Week 2: the brain

consciousness

identity theorists

identity theorists

mind and brain are identical (consciousness=brain activity)

eliminative materialists

quali don't exist, understanding of the mind is wrong. mind=brain (since qualia of the mind don't exist)

extended minfers/embodies cognition

neural activity alone can't provide answers. need to take body and environment into account

mysterians

can never understand consciousness (not possible for humans)

peripheral nervous system

sensory and motor neurons that run through spinal cord and brainstem

central nervous system

spinal cord and brain

medulla, pons, mid-brain

brainstem (controls: cardiac, respiratory and sexual functions)

cerebellum

motor control

thalamus

relay areas for sensory inputs

• thalamocortical loop

reticular formation

involved in pain desensitisation and forms reticular activating system (sleep-wake transitions)

necessary but not sufficient

reticular formation role for consciousness

hypothalamus

regualtes autonomic nervous system

cingulate gyrus

plays role in emotion, pain and motivational responses

neocortex

expanded more than any other brain structure during human evolution

• no ultimate top

• interlinked system

excitatory pyramidal cells and inhibitory interneurons

two main types of neurons running through neocortex

parietal lobe

sensory association areas, somatosensory cortex and dorsal stream

temporal

auditory, memory, ventral stream

single cell recordings

animal studies. microelectrode inserted into neuron and records activity

neural correlates of consciousness

measure an aspect of neural functioning and correlate it with conscious experience reports

contrastive method

conscious perception is compared to unconscious perception

Classic Method

rivalry in vision

• binocular rivalry

binocular rivalry

different images are presented to each eye resulting in perception flipping between both eyes

• both images compete for consciousness

unconscious homunculus

(Francis Crick) front of the brain is observing sensory areas with many zombie modes of processing all over brain

• contain transient groups of neurons corresponding to thoughts, images and perceptions

bridge locus

locatable part of brain, crossing point for matter and consciousness (1980s)

• neural activity here is sufficient for visual consciousness (elsewhere isn't)

V1 neurons

don't contribute to phenomenal experience

• all unconscious info is necessary precursor for conscious experience (not responsible for it tho)

global neuronal workspace theory

NCCs of visual consciousness comprise of many diff areas associated with vision working together

mereological fallacy

giving attributes to parts of a person/thing than can only be given to person/thing as a whole

central areas

where were conscious visual experiences correlated with instead of V1 or early parts of sensory pathways?

reciprocal inhibition

dominant image inhibits the other (suppressed image)

• weakened as neurons become habituated to dominant image (suppressed image becomes dominant)

anesthesia

blocking at thalamus level (disconnect similar to PVS)

consciousness switch

thalamus

ketamine

antagonist of NMDA receptor, blocks normal excitatory effect of glutamate

• anesthetic

integrated information theory of consciousness

conscousness increases and decreases with integration of info in brain

source amnesia

inability to remember source of knowledge.

• related to unconscious plagiarism

unconscious plagiarism

false belief of having invented an idea when it was actually learned from someone else

dual-process theory

thoughts can arise from two diff processes: conscious or unconscious

• contrasts automatic processing vs controlled

level-of-processing hypothesis

transition from unconscious to conscious is influenced by level of processing required by task

cartesian theatre

physical and metaphorical place where conscious experience takes place

• ideas, images, feelings we are consciously aware of are presented

cartesian materialism

discarding Descartes' dualism, but fail to discard imagery of central (but material) theatre

parallel processing

mutual interactions between several areas (no 'top' can be located/ no where can we say consciousness happens 'here')

pictoralists

incorrectly associate observing similarities between imagery and vision with saying pictures in the brain are painted on a mental canvas

propositionalists

mental imagery is language-like

enactivistic

when we imagine, sensory exploration is performed without any interaction with environment

sensorimotor theories

potential for sensory exploration is enough for imagination

• imagining/seeing depends on bodily engagement with environment

neuronal global workspace model

no info has to become conscious and a collection of specialised unconscious processors competes for access to GW

conscious mental field

cut off piece of cortical tissuel, if activated communication would take place in form of field that doesn't depend on nerve pathways

binding problem

how features from diff circuits can be combined for perception

attention

what makes binding possible

help coalition in competition for consciousness

what is the primary role of synchrony?

temporal binding

neurons representing 1 object fire in synchrony with each other, but out of synchrony with neurons representing other objects simultaneously

integration information theory

consciousness is the capacity of a system to integrate info

synesthesia

integrated cross-modal perception

interpreter

produces plausible explanations for RH's actions

executive and supervisory levels

what two brain functions were studied on SB patients (MacKay)

executive levels

unconsciously control goal-directed activities and evaluate them in terms of priorities

self-supervisory levels

determine and update priorities evaluated by executive levels

amnesiac syndrom

dissociation between performance and consciousness

• conscious but stuck in present, disconnected from past

anterograde amnesia

inability to form new LT memories

retrograde amnesia

inability to have LT memories of past events