Biomedical subjects

Massimiliano Zampini

Publications and source records attributed to Massimiliano Zampini.

18 recordsLinked to original sources

PubMed2007

'Prior entry' for pain: attention speeds the perceptual processing of painful stimuli.

We investigated whether the perception of simultaneity for pairs of nociceptive and visual stimuli was dependent upon the focus of participants' attention to a particular sensory modality (either pain or vision). Two stimuli (one painful and the other visual) were presented randomly at different stimulus onset asynchronies (SOAs) using the method of constant stimuli. Participants made unspeeded verbal responses as to which stimulus they perceived as having been presented first, or else responded that the two stimuli were presented simultaneously. This temporal discrimination task was repeated under three different attention conditions (blocks): divided attention, attend pain, and attend vision. The results showed that under conditions of divided attention, nociceptive stimuli had to be presented before visual stimuli in order for the two to be perceived as simultaneous. A comparison of the two focused attention conditions revealed that the painful stimulus was perceived as occurring earlier in time (relative to the visual stimulus) when attention was directed toward pain than when it was directed toward vision. These results provide the first empirical demonstration that attention can modulate the temporal perception of painful stimuli.

Adult↗

PubMed2006

Tactile perception of the roughness of the end of a tool: what role does tool handle roughness play?

We investigated whether the perceived roughness of the end of a tool is influenced by the texture of the handle used to hold it. Participants rated the roughness of the ends (caps) of a series of tools by rubbing them along their forearm, and indicated the perceived roughness of the tool's cap by means of an anchored visual scale. The caps of the tools had one of eight different levels of roughness varying from very smooth (sample 1) to very rough (sample 8). The participants held the tool handle in one hand while rubbing the cap of the tool against their contralateral forearm. The tool handle was either smooth (similar in smoothness to sample 1) or else very rough (matched in roughness to sample 8). Overall, participants were remarkably good at ignoring the roughness of the tool's handle when discriminating the roughness of the tool's cap. Nevertheless, the roughness of the tool handle was shown to modulate roughness judgments concerning the tool cap under certain conditions: in particular, tool caps at the rougher end of the scale (6 and 7) were rated as being significantly less rough when the participants held tools with a rough handle than when they held tools with a smooth handle. Our results therefore demonstrate a small but significant effect of the roughness of the handle of a tool on the perceived roughness of its cap.

Adult↗

PubMed2005

Exposure to asynchronous audiovisual speech extends the temporal window for audiovisual integration.

We examined whether monitoring asynchronous audiovisual speech induces a general temporal recalibration of auditory and visual sensory processing. Participants monitored a videotape featuring a speaker pronouncing a list of words (Experiments 1 and 3) or a hand playing a musical pattern on a piano (Experiment 2). The auditory and visual channels were either presented in synchrony, or else asynchronously (with the visual signal leading the auditory signal by 300 ms; Experiments 1 and 2). While performing the monitoring task, participants were asked to judge the temporal order of pairs of auditory (white noise bursts) and visual stimuli (flashes) that were presented at varying stimulus onset asynchronies (SOAs) during the session. The results showed that, while monitoring desynchronized speech or music, participants required a longer interval between the auditory and visual stimuli in order to perceive their temporal order correctly, suggesting a widening of the temporal window for audiovisual integration. The fact that no such recalibration occurred when we used a longer asynchrony (1000 ms) that exceeded the temporal window for audiovisual integration (Experiment 3) supports this conclusion.

Acoustic Stimulation↗

PubMed2005

Audiotactile interactions in near and far space.

In this study we investigated audiotactile spatial interactions in the region behind the head. In experiment 1, participants made unspeeded temporal order judgments (TOJs) regarding pairs of auditory and tactile stimuli presented at varying stimulus onset asynchronies (SOAs) using the method of constant stimuli. Electrocutaneous stimuli were presented to the left or right earlobe while auditory stimuli were presented from just behind the participant's head on either the same or opposite side. Participants responded significantly more accurately when the stimuli were presented from different sides rather than from the same side. In experiment 2, we used a distractor interference task to show that speeded left/right discrimination responses to electrocutaneous targets were also modulated by the spatial congruency of auditory distractors presented behind the head. Performance was worse (i.e. response latencies were slower and error rates higher) when the auditory distractors were presented on the opposite side to the electrocutaneous target than when they were presented on the same side. This crossmodal distractor interference effect was larger when white noise distractors were presented from close to the head (20 cm) than when they were presented far from the head (70 cm). By contrast, pure tone distractors elicited a smaller crossmodal distractor interference effect overall, and showed no modulation as a function of distance. Taken together, these results suggest that the spatial modulation of audiotactile interactions occurs predominantly for complex auditory stimuli (for example, white noise) originating from the region close to the back of the head.

Acoustic Stimulation↗

PubMed2005

Effect of posture change on tactile perception: impaired direction discrimination performance with interleaved fingers.

We report a series of experiments in which participants had to judge the direction in which a pair of vibrotactile stimuli presented to two adjacent digits of either the same or different hands were stimulated (left-to-right or vice versa in experiments 1 and 2; near-to-far or vice versa in experiment 3, at stimulus onset asynchronies varying between 100 and 600 ms). When the participant's hands were placed side-by-side (anatomical posture), with their fingers either pointing away from them or else pointing toward the midline, directional discrimination performance was generally accurate. By contrast, when the fingers of the two hands were interleaved in either of these postures, performance deteriorated significantly for certain specific combinations of digits, with a more pronounced impairment seen when the fingers pointed away from the participant than when they pointed toward the midline. This decline in tactile direction discrimination performance in the interleaved fingers posture appears to reflect a failure to represent the position of tactile stimuli correctly when the fingers of the two hands are interleaved.

Adult↗

PubMed2005

Vibrio cholerae persistence in aquatic environments and colonization of intestinal cells: involvement of a common adhesion mechanism.

Forty-one Tnpho A mutants of Vibrio cholerae O1 classical strain CD81 were analyzed for their ability to interact with chitin particles, Tigriopus fulvus copepods and the Intestine 407 cell line compared to the parent strain. Thirteen mutants were less adhesive than CD81; in particular, T21, T33 and T87 were less adhesive towards all substrates and insensitive to inhibition by N-acetyl glucosamine (GlcNAc). By SDS-PAGE analysis of sarkosyl-insoluble membrane proteins (siMPs) isolated from mutants and parent, it was found that a 53 kDa siMP is missing in T21, T33 and T87 mutants. It is hypothesized that this protein might have the function to mediate adherence to GlcNAc-containing substrates both in the aquatic environment and in human intestine.

Animals↗

PubMed2005

Audiovisual prior entry.

It is almost one hundred years since Titchener [E.B. Titchener, Lectures on the Elementary Psychology of Feeling and Attention, Macmillan, New York, 1908] published his influential claim that attending to a particular sensory modality (or location) can speed up the relative time of arrival of stimuli presented in that modality (or location). However, the evidence supporting the existence of prior entry is, to date, mixed. In the present study, we used an audiovisual simultaneity judgment task in an attempt to circumvent the potential methodological confounds inherent in previous research in this area. Participants made simultaneous versus successive judgment responses regarding pairs of auditory and visual stimuli at varying stimulus onset asynchronies (SOAs) using the method of constant stimuli. In different blocks of trials, the participants were instructed to attend either to the auditory or to the visual modality, or else to divide their attention equally between the two modalities. The probability of trials containing intramodal stimulus pairs (e.g., vision-vision or audition-audition) was increased in the focused attention blocks to encourage participants to follow the instructions. The perception of simultaneity was modulated by this attentional manipulation: Visual stimuli had to lead auditory stimuli by a significantly smaller interval for simultaneity to be perceived when attention was directed to vision than when it was directed to audition. These results provide the first unequivocal evidence for the existence of audiovisual prior entry.

Acoustic Stimulation↗

PubMed2005

Audio-visual simultaneity judgments.

The relative spatiotemporal correspondence between sensory events affects multisensory integration across a variety of species; integration is maximal when stimuli in different sensory modalities are presented from approximately the same position at about the same time. In the present study, we investigated the influence of spatial and temporal factors on audio-visual simultaneity perception in humans. Participants made unspeeded simultaneous versus successive discrimination responses to pairs of auditory and visual stimuli presented at varying stimulus onset asynchronies from either the same or different spatial positions using either the method of constant stimuli (Experiments 1 and 2) or psychophysical staircases (Experiment 3). The participants in all three experiments were more likely to report the stimuli as being simultaneous when they originated from the same spatial position than when they came from different positions, demonstrating that the apparent perception of multisensory simultaneity is dependent on the relative spatial position from which stimuli are presented.

Adult↗

PubMed2004

Audiotactile temporal order judgments.

We report a series of three experiments in which participants made unspeeded 'Which modality came first?' temporal order judgments (TOJs) to pairs of auditory and tactile stimuli presented at varying stimulus onset asynchronies (SOAs) using the method of constant stimuli. The stimuli were presented from either the same or different locations in order to explore the potential effect of redundant spatial information on audiotactile temporal perception. In Experiment 1, the auditory and tactile stimuli had to be separated by nearly 80 ms for inexperienced participants to be able to judge their temporal order accurately (i.e., for the just noticeable difference (JND) to be achieved), no matter whether the stimuli were presented from the same or different spatial positions. More experienced psychophysical observers (Experiment 2) also failed to show any effect of relative spatial position on audiotactile TOJ performance, despite having much lower JNDs (40 ms) overall. A similar pattern of results was found in Experiment 3 when silent electrocutaneous stimulation was used rather than vibrotactile stimulation. Thus, relative spatial position seems to be a less important factor in determining performance for audiotactile TOJ than for other modality pairings (e.g., audiovisual and visuotactile).

Acoustic Stimulation↗

PubMed2004

Environmental estrogens can affect the function of mussel hemocytes through rapid modulation of kinase pathways.

Estrogens and estrogenic chemicals can affect several vertebrate non-reproductive functions, the immune response in particular. We have previously shown that in the hemocytes of the marine mollusc Mytilus the natural estrogen 17beta-estradiol (E(2)) can affect the immune function through rapid tyrosine kinase-mediated signalling pathways converging on phosphorylation of both mitogen activated protein kinases (MAPKs) and signal transducers and activators of transcription (STATs), whose activation plays a key role in the immune response. In this work the effects of synthetic estrogens (such as DES), estrogenic chemicals (such as Bisphenol A, Nonylphenol), and plant estrogens (genistein) on mussel hemocytes were evaluated. The results demonstrate that all the EDCs tested exert in vitro effects similar to those of E(2) on lysosomal membrane stability, although at concentrations 1000 times higher than those of the natural estrogen. When the effects of DES, BPA, and NP on tyrosine kinase-mediated cell signalling were investigated, estrogenic compounds showed distinct effects on the phosphorylation state of MAPK and STAT members. In particular, only DES, like E(2), induced p38 MAPK phosphorylation, whereas BPA and NP seem to have opposite effects. Moreover, different EDCs significantly decreased the tyrosine phosphorylation state of STAT3 and STAT5, showing a distinct effect with respect to E(2). Experiments with specific kinase inhibitors showed that activation of p38 MAPK, but also of ERK MAPK and PI3-kinase, plays a key role in mediating the effect of DES. On the other hand, the effects of NP were partly mediated by ERK MAPK activation. BPA-induced lysosomal membrane destabilisation was unaffected by either MAPK or PI3-K inhibitors. However, hemocyte pre-treatment with the PKC inhibitor GF109203X prevented the effects of both BPA and NP, this indicating that kinase pathways other than those involving MAPKs are also responsible for mediating the effects of certain EDCs. Overall, the results support the hypothesis that EDCs may rapidly modulate the function of mussel hemocytes through activation of transduction pathways involving different kinase-mediated cascades. Moreover, the effects of EDCs on the phosphorylation state of transcription factor STATs suggest that these compounds may lead to changes in gene expression secondary to modulation of kinase/phosphatases. Our data address to the importance of investigating full range responses to estrogenic chemicals and may help understanding their basic mechanisms of action in ecologically relevant invertebrate species.

Animals↗

PubMed2004

Changes in spatial position of hands modify tactile extinction but not disownership of contralesional hand in two right brain-damaged patients.

Somatic misperceptions and misrepresentations, like supernumerary phantom limb and denial of ownership of a given body part, have typically been reported following damage to the right side of the brain. These symptoms typically occur with personal or extrapersonal neglect and extinction of left-sided stimuli, suggesting that all these different symptoms may be linked to the same neural substrate. In the present research, we tested two right brain-damaged (RBD) patients to find out whether changing the position of the hands in space influences tactile extinction and denial of ownership to the same extent. Results showed that manipulation of the spatial position of the hands reduces tactile extinction but leaves denial of ownership of the left hand unaffected. Such a dissociation suggests that delusional misperceptions may be independent from somatic neglect and that representation of hands in space and attribution of ownership are dynamically mapped in at least partly separate neural substrates.

Aged↗

PubMed2004

Adhesion of Enterococcus faecalis in the nonculturable state to plankton is the main mechanism responsible for persistence of this bacterium in both lake and seawater.

The presence of enterococci in lake and seawater in an 18-month survey comparing molecular (PCR and quantitative PCR) and culture methods was evaluated, as well as the possibility that zooplankton could act as reservoirs for enterococci. Samples of both water and zooplankton were collected monthly from a Lake Garda site and an Adriatic Sea site. In lake water, the positive samples numbered 13 of 54 (24%) by culture and 32 of 54 (59%) when PCR was applied. In seawater, they numbered 0 of 51 by culture and 18 of 51 (35%) by PCR. Enterococci were found either totally bound to plankton or totally in water, depending on the presence or absence of plankton, respectively. These results clearly indicate that the PCR assay is a powerful tool for detecting fecal indicators and pathogens in the environment, thus providing a much more sensitive method than culture.

Animals↗

PubMed2003

Audiovisual temporal order judgments.

In two experiments, we examined the extent to which audiovisual temporal order judgments (TOJs) were affected by spatial factors and by the dimension along which TOJs were made. Pairs of auditory and visual stimuli were presented from either the left and/or right of fixation at varying stimulus onset asynchronies (SOAs), and participants made unspeeded TOJs regarding either "Which modality was presented first?" (experiment 1), or "Which side was presented first?" (experiment 2). Modality TOJs were more accurate (i.e. just-noticeable differences, JNDs, were smaller) when the auditory and visual stimuli were presented from different spatial positions rather than from the same position, highlighting an important potential confound inherent in previous research. By contrast, spatial TOJs were unaffected by whether or not the two stimuli were presented in different modalities. A between-experiments comparison revealed more accurate performance (i.e. smaller JNDs) when people reported which modality came first than when they reported which side came first for identical bimodal stimulus pairs. These results demonstrate that multisensory TOJs are critically dependent on both the relative spatial position from which stimuli are presented and on the particular dimension being judged.

Acoustic Stimulation↗

PubMed2003

Multisensory temporal order judgments: the role of hemispheric redundancy.

Participants made unspeeded 'Which modality came first?' temporal order judgments (TOJs) in response to pairs of auditory and visual stimuli presented at varying stimulus onset asynchronies (SOAs), using the method of constant stimuli. The presentation of auditory and visual stimuli from different spatial positions facilitated performance (i.e. just noticeable differences were lowered) only when the stimuli were presented across the body midline (Experiment 4), but not when both stimuli were either placed on the body midline (Experiments 1-3), or else within the same hemifield (Experiment 5). These results demonstrate that hemispheric redundancy may account for the facilitatory effects reported in previous multisensory TOJs research when stimuli were presented from different spatial locations. Our results also show that the accuracy with which people can make multisensory TOJs is unaffected by the predictability of target stimulus locations, suggesting little role for spatial attention in this aspect of multisensory temporal perception.

Acoustic Stimulation↗

PubMed2003

Persistence of adhesive properties in Vibrio cholerae after long-term exposure to sea water.

The effect of exposure to artificial sea water (ASW) on the ability of classical Vibrio cholerae O1 cells to interact with chitin-containing substrates and human intestinal cells was studied. Incubation of vibrios in ASW at 5 degrees C and 18 degrees C resulted in two kinds of cell responses: the viable but non-culturable (VBNC) state (i.e. <0.1 colony forming unit ml-1) at 5 degrees C, and starvation (i.e. maintenance of culturability of the population) at 18 degrees C. The latter remained rod shaped and, after 40 days' incubation, presented a 47-58% reduction in the number of cells attached to chitin, a 48-53% reduction in the number of bacteria adhering to copepods, and a 48-54% reduction in the number of bacteria adhering to human cultured intestinal cells, compared to control cells not suspended in ASW. Bacteria suspended in ASW at 5 degrees C became coccoid and, after 40 days, showed 34-42% fewer cells attached to chitin, 52-55% fewer adhering to copep-ods, and 45-48% fewer cells adhering to intestinal cell monolayers, compared to controls. Sarkosyl-insoluble membrane proteins that bind chitin particles were isolated and analysed by SDS-PAGE. After 40 days incubation in ASW at both 5 degrees C and 18 degrees C vibrios expressed chitin-binding ligands similar to bacteria harvested in the stationary growth phase. It is concluded that as vibrios do not lose adhesive properties after long-term exposure to ASW, it is important to include methods for VBNC bacteria when testing environmental and clinical samples for purposes of public health safety.

Animals↗

PubMed2003

Role for mannose-sensitive hemagglutinin in promoting interactions between Vibrio cholerae El Tor and mussel hemolymph.

The role of mannose-sensitive hemagglutinin (MSHA) in Vibrio cholerae O1 El Tor interactions with hemolymph of the mussel Mytilus galloprovincialis was studied. Bacterial adherence to and association with hemocytes were evaluated at 4 and 18 degrees C, respectively. In hemolymph serum, the wild-type strain N16961 adhered to and associated with hemocytes about twofold more efficiently than its mutant lacking MSHA. In artificial seawater (ASW), no significant differences between the two strains were observed. N16961 was also more sensitive to hemocyte bactericidal activity than its MSHA mutant; in fact, the percentages of killed bacteria after 120 min of incubation were 60 and 34%, respectively. The addition of D-mannose abolished the serum-mediated increase in adherence, association, and sensitivity to killing of the wild-type strain without affecting the interactions of the mutant. A similar increase in N16961 adherence to hemocytes was observed when serum was adsorbed with MSHA-deficient bacteria. In contrast, serum adsorbed with either wild-type V. cholerae El Tor or wild-type Escherichia coli carrying type 1 fimbriae was no longer able to increase adherence of N16961 to hemocytes. The results indicate that hemolymph-soluble factors are involved in interactions between hemocytes and mannose-sensitive adhesins.

Animals↗

PubMed2003

Multisensory temporal order judgments: when two locations are better than one.

In Experiment 1, participants were presented with pairs of stimuli (one visual and the other tactile) from the left and/or right of fixation at varying stimulus onset asynchronies and were required to make unspeeded temporal order judgments (TOJs) regarding which modality was presented first. When the participants adopted an uncrossed-hands posture, just noticeable differences (JNDs) were lower (i.e., multisensory TOJs were more precise) when stimuli were presented from different positions, rather than from the same position. This spatial redundancy benefit was reduced when the participants adopted a crossed-hands posture, suggesting a failure to remap visuotactile space appropriately. In Experiment 2, JNDs were also lower when pairs of auditory and visual stimuli were presented from different positions, rather than from the same position. Taken together, these results demonstrate that people can use redundant spatial cues to facilitate their performance on multisensory TOJ tasks and suggest that previous studies may have systematically overestimated the precision with which people can make such judgments. These results highlight the intimate link between spatial and temporal factors in determining our perception of the multimodal objects and events in the world around us.

Adult↗

PubMed2002

In vitro adhesion to human cells by viable but nonculturable Enterococcus faecalis.

The ability of viable but nonculturable (VBNC) Enterococcus faecalis to adhere to Caco-2 and Girardi heart cultured cells and to urinary tract epithelial cells (ECs) was studied. Enterococci were harvested during the vegetative growth phase (early exponential and stationary), in the VBNC state, and after recovery of the ability to divide. VBNC bacteria maintained their adherence capability but the efficiency of attachment was reduced by about 50 to 70%, depending on the target cell employed. The decrease was transient, since enterococci that regained their culturability showed adherence values similar to those observed for actively growing cells. Analysis of the invasive properties of E. faecalis revealed that the VBNC state caused a decrease in the number of bacteria that entered the cultured HEK cells as a result of the reduction in the number of adhering bacteria. These results highlight the importance of studies of the VBNC phenomenon, with respect to both microbial survival in the environment and the impact on human health.

Bacterial Adhesion↗