Neurobiological basis of memory

81 - 87

What is the law of mass action

the severity of the memory impairment for maze performance correlated with the size of the cortical area removed and not with its specific location

Describe the case of Patient H.M.

• Sustained a head injury at age 7

• Experienced his first major seizure at age 10

• Experienced his first generalised convulsion at age 16

 

• Had tissue removed from the temporal lobes (hippocampus)

• Short-term memory intact (supporting distinction between LTM and STM)

• He was unable to remember events that happened several years before surgery (retrograde memory impairment)

• Unable to form new memories/learn new information (anterograde memory impairment)

• Unable to learn to navigate a new neighbourhood

What did Hebb’s (1949) theory argue

that the neurophysiological changes underlying learning and memory occur in three stages:

1. synaptic changes

2. formation of a cell assembly

3. formation of a phrase sequence

When an axon of cell A is near enough to excite a cell B and repeatedly or persistently takes part in firing it, some …

growth process or metabolic change takes place in one or both cells such that A’s efficiency, as one of the cells firing B, is increased

What is the gill-withdrawal reflex

a defensive motor response behaviour

What does the gill-withdrawal reflex circuit rely on

two different populations of neurons:

• the gultamatergic sensory neurons that receive somatosensory information from the skin of the siphon

• the motor neurons that control the muscles of the gill

What is habituation

a decreased response to a stimulus after repeated presentations

What is sensitisation

prior to strong stimulation increases response to most stimuli

neuron

LTP is found to be essential for

declarative memory

What is LTP defined as

strengthening of synaptic efficacy between neurons in the brain

Changes at synapses could include

• increased neurotransmitter release

• effectiveness of restores (receptor numbers or enhance)

Synaptic plasticity can change:

1. the amount of neurotransmitters released

2. the number of postsynaptic receptors available

3. both

What is long-term depression (LTD)

it’s expressed by a long-lasting decrease in the efficiency of synaptic transmission

What is synaptic plasticity

ability of neurons to modify the strength of their connections in response to increases or decreases in their activity

Synaptic plasticity is important neurophysiological process involved in

brain networks development and reorganisation after damage