LECTURE 2 - Cognitive Neuroscience Flashcards
what is dualism?
- the idea that the mind exists separately from the body
- thought of by Rene Descarte
- mind/soul = thinking, body = matter and unthinking
- argued that the mind could exist without the body, but body cannot exist without the mind
- mind can be subject to scientific study, challenging the notion of divine soul
what is materialism?
- the idea that the mind is entirely a product of the brain
- most psychological theories are based on materialism
what determines whether we think someone is innocent or guilty of a crime based on materialism and dualism?
- materialism, mind = body/brain, would assume same culpability for someone who gets in an accident because of a seizure, and another who murders because of a brain tumour (not guilty)
- dualism, mind ≠ body/brain, would assume that they are guilty because their brain and mind are separate
why do we consider whether we have free will or not?
if there is no way to tease apart one’s choices and one’s neural circuitry, then do we have free will?
- if materialism is true and the mind = brain
what experiment was done to test whether we have free will?
- benjamin libet used EEG to record brain activity during a key press
- they pressed the key whenever they felt the urge to (free choice)
- found that neuronal activity comes before the urge to move by 100ms
- claimed that unconscious electrical processes in the brain, “readiness potentials” come before conscious decisions to act
- determined that we do not have free will
what is determinism?
philosophical stance claiming that unconscious neuronal processes come before, and potentially cause volitional acts which are then felt to be driven by conscious thought
what is cognitive neuroscience?
- study of neural mechanisms of cognition and behaviour
- aims to understand how we perceive, think, learn, remember, communicate, and control actions
- unlike cognitive psychology, it focuses on role of underlying brain networks and mechanisms
- neural signals transform information from the environment and past experience into representations that underlie thought, emotion, and action
what is the idea of functional specialization?
- different parts of the brain can serve different functions
- some areas specialize in serving specific perceptual and cognitive skills
what is an example of functional specialization?
- fusiform gyrus is involved in face perception
- malfunction can cause prosopagnosia (face blindness)
- hippocampus is critical for memory and lesions can result in memory loss
what are neurons?
- neurons receive input via dendrites and transmit info to other neurons via axons
- the cell body/soma also receives input and provides metabolic machinery for the neuron
- neural signals are transmitted via electrical/chemical signal process across synapses
how can synapses be altered?
- synapses are plastic, their strength can change with learning and experience
- learning changes the probability of neural transmission from one neuron to another
- changes in synapse strength is a foundation of memory formation
what are glial cells?
- non-neuronal cells that give structural and functional support for neurons
- the brain’s connective tissue and are the most common cell type in the CNS
how is the brain organized?
- divided into left and right hemispheres
- lateralization = physically symmetrical but functionally distinct
- left hemisphere = info for the right side of the body, and language function
- right hemisphere = info for the left side of the body, and visuospatial tasks
- if a person is left-handed, language and visuospatial task brain areas can be flipped
what happens in split brain patients?
- corpus callosum is severed, the hemispheres cannot communicate and a range of function loss in perception, speech and memory can occur
- testing showed that each hemisphere could do things that the other could not
- eventually the two hemispheres adapt and the symptoms lessen
what was a test on split brain patients and what did it reveal?
- left side of the brain is responsible for language
- right side of the brain is responsible for visuospatial things
- split brain patients have an image show up in either the right field of vision or the left
- when the image was on the right side, info went to the left side of the brain, and patient is able to repeat the word
- when the image was on the left side, info went to the right side of the brain, and patient is not able to repeat the word, but can draw it
what are the four lobes of the brain? what does the cerebellum do?
- occipital - visual perception
- temporal lobe - complex perception, memory, and language
- frontal lobe - thinking, planning, and decision making
- parietal lobe - visuospatial and motor functions
- cerebellum - movement and complex cognition, emotion and social function
how do neuroscience research methods differ?
- they differ in spatial resolution, temporal resolution, and invasiveness
- spatial resolution: ability to pinpoint where neural activity occurs
- temporal resolution: ability to pinpoint where neural activity occurs
- invasiveness: amount of impact a method has on an individual’s brain
what is neuropsychology?
- studies the behavioural impact of brain lesions
- resulting naturally from stroke/illness or unnaturally from trauma/surgery
- areas controlling a brain function can be determined by mapping out overlapping areas of damage in patients with the same deficit
what are the main discoveries of neuropsychology?
- mapping brain mechanisms to behaviour is possible because of functional specialization
- broca’s area: in the left frontal lobe, controls motor aspects of language
- wernicke’s area: in the left temporal lobe, controls understanding of language
- discovery of these areas supports materialism over dualism
what are some limitations of neuropsychology as a scientific method?
- lesions are often broad and affect more than just one area
- brain damage impairs several functions and it is difficult to define a group of healthy controls
- treating patients takes precedence over testing them
what is electrophysiology?
- studying direct electrical activity of neurons measured by inserted electrodes
- electrodes can pick up activity of groups of neurons and single-neuron activity can be calculated
- changes in firing rates signify a change in neuronal function
- brain cells are selective for the stimuli to which they respond
what did Hubei and Wiesel win their Nobel Prize for?
determining firing rate of neurons in primary visual cortex in response to different visual stimuli
what is an example of a brain cell that is selective to the stimuli they respond to?
- a face-selective neuron will respond strongly to a face but not to a non-face stimuli
- scrambled images do not elicit a strong response
what are some limitations of electrophysiology as a scientific method?
- highly invasive and requires animal models
- animal models are not always good models of human perception, cognition, and action
- expensive to set up and maintain
- only possible in humans if done during a required surgery
what is electrocorticography (ECoG)?
- intracranial recordings
- used to localize origin of seizure activity
- guides surgery to remove minimal amount of brain tissue
- revealed highly selective face neurons (halle berry neuron)
- other selective neurons for non-face objects and words found in visual cortex
what is electroencephalography (EEG)?
- less invasive recording of neural activity using scalp electrodes
- shows activity of millions to billions of neurons
- limited spacial resolution
- can look different states of consciousness and sleep
- can see large oscillating waves in epileptics
what are event-related potentials from EEGs?
- EEG in response to a stimulus or task
- N170 is a face selective ERG (shows that our brain differentiates between face and non-face stimuli)
- N170 shows high temporal resolution of EEGs
- EEGS also inexpensive compared to fMRI
what is functional magnetic resonance imaging (fMRI)?
- blood oxygen level dependent signal increases with increased brain activity
- neurons use more oxygen when active
- BOLD signal can be plotted on structural image to show where brain activity is changing
what is magnetic resonance imaging (MRI)?
measures differences in magnetic properties of different tissues to provide detailed structural information
what is functional brain mapping? what did this show us?
- helps clinicians predict deficits with damage
- identifies regions of interest for future testing
- showed face areas of individuals with ASD show less activity in response to faces than do others
what are the advantages of fMRI over intracranial recording or EEG?
- less invasive than intracranial recordings
- better spatial resolution than EEG, but not as good as single-cell recordings
what are some limitations of fMRI?
- correlation vs. causation problem: brain activity in a region does not mean the region is necessary for the cognitive task or perception
- expensive
- poor temporal resolution
what is transcranial magnetic stimulation (TMS)?
- brain stimulation methods stimulate or disrupt activity to study causation of perceptual or cognitive function
- TMS temporarily disrupts brain activity using focal magnetic pulses
- helps determine if a brain region is needed for a function
- noninvasive and good temporal resolution
what is psychophysics?
- observing our own sensations and perceptions to learn about our body and mind
- includes reaction time, detection, discrimination methods
- we can use more objective modern tools; measuring eye movements, asking observers what they see
how is sensory information filtered?
- most sensory info is filtered through a lens of what is good and what is bad for us
- emotion infuses perception, attention, learning, memory, and other cognitive processes
- this evaluation happens within 100 ms
how is the subjective experience of emotions described?
- based on two dimensions, arousal and valence
- arousal: degree of agitation or excitement (high/low)
- valence: positive or negative
what is multivoxel pattern analysis (MVPA)?
- focuses on patterns of activation across distributed voxels
- to predict a stimulus category or cognitive process
