Sequence? What Sequence?: the human medial temporal lobe and sequence learning

Schendan, Haline E.; Searl, Meghan; Stern, Chantal E.

doi:10.1038/sj.mp.4001424

Cited by 15 publications

(17 citation statements)

References 14 publications

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“…These findings are consistent with previous work implicating subcortical areas in associative learning and temporal memory, while prefrontal circuits in rule-based behaviors and prediction of future events (Bar, 2009;Leaver et al, 2009;Pasupathy and Miller, 2005). In particular, striatal regions have been implicated mainly in implicit learning (Hazeltine et al, 1997;Rauch et al, 1995), while the medial temporal lobe in both implicit and explicit learning (Schendan et al, 2003a(Schendan et al, , 2003b. Finally, our results are consistent with recent work implicating cerebellum in sequence learning (e.g.…”

Section: Discussionsupporting

confidence: 94%

Learning temporal statistics for sensory predictions in mild cognitive impairment

et al. 2015

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Training is known to improve performance in a variety of perceptual and cognitive skills. However, there is accumulating evidence that mere exposure (i.e. without supervised training) to regularities (i.e. patterns that co-occur in the environment) facilitates our ability to learn contingencies that allow us to interpret the current scene and make predictions about future events. Recent neuroimaging studies have implicated fronto-striatal and medial temporal lobe brain regions in the learning of spatial and temporal statistics. Here, we ask whether patients with mild cognitive impairment due to Alzheimer's disease (MCI-AD) that are characterized by hippocampal dysfunction are able to learn temporal regularities and predict upcoming events. We tested the ability of MCI-AD patients and age-matched controls to predict the orientation of a test stimulus following exposure to sequences of leftwards or rightwards orientated gratings. Our results demonstrate that exposure to temporal sequences without feedback facilitates the ability to predict an upcoming stimulus in both MCI-AD patients and controls. However, our fMRI results demonstrate that MCI-AD patients recruit an alternate circuit to hippocampus to succeed in learning of predictive structures. In particular, we observed stronger learning-dependent activations for structured sequences in frontal, subcortical and cerebellar regions for patients compared to age-matched controls. Thus, our findings suggest a cortico-striatal-cerebellar network that may mediate the ability for predictive learning despite hippocampal dysfunction in MCI-AD.

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Section: Discussionsupporting

confidence: 94%

Learning temporal statistics for sensory predictions in mild cognitive impairment

et al. 2015

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“…For example, studies ( Foerde et al 2006 ; Poldrack et al 1999 , 2001 ) using the weather prediction paradigm have implicated these regions in implicit learning of probabilistic associations. Previous work has implicated mainly striatal regions (e.g., caudate and putamen) in implicit learning ( Hazeltine et al 1997 ; Rauch et al 1995 ) and the medial temporal lobe in both implicit and explicit learning ( Schendan et al 2003a , 2003b ). Our results suggest interactions between these memory circuits and visual cortex; that is, learning of temporal structures that is known to engage this circuit may shape representations in primary visual cortex that relate to our ability to make sensory predictions.…”

Section: Discussionmentioning

confidence: 99%

Decoding the future from past experience: learning shapes predictions in early visual cortex

Luft

Meeson

Welchman

et al. 2015

Journal of Neurophysiology

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Learning the structure of the environment is critical for interpreting the current scene and predicting upcoming events. However, the brain mechanisms that support our ability to translate knowledge about scene statistics to sensory predictions remain largely unknown. Here we provide evidence that learning of temporal regularities shapes representations in early visual cortex that relate to our ability to predict sensory events. We tested the participants' ability to predict the orientation of a test stimulus after exposure to sequences of leftward- or rightward-oriented gratings. Using fMRI decoding, we identified brain patterns related to the observers' visual predictions rather than stimulus-driven activity. Decoding of predicted orientations following structured sequences was enhanced after training, while decoding of cued orientations following exposure to random sequences did not change. These predictive representations appear to be driven by the same large-scale neural populations that encode actual stimulus orientation and to be specific to the learned sequence structure. Thus our findings provide evidence that learning temporal structures supports our ability to predict future events by reactivating selective sensory representations as early as in primary visual cortex.

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“…Although more research is needed to test this hypothesis, results from Schendan et al . indicate that the hippocampus contributes to both implicit and explicit expressions of memory for complex motor sequences …”

Section: Boundary Conditions Of Hippocampal Involvementmentioning

confidence: 99%

“…Although more research is needed to test this hypothesis, results from Schendan et al 71 indicate that the hippocampus contributes to both implicit and explicit expressions of memory for complex motor sequences. 106 Another nonexclusive possibility is that the extent of hippocampal involvement in sequential learning could depend on how a sequence is learned. Earlier, we speculated that the hippocampus encodes actions and objects according to their temporal position in a sequence context.…”

Section: Boundary Conditions Of Hippocampal Involvementmentioning

confidence: 99%

The hippocampus: a special place for time

Ranganath

Hsieh

2016

Ann. N.Y. Acad. Sci.

101

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Many findings have demonstrated that memories of past events are temporally organized. It is well known that the hippocampus is critical for such episodic memories, but, until recently, little was known about the temporal organization of mnemonic representations in the hippocampus. Recent developments in human and animal research have revealed important insights into the role of the hippocampus in learning and retrieving sequences of events. Here, we review these findings, including lesion and single-unit recording studies in rodents, functional magnetic resonance imaging studies in humans, and computational models that link findings from these studies to the anatomy of the hippocampal circuit. The findings converge toward the idea that the hippocampus is essential for learning sequences of events, allowing the brain to distinguish between memories for conceptually similar but temporally distinct episodes, and to associate representations of temporally contiguous, but otherwise unrelated experiences. Each experienced event always occurs at a particular spatial location and in a particular temporal relation to other events that already have occurred. .. Retrieval of information of this kind from episodic memory is successful if the person can describe the perceptible properties of the event in question and more or less accurately specify its temporal relations to other events. 1 (p.388) When Endel Tulving defined episodic memory, he proposed that recollection of a past episode includes awareness of when the event took place, and, consistent with this view, empirical evidence suggests that our memories of the past are temporally organized. 2,3 This is not to say that memories have an explicit time stamp. People can often remember the date or time of a past event, but these attributions are often based on simple inferences or decision heuristics, rather than explicit retrieval of temporal information. 4 Rather than having a time stamp, evidence suggests that memories are associated with one another according to their temporal context. There is strong evidence to suggest that episodes are encoded as organized sequences of events, 5-7 such that retrieving one event obligatorily triggers recollection, 8,9 or implicit retrieval, 10-12 of the rest of the sequence. In addition to facilitating memory for the past, temporal sequence representation allows people to make predictions about the future, 13-16 and it is fundamental for spatial cognition, 17,18 narrative comprehension, 19,20 and imagination and mental simulation. 21,22 Despite the centrality of time to episodic memory and cognition, until recently little was known about the neural mechanisms that support temporal organization in memory. The hippocampus has long been known to play a central role in episodic memory, but most studies of hippocampal function in rodents have focused on studies of spatial cogni-tion, and human studies have focused on recall or recognition of specific items from a study list. Recent developments in human and animal research, however , h...

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Sequence? What Sequence?: the human medial temporal lobe and sequence learning

Cited by 15 publications

References 14 publications

Learning temporal statistics for sensory predictions in mild cognitive impairment

Learning temporal statistics for sensory predictions in mild cognitive impairment

Decoding the future from past experience: learning shapes predictions in early visual cortex

The hippocampus: a special place for time

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