PSYC 326 Final (Ch. 11, 13, 14, 15, 18, 19)

Learning

• Relatively persistent change in behavior due to an experience 

• Acquiring new info

• Our experiences change our nervous system and behavior

Memory

Long term changes in the nervous system following learning

Stimulus

• Anything that an animal can detect with its senses 

  • Ex: lights, tones, odors, food

Response

• A measurable behavior by an animal. Often caused or related to a stimulus 

Types of Stimulus-Response Learning

• Non Associative

• Associative 

Non-Associative

• No connections between stimuli and responses

• Involves habituation and sensitization

Habituation

• A decline in a response to a stimulus that is not important 

Sensitization

An increase in response to stimuli after an avers or highly arousing event

Associative

Connections between stimuli and responses

• Classical Conditioning 

• Operant Conditioning 

Classical Conditioning (Pavlovian)

• Two stimuli brought together in time 

• Independent of the animal’s behavior 

• The animal associates the two stimuli 

Ex./ Steps of Classical Conditioning

• Unconditioned stimulus (US): food

• Unconditioned response (UR): salivation to the food

• *Conditioned stimulus (CS): the bell

• Conditioned response (CR): salivating to the bell

Classical Conditioning in Humans

• Unconditioned stimulus (US): puff of air

• Unconditioned response (UR): blink of the eye

• *Conditioned stimulus (CS): a tone/sound

• Conditioned response (CR): tone elicits a blink

Neural Model of Classical Conditioning

Operant Conditioning (instrumental conditioning)

Outcome is dependent on the animal’s behavior

Positive reinforcement: the addition of something to increase a behavior (giving a treat)

Negative reinforcement: the removal of something to get a certain behavior 

Motor Learning

• Component of stimulus-response learning 

• Changes in responses of motor system following a stimulus

Perceptual Learning

• Ability to learn to recognize stimuli that have been perceived before

• Each sensory system is capable 

Relational Learning

• Connections between association cortex

• Includes spatial learning 

Perceptual, Stimulus-Response, and Motor Learning Model

Henry Molaison (H.M)

• Had severe epilepsy as a child that originated in the temporal lobes

• Received a bilateral temporal lobectomy that removed much of his temporal lobe included a large portion of his hippocampi 

• He could only maintain short-term declarative memories but no long-term memories 

• Could still learn practiced motor skill and associative learning

Engram

Anatomical/physical representation of memory

Equipotentiality

The idea that memory is spread equally throughout the cortex

Does hippocampal formation play a part in memory consolidation?

yes

Sensory Memory

• Brief and fleeting 

• Kept only for a few seconds

Short Term Memory

• Kept for a few seconds to a minute if rehearsed 

Working Memory

• Similar to short term memory but used to solve problems 

Long Term Memory

• If the short term memory is rehearsed a lot and is important 

• And the memory is returned to at different time then it is transferred from short-term memory to long term memory in a process called consolidation 

Non declarative (implicit memory)

• Unconscious 

• Not well controlled

• Procedural memory (ex: riding a bike)

• Classical conditioning/associative learning 

Declarative (explicit memory)

• What we can bring to our conscious mind

• Memories of place, events, and facts 

Episodic Memor

• Memory of life events or episodes 

• Hippocampus helps create episodic memory

• Prefrontal cortex (more on the right hemisphere)

• Parietal lobe, specifically the precuneus

Semantic Memory

• Memory of facts, ideas, and concepts

• Hippocampus

• Prefrontal cortex

• Inferior and medial temporal lobe 

Spatial Memory

• Memory that represent one’s environment 

• Uses episodic and semantic memory

• Hippocampus is highly involved

Morris Water Maze

• Maze with cloudy water 

• Rats swim around trying to find a platform that it cannot see

• Rat gets faster at finding the platform by learning spatial cues 

• Used for research in spatial memory

Memory Consolidation

• Mainly takes place in the hippocampus

• Entorhinal cortex (EC) sends axon into the hippocampus to granule cells into the dentate gyrus (DG) in a tract called the performant pathway

• Long term potentiation

Long term potentiation (LTP)

Long term increase in excitability of neuron caused by repeated high-frequency activity of that input 

• Involves the activation of NMDA glutamate receptor

• Increasing AMPA glutamate receptors at synapse

What concepts involve LTP?

Memory

Classical conditioning 

Consolidation of long term memories that take place in hippocampus

Neural Plasticity

NMDA receptor for glutamate (postsynaptic)

Glutamate is the #1 excitatory neurotransmitter

Typically only allow a small amount of Ca++

Typically blocked by Mg++

AMPA receptors

• Second type of postsynaptic receptor

• Allows in Na+ 

Long Term Potentiation Sequence

1. Glutamate is released from the presynaptic neuron 

2. Glutamate binds to AMPA and NMDA receptors 

3. Na+ influx via AMPA causes a large depolarization of the post-synaptic neuron causing the Mg++ to be removed from the NMDA receptor 

4. Ca++ influx via NMDA receptors 

5. Ca++ activates intracellular signaling pathways affecting protein kinase 

6. Protein kinase affects CREB 

7. CREB activates genetic markers for the production of proteins involved in synthesizing new synaptic connections

Long Term Potentiation Result

• New AMPA receptors are created 

• New dendritic and axonal branching

• New dendritic spines 

• The communication between the two neurons is more efficient and more easily activated 

Long Term Depression

• Caused by low-frequency stimulation between neurons for a long time 

• Opposite of LTP in that it weakens signals between neurons 

• A way for the nervous system to be adaptable to changes-neuroplasticity

• The neurological representation of forgetting 

• Caused by a slow influx of calcium in the postsynaptic cell that activates the enzyme PP1 

Amnesia

• A difficulty with memories caused by an event 

  • Damage to the central nervous system caused by a stroke or accident 

  • Taking a psychoactive drug such as alcohol or benzodiazepines 

  • Krsakoff Syndrome 

    • Excessive alcohol use. Alocohol use leads to thiamine deficiency and hinders LTP

Anterograde Amnesia 

• Difficulty or inability create new memories after an event 

Retrograde Amnesia 

• Difficulties or inability to remember events before an event 

Language

• The set of symbols that we use as a means of communication

• Subserved by the left hemisphere

Speech

• The mechanical process of communication

• Is supported by the entire motor system for vocalization

How is speech produced?

• Speech is produced by airflow from the lungs that passes through the larynx and from there through the oral and nasal cavities 

Production of Vowels

• created by movements of the lips and tongue that change the size and shape of the oral cavity 

Production of Consonants

• produced by movements that temporarily obstruct the airflow through the vocal tract

Communication

• The context of disturbances of specific areas of the brain that controls language expression and comprehension

Aphasia

• A disturbance of language with damage in a specific area of the brain that controls language expression and comprehension

• Breakdown in grammar and syntax (arrangement of words and phrases to create well-formed sentences

Anomia

Difficulty finding words

Paraphasias

Produce the wrong sounds

ex: pike isntead of pipe

Dysarthria

Poor articulation

Hypophonia

Soft output

Other disturbances of language

• Repetition

• Verbal fluency

• Writing:

Agraphia

Inability to write

Paragraphia

Writing incorrect words in a manner similar to saying incorrect words

Prosody

Intonation and stress patterns of words

Hyperprosody

Excessive intonation, almost like mania 

Dysprosody

• Distorted prosody as if one has acquired a foreign accent

Aprosody

• Lack of prosody as in parkinson’s

The Wada Test

A neurological test used to determine which hemisphere of the brain is responsible for language and memory functions, typically involving the injection of a barbiturate into one carotid artery.

Lichtheim

Proposed Connectionist model of the brain

Connectionist Model

Different brain centers are interconnected, and that impaired langauge function may result from damage to either to one of the centres or to the pathways between centeres 

Geschwin discoverswhat?

Conduction aphasia

Conduct aphasia

Damage to arcuate fasciculus, failure to repeat words 

Where is Wernicke’s Area?

Left temporal lobe

Where is Broca’s Area?

Left frontal lobe

Functional Asymmetry

left = verbal

right = non-verbal 

Cortical areas involved in language production and perception

1. auditory cortex

2. wernicke’s area

3. arcuate fasciculus

4. Broca’s area

5. Motor cortex

6. Primary visual cortex

7. Angular gyrus

What is the wernicke-geschwind model?

An early model for understanding how speech is produced in humans

Conversation

Auditory signals are received by the primary auditory cortex

Signals are condcuted to the wernicke’s area where it is comprehended

Neural representaion of thought is transmitted to the Broca’s area through arcuate fasciculus

Broca’s area then articulates the speech in the form of neural signals

Signals are transmitted to the primary motor cortex and muscles of articulation

Reading Aloud

Primary visual cortex analyzes the image and transmits the information to the angular gyrus

Wernicke’s area then sends information to the Broca’s area through the arcuate fasciculus 

Broca’s area then triggers motor cortex to read aloud 

Angular Gyrus

Decodes the image information to recognize the word

Important for reading 

Connects words we read through the visual system to the language system 

If lesioned we get pure Alexia

Alexia

Reading disturbance results from a brain damage

Dyslexia

Reading disturbance is developmental

Auditory Code

Transmitted to Wernicke’s area for comprehension

Broca’s Aphasia

• Characterized by slow, laborious, nonfluent speech 

• Better language comprehension than production 

  • Nonfluent aphasia 

• Difficulty with function words (grammar)

• Better with content words (nouns, verbs, adjectives)

Wernicke’s Aphasia

• Production of meaningless speech 

  • Speech is fluent and unlabored

  • The person does not strain to articulate words and does not appear to be searching for them. 

    • “Fluent aphasia”

  • The patient maintains a melodic line, the the voice rising and falling normally

  • When you listen to the speech of a person with Wernicke’s aphasia, it appears to be grammatical

    • Normal use of function words

    • Use of few content words 

Is addiction treated as other neuropsychiatric disorders? (depression, autism, or alzheimer’s disease)

NO (addiction)

Where do problems with addiction come from?

• Social stigmas

• Personal shaming

• Assumptions of character flaws 

Addiction

• A pattern of compulsive behaviors such as drug taking/ gambling

• Measured by the degree it causes harm to the individual or those around them

• A disorder that often comes with social stigma 

• Addiction has components of associative learning (aka classical conditioning)

Risk Factors of Addiction

• Adolescents 

• Other disorders such as depression, anxiety, autism, schizophrenia, antisocial personality disorder, PTSD

• Early trauma 

• Stressful environment

Adolescents and Addiction

25 or older = least likely to become addicted

Drug addiction may be a developmental disorder

• Rates of addiction are highly correlated with the age at which the drug is first tried 

Disorders and Addiction

Drug abuse and addiction often coincide with or predate neuropsychiatric disorders such as depression, bipolar disorder, and anxiety disorders

Children with ADHD and Addiction

Children with ADHD are more likely to develop problems with addictions

Adults with Autism and Addiction

Adults with Autism and more likely to develop problems with addictions

Antisocial personality disorder and Addiction

Addiction is prevalent in people with APD,

Sensation seeking and Addiction

People who are sensation seeking are more prone to develop addictions

Trauma and Addiction

• A strong predictor of drug addiction developing in adolescence and early twenties is whether an individual experienced abuse or trauma as a child 

Adolescents suffering from addictions had five times the prevalence of PTSD than their nonaddictive peers

Rat Park Study

Rats that live in a comfortable and socially stimulating environment are not motivated to take drugs

Negative Reinforement Theory

• Taking drugs to counteract withdrawal symptoms or a negative state 

• Problems 

  • Highly addictive drugs like nicotine and cocaine do not produce severe withdrawal symptoms 

  • People relapse long after withdrawal symptoms are gone

  • Some drugs like tricyclic antidepressants produce withdrawal but do not promote addiction  

Positive Reinforement Theory

• Taking drugs because they produce euphoric pleasure 

• Problems 

  • Euphoric feeling often goes away 

  • Some addictive drugs do not produce pleasurable feelings

  • The destruction of drug addiction. produce far outweigh any pleasure from the drug 

Mesotelencephalic dopamine system (MTDS)

• Ventral tegmentum sends signals to the nucleus accumbens 

• Activated by addictive drugs

• Activated by the stimuli associated with the drug 

• Activated in anticipation of a reward or drug

• Activated most when there is uncertainty about the rewards 

Incentive-sensation theory of drug addiction

The MTDS becomes sensitized to the drugs and to stimuli associated with the drug

When the MTDS is activated it creates strong cravings for the drugs

Classical conditioning of stimuli associated with taking drugs

Dorsal striatum functions in the learning process

Does drug addiction fundamentally change the normal function of the MTSD??

Yes

Dopamine Receptors/ Levels and Addiction

People with an addiction to cocaine and heroin had a decrease in dopamine receptors and endogenous dopamine levels

CREB

• Increases in the nucleus accumbens with drug taking

• CREB activates genes that produces dynorphin, which reduces the pleasurable feelings of a drug and causes a person to increase dosage

• CREB declines quickly when a person stops taking drugs

FosB

• Released with drug taking

• Causes sensitization of craving behavior to drugs and drug stimuli to create cravings

• Long-lasting even after a person stops taking drugs

• Increases BDNF that causes dendritic branching and spine formation to the frontal lobes-facilitates learning

• Influences relapse