Neuropsychology 2

Association Areas

Three unimodal association areas

As areas get further away from the primary sensory areas, the associative functions become more general

• Limbic association area

• Posterior association area

• Anterior association area

Limbic association area

Posterior & Anterior association areas

Parietal lobe functions

Major Functional Regions

Parietal Functions by Zone

• Anterior zone = Somatic sensations and perceptions

  • Somatic = bodily

• Posterior zone = Sensory integration and whole-body movements

• Networks connect to all other lobes (see later)

  • Feeds into frontal lobe

Major Functional Regions of the Parietal lobe

1. Superior parietal lobule (SPL)

• visuomotor, cognitive, sensory, higher order, working memory and attentional

2. Inferior parietal lobule (IPL)

• spatial attention, multimodal sensory integration, and oculomotor control

3. Somatosensory cortex 

• detects sensory information, initiates movement

4. Precuneus

• Gestalt integration of information, mental imagery, episodic memory retrieval, self-referential processing

Superior Parietal Lobule

Dorsal Stream Anatomy

Inferior Parietal Lobule

Somatosensory cortex

• detects sensory information from the body regarding temperature, proprioception, touch, texture, and pain

• receives neuronal projections from the thalamus

• adjacent to the primary motor cortex

4 representations of the body

Somatosensory receptors - 3 types

Generating movement

• Integrating sensory input

• Initiating movement

Sequential Production / Initiation of Movement

Sensory-to-motor movement

Hierarchical Control of Movement

Precuneus

Hypothesised that functions can be explained by its central location in the cortical network

•   May facilitate over 60 processes

•  Visuo-spatial imagery, episodic memory retrieval, self-processing, first-person perspective taking, experience of agency, self-consciousness (and possibly consciousness)

•  Default mode network (DMN) = brain processes when brain is at rest; mostly social activations

  •  Precuneus is functionally central to DMN

Default Mode Network

Default Mode Network & MNS

Default Mode Network & Other Networks

Fronto-parietal Network

Parietal Memory Network

Other Major Functional Regions - Posterior cingulate cortex (PCC)

• Controls state of arousal, the breadth of focus and the internal or external focus of attention

• Participates in self-referential processing, episodic or autobiographical memory, future thinking, mentalizing, spatial navigation, and conceptual processing

Temporal-Parietal Junction (TPJ)

Also called Temporoparietal Junction

• Where the two lobes meet

  • Forms a bridge at the inferior parietal lobule & posterior superior temporal sulcus

Self and Other - Mentalizing

Common symptoms of parietal lesions and their clinical assessment

Asomatognosis

• A loss of knowledge of one’s body, usually considered a type of agnosia caused by parietal lesion

• There are several types:

  • Anosognosia = unawareness/denial of illness

  • Anosodiaphoria = indifference to illness

  • Autopagnosia = inability to localize/name body parts

    • Finger agnosia = the most common type of autopagnosia; unable to identify fingers

  • Asymbolia for pain = absence of typical pain responses

Apraxia

• Loss of movement caused by a brain lesion and not by any damage related to the muscles or other body parts/processes

  • Ideomotor apraxia = Disturbance to physical movements; unable to copy or make gestures (e.g., waving hello)

  • Constructional apraxia = Disturbance to spatial processing; unable to build a puzzle or draw a picture

  • Speech apraxia = Disturbance to speech due to brain lesion and not caused by other types of language disorders

Gerstmann's syndrome

• Josef Gerstmann (1924) observed a patient with left parietal stroke and unusual symptoms

  • Finger agnosia

  • Left-right confusion

  • Agraphia = inability to write

  • Acalculia = inability to perform arithmetic tasks

    • Double dissociation: different regions for subtracting (IPS) and multiplications (AG)

Balint syndrome

• Rezsö Bálint (1909) observed a patient with bilateral parietal lesions and unusual symptoms

  • Could move his eyes but not fixate on visual stimuli

  • Displayed simultagnosia = could only attend to one stimulus at a time and would not notice other stimuli

  • Displayed optic ataxia = difficulty in reaching for stimuli even when guided

Parietal Lobe Epilepsy (PLE)

• A rare form of epilepsy

• Causes bodily sensations during seizures

• Somatic illusions = a common symptom that causes misperception of real stimuli (e.g., feeling like body is falsely morphing, moving, or damaged)

• Inability to detect space/distance

• Dysesthesia = distortion to the sense of touch that causes feeling of pain without nerve stimulation

• Vertigo

• Disturbs other brain processes because of network connections

  • E.g., can cause loss of language processes that are in the frontal lobe

Parietal Lobe Seizure

• Focal seizures cause bodily distortions

  • Consider what’s different from a temporal lobe seizure:

    • Falls to one side, eyes change, loses body control

  • Because parietal lobe networks across the brain, it is hard to identify the onset location of focal parietal lobe seizures using brain imaging

    • Electrical disruptions tend to be more spread out

Schizophrenia (not a “Parietal Lobe Disorder”, but...)

• Disruptions to frontal and temporal lobe are most pronounced in schizophrenia

• Abnormal parietal lobe activations can cause psychotic-like symptoms

  • I.e., Parietal dysfunction can mimic symptoms of schizophrenia

  • But parietal lobe disruptions in schizophrenia are usually modest

• Parietal lobe may be responsible for several symptoms

  • Gray matter volumes is reduced across parietal lobe in patients with schizophrenia

  • During hallucinations, activity in the postcentral gyrus and the inferior parietal lobule increases

  • Distorted sensory integration / misinterpretation

  • Illusions of control

  • Poor distinction between self and other

  • Poor social cognition

The Acquisition of Culture

• Was better social intelligence the cause of the larger brain?

  • Unclear.

• What is clear:

  • Once the larger brain developed, so did culture

  • Humans used larger brains for social coordination

• Memes

  • Ideas and behaviors that are passed easily from person to person in a culture

  • Allow rapid social transmission of ideas

  • Richard Dawkins (1976) ”Selfish Gene” famously coined the term

Cultural transmission of ideas

• 3 primary types of cultural transmission:

  • Vertical = from parents to children

  • Oblique = from older generation (non-parents) to younger generation

  • Horizontal = between peers

• These transmission structures are commonly seen in social species

  • Unconcious inference - processes developed through experience but outside of our awareness

Types of Intelligences

Unclear if brain size is tied to intelligence

• Species-typical behavior is used to define intelligence

• Many types of intelligences and they are hard to measure

  • Musical

  • Verbal

  • Mathematical

  • Spatial

  • Logical

  • Social

• IQ tests only measure one or two of these, and are culture-bound

When is brain size relevant among humans?

• Normal brain size changes over an individual’s life span

  • Just as good nutrition early in life can promote larger brain size, a culturally enriched environment is associated with growth of existing brain cells

    • One way that the brain stores new skills and memories is to add cells and to form new connections among brain cells.

    • These plastic adaptations in turn contribute to increased brain size.

• Size changes from misfortune

  • Brain injury around birth can cause large shrinkage of brain size

  • Stress from physical or behavioral deprivation in infancy also leads to decreased brain size

  • Neurological disorders associated with a mother’s abuse of alcohol or other drugs are associated with conditions such as fetal alcohol spectrum disorder (FASD)

  • Autism spectrum disorder (ASD), a largely genetic condition affecting development, produces a variety of brain abnormalities, including increases or decreases in brain size in different individuals

• Neurological diseases associated with aging accelerate the age-related decrease in brain size

Frontal Cortex

Gross anatomical subdivisions of FC (1)

Gross anatomical subdivisions of FC (2)

Major Frontal Lobe Functions

Prefrontal Cortex Functions

Lateral PFC

Medial PFC

Premotor cortex

Adjacent to and organised like the somatosensory cortex

•   Generates signals to initiate body movements

•   Controls muscle activity

•   Acquisition and performance of skilled movements

•   Activated when observing the actions of others (may facilitate skill learning)

Functional zones

Frontal Lobe Networks

Executive functions: planning and generation of novel actions

• Prefrontal lobe damage: attentional control, planning, reasoning, working memory, problem solving, abstract thinking, and self-monitoring are intact, same as language and memory; however regulation behavior in a contextually appropriate way is problematiс

• Left frontal lobe involved in task setting, the right frontal lobe is more involved in task monitoring;

• Hot and Cold executive functions, that rely on different executive subsystems that are anatomically and behaviorally separate.

• Behavior Rating Inventory of Executive Function (BRIEF)

Symptoms of Frontal Lobe Lesions

• Motor disturbances

  • Loss of Fine motor movements, speed & strength

  • Poor Movement programming 🎹

  • Poor Voluntary eye gaze

  • Corollary discharge 

    • Motor-related timing (how you know that something has occurred because of your own actions - you have a sense for when you acted and that something occurred after your action)

  • Speech (Broca’s aphasia) (Agrammatism; mutism – left medial frontal area)

• Thinking alterations

  • Decreases in IQ score

  • Loss of divergent thinking (i.e., creativity / problem solving abilities)

  • Loss of behavioral spontaneity (Thurstone Word Fluency Test) + fewer spontaneous facial movements

  • Loss of strategy formation 

• Difficulty using environmental cues

  • Poor response inhibition

    • “Form is probably the correct solution now so this [sorting to color] will be wrong, and this will be wrong, and wrong again.”

  • Impaired associative learning (right hand – red light)

  • Risk taking / rule breaking (MAZE)

  • Decrease of self-regulation (loss of autonoetic awareness)

  • Gambling (OFC)

• Poor temporal memory

  • Delayed response

  • Recency memory 🂦 🃂 🃟

• Impaired social & sexual behavior (responses that are dependent on contextual cues)

  • Pseudodepression / pseudopsychopathy

    • ”Pseudo” = not genuine, false (e.g., depression-like traits but cause is the brain lesion on the left)

  • Orbitofrontal syndrome = brain lesion (on the right) that causes disinhibition:

    • Immature behavior, lack of tact and restraint, coarse language, promiscuous sexual behavior , increased motor activity, and a general lack of social graces (dementia), difficulty understanding facial expressions, directing spatially guided behaviors.

• Impaired olfactory discrimination

Frontotemporal Dementia

• The most common signs of frontotemporal dementia are usually in the form of extreme changes in behavior and personality

  • Increasingly inappropriate social behavior

  • Loss of empathy and other interpersonal skills (e.g., insensitivity to another's feelings)

• Affects men and women equally

• 10% - 30% of cases have genetic causes

  • Runs in families

  • Clumps of abnormal protein forms inside neurons

  • Cause of other 70% - 90% of cases is usually unknown

Lateral Brain Tumor

• What’s the difference between a tumor and a lesion?

  • Dementia and lesions have interventions but not treatments

  • Brain tumors can be benign (non-cancerous) but still disrupt functioning

    • Tumors can often be removed through surgery

• Laterality in the frontal lobe

  • Left side tumors and lesions affect language and movement

  • Right side tumors and lesions affect non-verbal processes (like emotion)

Emotions

• Emotion is an internal subjective state and involuntary physiological response to an object or a situation.

• Emotions have impact on attention, perception, decision-making and memory

• Emotionally charged stimuli capture attention (your name, threatening stimuli, a fearful facial expression)

• Emotional memories are better remembered and retained (memory)

• Emotions guide decision-making by helping to unconsciously make the most advantageous choice (obtaining benefits, avoiding looses)

• Cognitions and emotions are inseparable

• Emotions inform us about events that matter to us, to our needs, values, and well-being

• They determine how we perceive the environment

Emotion and the Social Brain

• Emotions = complex reactions

  • Physiological, experiential, neurobehavioral

  • Probably had early evolutionary benefits

• Social emotions = emotions that depend on other people

  • People cause emotions

  • We cause emotions in people

  • People are often the most salient stimuli

• Self-reported cognition → this is a major measure of our internal states (emotions, thoughts, dis/comfort, etc)

  • Many patient groups have difficulty accessing their internal states

  • Some healthy people do too

  • Most healthy people are good at reporting their experiences, but might use a variety of terms to describe them (natural language isn’t as standardized as scientific language is)

Principal behavioral components of emotions

1. Psychophysiology

2. Distinctive motor behavior

3. Self-reported cognition

4. Unconscious behavior

Emotions arise as a result of the influence of subjective and objective factors that interact with the nervous and endocrine systems, trigger the experience of pleasure or avoidance, modulate various cognitive processes (memory, attention), cause physiological changes (heart rate), and lead to behavioral changes that help a person adapt to the situation that caused them

Limbic System & Emotions

• Cingulate cortex = links rewards, punishments, and emotional responses

• Fornix = episodic memory

• Septum = mediates connections with the cortical areas

• Olfactory bulb = smell

• Amygdala = fear and threat

• Hypothalamus = homeostasis; turns emotions physical (e.g., heart rate when scared)

• Hippocampus = learning & memory

→ Frontal lobe connects with the limbic system.

Although the entire circuit is important to emotional behavior, the prefrontal cortex (especially the orbitofrontal and ventromedial regions) and amygdala hold the key to understanding the nature of emotional experience

• The orbitofrontal cortex (OFC) is especially important in emotion because it represents positive and negative rewards and learns which previously neutral stimuli are associated with positive and negative rewards and when these associations change

Social Brain Networks - how the brain mediates social interactions

• Amygdala Network

  • Amygdala, orbitofrontal cortex, temporal cortex

  • Responding emotionally & detecting socially-relevant stimuli

• Mentalizing Network

  • Superior temporal sulcus, anterior temporal cortex

  • Thinking about the internal states of others

  • Understanding others’ actions

• Empathy Network

  • Insula, cingulate cortex

  • Attributing emotion and perspective to others

• Mirror / stimulation / action-perception network

  • Mirror neuron system (MNS) – parietal & premotor regions

  • Activate when we observe the actions of others

  • Developing concept of self

N.B.: these networks also recruit subcortical regions such as the nucleus accumbens, globus pallidus, hypothalamus, and ventral tegmentum

Behavioral changes after frontal lesions associated with emotional processes

• Reduced social interaction

• Loss of social dominance

• Inappropriate social interaction

• Altered social preference

• Reduced affect

• Reduced vocalization

Social Brain Lesions

• Lesion case studies

  • Frontal and temporal lesions = deficit in producing facial expression, social  speech and processing deficits in facial expression, social context-driven emotions, personality changes

    • The ability to be humorous and to comprehend humor (social glue): Right-frontal injuries were the most affected in that they reacted less than other patients, with diminished laughter and smiling, and failed to grasp the jokes.

  • Insula = increase pain threshold, impair pain recognition in others

    • Anterior insula = emotion awareness

  • Amygdala = fear recognition in others

  • Bilateral vmPFC = impaired social conduct, decision making, emotion processing

    • right sight lesions → pseudo-psychopathy (acquired sociopathy)

    • left side lesions → not much changes...

WHAT ARE COGNITIVE DISORDERS?

Major Cognitive Processes

1. Language

2. Spatial Navigation

3. Learning & Memory

4. Attention

And more ...

Perception, Executive functioning, Reasoning, Decision making

Language Disorders

• Aphasia's (Broca’s, Wernicke’s)

• Paraphasia

• Alexia

• Agraphia

• Dyslexia

Paraphasia

Dyslexia

Characterized by poor fluent / accurate word recognition, poor spelling, and difficulty with word decoding. It is a learning disability and neurobiological in nature.

• Attentional dyslexia = multiple letters or words cause difficulty (one letter or one word is fine)

• Neglect dyslexia = may misread the first or last part of a word (e.g., whether as smother; strong as stroke)

• Letter-by-letter reading = affected persons read words only by spelling them out to themselves (aloud or silently)

• Deep dyslexia = semantic errors (e.g., misreading merry as Christmas, because the words are often paired); usually have more trouble with abstract words and have difficulty with short term verbal memory (as we will see later, meaning plays a role in memory)

• Phonological dyslexia = inability to read nonwords aloud (most common)

• Surface dyslexia = cannot recognize words directly but can understand them by using letter-to-sound relations if they sound out the words. Surface dyslexia does not develop in languages that are totally phonetic and sounded out as they are written (e.g., Italian). Surface dyslexia is a common symptom of children who have difficulty learning to read

Dual route theory of reading

• Lexical route

  • Relies on the activation of picture or sound representations of a whole word

  • The lexical route can process all familiar words, both regular and irregular, but it fails with unfamiliar words or nonwords because it lacks a means for representing them.

• Nonlexical route

  • Uses a subword procedure based on sound-spelling rules

  • The nonlexical route can succeed with nonwords (e.g., klanley) and regular words that obey letter-sound rules, but it cannot succeed with irregular words that do not obey these rules (e.g., winding, choir).

  • Most impaired in developmental dyslexia

Lexical = related to words as whole units, “pictures” (as opposed to grammar or parts of words)

Brain regions for Speech and Sound to Meaning

Key Brain Regions Related to Reading

(Language) Found in the following disorders

Topographic Disorientation

Egocentric Disorientation

Difficulty perceiving the relative location of objects with respect to the self

• Able to gesture toward objects with eyes open, but cannot with eyes closed

• Performance is impaired on a wide range of other visuospatial tasks

  • Impaired mental rotation = the ability to visualize the appearance of three-dimensional objects from different perspectives

  • Impaired ability to judge distances between objects

• These patients are uniformly impaired in way-finding tasks both in formerly familiar and in novel environments

Spatial disorientation

Distortions in the perception of the body or environment (PCC)

• Alice in Wonderland effect

• Out-of-body feeling

• Missing places

  • During a walk down a hospital hallway, an 80-year-old woman who had suffered a stroke stopped and declared that she could go no farther because that is where the hospital ended. When released from the hospital, she refused to return to her home of 20 years because, she declared, it was in a place that was not there. Even after her daughter found a new apartment for her, she became upset because the place did not exist.

Spatial Disorders in the Brain

(Space) Found in the following disorders

Information Processing Model

Working and Short-Term Memory

Long-Term Memory

Forgetting - Overload

Types of memory

Learning and the power-law

Learning and long-term potentiation

Neural correlate of the power-law: long-term potentiation (LTP)

• Neurons that are activated simultaneously adjust their connection strength over time

  • They require less and less time to transmit electrical signals between them (myeline)

• Connection change follows the same (though inverse) logarithmic relation as the power law of learning

Brain activation changes with skill acquisition

As people become more proficient at a task, they seem to use less of their brains to perform that task (efficient)

• Regions activated in the symbol-manipulation task of Qin et al. (2003)

• Less is (sometimes) more: The brain seems to have become more efficient

• Important to remember that bigger is not always better in brain-terms

Long-term memory - declarative memory

Long-term - non-declarative memory

Procedural memory = memory for skills, motor acts, routines

Summary of memory in the brain

• Medial temporal lobe (esp. hippocampus and parahippocampal regions): form, organize, consolidate, and retrieve memories

  • ....and the hippocampus is a brain structure deep in the brain which has a central function for memory:

    • Storage of new memories

    • Link together different kinds of information in many regions of brain (perceptual, affective, conceptual etc.)

• Prefrontal brain regions: encoding of new memories and retrieval of old memories

• Associative regions in the cortex: integrate sensory inputs, enabling to understand the environment and encode memories

• Other brain areas (including amygdala, striatum, and cerebellum): other kinds of memories, such as emotional or behavioral memories

Types of amnesia

• Anterograde amnesia = an inability to form new memories

• Retrograde amnesia = a loss of memory acquired prior to the injury

  • Time-dependent retrograde amnesia = loss of more recently acquired memory, while memories from the distant past are retained

• Childhood (infantile) amnesia = an inability to remember events from the first 4 years and the recall of fewer than expected memories up to 7 to about 11 years of age

Dissociating memory systems

• Episodic and procedural memory:

  • HM learned to mirror draw over a 3-day period

  • Clive Wearing still plays the piano

  • Thus, procedural learning can often be intact in amnesia

• Episodic and short-term memory

  • Amnesiacs have normal digit span

  • HM could remember a number for 15 minutes by continuously repeating, but forgot it within 1 minute of stopping and had no recollection of attempting it (Milner, 1971)

(Memory) Found in following disorders

Types of attentional processes

• Selective attention

  • Paying attention to one thing while ignoring others

• Switching attention

  • From one task to the other

• Divided attention

  • Paying attention to more than one thing at a time

  • Hard to do sometimes

    • Similarity, difficulty and practice

• Sustained attention

  • Paying attention over longer time

• Focused attention

  • Paying attention to one task

• Attentional capture

  • Shift of attention to very salient stimuli (e.g., loud noise)

  • Cocktail party effect: selective attention to one stimulus (conversation) until something catches your attention (hearing your name, spotting a celebrity)

Attention – quantitative limits

• There are limits to the amount of information in the world that the mind can attend to and process simultaneously

  • Unnecessary computational load

  • Energy inefficient and maladaptive

• Serial bottlenecks

  • A point in the path from perception to action at which people cannot process all the information in parallel

  • When do they occur? (e.g., parties)

The study of attention and Serial Bottlenecks

• Early selection theories

  • Filter occurs before we perceive the stimulus

• Late selection theories

  • Filter occurs after we perceive the stimulus

Processing capacity & perceptual load

"Blindness"

Caused by selective attention and the attentional bottleneck

• Inattentional blindness = not noticing something that is clearly there when paying attention to other stimuli

• Change blindness = not noticing changes to stimuli when paying attention to other stimuli

• Attentional blink = Difficult to process back-to-back stimuli

Attention and Cognitive control

• The ability to control your cognitive functions (sometimes called “executive functions”), which include attention, memory, and other cognitive processes

  • Frontal lobe

• Cognitive load = relative difficulty of the cognitive task

  • Different from perceptual load

  • Different from processing capacity because load refers to how many resources you’re using while capacity refers to how much stimuli your can take in

What factors determine to what we attend?

Attention and the Brain

• Parietal cortex is activated for attention to location

• Occipitotemporal cortex is activated for attention to features such as color and form

• Anterior cingulate and prefrontal areas show activation during both visual tasks

Cognitive control and the Brain

(Attention) Found in the following disorders

• Attentional problems are common to many disorders

• Often in combination with EF: inhibition, working memory