LECTURE 2 Flashcards
In visual cortex we find ocular dominance columns and orientation columns. Explain one line of research (methodology & results) for each of these columnar structures that shows that their properties are strongly altered by experience.
Ocular Dominance Columns:
Methodology: One line of research that investigated the plasticity of ocular dominance columns uses animal models and employed techniques such as monocular deprivation (covering one eye of the animal so it gets no response (suturing)).
Results: When the left eye is deprived for a period (1-2 weeks depending on species) and then it is opened again, we see that the ocular dominance columns for the right eye are much bigger. Meaning there are much more neurons responding to the input of the right eye compared to the left eye.
Orientation Columns:
Methodology: Induction of function in cortex by novel activity in ferrets. Visual and auditory pathways in normal ferrets (top) originate from the retina and cochlea, respectively. Eliminating inferior colliculus projections to the medial geniculate nucleus (MGN) in neonatal animals’ results in retinal fibres innervating the MGN. The MGN still projects to the auditory cortex (A1) and amygdala but now relays visual information.
Results: In rewired A1, horizontal connections are patchy and resemble connections in Primary visual cortex (V1)
Describe the evidence in monkeys that exposure to faces is a necessary condition for face-specific behavior and neural responses. Compare these effects to the long-term visual deficits in face perception seen in patients that were born with congenital cataract and for who vision was restored after a few months
When monkeys are raised without exposure to faces, they show no face-specific neural activity in MRI scans. Behaviourally, they exhibit a preference for looking at hands rather than faces, unlike control monkeys. Similarly, in patients with reversal cataract, deprived of patterned vision in early infancy, they fail to demonstrate normal holistic face processing. This is reflected in their ability to differentiate between the top halves of faces when the faces are aligned, unlike normal adults who show composite-face effect. These findings suggest that early visual experiences are crucial for the development of normal face processing abilities, as observed in both animal and patient studies.
Describe the evidence that the emergence of visual word form selectivity is dependent upon experience. How can we predict where this selectivity will appear before it appears? Will such a local change in selectivity be the only change in the brain as a consequence of this type of experience?
When showing Ex literates, illiterates, and literates. Different stimuli like objects, faces, words, pseudo words and complex patterns. We can see that literates VWFA response mostly to Words and pseudo words while almost not responding to the other stimuli. This is not shown for the illiterates while the ex-literates show some activation between the literate and ex literates.
Selectivity will appear at the most appropriate place meaning that use of already available functions (‘cultural recycling’) is informative to the new thing you are learning.
No, this changei n the brain region by consequence will change different parts of the brain that are connected to the changing area and make new connections to related tasks if they arent already there.
