Loss and Plasticity Flashcards
What is crossmodal plasticity?
idea that neural wiring for perception of each sense is not fixed and can be changed
Give a summary of the blind being better at touch
Evidence shows that blind are better at tactile discrimination and show visual area activity during these tasks that sighted do not, suggesting they recruit unused visual area.
There seems to be a critical period for this plasticity as there is less enhancement in the late versus congenitally blind.
Plasticity seems to be prompted by practice, as see enhancement and activity in visual area in sighted with more pratice.
The critical period is at odds with practice findings, as non-congenitally blind who had been blind for decades still worse than congenitally blind. Suggests a mix of practice and loss prompts plasticity.
Explain Sadato et al. 1996 and Ptitio et al. 2005
Sadato et al - early visual areas are more active in early blind reading braille/other tactile discrimination tasks compared to sighted
Pititio et al. 2005 - blind better performance discriminating shapes using tongue display than blindfolded sighted, blind participants showed visual area activity but sighted did not
Suggests that blind are recruiting unused visual areas to enhance their touch
Explain Roder et al. 2004
Temporal order judgement task, which of two hands did feel touched/stimulated first, perform with handw in front of you uncrossed or crossed over
Sighted much better performance when uncrossed versus crossed (didn’t matter if blindfolded or hands covered)
Congenitally blind better performance than sighted and no confusion when crossed
Late blind worse when arms crossed like sighted
Suggests critical period for plasticity - congenitally blind never seen hands so don’t get confused between touch based somatosensory and external visual reference frames
Explain Kobor et al. 2006 and Saito et al. 2007
Kobor et al - musicians (highly skilled/practiced with hands) show no crossed arm deficit, more practice attending to hands in area can’t see, suggests enhancement is due to just practice
Saito et al. 2007 - Mahjong experts (who feel characters under fingertips so have practice attending to touch) show recruitment of visual areas for tactile tasks, suggests enhancement is due to practice prompting plasticity not just unused area
Give a summary of the blind hearing better
Evidence supports that the blind hear better, but only in the periphery.
Evidence suggests from practcie with spatial listening.
Suggestion that recruitment of visual areas could be for brain hygiene to control noisy activity from lack of input.
Explain Roder et al. 1999 and Munte et al. 2001
Roder et al. 1999 - spatial discrimination task, array of loudspeakers arround participant, one of which target meant to respond to rest distractors, blind similar performance to sighted with target in front, but fewer fasle alarms when in periphery.
Munte et al. 2001 - conductors enhanced auditory localisation in pheriphery compared to painists and non-musicians
Shows blind do hear better but only in periphery and suggests due to practice listening spatially
Explain Singh et al. 2018
blind have little difference in taste sensitivty but replicated periphery hearing, idea that recruitment of cortex by nearby senses but not far away ones, recruitment due to noisy activity in visual areas without input, for brain hygiene rather than extra resources
Give a summary of enhanced senses under deprivation
Deprivation of mechanical senses results in enhancement of other mechanical senses performance and brain areas. Too rapid to be rewiring suggest using latent connections.
No benefit of deprivation to chemical senses.
Explain Zubeck 1969 and Marabet et al. 2004
Zubeck 1969 - within a few days of sensory deprivation participants start to hallucinate/generate visual percepts
Marabet et al. 2004 - blindfolded for 5 days waking hours, 70% experienced visual hallucinations typically after first day, simple like spots of light and complex like Elvis
Explain Boroojerdi et al. 200
Enhanced visual cortex excitability after 45 minutes light deprviation, too rapid to be rewiring so suggests connections already there and deprivation removes inhbition
Explain Facchini and Aglioti 2003 and Lewald 2007
Facchini and Aglioti 2003 ehanced tactile spatial acuity after 90 mins of visual deprviation in sighted, back to normal after 130 mins exposure to light
Lewald 2007 spatial acuity of sound localisation significantly enhanced by 45 mins blindfoldind compared to non-blindfolded sighted
Explain how deprivation is different for chemical senses
Spence and Piqueras-Fiszman 2012 no evidence for enhancement of taste following short term visual deprivation, long term auditory and visual defecits undermine food experience (deafness lower gustatory sensitivity, blindness increased to salty tastes)
Explain how multisensory integration is affected by sensory loss
Hotting and Roder 2004 - change in sensory dominance in congenitally blind with less dominance of hearing over touch
Peter et al. 2019 simultineity judgement task those with los of smell increased ability to detect temporal asynchronies, narrowing of binding window/enhanced MSI
