CB7b

The ventral stream hypothesis

NCCs of visual consciousness are located in areas along the ventral visual stream

Binocular rivalry studies

Monkeys saw two things at the same time and the brain were scanned.’

They checked how many of the cells changed during this process (%)

fMRI studies of human visual consciousness

They compared faces and places

Since the two is processed by different areas in the brain, they wanted to compare it.

Ventral stream is strengthen by these experiments

Victor Lamme’s Recurrent processing theory

It is a leading “early” theory of visual consciousness

Fast visual processing without consciousness = feedforward processing up to 100 ms after stimulus onset

Phenomenal Visual Consciousness = local recurrent processing in the ventral visual stream, 100-200 ms after stimulus onset

Access Consciousness, reportability = widespread (global) recurrent processing reaching also to the frontoparietal networks and working memory

Contrastive analysis

The DIFFERENCE in ERPs between a stimulus that enters consciousness and a similar stimulus that remains outside consciousness

How to make stimuli invisible for contrastive analysis?

• above perceptual threshold vs below perceptual threshold stimulus

• masked vs non-masked stimulus

Where and when does event-related activity correlate with the conscious perception of objects?

There was an early MEG study of conscious visual perception was to show the subject objects and non objects in different duration. The study tried to localize the source that correlates with visual consciousness. It showed that the Right later occipital cortex had something to do with it. Visual awareness negativity (VAN) is an ERP event that correlate of visual awareness was found at the same window as a MEG component.

Problem with event related acitivty

There is a physical difference between stimuli that enter consciousness vs remain nonconscious, and does the results hold for physically identical stimuli

They don't know if the difference was the time that they showed the stimuli or if it was the consciousness that acted

Is VAN the earliest correlate or is it P1?

According to Antti it is VAN, but there was some other scientists that have published that suggested P1. But when they tried to replicate it they got the result that it was WAN and not P1.

Works/fit well with ventral stream consciousness theory

VAN may be an indicator of the onset of phenomenal visual consciousness

• The later positivity (LP) that also correlates with awareness of stimuli) may be an indicator of further, post-phenomenal conscious processing or reflective consciousness

The posterior “HOT ZONE” of NCC

States that the “visual consciousness” is located towards the back of the head

Global neuronal workspace theory

Is a leading “Late” theory of visual consciousness

It focus on:

• Preconscious processing

• Conscious Access (reportability)

And does not include phenomenal consciousness.

According to Victor Lama’s theory “preconscious” would be phenomenal consciousness

P3 = ERP NCC

P3 = late positivity

Peaks around 350 - 500 ms which is pretty late/slow from the stimuli happens to it actually enter consciousness

He (Haynes) states that we live in a world that is a third of a second late (high ping in league)