Week 2 Articles Flashcards
(19 cards)
Bucur (are TBS effects long-lasting in post-stroke aphasia?)
Introduction
Introduction
prevalence, language impairments, recovery/course, stardard treatment
- Post-stroke aphasia affects 38% of stroke survivors
- Language impairments can include: speech production, comprehension, repetition, and word retrieval
- While spontaneous recovery happens, 40% still show symptoms after 1 year
Standard treatment: Speech and language therapy (SLT) = effective but:
* time intensive = 100 hours recommended
* resource limited
* slow recovery
Bucur (are TBS effects long-lasting in post-stroke aphasia?)
Aim
Introduction
Investigate whether non-invasive brain stimulation (NIBS) methods have long-term benefits on naming performance.
Thus, assess if naming improvements are sustained over time, and compare the effectiveness for:
* repetitive transcranial magnetic stimulus (rTMS)
* transcranial direct current stimulation (tDCS)
Bucur (are TBS effects long-lasting in post-stroke aphasia?)
Overall NIBS effects (at follow-up)
Results
Medium effect size = suggests sustained improvement in naming
Bucur (are TBS effects long-lasting in post-stroke aphasia?)
rTMS vs tDCS
Results
rTMS:
* medium to large effect with high grade quality
* effective in both chronic and sub-acute aphasia
tDCS:
* small to medium effect with low grade quality
* only effective in chronic aphasia
Bucur (are TBS effects long-lasting in post-stroke aphasia?)
RCT-only analysis
Results
rTMS RCTs = significant
tDCS RCTs = not significant
Bucur (are TBS effects long-lasting in post-stroke aphasia?)
Chronic vs Sub-acute aphasia
Results
Chronic (6+ months):
* rTMS = small to medium effect
* tDCS = small to medium effect
Sub-acute (<6 months):
* rTMS = large effect
* tDCS = no significant effect
Bucur (are TBS effects long-lasting in post-stroke aphasia?)
Immediate vs follow-up
Results
- No significant decline over time = gains are maintained
- Stability shown for both rTMS and tDCS effects on naming
Bucur (are TBS effects long-lasting in post-stroke aphasia?)
Mechanisms of action
rTMS, tDCS, aim to rebalance interhemispheric activation post-stroke
rTMS:
* uses magnetic pulses to induce action potentials
* can excite or inhibit brain areas depending on frequency
tDCS:
* modulates resting membrane potential
* effects are state-dependent (depends on neural activation level)
Both aim to rebalance interhemispheric activation post-stroke:
* suppress overactive right hemisphere
* boost left preilesional areas
Bucur (are TBS effects long-lasting in post-stroke aphasia?)
Conclusion
- rTMS is effective and reliable for long-term naming improvements in both and sub-acute aphasia
- tDCS may be helpful in chronic aphasia but not reliable for sub-acute phase
- Neither method is effective as mono-therapy = best used as an adjunct to SLT
- Further large-scale, high-quality RCTs are needed
Vaidya (VMF damage affects interpretation, not exploration of faces)
Introduction
Introduction
Introduction (emotion recognition and information) + previous lesion studies results
- Emotion recognition is critical for social functioning
- Deficits are common in neuropsychiatric disorders
- Emotional information is inferred from facial features, especially the eyes
Previous lesion studies:
* Amygdala = impaired fear recognition due to disrupted fixation
* Ventral medial frontal lobe (VMF) = unclear role, possibly involved in subtle emotion recognition
Vaidya (VMF damage affects interpretation, not exploration of faces)
Aim
Introduction
To determine if VMF damage affects interpretaton or exploration (fixation) of emotional facial expressions
Vaidya (VMF damage affects interpretation, not exploration of faces)
Participants
Method
37 frontal lobe patients:
* 17 with VMF damage (damage to vmPFC and OFC)
* 20 with frontal control (FC) damage (frontal lesions sparing VMF)
Vaidya (VMF damage affects interpretation, not exploration of faces)
Stimuli
Methods
- Faces (neutral, subtle, extreme) showing fear, disgust and happiness
- Areas of interest (AOIs) = eyebrows, nose, eyes etc.
- Heat maps generated from dwell time.
Vaidya (VMF damage affects interpretation, not exploration of faces)
Conditions
Methods
Free viewing, gaze contingent and instructed viewing
Free Viewing condition:
* viewed faces freely and rated how much emotion they perceived
* each block focused on one target emotion (3 blocks with 36 trials)
Gaze contingent viewing condition:
* judged how afraid a face looked while viewing it through a gaze-contingent aperture
* required participants to actively explore facial features to gather information (top-down exploration)
Instructed viewing condition
* instructed to look only at the eyes while rating how afraid the faces appeared.
* Used to test if eye fixation improves performance.
Vaidya (VMF damage affects interpretation, not exploration of faces)
Free Viewing results
Results
Emotion detection, emotion discrimination, fixation, fixation pattern, heat maps, VLSM
Emotion detection:
* Subtle disgust = VMF group significantly impaired.
* Subtle fear = trend towards impairment, not significant
* Happiness = no group differences
* Extreme emotions = no group differenes.
Emotion discrimination (specificity):
* VMF group had reduced specificity for extreme expressions.
* No group differences for subtle expressions.
Fixations:
* No group differences in number, location, heat maps or early fixations, thus = no disruption in exploration.
Vaidya (VMF damage affects interpretation, not exploration of faces)
Gaze-Contingent results
Results
Emotion detection, emotion discrimination, fixation, fixation pattern, heat maps, Fixation-behaviour relationship
Emotion detection:
* VMF tended lower but not signfiicant.
Emotion discrimination:
* Significant interaction for subtle fear specificity
* FC group rated happy faces as more fearful
Fixations:
* FC group looked less at eyes, more at nose/chin for extreme fear
* VMF group showed no abnormal pattern
Heat maps:
* No group differences
Fixation-behaviour relationship:
* Fixations to eyes positively correlated with predicted better recognition of extreme fear.
* Nose fixations negatively correlated with subtle fear.
Vaidya (VMF damage affects interpretation, not exploration of faces)
Instructed viewing results
Results
Emotional detection and discrimination
Emotional detection:
* All groups improved subtle fear detection when fixating eyes.
* No group differences in improvement
Emotional discrimination:
* FC group less specific for subtle fear
* VMF group not significantly impaired.
Vaidya (VMF damage affects interpretation, not exploration of faces)
Discussion
Discussion
What does the VMF do and does not do?
What the VMF does not do: Does not impair visual exploration.
* No difference in free viewing, gaze-contingent, or instructed viewing.
* Contrast with amygdala lesions = these do disrupt fixations (esp to eyes).
What the VMF does do:
* VMF damage impairs emotion interpretation, not attention, specifically for subtle disgust and discrimination of extreme emotions.
* It suggests a role in emotional meaning extraction (could reflect noisier emotional signal processing or impaired integration of valence/arousal).
Vaidya (VMF damage affects interpretation, not exploration of faces)
Conclusion
Conclusion
VMF is not required to guide fixations toward emotionally informative featues but is necessary to correctly interpret emotional meaning from facial expressions.
All in all, VMF supports accurate interpretation of emotional expressions, while visual attention mechanisms remain intact.
