exam two

left hemisphere

1. language

2. local representation

3. right visual field and motor control

4. semantic and syntax processing

right hemisphere

1. visuospatial processing

2. spatial attention

3. global representation

4. left visual field and motor control

5. face processing - better at unfamiliar face recogn.

6. process emotional content of speech

wada test

ambarbitol is injected to temporarily disrupt one of the cerebral hemispheres - used to identify source of seizures and provide insight into hemispheric specialization

planum temporale

part of Wernicke’s area - involved in speech comprehension — larger in the LH

sylvian fissure

separates the frontal and temporal lobes; has a more pronounced curve in the RH

homotopic areas

corresponding locations on the two hemispheres

heterotopic areas

signal sent to different location on the other hemisphere

ipsilateral

communication sent to a different brain region on the same side

split brain research

study of patients who have had corpus callosum severed - radical treatment for intractable epilepsy

genu

anterior portion of CC

body

middle portion of CC

splenum

posterior portion of the CC; interconnect the occipital lobes with large axonal fibers that maintain topographical organization

anterior commissure

connect parts of the amygdala and the temporal lobe

• form the olfactory tract

posterior commissure

contribute to the pupillary light reflex

corpus callostomy

surgery that severs the corpus callosum; difficult because a thin wall of cells separate the ventricles from CC

making inferences

right hemisphere has a limited capacity with making inferences

partial split (posterior/splenum resection)

• participant can see and vaguely describe image flashed in LVF

• visual, tactile and auditory info is disrupted

• maintains high order information

letter recognition

right hemisphere is deficit in letter recognition

self

left hemisphere is better at recognizing self

familiar others

right hemisphere is better at recognizing familiar others

visuospatial processing

the neural pathway that controls voluntary and spontaneous facial expression are different

voluntery expression

left hemisphere has direct connections to face, while right hemisphere has indirect pathway via the corpus callosum — individuals with right hemi damage or split brain have asymmetric smiles

spontaneous expression

originate in the older parts of the brain

• basal ganglia - damage to this structure does not allow for the production of spontaneous expressions

attention and visual perception

spatial info is transferred between hemispheres, it enables attention to be transferred to either visual field

• 2 hemispheres maintain a single focus of attention

left hemisphere lesion

slower with local targets

right hemisphere lesion

slower with global targets

hierarchical representation

a configuration that may be described at multiple levels - from global to local features — finer components embedded in higher level components

theory of mind

refers to the ability to understand that others have thoughts, beliefs and desires

right hemisphere and moral reasoning

fast, automatic processing of belief attributions

left hemisphere and moral reasoning

slower, more deliberate reasoning mechanisms — performing same function as right hemisphere if given time for deliberation

the interpreter

LH - formulate hypothesis and predictions about actions and events; creates a sensible narrative about our place in the world and rationalize events

dichotic listening task

competing message presented in each ear - subject consisting reported words presented to the right ear — LH is responsible for language

non-humans LH

categorization of stimuli

non-humans RH

localization of stimuli

modules

localized networks which can perform unique functions and adapt/evolve to external demands

• hypothesized to perform specific computations

emotional prosody

emotional content of speech - processed by right hemisphere

agonsia

neurological disorder in which disturbances of perceptual recognition cannot be attributed to impairements in the basic sensory processes

• can be restricted to a single modality

visual agnosia

failure of perception that is limited to the visual modality - can perceive properties, but cannot recognize objects or identify their uses

object is perceived as

a unified whole and not as an entity separated by details

product of perception is

interwoven with memory

ventral pathway

the what pathway - object identification and ends at the inferotemporal cortex

dorsal pathway

the where pathway - object location and ends at the posterior parietal cortex

ITC neurons

respond to complex stumuli - objects with details of shape, color, motion, texture = more heavily detailed an object is, the more these neurons will fire

object idenitification task PET contrast

bilaterally at junction of occipital and temporal

object position task PET contrast

right parietal lobe

lesion in lateral occipital complex

patient cannot recognize the orientation of an object, but can easily perform a task requiring some knowledge of the object’s orientation

optic ataxia

people can recognize objects, but cannot use visual info to guide actions

• see and report orientation of slot, but cannot insert object into the slot

  • parietal cortex lesions

object constantcy

ability to recognize invariant properties of an object across a wide range of contexts; ability to recognizie that an object is the same when seen from different perspectives

view dependent frame of reference

requires that we have many specific representations in memory - heavy burden on perceptual memory

view-invariance frame or reference

perceptual system extracts structural info about the components of an object and the relationship between components

repitition suppression effect

phenomenon seen during fMRI in which the BOLD response decreases with each sub. stimulus rep

RSE

• seen in left hemi. support view-invariance

RSE and RH

right fusiform area sees this effect only when the object was presented at the same viewpoint — support view dependent

cue invariance

insenitivity ti the special visua cues that define an object

grandmother, gnostic cells

a cell with high specificity and sits atop a perceptual neural network hiarchy

hierarchical coding hypothesis

features organized in hierarchy for sparse coding

efficient ways to represent many objects

invariant to orientation, location or lightning

ensemble encoding

indicates a specific pattern of activity for a specific object

• activatiion from multiple feature detectors causes recognition

gnostic unit

a neuron or a small subset of neurons toned for a specific percept - selective to what they respond to at the higher levels

apperceptive agnosia

deficits in the operation of higher-level perceptual analyses - may recognize an object from normal view - but if orientaton is unusual or object is occulded by shadows, recognition deterioates

• damage to the right posterior region

integrative agnosia

problems integrating features into parts or parts of an object into a whole - problems processing things holistically a

associative agnosia

problem with linking perceptual representations with long term knowledge of the percepts

• fail to demonstrate what the function of the object is and where it is likely found

  • damage to posterior LH and RH

LH posterior damage

cannot make functional connection

RH posterior damage

failure to recognize many things at different orientations or occulded by shadows

alexia

neurological syndrome where ability to read is damaged - caused by a neurological disturbance rather than genetics (dsylexia)

lesions in visual semantic memory units

impairment in correctly iding living things

lesion in functional memory units

impairement is milder and limited to iding non-living things

prosoagnosia

deficit in the ability to recognize faces - cognetial and genetically linked

superior temporal sulcus

neurons here exhibit face-selective firing; some non-face stimuli provoke either zero or even suppressed firing activity

• react to emotional content in faces

fusiform face area

a functionally defined area of the brain, located on the ventral surface of the temporal lobe in the fusiform gyrus, that responds to selective stimuli, such as faces

fusiform gyrus

located along the ventral surface of the temporal lobe, activates when people view face stimuli — lesions associated with prosopagnosia

ventral occipitotemporal cortex

involved in object recognition

holistic processing

perceptual analysis that emphasizes overall shape of an object

analytical processing

perceptual analysis that emphasizes the components parts of an object

parahippocampal place area

located in the temporal region that respond to stimuli depicting scenes or places

extrastraite body area

action perception; damage may lead to inability to recognizie static and potentially moving images of body parts (body selective)

occipital face area

face selective

fusiform body area

involved in face and body selectivity; integrate color, motion, and shape of body parts

decoding

using brain activity (which is provided by a stimulus and detected by such methods such as fMRI) in order to determine the og stimulus

• predicting a stimulus that is being experienced based on brain activity

encoding

stimulus - feature space - bold response

decoding (mechanism)

bold response(s) - feature space - stimulus

attention

1. taking possession by the minds

2. focus on one out of several simultaneously possible objects or trains of thought

3. implies withdrawal from several things to deal effectively with others

balint’s syndrome

bilateral damage of posterior parietal and occipital cortex; one or small set of objects are perceived at a time; object is mislocalized in space

simulatagnosia

difficulty perceiving visual field as a whole scene

ocular apraxia

deficit in making eye saccades to scan visual field

optic ataxia (2)

problems making visually guided movements

selective attention

ability to proritize and attend to some things while ignoring others

arousal

nonselective attention; global physiological and psychological state of organism

neglect

unilateral lesions that result in failure in acknowledging objects ot events in the contralateral hemispace

most severe = damage to right posterior cortex

extinction

failure to perceive a stimulus contralateral to a lesion when served with a simultaneous stimulus ipsilateral to the lesion

voluntary attention

our ability to intentionally attend to something

reflexive attention

stimulus driven process in which a sensory event captures our attention

overt attention

obserable actions related to attention

covert attention

unobservable actions related to attention

cocktail party effect

in a noisy, confusing environment, people can focus attention on one single conversation

bottleneck

a stage of processing where not all input gains access or passes through

limited capacity

the concept that stages of information processing have a finite processing capacity - leading to the need for the system to select high prority information for access to these stages of analysis

gating mechanism

determines what limited info is passed on for higher levels of analysis

• mechanism takes the form of descending influences on perceptual processing uder the control of higher-order executive processes

early selection model

a stimulus can be selected, or it can be tossed out as irrelevant before perceputal analysis of stimulus is complete

late selection model

all inputs are processed equally by the perceptual system; selection follows to determine what will undergo additional processing, and that will be represented in awareness