Biomedical subjects

Nick Cumming

Publications and source records attributed to Nick Cumming.

4 recordsLinked to original sources

PubMed2006

Repetition learning in the immediate serial recall of visual and auditory materials.

In 5 experiments, a Hebb repetition effect, that is, improved immediate serial recall of an (unannounced) repeating list, was demonstrated in the immediate serial recall of visual materials, even when use of phonological short-term memory was blocked by concurrent articulation. The learning of a repeatedly presented letter list in one modality (auditory or visual) did not transfer to give improved performance on the same list in the other modality. This result was not replicated for word lists, however, for which asymmetric transfer was observed. Inferences are made about the structure of short-term memory and about the nature of the Hebb repetition effect.

Adolescent↗

PubMed2005

Automated post-hoc noise cancellation tool for audio recordings acquired in an MRI scanner.

There are several types of experiment in which it is useful to have subjects speak overtly in a magnetic resonance imaging (MRI) scanner, including those studying the articulatory apparatus and the neural basis of speech production, and fMRI experiments in which speech is used as a response modality. Although it is relatively easy to record sound from the bore, it can be difficult to hear the speech over the very loud acoustic noise from the scanner. This is particularly a problem during echo-planar imaging, which is usually used for fMRI. We present a post-hoc sound cancellation algorithm, and describe a Windows-based tool that implements it. The tool is fast and operates with minimal user intervention. We evaluate cancellation performance in terms of the improvement in signal-to-noise ratio, and investigate the effect of the recording medium. A substantial improvement in audibility was obtained.

Algorithms↗

PubMed2004

Prefrontal cortical involvement in verbal encoding strategies.

The lateral prefrontal cortex is critical for the control and organization of information in working memory. In certain situations, effective reorganization can attenuate task difficulty, suggesting a dissociation between lateral prefrontal activity and basic memory demand. In a verbal working memory task, we investigated the enhancement of performance that occurs when incoming information can be reorganized into higher-level groups or chunks. In the fMRI scanner, volunteers heard and repeated a sequence of digits. Mathematically structured sequences, encouraging 'chunking', were compared with unstructured, random sequences. Though structured sequences were easier to remember, fMRI showed increased lateral prefrontal activation for these sequences. Specifically, both the dorsolateral and ventrolateral prefrontal cortices were activated preferentially for the structured sequences during encoding. When visual stimuli that can be chunked using spatial structure are used, similar results are observed. These results demonstrate that cognitively less demanding tasks may elicit greater lateral prefrontal recruitment. Thus, the lateral prefrontal cortex appears to play a general role in strategically recoding information from memory, in order to optimize performance.

Acoustic Stimulation↗

PubMed2003

Testing a positional model of the Hebb effect.

In two experiments, we investigated the hypothesis that a strengthening of position-item associations underlies the improvement seen in performance on an immediate serial recall task, for a list that is surreptitiously repeated every third trial. Having established a strong effect of repetition, performance was tested on transfer lists in which half the items held the same position as in the repeated list (S-items) and the remainder moved (D-items). In Experiment 1, S-items showed a small advantage in order errors over control and D-items. A second experiment tested whether a design feature in Experiment 1 underlay this advantage. When the experimental design was better controlled, no improvement was shown for either S- or D-items over controls. These data were shown to be inconsistent with the results of computer simulations of a positional model. An alternative model is outlined.

Adolescent↗