Procedural/Emotional Memory: Lecture 11 Flashcards
Procedural memories (2 types)
Allows for co-ordinated behaviours.
Procedural memories involving the motor system can be divided into: 1) habits and skills (e.g. playing an instrument) and 2) sensory-to-motor adaptations involving the adaptation of reflexes (e.g. changing the force to compensate for a given load).
Rely on different, but overlapping, brain circuits.
Primary vs pre motor cortex (and what they connect to)
Primary motor cortex: controls force and flow of muscle movements
Premotor cortex: involved in movement preparation and sequencing, coordination of muscles on either side of the body.
Both work with 2 subcortical structures: striatum (caudate + putamen) and cerebellum.
Both then –> thalamus –> back to cortex
Striatal habit system (X2 experiments)
Exp. 1) water maze with two platforms marked by discriminable floating balls. One platform = escape, the other = too small. Rats will learn where to swim to get out.
3 groups: control, striatal lesion, fornix (hippocampus) lesion.
With each trial the platforms are moved so that they are ONLY using the markers (not the cognitive map). With each trial, control and fornix group improve. Striatal group never improves (doesn’t learn the habit of swimming to the right marker).
Can also make a spatial discrimination version: platforms are always in the same position, markers are changed. Produces opposite effect (fornix group never learns).
2) 8 arm maze with food rewards. Animals trained BEFORE lesion. “Place” task unaffected by striatal lesion (because using cog. map/hippocampus). “Response” task is affected (never learn the habit).
Response sequencing in the striatum
Monkey trained to fixate on central point. 3 Dots appear in sequence (left, right or above fixation point). Must repeat pattern by fixating on each location.
Some striatal neurons respond to one location but ONLY within a certain pattern e.g. L but only in U, R, L pattern.
Striatum vs cerebellum in motor control
Striatum has very few projections to the brainstem and none to spinal cord, suggesting it doesn’t directly control motor activity. Connections to premotor and motor cortices suggest a role in higher motor functions e.g. planning and execution of complex sequences. Connections with other regions involved in motivation/emotion (amygdala) and planning (PFC) suggests it is more generally involved in goal-oriented behaviour.
Cerebellum has major bi-directional connections with brainstem and receives direct input from the spine. Projections to premotor/motor cortices are also smaller. Suggests more involvement in execution of movements.
Rabbit eye blink conditioning
Tone or light (CS) presented, followed immediately by airpuff to eyelid (US) –> blink (UR).
Becomes conditioned. Information about the CS and US is sent to cerebellum, which creates an association, and can then cause the CR.
CR prevented by: lesion of interpositus nucleus or blocking protein synthesis in the same area. This is a cerebellar nucleus which sends projections to the red nucleus and then motor nuclei to cause the CR.
Inactivation of the red nucleus or pathway between interpositus and red also prevents CR.
Summary of procedural learning
Involves motor cortices and two subcortical loops: striatum and cerebellum.
Striatum is key for habit learning, particularly for tasks involving responses to specific stimuli. Independent of MTL episodic learning pathway.
Cerebellum involved in reflex adaptation. Not entirely independent of the MTL episodic learning pathway.
What are emotions?
4 aspects. 8 categories.
Range of observable behaviours, expressed feelings and changes in body state.
Can be difficult to describe or identify/interpret.
1) Feelings 2) Actions 3) Physiological Arousal 4) Motivational Programs (emotions as adaptive programs that solve specific problems)
Plutchik defined 8 basic emotions: joy/sadness, affection/disgust, anger/fear, expectation/surprise (middle intensity forms). Other emotions are mixtures of these 8.
Limbic system
Primitive CNS system involved in emotion. Originally centered on hypothalamus (Papez circuit), later expanded to include other structures (MacLean’s limbic system)
Important target for drugs such as antidepressants.
MacLean’s triune brain theory
“Tri”
Said brain evolved in 3 stages: reptilian brain (brainstem), paleomammalian brain (limbic system), neomammalian brain (neocortex)
Paleomammalian provided conscious experience of positive or negative thoughts. Early warning system for danger. Also involved in reproduction, maternal care etc.
Decortication rage
Removal of cortex in dogs and cats –> aggression to routine handling.
Other experiment showed subcortical sites, particularly posterior hypothalamus, important in emotions such as rage (removing hypothalamus + cortex –> no rage). Cortex controls (inhibits) emotional responses.
Papez circuit
Suggested circuit for emotional expression based upon studies on neurological patients and animals.
Hypothalamus –> thalamus –> cingulate cortex –> hippocampus –> back to hypothalamus
(begins and ends in hippocampus)
Cingulate gyrus = centre for production of conscious emotional feelings. Cortical and subcortical inputs are integrated here.
MacLean’s Limbic System Theory
Described the “visceral brain” comprising: papez circuit, broca’s limbic lobe, septum & portions of basal ganglia
Later added amygdala, ventromedial PFC and OFC.
Links internal states (viscera) to external environment (sensory) to provide adaptive responses.
Amygdala (major divisions)
Stimulation –> fear/rage in animals. Involved in emotion and memory.
Major divisions: lateral nucleus, centro-medial nucleus, basal nuclei.
Most inputs go to L and B (from cortex and thalamus)
Most outputs from CM. Control physiological responses (e.g. ANS –> HR, respiration etc)
Olfactory system, hippocampus and hypothalamus in the limbic system
Olfactory system: ONLY direct sensory input to limbic system.
Hippocampus: involved in some forms of memory and learning
Hypothalamus: links emotions with autonomic responses (e.g. fear –> sympathetic responses)
