimination. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intensity and pattern discrimination in turtles after lesions of nucleus rotundus.

In turtles, the nucleus rotundus, a dorsal thalamic cell group, is known to receive a massive input from the optic tectum. Electrophysiological and anatomical data indicate that nucleus rotundus has a role in visual functions. To study role, 21 eastern painted turtles (Chrysemys picta picta) were trained in an appetitive situation on a simultaneous intensity discrimination or a simultaneous pattern discrimination. After reaching criterion, most Ss received lesions aimed at nucleus rotundus. Two Ss in the intensity-discrimination group received sham lesions. Following surgery, Ss were retrained and then sacrificed, and the lesion damage in each S was reconstructed. Ss with severe damage to nucleus rotundus were unable to relearn the discriminative task, and those with moderate amounts of damage required more sessions to relearn than they had required preoperatively. Ss with slight damage to nucleus rotundus were unimpaired. For both the intensity- and the pattern-discrimination groups, there was a significant correlation between postoperative performance and amount of damage to nucleus rotundus. Results suggest that nucleus rotundus plays a critical role in visual discriminative functions in the turtle. (57 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Changes of auditory word discrimination induced by inversion of the visual field.

Examined auditory discrimination in normal hospital staff members during induced visual conflict. Discrimination of words accompanied by background noise was measured at 6 speech-signal-noise intensity levels during preexperimental (normal vision), experimental (inverted vision), and postexperimental (normal vision) periods. A control condition (no inverted vision) served as a check for the possible effects of practice or fatigue. Significant losses of word discrimination occurred only in the inverted vision condition. Discrimination losses occurred at all intensity levels in which speech was accompanied by noise, prior to walking in the inverted vision condition, following a walking period, and after removal of inversion eyepieces. Results are attributed to a process of visually induced conflict in which Ss were unable to decenter the altered contents of vision. Affinities between reports of induced alterations of experience and pathological alterations of experience are discussed. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of ventral putamen lesions on discrimination learning by monkeys.

Studied the effect of caudoventral putamen lesions on the postoperative retention of visual and auditory discriminations and on the postoperative acquisition of delayed alternation in 19 adolescent rhesus monkeys. Lesions in the caudoventral putamen and the adjacent white matter impaired performance of the visual but not the auditory and alternation tasks, indicating that this area is part of the neural circuitry underlying visual discrimination. However, the relative contribution to the deficit of the putamen damage and of the white matter damage could not be ascertained. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rhinal cortex lesions impair simultaneous olfactory discrimination learning in rats.

Previous studies have found that combined lesions of the perirhinal and entorhinal (PRER) cortical areas do not impair, and in fact may facilitate, acquisition of successive olfactory discriminations. The present study sought to determine the effect of PRER lesions on the acquisition of simultaneous olfactory discriminations. Rats (N?=?24; 9 PRER-lesioned, 15 sham-operated controls) were trained on a single simultaneous olfactory discrimination; PRER-lesioned animals were dramatically and persistently impaired in acquisition of the discrimination relative to sham-operated subjects. These data are consistent with the view that, in concert with the hippocampus, these cortical regions participate in the encoding of relations among multiple extant stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociation of spatial discrimination deficits following frontal and parietal lesions in monkeys.

Gave 40 rhesus monkeys dorsolateral prefrontal, posterior parietal, or inferotemporal lesions. 4 additional Ss served as unoperated controls. Ss then received 2 forms of spatial discrimination training, based on body position ("egocentric" cues) and on the position of an external referent ("allocentric" cues), respectively. On the former, a place discrimination reversal, frontal Ss were impaired but not parietals. On the latter, a landmark discrimination reversal, parietal Ss were impaired but not frontals; this result was also obtained on a test involving distance discrimination without reversal. Finally, the inferotemporals but not the frontals or parietals were impaired on a nonspatial object discrimination reversal. Results suggest that the 2 modes of spatial orientation, egocentric and allocentric, are related to frontal and parietal mechanisms, respectively. (18 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A probe-signal study of auditory discrimination of complex tones

The present experiments used an analogue of the probe-signal method of Greenberg and Larkin [J. Acoust. Soc. Am. 44, 1513-1523 (1968)] to investigate the extent to which listeners direct attention to a particular spectral region when discriminating complex tones. The listeners' task was to discriminate between two seven-component complex tones on the basis of an increment in the level of a single component. On two-thirds of trials the increment was achieved by adding a fixed primary signal to one component of the complex. The primary-signal trials were relatively easy and were intended to cue listeners to attend to the component to which the primary was added. On the remaining trials a smaller probe signal was added either to the cued component, or to one of three other components. The results of the first experiment, in which the complex tones had a flat spectrum, showed significantly better performance for probe signals applied to the cued component compared to the other three components. To control for the possibility that the observed pattern of results was due to the use of timbral cues, a second experiment was conducted in which the spectral profile of the tones was randomized between trials. The results for the second experiment were similar to those of the first experiment and are consistent with the idea that listeners were focusing attention on the spectral region defined by the primary signal.     

Evaluation of auditory discrimination in children with ADD and without ADD

BACKGROUND: Through antibody engineering, immunoglobulins can be tailored for their particular application. In this respect, small recognition units are desired for the targeting of antigens in obstructed locations like solid tumors. OBJECTIVES: To design efficient, minimum size recognition units, heavy chain variable regions (VH) had previously been modified for the use as antigen specific, single domain antibody fragments. To develop a rational approach to improve affinity, antigen binding is investigated here by analysing the effect of randomisations of CDR1 and 2 residues in VH domains specific for hapten and protein ligands. STUDY DESIGN: Randomised repertoires were displayed on phage and affinity selected to improve and analyse antigen binding. Affinities of newly selected VH domains were determined in their soluble format to assess the role of modified residues in binding. RESULTS: In four of five randomisation experiments, a new VH with an improved antigen affinity compared to the primary VH was selected. Dissociation constants decreased from 160 nM to 25 nM or 47 nM (CDR1 or CDR2 randomisation of an anti-Ox VH), from 300 nM to 31 nM (CDR2 randomisation of an anti-NIP VH) and from 3.1 microM to 1.6 microM (CDR2 randomisation of an anti-lysozyme VH). CONCLUSIONS: Thus the affinity of VH domains can be improved after site specific, secondary randomisations in CDR1 and CDR2, phage display and antigen selection. As differences in the CDR3 sequences had formed the only difference between the primary VH domains used in this study, the effect of CDR1 and CDR2 mutations of affinity is consistent with a participation of all three CDRs in antigen binding by single VH domains.     

Infant auditory discrimination in preterm and full-term infants as a predictor of 5-year intelligence.

Examined the relation between responsiveness to auditory novelty in full-term and preterm infants at 4 mo and subsequent intellectual performance at 5 yrs of age. At 4 mo, cardiac response to repetitive and novel auditory stimulation was assessed using a variable-trials habituation procedure for 9 full-term and 19 preterm infants. Ss were followed until the age of 5 yrs, and intellectual performance was measured using the Stanford-Binet Intelligence Scale. A statistically significant correlation of .60 was found between infant novelty response scores and 5-yr intelligence scores. Mother's education also related to 5-yr performance, although not significantly when the novelty response was partialed out. Results suggest that measures of early perceptual-memory development may reflect early cognitive processes necessary for later intellectual performance. Within the preterm group, there was a sample of male infants with below-average intelligence at 5 yrs. These Ss failed to respond to novelty, and their mothers had not completed high school. Thus, a subsample of high-risk Ss can be identified early in life. A significant positive relation was also found between scores on the Bayley Scales of Infant Development and intelligence at 5 yrs of age. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)