Memory and the brain

Memory involves the mental functions of retaining information about stimuli, events, images, ideas, etc. after the original stimuli are no longer present. Short term meories allow tasks to be performed efficiently. Long term memory allows usto make plans and decisions.

Memory is important to a fully funcitoning animal. Prosopagnosia, the inability to recognise specific faces, allows it sufferer to function, but their social skills will be blunted. Loss of pattern memory allows moderate function as long as the person lives in a supportive social situation

Short-term memory: includes sensory memory and working memory

Long-term memory: includes declarative (explicit) memory and non-declarative (implicit) memory

Retrograde amnesia: loss of memories for events prior to damage

Anterograde amnesia: loss of ability to form new memories

Evidence from amnesiac patients: short-term memory is spared, whilst long-term is impaired. Also, declarative memory is impaired whilst non-declarative memory is spared.

Patient "HM": bilaterally severed the hippocampus for epilepsy treatment. He had long-term memory problems - severe anterograde amnesia and some retrograde amnesia for events prior to surgery. His short-term memory was relatively spared. His declarative memory was impaired, he could not learn meanings of new words, but could learn a new skill (which is non-declarative).

Hebbian theory: an increase in synaptic efficacy arises from the presynaptic cell's repeated and persistent stimulation of the postsynaptic cell. "Cells that fire together wire together". Simply - when neuron A causes activation of neuron B, the connection strength between A and B is increased.

Long-term potentiation: persistent strengthening of synapses based on recent patterns of activity. These are patterns of snypatic activity that produce a long-lasting increase in signal transmission between 2 neurons. LTP occurs in several pathways in the hippocampus

The hippocampus is highly implicated in the functions of memory. The prefrontal cortex is also involved in memory encoding (Wagner et al, 1998) and retrieval (Fletcher et al, 1998). Preston & Eichenbaum (2013) explain that the hippocampus and prefrontal cortex work together to support memory processes.

Brain stimulation interventions: Asthana et al (2013): transcranial direct current stimulation sutdy (tDCS)

Pharmacological interventions: Ressler et al (2004): D-cycloserine to disrupt the brain's glutamate system

Reducing impact of harmful memories can improve wellbeing, but blocking harmful memories may mean the individual struggles to come to terms with or process traumatic experiences.