Explain how biological factors may affect one cognitive process

Damage to the hippocampus and memory(The HM Study)

Scoville and Milner (1957)

• HM fell off his bicycle when he was 7, injuring his head.

• He began having epileptic seizures when he was 10.

• By the time he was 27 he had so many seizures he could not live a normal life.

The HM StudyScoville and Milner (1957)

• Scoville performed experimental surgery on HM to stop the seizures.

• Seizures did stop, but HM had amnesia for the rest of his life.

• We learned a whole lot from HM’s issues.

HM’s Memory

• HM could no longer store new memories (antrograde amnesia)

• Most of his memories before the surgery remained intact (partial retrograde amnesia).

HM’s Memory• He could not transfer new

episodic or semantic memories (explicit memories) into his LTM.

• He COULD form new long-term procedural memories (implicit memories).

• He could carry on a normal conversation (working memory) but would forget it almost immediately.

OK…what actually happened to HM’s brain?

• Corkin (1997) gave an old HM an MRI

• He found missing parts of the temporal lobes and hippocampus and surrounding areas.

• These areas tend to be pathways for memory (highways for ACH).

What can be learned about the relationship between brain and memory with HM?

• Our memory system is specialized and complex.

• The hippocampus plays a critical role in converting memories of experience from STM to LTM.

• HM retained some memories, so hippocampus does not store the memories, but processes them.

What can be learned about the relationship between brain and memory with HM?

• The fact that HM and others with amnesia have problems with some types of memories and not others is evidence for a multiple memory system.

The Nervous System

Central Nervous System

•The Brain and spinal cord•CNS

Peripheral Nervous System• All nerves that are

not encased in bone.

• Everything but the brain and spinal cord.

• Is divided into two categories….somatic and autonomic.

Somatic Nervous System• Controls voluntary

muscle movement.• Uses motor

(efferent) neurons.

Autonomic Nervous System• Controls the

automatic functions of the body.

• Divided into two categories…the sympathetic and the parasympathetic

Sympathetic Nervous System

• Fight or Flight Response.

• Automatically accelerates heart rate, breathing, dilates pupils, slows down digestion.

Parasympathetic Nervous System

• Automatically slows the body down after a stressful event.

• Heart rate and breathing slow down, pupils constrict and digestion speeds up.

High levels of cortisol and memory deficits

• Cortisol is a stress hormone secreted by the adrenal glands in response to stress.

• Long term stress can hurt both the immune system and memory.

• Chronic cortisol secretion can hinder the brain in forming new memories and accessing old ones.

Lupien et al 2002Experiment on cortisol level and memory

Aim:• The experiment was a

longitudinal 5 year study with elderly people.

• The aim of the experiment was to see if you could reverse memory problems with a drug.

Lupien et al 2002Experiment on cortisol level and memory

Procedure• Group 1 had moderate

levels of cortisol at baseline

• Group 2 had high levels of cortisol and decreased memory function.

Lupien et al 2002Experiment on cortisol level and memory• Both groups were given a drug

that reduces the secretion of cortisol (metyrapone).

• Then they performed a memory test.

• After this they were both given another drug (hydrocortisone) to restore levels of cortisol to previous levels.

• Results were compared to placebo group.

Lupien et al 2002Experiment on cortisol level and memory

Results• The results showed

participants with moderate levels of cortisol who were given metyrapone had no problem restoring normal memory function.

Lupien et al 2002Experiment on cortisol level and memory

• Participants, who, from the start, had high levels of cortisol had no memory improvement.

• The hydrocortisone caused even more memory loss.