How does this apply to clinical practice?

Memory and learning

Understanding memory as a representation and record of altered brain functioning is helpful in the context of learning. A child’s brain functions very differently to an adult’s brain. Memories and emotional reactions early in childhood are based on a more ‘immature and primitive’ mechanism of brain functioning. Brainstem reflexes and limbic activity organize much of the infant’s experiences. Development of more primitive brain structures precedes the development of later evolving ones. Early experiences influence the wiring that is installed in the brain, whilst later adult learning usually influences how already established wiring fires. Once neural networks are established, new learning often relies on the modification of these established patterns.

The basic feature of the intercellular memory process is the pairing of neurons with each other. When two connecting neurons fire at the same time, they are more likely to fire together again in the future, because the strength of the connections between them will be greater. When two connected neurons fire frequently together, they develop new synaptic connections. These memory processes seem likely to be the basis for what is known as implicit (procedural, non-hippocampal) learning (see E Memory and emotions in Chapter 11, pp. 531-3).

Simple repetition can effect change, even in the absence of reasoning or logic to support the change. The development of associations between events and emotions is an example of non-hippocampal learning based on simple pairing, even in the absence of awareness and insight.

Non-hippocampal learning will not readily change despite the presence of new insight. When implicit memory associations weaken, they are likely to do so slowly and incrementally over time. Memory is highly influenced by affect.

Explicit (sometimes called declarative or autobiographic) memory (see E mory and emotions in Chapter 11, pp. 531-3) is based in the hippocampus and affiliated structures. When two neurons both innervate a third neuron, the process of long-term potentiation can, in effect, form a bond between them, even though they are not directly connected. Pyramidal cells are neurons that receive input from extremely high numbers of other neurons. They are structured in a way that facilitates development of such new connections. These cells occur in high numbers in the hippocampus, as well as in the outer surface layers of the cerebral cortex.

Connections between the hippocampus and frontal cortical areas appear to support conscious processing and decision-making, and the area as a whole is particularly well suited to establish novel connections supporting new learning. Hippocampal learning coincides with declarative and explicit conceptualizations of learning, whilst non-hippocampal learning coincides with implicit memory formation. Hippocampal learning supports efficient processing of incoming information and integration of new information with information previously stored in the brain. It also supports flexible retrieval of stored information.

The concept of the 'remembered present' suggests that much of what we take to be perception is, in fact, memory. We adults project our expectations onto the world all the time. We largely construct, rather than perceive, the world around us. Memory traces may be unconsciously activated all the time. One does not have to explicitly retrieve a memory for it to be active and for it to influence cognition and behaviour.

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