MBB1 EXAM - NEUROSCIENCE & SENSATION & PERCEPTION

What was Posner’s study?

Attention speeds responses - 'fixation box w/ arrow, had to click where X was. Longest response time when X was on the opposite side of the box

What was the study by Carrasco et al.?

• attention makes perception have a higher contrast

• fixation cue moves/expands to attention drawn to fixation cue.

• Findings: participants who had their attention drawn to one side due to the movement of the fixation cue reported that the grating on that side had higher contrast

What did Treisman & Schmidt study?

• illusory conjunctions as part of FIT, where inhibition of attention causes incorrect binding of features from different objects (part of the binding problem)

• brief presentation of character strings for 95-168 ms followed by noise mask → participants often associated the wrong colour w/ the wrong letter

• RM w/ parietal lobe damage Balint’s syndrome → reported wrong letter-colour combinations for 23% trials

  • prone to illusory conjunctions b/c he could not focus his attention on just a single object

What did Potter study?

• Gist perception

• observer cued w/ particular scene description → shown 16 randomly chosen scenes for 25 ms

• asked if any scenes matched description → almost 100% accuracy

• Finding: observers can rapidly perceive a scene’s gist

What did Fei-Fei et al. study?

• minimum scene exposure time needed to perceive a scene gist

• single scene presented followed by a mask → participants described what they saw

• Finding: the longer the stimulus presentation time, the more detailed & accurate the description

  • people could start to perceive aspects of a scene @ 27 ms, but very accurate perceptions could be achieved @ 250 ms

What did Robert Adams study?

• motion aftereffects; waterfall illusion

What is Korte’s Third Law of Apparent Motion?

for apparent motion to occur, as separation increases, alteration rate needs to decrease

What did Bonner, Cooperman & Sagi study?

• motion-induced blindness: movement of blue crosses while fixating on green dot made yellow dots disappear

What did Suchow & Alvarez study?

• motion-induced change blindness

• colour changes less apparent when dots are moving

Describe protanopes

• do not have L cones

• cannot distinguish b/w red & green

• can distinguish b/w blue & green, & blue & red

• see world in shades of blue & a yellow-green

Describe deuteranopes

• do not have M cones

• cannot distinguish red & green

• can distinguish b/w blue & green, & blue & red

• see world in shades of blue & a yellow-green

Describe tritanopes

• do not have S cones

• can’t distinguish b/w blue & green (cannot see yellow)

• can distinguish b/w red & green, & blue & red

What is the equation for reflected light

reflectance x illumination

What are the 2 ways that the visual system achieves colour constancy?

• Habituation

• Discounting the illuminant

What are the 3 types of cues to perceive depth

• oculomotor cues: cues based on the ability to sense the position & state of our eyes

• monocular cues: cues based on the visual information available within an eye

• binocular cues: cues that depend on visual information within both eyes

What are the 2 types of occulomotor cues?

• binocular convergence

• accommodation

What are the 3 main types of monocular cues?

• accommodation

• pictorial cues

• movement-based cues

What is the main type of binocular cue?

binocular disparity → relative & absolute disparity, & the correspondence problem

What are the 7 types of pictorial cues?

• occlusion

• relative height

• familiar & relative size

• perspective convergence

• atmospheric perspective

• texture gradient

• shadows

What are the 2 types of movement-based cues?

• motion parallax

• deletion & accretion

What did Holway & Boring study?

• how observers accurately estimate the size of objects

• condition 1 & 2 w/ sufficient depth cues → test patch accurately estimated

• condition 3 & 4 w/ insufficient depth cues → test patches perceived smaller than they really are b/c apparent size of test patch was biased towards the visual angle

What are the 4 components of architectural acoustics?

• reverberation time

• intimacy time

• bass ratio

• spaciousness factor

what are the 5 components of auditory organisation?

• location

• onset time

• timbre & pitch

• auditory continuity

• experience

What did Rensik et al. study?

The need for attention to perceive changes in scenes

What is the general summary of the results by Rensik et al?

• Low-level cues that draw attention are swamped → large changes in images of real-world scenes become extremely difficult to identify, even if the changes are repeated dozens of times & observers have been told to expect them.

• changes are easily identified when a valid verbal cue is given, indicating stimulus visibility is not reduced

• changes easily identified when made to objects considered to be important in the scene

What is the main finding of Rensik et al.’s study"?

• an observer does not build up a representation of scene that allows them to perceive changes automatically

• perception of change is mediated through a narrow attentional bottleneck → attention is attracted to various parts of a scene based on high-level interest

What was the hypothesis for study 2 of Rensik et al.?

Saccade-contingent change blindness may not be due to saccade-specific mechanisms, but rather may originate from a failure to allocate attention correctly

• transients play a large role in drawing attention

What was the general method of Rensik et al.’s paper?

• A. A, A’, A’ … w/ grey blank fields placed b/w successive images (degree of temporal uncertainty as to when the change was being made)

• each image displayed for 240 ms & each blank for 80 ms

What were centra interests & marginal interests in the study by Rensik et al.?

• Central interest (CI): objects of areas mentioned by three or more observers

• Marginal interest (MI): objects or areas mention by no observers

What was the dependent variable for Rensik et al.’s studies?

DV: average number of alterations (proportional to the reaction time) needed to see the change

*averages only taken from correct responses

What did experiment 1 of Rensik et al. investigate & what were the findings?

• Whether the basic flicker paradigm could induce change blindness

• Predictions:

  • Insufficient viewing time for change blindness (brief-display experiments) → changes in the experiment to be seen within a few seconds of viewing

  • saccade-specific mechanisms responsible for change blindness (saccade experiments) → changes to be easy to see by keeping eyes still

  • change blindness due to attention mechanism (flicker conditions) → changes under flicker conditions would take a long time to see

• Results:

  • flicker conditions: changes in MI extremely difficult to see, changes in CI noticed much more quickly

What did experiment 2 of Rensik et al. investigate & what were the findings?

• Hypothesis: old & new scene descriptions could not be compared because of time limitations

  • Prediction: if memory process = limiting factor, longer display of images → consolidation to take place → changes easily seen

• A, A’, A, A’ (shown for 560 ms each)

• Findings: slight speedup for MI interest, response times for MI & CI for all 3 kinds of change not significantly different from counterparts in Experiment 1

What did experiment 3 of Rensik et al. investigate & what were the findings?

• repeated experiment 1 but w/ verbal cue placed in white rectangle for 3 seconds @ beginning of each trial

  • Partially valid conditions:

    • half valid cues (named the part of scene changed)

    • half invalid cues (named another part)

  • Completely valid condition: always valid cues

• hypothesis: flicker reduces the visibility of items in the image to the point where they simply become difficult to see

  • Prediction: visibility = limiting factor → not large effect of cuing should have occurred; target would remain difficult to find. Visibility is NOT limiting factor → valid cues improve performance, not affected by invalid cues

• Results: valid cues always caused identification of both MI & CI changes to be greatly sped up (significant for both conditions)

  • completely valid conditions: difference in response item for MIs & Cis declined → no longer significant

    • indicates that the faster performance for CIs in experiment 1 is unlikely to be due to simple salience of their features

What were the final proposals by Rensik et al?

• visual perception of change in an object occurs only when that object is given focused attention

• absence of focused attention → contents of visual memory are overwritten by subsequent stimuli → cannot be used to make comparisons

What were the conclusions of a saccade-contingent change in Rensik et al.’s study?

most (all) of the blindness to saccade-contingent change is simply due to the disruption of the retinal image during a saccade, causing swamping of the local motion signals that would normally draw attention

Which depth cues can indicate absolute depth at 0-2 metres?

• size of the retinal image

• motion parallax

• accommodation

• convergence

Which depth cues can indicate absolute depth at 2-20 metres?

• size of the retinal image

• texture gradients

• motion parallax

Which depth cues can indicate absolute depth at > 20 metres?

• size of the retinal image

• texture gradients

What depth cue can indicate relative depth @ 0-2 metres?

occlusion

What depth cues can indicate relative depth @ 2-20 metres?

• occlusion

• deletion & accretion

• relative height

What depth cues can indicate relative depth @ > 20 metres?

• occlusion

• deletion & accretion

• relative height

• atmospheric perspective

List the brief history of Neuroscience

• Original belief linking the mind to the heart (Egypt, India, China), but then linking the mind to the brain (Egypt)

• Hippocrates (Ancient Greece)

• Rene Descartes (France)

• Luigi Galvani (Italy)

• Franz Joseph Gall (Germany)

• Paul Broca (France)

• Carl Wernicke (Germany)

Detail the ancient cultures’ beliefs that the mind was connected to the heart and the first piece of evidence to suggest otherwise

• heart constantly beating & is heightened during emotional states

• Papyrus scroll from Egypt (~1600 BCE) is the first documented link b/w the brain & the mind, describing the symptoms & diagnosis of 2 individuals w/ brain disease

Detail Hippocrates & his beliefs

• suggested the brain is the command centre, not the heart

• notes the behavioural effects of brain damage

• Dissection not allowed → observed anatomy through open wounds after traumatic head injury

Detail Rene Descartes & his beliefs

• formulated the mind-body problem; ‘I think therefore I am’

• the mind controlled the movements of the body & the body supplied the mind w/ information about the environment

• believed humans & animals were machines & that behaviour was driven by a system of fluid & pistons (which were controlled by the environment) → interested in involuntary reflexes

Detail Luigi Galvani & his beliefs

• rejected the idea that animal spirits flow through hollow nerves

• discovered electrical charge applied to frog’s leg made the muscle contract & contraction occurred even when the nerve & muscle were detached from the rest of the body → characteristic of the tissues

• nerves must be coated in fat to prevent electricity form leaking out

• Inspired Frankenstein

Detail Franz Joseph Gall & his beliefs

• proposed the idea of the modular brain; different parts of the brain do different things

• proposed that the brain is composed of several faculties/’organs of thought’ → reflected by patterns of bumps on the skull

• skull maps used to read a person’s character

• Had his work termed as phrenology; a pseudoscience involving the measurements of bumps on the skull to predict mental traits

• influenced by physiognomy: ascribing personality characteristics to facial features

• compared animal & human skulls, & people from societal ‘extremes’ (e.g. criminals, artists)

Detail Paul Broca & his beliefs

• provided the first solid evidence for brain modularity

• Patient Leborgne; unable to speak after damage to left frontal lobe, normal chewing & language comprehension

  • similar patients had damage in the same area

  • Broca’s aphasia caused by damage to Broca’s area - inability to produce coherent speech, but can understand speech

Detail Carl Wernicke & his beliefs

described a patient w/ an inability to comprehend speech, normal hearing & language production, similar patients seen w/ damage to the posterior part of the superior gyrus

• Wernicke’s aphasia caused by damage to Wernicke’s area: issues w/ language comprehension, fluent but often meaningless speech

What are some other terms for behavioural neuroscience?

• behavioural physiology

• physiological psychology

• biological psychology

List some allied health disciplines in behavioural neuroscience

• Neuropsychology

• Psychopharmacology

• comparative neuroanatomy & psychology

• cognitive neuroscience

• psychophysiology

• neuromorphic computing

• cognitive computational neuroscience

• In Silico neuroscience

Detail neuropsychology

• research & clinical speciality

• linking brain damage w/ psychological processes

• assessing risk before surgery & assessing impairments & improvements

• behavioural & neuroimaging measures

Detail psychopharmacology

• role of neurochemistry in mind & behaviour

• neurotransmitters & hormones = natural

• drugs = artificial

detail comparative neuroanatomy & psychology

• brain evolution

• origin & purpose of behaviours

• commonalities across species

• links b/w brain regions & behaviour

detail cognitive neuroscience

• neural basis of cognition

• functional connectivity

• use of fMRI

detail psychophysiology

• linking electrical activity within the brain to cognitive functioning

• use EEG

• longer history & includes basic responses

detail neuromorphic computing

• began in 1980s

• using electronic circuits to emulate neural structures in the human brain

detail cognitive computational neuroscience

characterising the neural computations that underline complex behaviour

detail in silico neuroscience

using computer simulations or computer modelling

List & detail some career paths in neuroscience

• clinical careers (clinical neuropsychology)

  • e.g. neurology, neurosurgery & psychiatry

• Research careers

  • honours, masters, PhD

  • psychology, neuroscience, neuroengineering, computer science, & clinical professions

• Other careers

  • marketing, education, computer science

  • anything involved in the associations between the brain, thoughts, & behaviour

Name the anatomical subdivisions of the brain

• forebrain

  • telencephalon

    • cerebral cortex

    • basal ganglia

    • limbic system (hypothalamus, thalamus, amygdala, hippocampus, basal ganglia, cingulate gyrus, fornix, orbitofrontal cortex)

  • Diencephalon

    • thalamus

    • hypothalamus

• midbrain

  • mesencephalon

    • tectum

    • tegmentum

• hindbrain

  • metencephalon

    • cerebellum

    • pons

  • myelencephalon

    • medulla oblongata

• brain stem: medulla, pons & midbrain

What is the function of the cerebral cortex?

• has gyri which increase the surface area of the brain to increase neural connectivity

• the inner white matter is pale → high proportion of axon fibres covered in the myelin layer

• outer grey matter = where neuron synapses & neurons connect together

What is the function of the basal ganglia?

• nuclei (caudate nucleus & putamen): control involuntary movement i.e. aspects that are highly automized

  • deliberate initiation of these movements that we eventually fulfill unconsciously; we don’t have to think about these actions that we chose to do

• Parkinson’s disease: dysfunctional basal ganglia → weakness, tremors, limbic rigidity, poor balance, difficulty initiaiting movements

What is the function of the limbic system?

• James Papez: suggested it is an emotion circuit

• amygdala plays a crucial role in emotion

• hippocampus & parts surrounding cortex are involved in learning & memory

What is the function of the thalamus?

• major relay station for sensory inputs to cerebral cortex

• divided into several nuclei

• thalamus functioning is critical for consciousness (stroke in thalamus → unconscious)

What is the function of the hypothalamus?

• controls autonomic NS & endocrine systems

• regulates survival behaviours (fighting, fleeing, feeding, mating)

What is the role of the mesencephalon?

• located within the brainstem w/ the hindbrain

• connects the pons & cerebellum w/ the forebrain

• plays an important role in motor movement (eye movements, auditory processing, visual processing)

What is the role of the tectum?

• dorsal part of the mesencephalon

• involved in sensory processing (visual & auditory information) → helps respond to sitmuli

What is the role of the tegmentum?

• ventral part of the mesencephalon

• involved in motor control & arousal regulation

What is the role of the cerebellum?

• receives information from visual, auditory, somatosensory & visual systems → helps coordination of movement & fluency of movement

• damage to cerebellum → problems w/ walking → jerky & poorly coordinated movements & poor balance maintenance

• involved in fine-tuning of movement (e.g. spatial awareness)

What is the role of the pons?

• lies on ventral surface of brain stem

• contains several nuclei involved in sleep & arousal regulation

• relays information from the cerebral cortex to the cerebellum

What is the role of the medulla oblongata?

• links hindbrain to spinal cord

• contains neurons important for autonomic functions (e.g. respiration & heart rate)

What are the 2 cortexes in the frontal lobe?

• frontal cortex

• primary motor cortex

What are the 2 cortexes in the parietal lobe?

• primary cortex

• primary somatosensory cortex

What is the cortex in the occipital lobe?

primary visual cortex

What are the cortexes in the temporal lobe?

• temporal cortex

• primary auditory cortex

What is the role of the frontal cortex?

• involves everything in the central sulcus

• involves higher level of connectivity w/ the rest of the brain compared to other apes

• involved in high order functions of the frontal lobes

  • voluntary & controlled behaviour

  • impulse control & emotion

  • abstract reasoning & planning

  • social cognition

  • language

• ***Phineas Gage: damage to frontal love → altered executive functioning

  • personality changes

  • angry, impatient, obstinate, capricious

  • unable to plan for the future

  • not employable in old jobs; only held jobs where he did not make decisions

What is the role of the primary motor cortex?

• located at the precentral gyrus immediately anterior to the central sulcus

• different parts of the primary motor cortex send signals that control different voluntary muscle groups

• controls muscles on the contralateral side of the body

What is the role of the parietal cortex?

• attention & spatial awareness

• ‘where’ pathway

• dorsal surface of the cortex

What is the role of the primary somatosensory cortex?

• located immediately posterior to the central sulcus

• receives sensory information from the skin

• different regions of skin surface are represented by different areas along the strip of the cortex; somatotopic map (homunculus)

What is the role of the primary visual cortex?

• occupy the medial & lateral parts of the occipital lobe @ the posterior part of the brain

• receive sensory information from the retina

• left & right visual fields are each projected to the contralateral hemisphere

• different regions of the retina are represented by different areas within the PVC

  • areas further out in the peripheral vision are processed by areas of the PVC that extend into the calcarine fissure

  • neural activity is primary devoted to central vision in the visual field; focus of peripheral vision is bad

• neurons show orientation selectivity; they are preferentially selective of specific orientations of objects (Nobel prize won by Hubel & Wiesel)

What is the role of the temporal cortex?

• involved in auditory processing & more complex visual processing (e.g. faces & complex objects)

• encodes long-term information

• located on the ventral surface of the cortex (part of the ventral stream)

• part of the ‘what’ pathway

What is the role of the primary auditory cortex?

• superior part of the temporal cortex & patch of cortex buried w/n Sylvian fissure

• receives auditory sensory information from the cochlea (inner part of ear concerned w/ hearing)

• sounds w/ different frequencies are represented by different areas within the PAC (tonotopic map)

How does action potential propagation work?

• Resting potential: membrane is polarised @ -70 mV

• Na+ ions flow into cell → membrane potential depolarises

• @ -50 mV, an action potential is propagated. K+ channels open & K+ leaves the neuron

• Na+ is still entering the cell so the membrane potential is still decreasing, despite the efflux of potassium ions

• After approx 1 millisec the action potential reaches its peak & the sodium channels become refractory (b/c the charge inside cell is > outside cell)

• Na+ channels do not open again until the membrane returns to its resting potential

• K+ channels still open → K+ exits cell → membrane potential is more -ve. K+ channels close @ -70 mV

• K+ channels close → cell is hyperpolarised until any extra K+ can diffuse out

• The subsequent action potential requires a greater Na+ influx immediately after the neuron has fired (because the membrane potential is even further from the threshold of activation) until the charge has stabilised again at the resting membrane potential

where is Broca’s area located?

left frontal gyrus

Where is Wernicke’s area located?

posterior to the left superior central gyrus (temporal lobe)

where do central executive processes occur?

dorsa-lateral prefrontal cortex & anterior-cingulate cortex of the frontal lobes

where is the phonological loop located?

left fronto-temporal lobe network (incl. Broca’s & Wernicke’s areas)

where is the visuo-spatial sketchpad located?

right occipital-parietal network

where does the episodic buffer integrate multi-modal information

association cortex in the parietal lobes

Describe the perceptual-cognitive cycle

• current experience = integrating percepual preset & cognitive past

• active, embodied, emotional agent embedded in the physical & socio-cultural world

• Start w/ a cognitive map of the world and its possibilities; this involves a schema of the present environment

• This schema directs attention to locomotion & action allowing for perceptual exploration

• The perceptual exploration then samples the actual world; what is actually present in the environment.

• Our perception of the modern world then modifies our cognitive map & schema, and the cycle begins again