week2cards

Commissurotomy (callosotomy)

Surgical section of the corpus callosum used historically for intractable epilepsy.

Corpus callosum

Major white-matter tract connecting left and right cerebral hemispheres.

Anterior commissure

Smaller interhemispheric fiber bundle connecting temporal lobes; may remain intact after callosotomy.

LVF → RH, RVF → LH

Left visual field projects to right hemisphere; right visual field projects to left hemisphere.

Contralateral motor control

Each hemisphere primarily controls the opposite side of the body.

Z-lens / lateralized tachistoscopy

Methods to isolate visual input to a single hemisphere using brief or monocular presentation.

Left-hemisphere interpreter

Proposed mechanism where LH generates explanations to create a coherent narrative of behavior.

Right hemisphere and intent-based moral judgment

Evidence from split-brain cases indicates RH can rely on intent over outcome in moral evaluation.

Cross-cueing

Behavioral strategies that allow limited information transfer between hemispheres (e.g., subtle movements).

Tactile specialization (split-brain)

Left hand (RH) often excels at recognizing objects felt without vision; naming may fail if LH lacks access.

Speech lateralization

Language production is typically left-lateralized; RH speech is limited in most adults.

Bimanual conflict

In some split-brain patients, hands may act at cross purposes due to hemispheric independence.

Chimeric faces effect (split-brain)

Preference or report biased toward the LVF (RH) side when judging composite faces.

Callosal transfer time

Milliseconds-scale conduction needed for interhemispheric integration; abolished by full callosotomy.

Everyday function in split-brain

Despite lab dissociations, daily life is typically cohesive with minimal overt deficits.

Phantom limb sensation (PLS)

Non-painful perception that the missing limb is still present.

Phantom limb pain (PLP)

Painful sensations perceived as arising from the missing limb.

Residual limb pain

Pain localized to the stump/residual limb, distinct from PLP.

Telescoping

Perceived shortening or retraction of the phantom limb over time.

Referred sensations (face→hand)

Touch to the face evokes sensations in the phantom hand due to cortical remapping.

Cortical reorganization (amputation)

Invading representation of adjacent body parts into the deafferented cortical hand area.

Neuroma

Disorganized nerve ending at the stump that can fire ectopically and contribute to PLP.

Sensorimotor incongruence

Mismatch between motor commands and absent sensory feedback hypothesized to drive PLP.

Mirror therapy

Visual feedback using a mirror to restore congruence between motor intent and visual/proprioceptive input.

Graded motor imagery (GMI)

Stepwise therapy (laterality judgments → imagery → mirror movements) to reduce pain and improve function.

Parietal body representation

Parietal networks integrate multisensory body information; implicated in phantom phenomena.

Incidence of PLS/PLP

PLS is very common; PLP occurs in a majority but not all adult amputees.

Prosthesis use and PLS

Using a prosthesis can provide sensory feedback and may reduce phantom phenomena in some patients.

TMR (targeted muscle reinnervation)

Surgical rerouting of nerves to muscles to improve prosthetic control and potentially modulate pain.

Multimodal PLP treatment

No single therapy is universally effective; combine behavioral, pharmacologic, and interventional options.

Object constancy

Recognizing an object across changes in viewpoint, distance, illumination, and retinal size.

Binding problem (vision)

How separate features like color, form, and motion are combined into a single perceived object.

Gestalt: proximity

Elements close together are grouped as a unit.

Gestalt: similarity

Elements sharing visual properties (e.g., color/shape) are grouped together.

Gestalt: good continuation

Elements aligned in a smooth path are perceived as a single object.

Gestalt: closure

Partial contours are perceived as complete shapes when plausible.

Gestalt: common fate

Elements moving together are grouped as a single object.

Ventral visual stream (what)

Occipital→temporal pathway specialized for object identification and linking to meaning.

Dorsal visual stream (where/how)

Occipital→parietal pathway specialized for spatial processing and visuomotor control.

Area V4 (color)

Cortical region important for color processing; lesions cause cerebral achromatopsia.

Area MT/V5 (motion)

Cortical region important for motion perception; lesions cause akinetopsia.

Apperceptive agnosia

Failure to integrate features into coherent whole forms; copying and matching are impaired.

Associative agnosia

Perception relatively intact but mapping to stored semantic meaning is impaired; copying can be preserved.

Integrative agnosia

Deficit in integrating parts into wholes despite detection of features; intermediate between apperceptive and associative.

Category-specific agnosia

Selective recognition impairment for one semantic class (e.g., living things) with others preserved.

Case JI (achromatopsia)

Lost perception and imagery of color following cortical damage, indicating high-level color representation.

Case LM (akinetopsia)

Severe motion blindness with preserved color and form perception due to MT/V5 damage.

Prosopagnosia (face agnosia)

Selective impairment in recognizing faces; object and word recognition may be spared.

Fusiform face area (FFA)

Right-biased fusiform region with face-preferential responses; lesions can cause prosopagnosia.

Expertise hypothesis (FFA)

FFA supports fine-grained discrimination in domains of expertise, not just faces.

Domain-specific hypothesis (FFA)

FFA evolved as a face-specialized module for recognition.

Face inversion effect

Inversion disproportionately impairs face recognition compared to non-face objects.

Thatcher effect

Distortions in inverted faces are harder to detect than in upright faces, revealing holistic upright processing.

V4 activation in grapheme–color synesthesia

Synesthetes show heightened V4 activity to letter/number inducers relative to controls.

Apperceptive vs associative agnosia (contrast)

Apperceptive: impaired feature integration; Associative: impaired link to meaning with preserved copying.

Object decision task (agnosia testing)

Determine if a silhouette/line drawing depicts a real object; often impaired in apperceptive agnosia.

Matching-by-functions (agnosia testing)

Match objects by functional category; often impaired in associative agnosia.

Viewpoint invariance

Ability to recognize an object despite changes in viewpoint; a component of object constancy.

Feature-based coding

Early visual representation of local edges, orientations, and contrasts that feed grouping processes.

Holistic processing (faces)

Faces are processed as integrated wholes rather than as independent features.