Scalp-recorded N40 visual evoked potential: Sensory and attentional properties.

N40 is a well-known component of evoked potentials with respect to the auditory and somatosensory modality but not much recognized with regard to the visual modality. To be detected with event-related potentials (ERPs), it requires an optimal signal-to-noise ratio. To investigate the nature of visual N40, we recorded EEG/ERP signals from 20 participants. Each of them was presented with 1800 spatial frequency gratings of 0.75, 1.5, 3 and 6 c/deg. Data were collected from 128 sites while participants were engaged in both passive viewing and attention conditions. N40 (30-55 ms) was modulated by alertness and selective attention; in fact, it was larger to targets than irrelevant and passively viewed spatial frequency gratings. Its strongest intracranial sources were the bilateral thalamic nuclei of pulvinar, according to swLORETA. The active network included precuneus, insula and inferior parietal lobule. An N80 component (60-90 ms) was also identified, which was larger to targets than irrelevant/passive stimuli and more negative to high than low spatial frequencies. In contrast, N40 was not sensitive to spatial frequency per se, nor did it show a polarity inversion as a function of spatial frequency. Attention, alertness and spatial frequency effects were also found for the later components P1, N2 and P300. The attentional effects increased in magnitude over time. The data showed that ERPs can pick up the earliest synchronized activity, deriving in part from thalamic nuclei, before the visual information has actually reached the occipital cortex.

No other race effect (ORE) for infant face recognition: A memory task.

The aim of this study was to investigate how the other-race and baby schema effects interacted during face perception and recognition processes. 384 pictures representing Caucasian and non-Caucasian faces of infants and adults were shown to 24 Caucasian adult participants in an old/new recognition task. EEG/ERPs were recorded during face encoding and a successive memory session. ERP data showed a baby schema effect on N170, anterior N2 and P300 responses, which were larger to infant than adult faces, regardless of ethnicity. Conversely, an ORE was found, but only for adults faces, with N170 and N400 being larger to Caucasian than non-Caucasian adult faces. Consistently, reaction times were faster to unfamiliar faces of Caucasian than non-Caucasian adults, while no ORE was found for infants. SwLORETA, applied to the difference-waves (Caucasian - non Caucasian) elicited by adults faces (ORE), showed the strong activation of areas representing person-related information (i.e., inferior temporal gyrus), prejudice representation (i.e., the superior and middle frontal gyri), and theory of mind (i.e., the supramarginal gyrus and superior parietal lobe). The lack of ethnicity effect for infants faces is discussed in the light of their innate collative and attention capturing properties.

Shared neural mechanisms for processing emotions in music and vocalizations.

The neural mechanisms involved in the processing of vocalizations and music were compared, in order to observe possible similarities in the encoding of their emotional content. Positive and negative emotional vocalizations (e.g. laughing, crying) and violin musical stimuli digitally extracted from them were used as stimuli. They shared the melodic profile and main pitch/frequency characteristics. Participants listened to vocalizations or music while detecting rare auditory targets (bird tweeting, or piano's arpeggios). EEG was recorded from 128 sites. P2, N400 and Late positivity responses of ERPs were analysed. P2 peak was earlier in response to vocalizations, while P2 amplitude was larger to positive than negative stimuli. N400 was greater to negative than positive stimuli. LP was greater to vocalizations than music and to positive than negative stimuli. Source modelling using swLORETA suggested that, among N400 generators, the left middle temporal gyrus and the right uncus responded to both music and vocalizations, and more to negative than positive stimuli. The right parahippocampal region of the limbic lobe and the right cingulate cortex were active during music listening, while the left superior temporal cortex only responded to human vocalizations. Negative stimuli always activated the right middle temporal gyrus, whereas positively valenced stimuli always activated the inferior frontal cortex. The processing of emotional vocalizations and music seemed to involve common neural mechanisms. Notation obtained from acoustic signals showed how emotionally negative stimuli tended to be in Minor key, and positive stimuli in Major key, thus shedding some lights on the brain ability to understand music.

Distinct neural mechanisms for reading Arabic vs. verbal numbers: An ERP study.

In this electroencephalogram/event-related potential (EEG/ERP) study, 16 volunteers were asked to compare the numerical equality of 360 pairs of multidigit numbers presented in Arabic or verbal format. Behavioural data showed faster and more accurate responses for digit targets, with a right hand/left hemisphere advantage only for verbal numerals. Occipito-temporal N1, peaking at approximately 180 ms, was strongly left-lateralized during verbal number processing and bilateral during digit processing. A LORETA (low-resolution electromagnetic tomography) source reconstruction performed at the N1 latency stage (155-185 ms) revealed greater brain activation during coding of Arabic than of verbal stimuli. Digit perceptual coding was associated with the activation of the right angular gyrus (rAG), the left fusiform gyrus (FG,BA37), and left and right superior and medial frontal areas. N1 sources for verbal numerals included the left FG (BA37), the precuneus (BA31), the parahippocampal area and a small right prefrontal activation. In addition, verbal numerals elicited a late frontocentral negativity, possibly reflecting stimulus unfamiliarity or complexity. Overall, the data suggest distinct mechanisms for number reading through ciphers (digits) or words. Information about quantity was accessed earlier and more accurately if numbers were in a nonlinguistic code. Indeed, it can be speculated that numerosity processing would involve circuits originally involved in processing space (i.e., rAG/rIPS).

Neural correlates of automatic beliefs about gender stereotypes: Males are more prejudicial.

Aim of this study was to investigate the neural bases of stereotype representation, including the presence of gender bias. EEG was recorded from 128 sites in 38 Italian participants. While looking for rare animal words, participants read 240 sentences, half of which expressed notions congruent with gender stereotypes, and the other half did not (e.g., "Prepared the tomato sauce and then SHAVED", "The engineer stained HER SKIRT"). Event-related potentials (ERPs) were time-locked to critical words. Findings showed enhanced anterior N400 and occipito-parietal P600 responses to items that violated gender stereotypes, mostly in men. The swLORETA analysis applied to N400 potentials in response to incongruent phrases showed that the most activated areas during stereotype processing were the right medial temporal and medial frontal gyri, as well as the TPJ. The data hint at a gender difference in stereotyping, with men being more prejudicial especially when the depicted character is a male.

When listening to rain sounds boosts arithmetic ability.

Studies in the literature have provided conflicting evidence about the effects of background noise or music on concurrent cognitive tasks. Some studies have shown a detrimental effect, while others have shown a beneficial effect of background auditory stimuli. The aim of this study was to investigate the influence of agitating, happy or touching music, as opposed to environmental sounds or silence, on the ability of non-musician subjects to perform arithmetic operations. Fifty university students (25 women and 25 men, 25 introverts and 25 extroverts) volunteered for the study. The participants were administered 180 easy or difficult arithmetic operations (division, multiplication, subtraction and addition) while listening to heavy rain sounds, silence or classical music. Silence was detrimental when participants were faced with difficult arithmetic operations, as it was associated with significantly worse accuracy and slower RTs than music or rain sound conditions. This finding suggests that the benefit of background stimulation was not music-specific but possibly due to an enhanced cerebral alertness level induced by the auditory stimulation. Introverts were always faster than extroverts in solving mathematical problems, except when the latter performed calculations accompanied by the sound of heavy rain, a condition that made them as fast as introverts. While the background auditory stimuli had no effect on the arithmetic ability of either group in the easy condition, it strongly affected extroverts in the difficult condition, with RTs being faster during agitating or joyful music as well as rain sounds, compared to the silent condition. For introverts, agitating music was associated with faster response times than the silent condition. This group difference may be explained on the basis of the notion that introverts have a generally higher arousal level compared to extroverts and would therefore benefit less from the background auditory stimuli.

Non-expert listeners show decreased heart rate and increased blood pressure (fear bradycardia) in response to atonal music.

Previous studies suggested that listening to different types of music may modulate differently psychological mood and physiological responses associated with the induced emotions. In this study the effect of listening to instrumental classical vs. atonal contemporary music was examined in a group of 50 non-expert listeners. The subjects' heart rate and diastolic and systolic blood pressure values were measured while they listened to music of different style and emotional typologies. Pieces were selected by asking a group of composers and conservatory professors to suggest a list of the most emotional music pieces (from Renaissance to present time). A total of 214 suggestions from 20 respondents were received. Then it was asked them to identify which pieces best induced in the listener feelings of agitation, joy or pathos and the number of suggested pieces per style was computed. Atonal pieces were more frequently indicated as agitating, and tonal pieces as joyful. The presence/absence of tonality in a musical piece did not affect the affective dimension of pathos (being touching). Among the most frequently cited six pieces were selected that were comparable for structure and style, to represent each emotion and style. They were equally evaluated as unfamiliar by an independent group of 10 students of the same cohort) and were then used as stimuli for the experimental session in which autonomic parameters were recorded. Overall, listening to atonal music (independent of the pieces' emotional characteristics) was associated with a reduced heart rate (fear bradycardia) and increased blood pressure (both diastolic and systolic), possibly reflecting an increase in alertness and attention, psychological tension, and anxiety. This evidence fits with the results of the esthetical assessment showing how, overall, atonal music is perceived as more agitating and less joyful than tonal one.

The effect of background music on episodic memory and autonomic responses: listening to emotionally touching music enhances facial memory capacity.

The aim of this study was to investigate how background auditory processing can affect other perceptual and cognitive processes as a function of stimulus content, style and emotional nature. Previous studies have offered contrasting evidence, and it has been recently shown that listening to music negatively affected concurrent mental processing in the elderly but not in young adults. To further investigate this matter, the effect of listening to music vs. listening to the sound of rain or silence was examined by administering an old/new face memory task (involving 448 unknown faces) to a group of 54 non-musician university students. Heart rate and diastolic and systolic blood pressure were measured during an explicit face study session that was followed by a memory test. The results indicated that more efficient and faster recall of faces occurred under conditions of silence or when participants were listening to emotionally touching music. Whereas auditory background (e.g., rain or joyful music) interfered with memory encoding, listening to emotionally touching music improved memory and significantly increased heart rate. It is hypothesized that touching music is able to modify the visual perception of faces by binding facial properties with auditory and emotionally charged information (music), which may therefore result in deeper memory encoding.