International Students‘ Workshop: Publication and Presentation of

Scientific Research

The following is a 12-minute talk given at an international conference. It‘s about the same data

as the sample manuscript. Note the small number of slides!

Modulation of cortical feedforward dynamics by

visual attention

Thomas Schmidt & Anna SeydellJustus Liebig University Giessen

Department of Psychology

Lamme et al.‘s (2000) Feedforward Sweep Theory:

• Neural activation needs about 10 ms to spread from one cortical map to the next, so that the first wave of activation (the feedforward sweep) can‘t be based on intracortical feedback mechanisms.

• The feedforward sweep can reach any area of cortex, including semantic and motor areas, in about 100 ms.

• Thorpe, Fize & Marlot (1996) demonstrate very rapid classification of images; they propose that this might be based on the very first spikes in the feedforward wavefront (VanRullen & Thorpe, 2002).

Can the feedforward sweep be boosted by visual attention?

Rapid Chase Criteria

apply to situations where two successive stimuli try to control the same single motor response

1. First stimulus initiates response2. Second stimulus influences response before it is finished3. Initial response to first stimulus is independent of second stimulus

→ strictly sequential priming by sequential stimuli

Schmidt, Niehaus & Nagel (submitted) show that primed pointing movements exactly follow these criteria (Response Priming; Vorberg et al., 2003; Neumann & Klotz, 1994)

Varying exogenous and endogenous attention(e.g., Egeth & Yantis, 1997; Allport, 1990)

(Schmidt & Seydell, in prep.)

(Schmidt & Seydell, in prep.)

Discussion

Visual attention (endogenous and exogenous) enhances response priming effects in pointing movements

Time-course of priming meets two of the rapid chase criteria: 1. Primes initiate pointing response2. Masks capture response in midflight

However, the initial time-course is not invariant unless the SOA is long and deployment of attention is complete.

We conclude that visual attention boosts an early phase of visuomotor processing that is predominantly or entirely feedforward (Lamme & Roelfsema, 2000).

Vielen Dank an:Gerd Lüer, Nuria Vath, Lena Frank, Karl Gegenfurtner, Dirk Vorbergund die Deutsche Forschungsgemeinschaft.

Modulation of cortical feedforward dynamics by

visual attention

Thomas Schmidt & Anna SeydellJustus Liebig University Giessen

Department of Psychology