Cognition

Cognition

Mental processes used to acquire, use and generate knowledge: attention, memory, language, reasoning, judgment, planning, etc

·      Cannot be observed directly - infer it from measurable behaviour on cognitive tasks

6 common domains

1.        Executive function

2.        Attention/working memory

3.        Memory

4.        Language

5.        Visuospatial function

6.        Social cognition

Association cortex

Lies across all 4 cortical lobes and integrates incoming sensory info with stored knowledge, creating meaningful perception, supporting effective interaction, abstract thought and language

Association cortex - inputs

Primary/secondary sensory and motor cortices, thalamus and brainstem

Association cortex - outputs

Hippocampus, basal ganglia, cerebellum, thalamus and other association areas

Posterior association cortex

Area of grey matter that synthesises sensory info and memory and frontal association cortex supports complex behaviour

·      Parietal, temporal and occipital lobes

Dorsolateral prefrontal cortex (DLPFC)

Important for planning, temporal sequencing, speech and logical reasoning

Binding problem

How separate visual, auditory, tactile and motor signals become one coherent perception or action

Multimodal association

Neurons respond to more than one sensory modality so integration across modalities offers a solution to the binding problem

·      E.g. matching a person’s voice with their face

Attention

Selectively prioritising one stimulus or thought among competing inputs

·      Frontal lobes help control and disengage attention

-              Frontal injury can cause difficulty shifting away from irrelevant or environmental stimuli

·      Frontal and parietal systems help direct attention to contralateral space (e.g. orienting the eyes/head and reaching)

Letter-Number sequencing test

Assesses attention and working memory - part of the WAIS-IV

·       Procedure: participants hear mixed letters and numbers, then repeat them with numbers in ascending order followed by letters in alphabetical order

·       Higher scores indicate better attention and working memory

·       Those with frontal lobe deficits (e.g. Parkinson's disease or dementia) perform poorly

ADHD

·      Cortical thinning in attention/executive networks and atypical regulation of large-scale networks

-              Dorsal attention networks contribute goal-directed top-down control and interact with ventral networks during attentional tasks

Left hemispatial neglect vs visual extinction

·      Extinction can occur across multiple senses

Left neglect assessments to identify

1.        Copying/drawing (omit left details)

2.        Cancellation (miss left targets)

3.        Line bisection (mark midpoint too far right)

Planning

Formulating, evaluating and ordering thoughts/actions to achieve a goal

·      An executive function

Prefrontal cortex

Identify goals, prioritise, time and sequence actions

Temporal/occipital cortex

Recognise objects and surroundings

Parietal cortex

Guide movement through space

Frontal lobe

·      Coordinate all the cortex’s

·      What you need to do, when you need to do it, prioritise tasks, organize in sequence

WCST

·      Probes cognitive flexibility, rule shifting and perseveration

·      Frontal/DLPFC injury can increase perseverative errors

·      Scores include categories achieved, trials, errors and perseverative errors

·      12-20 mins

WCST - procedure

·      Match cards by an unstated rule (e.g. colour) and feedback indicates correct/incorrect

·      Rule changes to shape or number and the participant must discover and switch to the new rule

Mirror neurons

Discharge when an animal performs an action and when it observes another performing that action

·      Rizzolatti discovered they’re found in macaque premotor area F5

·      Human inferior frontal cortex and superior parietal lobe are active

Mirror-neuron theory

Shared action representations help us recognise others’ actions, imitate behaviour and possibly understand communication

·      Observing actions activates brain regions involved in action processing: inferior frontal and parietal regions, alongside visual areas in the occipital and temporal lobes.

·      Evidence limitations: direct evidence of individual mirror neurons in humans is limited, so their proposed functions are not fully established and therefore theoretical

Functional lateralization

Some functions are processed more efficiently in one hemisphere - but neither hemisphere performs only one type of task

·      Visual info from each visual hemifield reaches the opposite hemisphere

Left vs right hemisphere tendency

Split-brain experiments

·      Showed corpus callosum connects hemispheres

·      Surgical disconnection has been used as a last-resort treatment for refractory epilepsy as it prevents normal interhemispheric sharing of info

Split-brain experiments - experiment 1

·      Spoon in RIGHT visual field → LEFT hemisphere → person can verbally name “spoon”

·      Spoon in LEFT visual field → RIGHT hemisphere → person may be unable to name it aloud

·      Doesn’t mean the object was not perceived

Split-brain experiments - experiment 2

·      Spoon in LEFT visual field → RIGHT hemisphere → LEFT hand can reach for the spoon despite inability to name it

Split-brain experiments - experiment 3

·      Hands may select different objects or interfere with each other

·      Interhemispheric competition

Sex differences in cognition

·      Women higher on some verbal-fluency tasks, greater volume prefrontal and medial paralimbic systems and increased cortical grey matter concentration

·      Men higher on some mental-rotation tasks, greater volume medial/orbital frontal and angular gyrus and more uniform grey matter concentration and more aggressive

·      Rat findings: male rats had larger dendritic fields in medial frontal cortex and female rats in orbitofrontal cortex

-              Sex hormones impact cortical organisation and cognition

-              Cannot be assumed to generalise to human cognition

·      Evolutionary explanations involving historical spatial navigation and caregiving/language roles