Cognitive Neuroscience studies

Daselaar et al 2003

IMPORTANCE - Ageing generally has been found to have a generally negative effect on episodic memory performance AIM - Investigated separately the contributions of encoding and retrieval to the age‐related decline in memory METHOD - fMRI - 3 age groups: young, elderly (bad memory) and elderly (normal memory) - Compared brain activity patterns obtained during incidental encoding (pleasant/unpleasant judgements about nouns) and subsequent retrieval (recognition) - Included only correct responses in analysis RESULTS - Successfully remembered items -> Young ppts = increase in brain activation in the left anterior MTL compared with the elderly (bad memory) but not elderly (good memory) - Successfully rejected items -> elderly (bad memory) = increased activity throughout the brain compared with the other groups - However, when correctly recognized items (retrieval attempt + success) were com pared directly with correctly rejected items (retrieval attempt), these differences were greatly reduced, revealing common activity in the left parietal and left anterior prefrontal regions CONCLUSION - Reduced performance in the elderly (bad memory) group is likely to be due to MTL dysfunction during encoding - Lack of differences observed in relation to retrieval success suggests that ageing does not affect the processes that support the actual recovery of information.

Occipital lobe

Low-level vision Attention

Kim (2010)

MEMORY ENCODING Question - What neural activity predicts subsequent memory and forgetting? Method: - Meta-analysis - Only fMRI studies with healthy adults - Focused on visual information encoding Results: - Successful encoding was associated with 5 neural regions: - Left inferior frontal cortex - Bilateral posterior parietal cortex - Bilateral fusiform cortex - Bilateral hippocampal formation - Bilateral premotor cortex Conclusions: - Regions likely responsible for: - Left IFC & fusiform cortex = mediate content processing - Hippocampal region = support storage operations - PMC & PPC = likely responsible for attention during encoding Personal: - Given that 74 studies were included, likely to hold some empirical value

Episodic memory is associated with the following brain regions

MTL PFC PPC Temporal and midbrain regions

Fransson (2006)

AIM - 1st question - Is it possible to attenuate intrinsic activity in the self-referential, default mode of brain function by directing the brains resources to a goal-oriented and attention-demanding task? - 2nd question - What effect does a sustained attention-demanding task performance have on the two active networks in the brain, those being the task-negative, default-mode and the task-positive network? METHOD - fMRI - 14 ppts - Monitored spontaneous activity during rest and sustained performance of a working memory task. - Compared intrinsic activity during rest and the memory task to the signal increases and decreases observed in an epoch-related version of the working memory task RESULTS - Spontaneous intrinsic activity in the default-mode network is not extinguished but rather attenuated during performance of the working memory task. - Intrinsic activity in the task-positive network is re-organized in response to the working memory task CONCLUSION - Suggests that task-induced signal deactivations in the default-mode regions is modulated by cognitive load to also show that intrinsic, spontaneous signal fluctuations in the default-mode regions persist and re-organize in response to changes in external work load

Ochsner et al 2004

AIM - Directly compared brain regions involved in judging one's own, as compared to another individual's, emotional state IMPORTANCE - No studies have directly examined attributions about the internal emotional states of others to determine whether common or distinct neural systems support these abilities METHOD - fMRI (13 ppts) - Viewed photos, from the International Affective Picture System - Asked to evaluate either their emotional response to each photo, the emotional state of the central figure in each photo, or (control condition) whether the photo was taken indoors or outdoors RESULTS - Self and other judgments activated the mPFC and superior temporal gyrus - Self judgments selectively activated subregions of the MPFC - Other judgments selectively activated the left lateral prefrontal cortex CONCLUSION - Self and other evaluation of emotion rely on a network of common mechanisms centered on the MPFC - medial and lateral PFC regions selectively recruited by self or other judgments may be involved in attention to and elaboration of internally as opposed to externally generated information

Haznedar et al 1997

AIM - Investigated the glucose metabolism and volume of the anterior cingulate gyrus in autistic individuals METHOD - MRI and PET - 7 high-functioning autistic patients and 7 sex- and age-matched normal volunteers were co- registered. - After the anterior cingulate gyri were outlined on the MRI images, the volumes of the structures were measured and corrected for brain volume. - The volumes were then applied to the PET images and metabolic maps were obtained. RESULTS - Right anterior cingulate area was significantly smaller in relative volume in autistic patients - Right anterior cingulate area was metabolically less active, in the autistic patients CONCLUSION - Autism may be characterized by structural and functional alterations in the anterior cingulate gyrus. - Autistic patients have substantial difficulties in expressing affect, decoding affect, and performing higher executive functions—activities modulated by the anterior cingulate gyrus

Milham et al 2002

AIM - Investigated the neural activity during performance of the color-word Stroop task across two age groups given that previous evidence has shown that working memory efficiency decreases with age due to attentional control decline METHOD - fMRI - 2 age groups (21-27 and 60-75) - 22 ppts in total - Performed a Stroop task RESULTS - Found evidence of age-related decreases in the responsiveness of structures thought to support attentional control (e.g. dorsolateral prefrontal and parietal cortices) - Older participants exhibited more extensive activation of ventral visual processing regions (temporal cortex) and anterior inferior PFC, reflecting a decreased ability to inhibit the processing of task-irrelevant information. - Anterior cingulate cortex, a region involved in evaluatory processes at the level of response (e.g., detecting potential for error), showed age-related increases in its sensitivity to the presence of competing color information. CONCLUSION - Suggests possible impairments in the implementation of attentional control in older participants

Laufs et al 2003

AIM - Investigated the relation between hemodynamic and electrical indices of brain function by performing simultaneous fMRI and EEG in awake subjects at rest with eyes closed. METHOD - EEG and fMRI - 15 ppts - Instructed to lie still and not fall asleep RESULTS - Little positive correlation of localized brain activity with alpha power but strong and widespread negative correlation in lateral frontal and parietal cortices (known to support attentional processes) - Beta activity positively correlated with activity in temporo-parietal and dorsomedial PFCs - patterns of fMRI activity compared to EEG results indicated covariations of regional activity at rest CONCLUSION - Indicates that, during resting wakefulness, these areas constitute separable and dynamic functional networks, and that activity in these networks is associated with distinct EEG signatures - Suggest that alpha oscillations signal a neural baseline with ''inattention'' whereas beta rhythms index spontaneous cognitive operations during conscious rest

Gusnard et al 2001

AIM - mPFC has high baseline activity at rest which decreases during goal-directed behaviours -> suggests the existence of an organized mode of default brain function - Investigated whether this region may contribute to the neural instantiation of aspects of the multifaceted ''self given previous data suggesting this METHOD - fMRI - Ppts made two judgments (1 self-referential, 1 not) in response to affectively normed pictures: pleasant vs. unpleasant (an internally cued condition, ICC) and indoors vs. outdoors (an externally cued condition, ECC). RESULT - ICC was preferentially associated with activity increases along the dorsal MPFC - Accompanied by decreases in both active task conditions in ventral MPFC CONCLUSION - Self-referential mental activity appears to be associated with increases from the baseline in dorsal MPFC - Reductions in ventral MPFC suggest that attention-demanding tasks attenuate emotional processing. - Overall, suggests that self-referential mental activity and emotional processing represent elements of the default state as represented by activity in MPFC PERSONAL - This last conclusion seems a bit premature given that no causal relationship has been established

Temporal lobe

Auditory processing High-level vision Language

Gilbert et al 2005

Executive Functions Aim - Investigated brain activity to understand involvement of rostral prefrontal cortex in selection between stimulus-oriented and stimulus-independent thought Method -fMRI study - Healthy subjects performed three different tasks each of which alternated between: 1. phases relying on stimulus-oriented thought 2. phases relying on stimulus-independent thought Results - In all three tasks, lateral rostral prefrontal cortex was transiently activated by a switch between stimulus-oriented and stimulus-independent thought - Medial rostral prefrontal cortex consistently exhibited sustained activity for stimulus-oriented vs. stimulus-independent thought Conclusion - Suggest the involvement of rostral prefrontal cortex in selection between stimulus-oriented and stimulus-independent cognitive processes.

Rainer et al 1999

From Neuroimaging 2 lecture - Examined neural activity in prefrontal cortex of monkeys performing delayed paired associate task Method - Monkeys cued with object and then, after delay, presented with a test object - If cue object then had to release a lever Results: - During and shortly after sample presentation, lateral PF cortex = increased neural activity - Towards the end of the delay -> increased PF activity reflecting the anticipated tarfet Conclusion - Suggests monkeys use prospective code (thinking ahead and expecting target object) - PF cortex not only moderate visual input but also selectively process information relevant to behavioural demands (even when recalled from long-term memory)

Critchley et al 2000

IMPORTANCE - Biological basis of social difficulties in autism is poorly understood AIM - Investigated if high-functioning people with autistic disorder show neurobiological differences from controls when processing emotional facial expressions METHOD - fMRI - Measured brain activity in 9 adults with autistic disorder and 9 controls when explicitly (consciously) and implicitly (unconsciously) processing emotional facial expressions RESULTS - Autistic ppts did not activate a cortical `face area' when explicitly appraising expressions, or the left amygdala region and left cerebellum when implicitly processing emotional facial expressions DISCUSSION - High-functioning people with autistic disorder have biological differences from controls when consciously and unconsciously processing facial emotions, and these differences are most likely to be neurodevelopmental in origin. - This may account for some of the abnormalities in social behaviour associated with autism.

Hamann et al 1999

IMPORTANCE - Emotional enhancement of episodic memory has been linked to the amygdala in animal and neuropsychological studies AIM - Investigated the relationship between amygdala activity during memory encoding of pleasant and aversive stimuli and enhanced long-term episodic memory (recall and recognition) for these stimuli METHOD - PET study - Ppts (only 10 males) presented with neutral, aversive and pleasant visual stimuli - Skin conductance was measued to assess emotional reaction - Performed surprise recall test RESULTS - Bilateral amygdala activity during memory encoding correlated with better episodic recognition for both pleasant and aversive visual stimuli relative to neutral stimuli - Data also suggested that the amygdala enhances episodic memory in part through modulation of hippocampal activity CONCLUSION - Human amygdala seems to modulate the strength of conscious memory for events according to emotional importance

Gläscher et al 2008

IMPORTANCE - Evidence suggests that ventromedial PFC is involved in encoding expectations of future reward during value-based decision making AIM - Investigated whether expected reward representations in ventromedial PFC could be driven by action-outcome associations, rather than being dependent on the associative value assigned to particular discriminative stimuli METHOD - fMRI study - 20 university Ppts did 2 variants of a simple reward-related decision task. - 1st variant -> made choices between 2 different physical motor responses in the absence of discriminative stimuli - 2nd variant -> chose between 2 different stimuli that were randomly assigned to different responses on a trial-by-trial basis RESULTS - Activity in ventromedial PFC tracked expected future reward during the action-based task as well as during the stimulus-based task CONCLUSION - Ventromedial PFC may play a role in encoding the value of chosen actions, irrespective of whether those actions denote physical motor responses or more abstract decision options

Johnsrude et al 2000

IMPORTANCE - Research with animals suggests the amygdala is critical for acquiring associations between rewarding events and neutral stimuli AIM - Investigated the relationship between the amygdala and preference learning in humans METHOD - 3 types of ppts: normal, with unilateral lesions to amygdala, and unilateral lesions to frontal cortex - 3 abstract monochrome patterns were presented over 180 trials in the context of a counting task requiring working memory. - One pattern was paired with food reward on 90% of the trials in which it was presented - Other 2 patterns were similarly reinforced, but at ratios of 50:50% and 10:90% RESULTS - Subsequently, a group of 21 normal participants preferred the pattern paired most often with reward - Patients with unilateral surgical lesions that included the amydgala did not show conditioned preferences, but performed normally on a measure of working memory - Patients with unilateral damage confined to frontal cortex exhibited normal conditioned preferences but were impaired on the working memory task. CONCLUSION - This double dissociation provides clear evidence that, in humans as in other animals, reward-related learning (conditioned reward) critically depends on a circuit involving amygdala

Knutson et al 2002

IMPORTANCE - The function of the mPFC quite unclear but recent evidence suggests that it may play a role in processing reward outcomes AIM - Investigated the possibility that a region of the MPFC would be preferentially recruited by monetary reward outcomes using a parametric monetary incentive delay (MID) task METHOD - 12 ppts in fMRI - Performed MID task that made them sometimes anticipate a reward which would be followed by either a true reward or no reward RESULTS - Ventral striatum was recruited by anticipation of monetary reward - MPFC region activated in response to rewarding monetary outcomes CONCLUSION - Suggests that in the context of processing monetary rewards, a region of the MPFC preferentially tracks rewarding outcomes. PERSONAL - Unclear how short-term versus long-term anticipation may play out in this

Koechlin et al 1999

IMPORTANCE - Complex problem-solving and planning involve regions in frontal lobes (very developed in humans compared with other primates) but specific roles of these regions are poorly understood AIM - Investigated the role of the anterior prefrontal cortex in human cognition METHOD - fMRI study - Subjects had to keep in mind a main goal while performing simultaneous (sub)goals RESULTS - Bilateral regions in the FPPC alone were selectively activated during task performance - Neither keeping in mind a goal over time (working memory) nor successively allocating attentional resources between alternative goals (dual-task performance) could by themselves activate these regions CONCLUSION - FPPC selectively mediates the human ability to hold in mind goals while exploring and processing secondary goals,

Sokol-Hessner et al 2009

IMPORTANT AIM Can we control our loss aversion? METHOD - Task where you can choose different types of gambles - Condition 1: think about each gamble individually - Condiction 2: think like a trader - Physiological measurements of arousal, and an economic model of behavior, this study examined changes in choices (specifically, loss aversion) and physiological correlates of behavior as the result of an intentional cognitive regulation strategy. RESULTS - Participants were on average more aroused per dollar to losses relative to gains, as measured with skin conductance response - difference in arousal to losses versus gains correlated with behavioral loss aversion across subjects. CONCLUSION - These results suggest a specific role for arousal responses in loss aversion. - Thinking like a trader made them less loss averse!

Volle et al 2011

INFO - Patients with lesions in rostral prefrontal cortex (PFC) often experience problems in everyday-life situations requiring multitasking. AIM - The aim of this study was to determine regions that are necessary for prospective memory performance, using the human lesion approach. METHOD - We designed an experimental paradigm allowing us to assess time-based (remembering to do something at a particular time) and event-based (remembering to do something in a particular situation) prospective memory, using two types of material, words and pictures. RESULTS - The results showed that lesions in the rPFC were specifically associated with a deficit in time-based prospective memory tasks for both words and pictures. - This deficit could not be explained by impairments in basic attention, detection, inhibition or multiple instruction processing - There was NO DEFICIT in event-based prospective memory conditions. CONCLUSION - This is the first lesion study showing that rostral PFC is crucial for time-based prospective memory. The findings suggest that time-based and event-based prospective memory might be supported at least in part by distinct brain regions. - Two particularly plausible explanations for the deficit rest upon a possible role for polar prefrontal structures in supporting in time estimation, and/or in retrieving an intention to act. - More broadly, the results are consistent with the view that the deficit of rostral patients in multitasking situations might at least in part be explained by a deficit in prospective memory.

Buckner et al. 2001

Memory Encoding Aim: - Demonstrate the pervasive nature of information processing that leads to episodic encoding via the Testing phenomenon (incidental encoding) Importance: - Episodic memory encoding appears to be pervasive across many kinds of tasks and usually does not require intentional memorisation Method: - Conducted 3 experiments (using behavioural and fMRI) - Asked to perform episodic memory retrieval task - Then completed a surprise test of recognition of new words Results: - Behavioural data: performing memory retrieval task was as effective as intentional instructions at encouraging episodic encoding - fMRI data: new words that were later remembered showed greater activity in left frontal regions Conclusion: - fMRI data shows same pattern of results as in intentional encoding tasks - Suggests we constantly encode Personal: - Could have integrated TMS measure to see if there is a causal relationship

Kensinger et al 2006

Memory Encoding Aim: - Examined role of amygdala activity and subsequent memory for positive and negative information Importance: - Unclear whether amygdala activity at encoding corresponds with all aspects of an item or only emotional bits Method: - fMRI study - Participants encoded positive and negative stimuli whilst performing a task (either judgement of animacy or commonness) Results: - Amygdala activity: - Related to encoding performance of positive and negative items - Unrelated to encoding performance of neutral items - Unrelated to successful retrieval of contextual information Conclusion: - Amygdala can be engaged during encoding of positive and negative items - However, its activity does not facilitate encoding of all contextual elements - Better for encoding of emotional items than non-emotional - Only help with the successful encoding of the item itself rather that the context of it Personal: - Causality of amygdala activity and successful emotional item encoding could be explored using TMS LIMITATION: - Only 21 participants

Shannon et al 2004

Memory Retrieval Aim - Explored the relationship between memory processes and classical notions of PPC function Importance - Imaging studies of long-term memory have demonstrated PPC activation during successful memory retrieval Method - Study 1: Investigated old-new recognition using picture and sound stimuli to test whether PPC memory effects were dependent on visuospatial attention Results - Study 1 -> medial PPC and posterior cingulate cortex showed strong retrieval success effects for both picture and sound stimuli Conclusion - Retrieval success effects in lateral and medial PPC regions are not affected by manipulations predicted by classical theories of PPC function but can be modulated by memory-related manipulations - Probably have prominent response properties associated with memory, which may arise through interactions with medial temporal cortex. Limitations - Young sample (less applicable) Personal - Conclusions concerning interactions with the MTL cannot be assumed until further investigated

Weis et al 2004

Memory Retrieval Aim - Investigated temporal and cerebellar brain regions that supported declarative memory formation and retrieval Importance - Method - Using an fMRI scanner, young subjects were asked to memorise photographs which they later had to recognise out of a series of new photographs - Compared recognition hits vs misses of the participants Results - Activity in the medial temporal lobe (MTL) and inferior prefrontal cortex was greater for subsequently remembered items than forgotten items. - When compared hits vs misses, anterior medial temporal lobe contributed to item loss whereas prefrontal and parietal regions contributed to item retrieval Conclusion - Likely that these areas are crucial for declarative memory retrieval and formation Limitations - No causal relationship can be confirmed Personal - Most likely associated but cannot confirm whether crucial for formation and retrieval

Damage to Medial Temporal Lobe (MTL), specifically anterior & posterior hippocampus and amygdala

Patient HM Anterograde amnesia

Parietal lobe

Sensation Perception Sensory integration

Frontal lobe

Voluntary movement Higher-level executive functions Decision-making