Animal Behaviour - Memory

Process by which information is stored and retrieved, the ability to retain information over time

Memory is necessary for learning - Shettleworth 1998

STM seconds->hours

LTM years

Learning- how relationships between events are learnt, which are learnt, how fast?

Memory- How information is encoded, stored and retrieved, what affects ease of this, how is information consolidated, mechanisms?

Tarbell 2004 - food storing animals, appear to remember which trees food is hidden in. May be a rule - eg. go to smallest tree first etc.

Strengthening synaptic connections

Gene expression and protein synthesis - growth of NEW synaptic connections

Behaviour alone or cued behaviour

Spontaneous behaviour (recall memory)

Cued behaviour (recognition memory)

Duratino of exposure to stimulus, no. of discriminable features a stimulus has, interference from other stimuli, salience of stimuli (surprise/distinctiveness/motivational relevance/value/stress/emotional state)

LTM is also used just to understand the task in the first place

Grant 1976 - pigeons delayed match to sample, extending time between first and second stimuli

Zentall et al 1990 - pigeons adding colour to different shaped stimuli (delayed match to sample)

Whitlow 1975- Habituation in rabbits to a tone demonstrated.

Then, light flashed between two tones same distance apart, habituation ruined and same initial response occurs upon second play of tone - information has been overwritten following encoding (RETROACTIVE INTERFERENCE)

Then, light and tone played first, again when tone played alone second time same initial response occurs - information has been interfered with during the encoding process (PROACTIVE INTERFERENCE)

Primacy - the first stimulus/picture/event is most memorable/ better recognition

Recency - the last stimulus/picture/event is most memorable/ better recognition

NB: Serial position curve of proactive and retroactive interference

Pigeons, monkeys and humans. Different retention intervals (RI) -> different prevalence of primacy/recency effects

- Short RI = Recency effects, last stimulus best memorised

- Medium RI = U shaped

- Long RI = Primacy effects, first stimulus best memorised

NB: Exact RI depends on species (Long RI = pigeons 10s, monkey 30s, human 100s)

Roberts 1980 - if matching to sample and all stimuli are circles, then one is a line, will be more easily matched

Laughlin and Mendl 2004 - pigs searching for food in 4 armed maze, when arms become costly to enter and search make fewer errors and remember better

Von Restorff effect

Attention narrowing/focus - {task relevant }

Flashbulb memories - { stressors}

Attention shifts/lapses (task irrelevent stressors)

- Yerkes-Dodson Law

The value or importance of the information attempting to be memorised

Cahill et al 1994 - Physiological responses to emotional stories increase memorisation. If given B blockers memory decreased

Chicks - food aversion with corticosterone/control injection. Corticosterone (HPA response) chicks showed markedly more avoidance

Also shown with adrenaline

Glucocorticoids and Catecholamines - GCs cross BBB -> Hippocampus directly, Catechols do not cross BBB but increase blood glucose enabling the brain to work more efficiently

Increased amygdala glucose associated with remembering more of an emotional film

Recognition - cue similarity to stored information influences retrieval success. Context is important (external - location, odour, weather etc. Internal - affect, body clock etc.)

Recall - Apparently not cued, but possible that context and subconscious cues are registered

Effect of neutral/emotional film on accuracy of recall and recognition

Failure of encoding and temporary stooge in STM (limited capacity, interference effects, decay of STM trace, low salience/value ->v attention)

Failure of consolidation into LTM (decay of STM trace, severe stress)

Failure to retrieve information (inappropriate clues/context . decay of LTM)

Active forgetting

Early - failure of encoding and temporary storage

| Late - failure to retrieve information

Maki and Hegvik 1980 Delayed match to sample in pigeons - learnt cue that meant forget and one that meant remember. If presented with task following forget cue did not perform well

Spatial awareness memory in rats - hippocampal place cells fire in sequence as move around a maze. Replay during sleep indicating consolidation of memory.

Basile and hampton 2011 - Recall: touch space where rest of shape should be (recall of shape even in its absence)

Recognition: delayed match to sample, or if not correct press "wrong" logo

Results shown are similar to human recall and recognition therefore good indicator

Explicit (Concious, declarative) -> Episodic (personal events, and episodic future planning) and semantic (facts)

Implicit (Non-concious, procedural) -> Habits and skills, priming (where stimulus before test influences outcome, even if only subconsciously) simple classical conditioning

Demonstrate that animals remember what happened, where and when -> episodic like memory

Suddendorf and Corballis 1997

Clayton and Dickinson 1998 - Florida scrub jays - cache food, prefer waxworks to peanuts, can be trained that worms decay after time. Show food, then let eat later, see which is preferred. Will choose peanuts if after time period where waxworms decayed

Raby et al 2007 - planning for breakfast in western scrub jays again - will cache a range of food to give themselves a choice in the morning

Pigs and rats remembering a familiar animal - memory acquisition and consolidation (length of time together, group size, rank)

Memory storage, interference and decay (duration of separation, interference stimuli, reminder cues)

Memory retrieval (social and contextual clues)

recognition disrupted if introduced to new individual during separation and enhanced if subject is well acquainted with stimulus animal

(Burman and Mendl 2000, 2003, 2004)